IDiseases and Disorders

881

P

PTG Pneumonia, Aspiration

i BASIC INFORMATIONDEFINITIONAspiration pneumonia is a vague term that refers to pulmonary abnormalities following ab-normal entry of endogenous or exogenous sub-stances in the lower airways. It is generally classified as: Aspiration (chemical pneumonitis) Primary bacterial aspiration pneumonia Secondary bacterial infection of chemical

pneumonitis

ICD-9CM CODES507.0 Aspiration pneumonia

EPIDEMIOLOGY & DEMOGRAPHICSINCIDENCE (IN U.S.): Few reliable data 20% to 35% of all pneumonias 5% to 15% of all community-acquired pneu-

moniasPEAK INCIDENCE: Elderly patients in hospitals or nursing homesPREVALENCE (IN U.S.): Unknown (unreliable data)PREDOMINANT SEX: Males and females af-fected equallyPREDOMINANT AGE: Elderly

PHYSICAL FINDINGS & CLINICAL PRESENTATION Shortness of breath, tachypnea, cough, sputum,

fever after vomiting, or difficulty swallowing Rales, rhonchi, often diffusely throughout lung

ETIOLOGYComplex interaction of etiologies, ranging from chemical (often acid) pneumonitis after aspiration of sterile gastric contents (generally not requiring antibiotic treatment) to bacterial aspirationCOMMUNITY-ACQUIRED ASPIRATION PNEUMONIA: Generally results from predominantly anaero-

bic mouth bacteria (anaerobic and micro-aerophilic streptococci, fusobacteria, gram-positive anaerobic nonspore-forming rods), Bacteroides species (melaninogenicus, inter-medius, oralis, ureolyticus), Haemophilus in-fluenzae, and Streptococcus pneumoniae

Rarely caused by Bacteroides fragilis (of un-certain validity in published studies) or Eikenella corrodens

High-risk groups: the elderly; alcoholics; IV drug users; patients who are obtunded; stroke victims; and those with esophageal disorders, seizures, poor dentition, or recent dental manipulations.

HOSPITAL-ACQUIRED ASPIRATION PNEUMONIA: Often occurs among elderly patients and oth-

ers with diminished gag reflex; those with nasogastric tubes, intestinal obstruction, or ventilator support; and especially those ex-posed to contaminated nebulizers or unster-ile suctioning.

High-risk groups: seriously ill hospitalized patients (especially patients with coma, aci-dosis, alcoholism, uremia, diabetes mellitus, nasogastric intubation, or recent antimicro-bial therapy, who are frequently colonized with aerobic gram-negative rods); patients undergoing anesthesia; those with strokes, dementia, or swallowing disorders; the el-derly; and those receiving antacids or H2 blockers (but not sucralfate).

Hypoxic patients receiving concentrated O2 have diminished ciliary activity, encouraging aspiration.

Causative organisms: 1. Anaerobes listed above, although in many

studies gram-negative aerobes (60%) and gram-positive aerobes (20%) predominate.

2. E. coli, P. aeruginosa, S. aureus including MRSA, Klebsiella, Enterobacter, Serratia, Proteus spp., H. influenzae, S. pneu-moniae, Legionella, and Acinetobacter spp. (sporadic pneumonias) in two thirds of cases.

3. Fungi, including Candida albicans, in fewer than 1%.

Dx DIAGNOSISDIFFERENTIAL DIAGNOSIS Other necrotizing or cavitary pneumonias (espe-

cially tuberculosis, gram-negative pneumonias) See Pulmonary Tuberculosis.

WORKUP Chest x-ray examination Complete blood count (CBC), blood cultures Sputum Gram stain and culture Consideration of tracheal aspirate

LABORATORY TESTS CBC: leukocytosis often present Sputum Gram stain

1. Often useful when carefully prepared im-mediately after obtaining suctioned or expectorated specimen, examined by ex-perienced observer.

2. Only specimens with multiple white blood cells and rare or absent epithelial cells should be examined.

3. Unlike nonaspiration pneumonias (e.g., pneumococcal), multiple organisms may be present.

4. Long, slender rods suggest anaerobes. 5. Sputum from pneumonia caused by acid

aspiration may be devoid of organisms. 6. Cultures should be interpreted in light of

morphology of visualized organisms.

IMAGING STUDIES Chest x-ray often reveals bilateral, diffuse,

patchy infiltrates and posterior segment upper lobes. Chemical pneumonitis typically affects the most dependent regions of the lungs.

Aspiration pneumonia of several days or lon-ger duration may reveal necrosis (especially community-acquired anaerobic pneumonias) and even cavitation with air-fluid levels, indi-cating lung abscess.

Rx TREATMENTNONPHARMACOLOGIC THERAPY Airway management to prevent repeated

aspiration Ventilatory support if necessary

ACUTE GENERAL RxAcute aspiration of acidic gastric contents with-out bacteria may not require antibiotic therapy; consult infectious disease or pulmonary expert. Community-acquired anaerobic aspiration

pneumonia: clindamycin (600 mg IV twice daily followed by 300 mg q6h orally). Intrave-nous penicillin G (1 to 2 million U q4 to 6h) can also still be used. Alternative oral agents include: amoxicillin-clavulanate (875 mg orally twice daily), amoxicillin plus metroni-dazole or oral moxifloxacin (400 mg orally once daily). Do not use metronidazole alone, as this is associated with high failure rates.

Nursing home aspirations: levofloxacin 500-750 mg qd or piperacillin-tazobactam 3.375 g q6h or ceftazidime 2 g q8h !/" vancomycin if MRSA suspected or known

Hospital-acquired aspiration pneumonia:C Piperacillin-tazobactam 3.375 g IV q6h, or

cefoxitin 2 g IV q8h !/" vancomycin IV to cover MRSA. Alternative agents are ceftri-axone 1 g IV q24h plus metronidazole 500 mg IV q6h or 1 g IV q12h.

C Knowledge of resident flora in the micro-environment of the aspiration within the hospital is crucial to intelligent antibiotic selection; consult infection control nurses or hospital epidemiologist.

C Confirmed Pseudomonas pneumonia should be treated with antipseudomonal beta- lactam agent plus an aminoglycoside until antimicrobial sensitivities confirm that less toxic agents may replace the aminoglycoside.

C Do not use metronidazole alone for anaer-obes.

DISPOSITIONRepeat chest x-ray examination in 6 to 8 wk.

REFERRALFor consultation with infectious disease and/or pulmonary experts for patients with respiratory distress, hypoxia, ventilatory support, pneumonia in more than one lobe, or necrosis or cavitation on x-ray examination or for those not responding to antibiotic therapy within 2 to 3 days.

SUGGESTED READINGSavailable at www.expertconsult.com

RELATED CONTENTAspiration Pneumonia (Patient Information)

AUTHOR: GLENN G. FORT, M.D., M.P.H.

e.881.e1Pneumonia, Aspiration

SUGGESTED READINGSDaoud E, Guzman J: Are antibiotics indicated for the treatment of aspiration

pneumonia? Cleve Clin J Med 77(9):573, 2010.Ott SR et al: Moxifloxacin vs. ampicillin/sulbactam in aspiration pneumonia and

primary lung abscess, Infection 36:23, 2008.Shigemitsu H, Afshar K: Aspiration pneumonias: under-diagnosed and under-

treated, Curr Opin Pulm Med 13(3):192-198, 2007.

882 Pneumonia, Bacterial PTG EBM

i BASIC INFORMATIONDEFINITIONBacterial pneumonia is an infection involving the lung parenchyma.

ICD-9CM CODES486.0 Pneumonia, acute507.0 Pneumonia, aspiration482.9 Pneumonia, bacterial481 Pneumonia, pneumococcal482.1 Pneumonia, Pseudomonas482.4 Pneumonia, staphylococcal482.0 Pneumonia, Klebsiella482.2 Pneumonia, Haemophilus influenzae

EPIDEMIOLOGY & DEMOGRAPHICS The incidence of community-acquired pneu-

monia (CAP) is 1 in 100 persons. CAP is the most common infectious cause of death in the U.S.

The incidence of health care facilityacquired pneumonia (HCAP) is 8 cases per 1000 per-sons annually.

Primary care physicians see an average of 10 cases of pneumonia annually.

Hospitalization rate for pneumonia is 15% to 20%.

Most cases of pneumonia occur in the winter and in elderly patients.

PHYSICAL FINDINGS & CLINICAL PRESENTATION Fever, tachypnea, chills, tachycardia, cough Presentation varies with the cause of pneu-

monia, the patients age, and the clinical situation:C Patients with streptococcal pneumonia

usually present with high fever, shaking chills, pleuritic chest pain, cough, and copi-ous production of rusty-appearing purulent sputum. Pleurisy and parapneumonic effu-sions are also common. Potential complica-tions include bacteremia, empyema, and distant infections (e.g., meningitis).

C Mycoplasma pneumoniae: insidious onset; headache; dry, paroxysmal cough that is worse at night; myalgias; malaise; sore throat; extrapulmonary manifestations (e.g., erythema multiforme, aseptic menin-gitis, urticaria, erythema nodosum) may be present.

C Chlamydia pneumoniae: persistent, non-productive cough, low-grade fever, head-ache, sore throat.

C Legionella pneumophila: high fever, mild cough, mental status change, myalgias, diarrhea, respiratory failure.

C MRSA pneumonia: often preceded by in-fluenza, may present with shock and respiratory failure.

C Elderly or immunocompromised hosts with pneumonia may initially present with only minimal symptoms (e.g., low-grade fever, confusion); respiratory and nonrespiratory symptoms are less com-monly reported by older patients with pneu monia.

C In general, auscultation of patients with pneumonia reveals crackles and dimin-ished breath sounds.

C Percussion dullness is present if the pa-tient has pleural effusion.

C The clinical impression of pneumonia has an overall sensitivity of 70% to 90%; specificity ranges from 40% to 70%.

ETIOLOGY Streptococcus pneumoniae (20% to 60% of

CAP cases) Haemophilus influenzae (3% to 10% of CAP

cases) L. pneumophila (1% to 5% of adult pneumo-

nias) (2% to 8% of CAP cases) Klebsiella, Pseudomonas, Escherichia coli Staphylococcus aureus (3% to 5% of CAP

cases) Atypical organisms such as M. pneumoniae,

C. pneumoniae, and L. pneumophila impli-cated in up to 40% of cases of CAP

Pneumococcal infection responsible for 50% to 75% of CAPs. Influenza infection is one of the important predisposing factors to S. pneu-moniae and S. aureus pneumonia; gram-negative organisms cause #80% of nosoco-mial pneumonias

Predisposing factors: 1. Chronic obstructive pulmonary disease:

H. influenzae, S. pneumoniae, Legionella 2. Seizures: aspiration pneumonia 3. Compromised hosts: Legionella, gram-

negative organisms 4. Alcoholism: Klebsiella, S. pneumoniae,

H. influenzae 5. HIV: S. pneumoniae 6. IV drug addicts with right-sided bacterial

endocarditis: S. aureus 7. Older patient with comorbid diseases:

C. pneumoniae

Dx DIAGNOSISDIFFERENTIAL DIAGNOSIS Exacerbation of chronic bronchitis Pulmonary embolism or infarction Lung neoplasm Bronchiolitis Sarcoidosis Hypersensitivity pneumonitis Pulmonary edema Drug-induced lung injury Viral pneumonias Fungal pneumonias Parasitic pneumonias Atypical pneumonia Tuberculosis

WORKUPLaboratory evaluation and chest x-ray. Table E1-329 summarizes diagnostic testing for CAP. Useful tools for assessing severity of illness are the CURB-65 (see following) and Pneumonia Severity Index. Poor prognostic indicators are hypotension (SBP $90 or DBP $60), respiratory rate #30/min, hyperpyrexia (#40 C), or hypo-thermia ($35 C). None of these indices is as valuable as clinical judgment of the physician.

LABORATORY TESTS Complete blood count with differential; white

blood cell count is elevated, usually with left shift

Blood cultures (hospitalized patients only): positive in approximately 20% of cases of pneumococcal pneumonia

Pneumococcal urinary antigen test can be used to detect the C-polysaccharide antigen of S. pneumoniae. It is a useful tool in the treatment of hospitalized adult patients with CAP.

Direct immunofluorescent examination of sputum when suspecting Legionella (e.g., direct fluorescent antibody stain is a highly specific and rapid test for detecting legionel-lae in clinical specimen) or urine Legionella antigen test

Serologic testing for HIV in selected patients Serum electrolytes (hyponatremia in suspected

Legionella pneumonia), BUN, creatinine Pulse oximetry or arterial blood gases: hy-

poxemia with partial pressure of oxygen $60 mm Hg while the patient is breathing room air, a standard criterion for hospital admission

IMAGING STUDIESChest x-ray: findings vary with the stage and type of pneumonia and the hydration of the pa-tient (Fig. 1-654): Classically, pneumococcal pneumonia pre-

sents with a segmental lobe infiltrate. Diffuse infiltrates on chest x-ray can be seen

with L. pneumophila, M. pneumoniae, viral pneumonias, P. jirovecii (carinii), miliary tu-berculosis, aspiration, aspergillosis.

An initial chest x-ray is also useful to rule out the presence of any complications (pneumo-thorax, empyema, abscesses).

Rx TREATMENTNONPHARMACOLOGIC THERAPY Avoidance of tobacco use Oxygen to maintain partial oxygen pressure

in arterial blood #60 mm Hg IV hydration, correction of dehydration Assisted ventilation in patients with signifi-

cant respiratory failure

ACUTE GENERAL Rx Initial antibiotic therapy should be based on

clinical, radiographic, and laboratory evaluation. Macrolides (azithromycin or clarithromycin)

or levofloxacin is recommended for empiric outpatient treatment of CAP. Box E1-47 sum-marizes empirical therapy regimens for severe CAP. Cefotaxime or a beta-lactam/beta-lactamase inhibitor can be added in pa-tients with more severe presentation who insist on outpatient therapy. Duration of treatment ranges from 7 to 14 days. The treatment of choice in suspected Legionella pneumonia is either a quinolone (e.g., moxi-floxaxin) or a macrolide (e.g., azithromycin) antibiotic.

In the hospital setting, patients admitted to the general ward can be treated empirically

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ARight middle lobe infiltrate

obscures right heart border B

Dense right middlelobe infiltrate

FIGURE 1-654 Pneumonia, right middle lobe. A, Anteroposterior chest x-ray. B, Lateral chest x-ray. This 73-year-old man presented with cough and yellow sputum, fever 39.3 C, tachycardia, and oxygen saturation of 93% on room air. His chest x-ray shows classic right middle lobe pneumonia. The opacity in A obscures the right heart border, which lies immediately adjacent. On the lateral x-ray (B), this appears as a more circumscribed density overlying the heart. (From Broder JS: Diagnostic imaging for the emergency physician, Philadelphia, 2011, Saunders.)

with a second- or third-generation cephalo-sporin (ceftriaxone, ceftizoxime, cefotaxime, or cefuroxime) plus a macrolide (azithromy-cin or clarithromycin) or doxycycline. An an-tipseudomonal quinolone (levofloxacin or moxifloxacin) can be substituted in place of the macrolide or doxycycline.

Empiric therapy in ICU patients: IV beta-lactam (ceftriaxone, cefotaxime, ampicillin-sulbactam) plus an IV quinolone (levofloxacin, moxifloxacin) or IV azithromycin.

In hospitalized patients at risk for P. aeruginosa infection, empiric treatment should consist of an antipseudomonal beta-lactam (merope-nem, doripenem, imipenem, or piperacillin-tazobactam) plus an aminoglycoside plus an antipseudomonal quinolone.

In patients with suspected methicillin-resistant S. aureus, vancomycin or linezolid is effective.

CHRONIC RxParapneumonic effusion empyema can be man-aged with chest tube placement for drainage. Instillation of fibrinolytic agents (streptokinase, urokinase) by chest tube may be necessary in resistant cases.

DISPOSITION Most patients respond well to antibiotic ther-

apy. Risk factors for a poor outcome from CAP. are summarized in Box E1-48.

Indications for hospital admission are: 1. Hypoxemia (oxygen saturation $90%

while patient is breathing room air)

2. Hemodynamic instability 3. Inability to tolerate medications 4. Active coexisting condition requiring hos-

pitalizationA criterion often used to determine hospital admission is known as the CURB-65: Con-fusion, BUN #19.6 mg/dl, Respiratory rate #30 breaths/min, systolic BP $90 mg Hg, and diastolic BP %60 mm Hg, age &65. Pa-tients are generally admitted to the hospital if they fulfill 2 or more criteria and to the ICU if they have 3 or more criteria.

! PEARLS & CONSIDERATIONSCOMMENTS Use of gastric acid suppressive therapy

(H2 receptor antagonists, proton pump inhibi-tors [PPIs]) has been associated with an increased risk of CAP. It appears that PPI therapy started within the previous 30 days is associated with an increased risk for CAP, whereas longer-term current use is not.

Causes of slowly resolving or nonresolving pneumonia: 1. Difficult to treat infections: viral pneumo-

nia, Legionella, pneumococci or staphylo-cocci with impaired host response, tuber-culosis, fungi

2. Neoplasm: lung, lymphoma, metastasis 3. Congestive heart failure 4. Pulmonary embolism

PTG EBM Pneumonia, Bacterial

5. Immunologic or idiopathic: Wegener gran-ulomatosis, pulmonary eosinophilic syn-dromes, systemic lupus erythematosus

6. Drug toxicity (e.g., amiodarone) If patients with pneumonia are not doing well,

repeat films should be taken promptly. In those with complete clinical recovery, it is reasonable to wait 6 to 8 wk before repeating the radiograph to document clearing of the infiltrate. The benefit of routine radiography after pneumonia has been questioned due to the low 1 yr incidence of lung cancer. Oppo-nents propose a selective approach limiting follow-up chest x-ray to middle-aged and older adults.

EVIDENCEavailable at www.expertconsult.com

SUGGESTED READINGSavailable at www.expertconsult.com

RELATED CONTENTBacterial Pneumonia (Patient Information)

AUTHOR: FRED F. FERRI, M.D.

e.883.e1

EVIDENCEAbstract[1]Background:Telavancin is a lipoglycopeptide bactericidal against gram-positive pathogens.Methods:Two methodologically identical, double-blind studies (0015 and 0019) were conducted involving patients with hospital-acquired pneumonia (HAP) due to gram-positive pathogens, particularly methicillin-resis-tant Staphylococcus aureus (MRSA). Patients were randomized 1:1 to telavancin (10 mg/kg every 24 h) or vancomycin (1 g every 12 h) for 721 days. The primary end point was clinical response at follow-up/test-of-cure visit.Results:A total of 1503 patients were randomized and received study medication (the all-treated population). In the pooled all-treated population, cure rates with telavancin versus vancomycin were 58.9% versus 59.5% (95% confidence interval [CI] for the difference, 5.6% to 4.3%). In the pooled clinically evaluable population (n=654), cure rates were 82.4% with telavancin and 80.7% with vancomycin (95% CI for the difference, 4.3% to 7.7%). Treatment with telavancin achieved higher cure rates in patients with monomicrobial S. aureus infection and comparable cure rates in patients with MRSA infection; in patients with mixed gram-positive/gram-negative infections, cure rates were higher in the vanco-mycin group. Incidence and types of adverse events were comparable between the treatment groups. Mortality rates for telavancin-treated versus vancomycin-treated patients were 21.5% versus 16.6% (95% CI for the difference, 0.7% to 10.6%) for study 0015 and 18.5% versus 20.6% (95% CI for the difference, 7.8% to 3.5%) for study 0019. In-creases in serum creatinine level were more common in the telavancin group (16% vs 10%).Conclusions:The primary end point of the studies was met, indicating that telavancin is noninferior to vancomycin on the basis of clinical response in the treatment of HAP due to gram-positive pathogens. A

Evidence-Based Reference1. Rubinstein E et al for the ATTAIN Study Group: Telavancin versus vancomycin

for hospital-acquired pneumonia due to Gram-positive pathogens, Clin Infect Dis 52:31-40, 2011. A

Pneumonia, Bacterial

SUGGESTED READINGSAujesky D et al: Prospective comparison of three validated prediction rules for

prognosis in community-acquired pneumonia, Am J Med 118:384-392, 2005. Bruns AHW et al: Patterns of resolution of chest radiograph abnormalities in adults

hospitalized with severe community-acquired pneumonia, Clin Infect Dis 45:983, 2007.

Carratala J et al: Outpatient care compared with hospitalization for community-acquired pneumonia, Ann Intern Med 142:165, 2005.

Davidson R et al: Resistance to levofloxacin and failure of treatment of pneumo-coccal pneumonia, N Engl J Med 346:747, 2002.

Halm EA, Teirstein AS: Management of community-acquired pneumonia, N Engl J Med 347:2039, 2002.

Sarkar M et al: Proton-pump inhibitor use and the risk for community-acquired pneumonia, Ann Intern Med 149:391-398, 2008.

Sord R et al: Current and potential usefulness of pneumococcal urinary antigen detection in hospitalized patients with community-acquired pneumonia to guide antimicrobial therapy, Arch Intern Med 171(2):166-172, 2011.

Tang KL et al: Incidence, correlates, and chest radiographic yield of new lung cancer diagnosis in 3398 patients with pneumonia, Arch Intern Med 171:1193, 2011.

Thibodeau K, Viera AJ: Atypical pathogens and challenges in community-acquired pneumonia, Am Fam Physician 69:1699, 2004.

Watkins RR, Lemonovich TL: Diagnosis and management of community-acquired pneumonia in adults, Am Fam Physician 83(11):1299-1306, 2011.

e.883.e2Pneumonia, Bacterial

Test Sensitivity Specificity Comment

Chest radiograph 65%-85% 85%-95% CT is more sensitive to infiltrates. Recommended for all patients.Computed tomography Gold standard Not infection specific Should not be done routinely but helpful to identify cavitation and

loculated pleural fluid. Recommended in the evaluation of non-responding patients.

Blood cultures 10%-20% High when positive Usually shows pneumococcus (in 50%-80% of positive samples) and defines antibiotic susceptibility. Recommended in patients with severe CAP, particularly if not on antibiotic therapy at the time of testing.

Sputum Gram stain 40%-100% depend-ing on criteria

0%-100% depending on criteria

Can correlate with sputum culture to define predominant organ-ism and can be used to identify unsuspected pathogens. Rec-ommended if sputum culture is obtained. May not be able to narrow empirical therapy choices.

Sputum culture Use if suspect drug-resistant or unusual pathogen, but positive result cannot separate colonization from infection. Obtain via tracheal aspirate in all intubated patients.

Oximetry or arterial blood gas Both define severity of infection, need for oxygen; if hypercarbia is suspected, a blood gas sample is needed. Recommended in severe CAP.

Serologic testing for Legionella, Chla-mydia pneumoniae, Mycobacterium pneumoniae, viruses

Accurate, but usually requires acute and convalescent titers col-lected 4-6 wk apart. Not routinely recommended.

Legionella urinary antigen 50%-80% Specific to serogroup 1, but the best acute diagnostic test for Legionella.

Pneumococcal urinary antigen 70%-100% 80% False positives if recent pneumococcal infection. Can increase sensitivity with concentrated urine.

Serum procalcitonin Not a routine test, but if done, should be measured with the highly sensitive Kryptor assay. May help guide duration of ther-apy and need for ICU admission.

TABLE E1-329 Diagnostic Testing for Community-Acquired Pneumonia (CAP)

From Vincent JL et al: Textbook of critical care, ed 6, Philadelphia, 2011, Saunders

No Pseudomonal Risk FactorsSelected -lactam (cefotaxime, ceftriaxone)plusIntravenously administered macrolide or quinolone (moxifloxacin or levofloxacin*)Pseudomonal Risk Factors PresentSelected antipseudomonal -lactam (cefepime, piperacillin/tazobactam, imipenem,

meropenem)plusCiprofloxacin or levofloxacin*orSelected antipseudomonal -lactamplusAminoglycosideplusIntravenously administered macrolide or antipneumococcal quinolone (moxifloxacin or

levofloxacin*)

BOX E1-47 Empirical Therapy Regimens for Severe Community-Acquired Pneumonia

*For patients with normal renal function, the recommended dose of levofloxacin is 750 mg daily. Note: Al-though routine MRSA coverage is not recommended for all severe community-acquired pneumonia, consider CA-MRSA, especially after influenza and with bilateral necrotizing pneumonia, and if suspected, treat by adding either linezolid or the combination of vancomycin and clindamycin.

From Vincent JL et al: Textbook of critical care, ed 6, Philadelphia, 2011, Saunders.

e.883.e3Pneumonia, Bacterial

Patient-Related Factors Male sex Absence of pleuritic chest pain Nonclassic clinical presentation Neoplastic illness Neurologic illness Age >65 years Family history of severe pneumonia or death from sepsisAbnormal Physical Findings Respiratory rate >30 breaths/min on admission Systolic (40 C) or afebrile ConfusionLaboratory Abnormalities Blood urea nitrogen >19.6 mg/dl Leukocytosis or leukopenia (

884 Pneumonia, Mycoplasma PTG

i BASIC INFORMATIONDEFINITIONMycoplasma pneumonia is an infection of the lung parenchyma caused by a small bacterium, Mycoplasma pneumoniae.

SYNONYMSPrimary atypical pneumoniaEatons pneumoniaWalking pneumonia

ICD-9CM CODES483 Mycoplasma pneumonia

EPIDEMIOLOGY & DEMOGRAPHICSINCIDENCE (IN U.S.): It is a frequent cause of community-acquired

pneumonia. CDC estimates 2 million cases a yr with 100,000 pneumonia-related hospitali-zations.

Many cases probably resolve without coming to medical attention.

Incidence is estimated at one case per 1000 persons annually.

Incidence is estimated to at least triple every (approximately) 5 yr during epidemics.

PEAK INCIDENCE: Some increased incidence in fall to early

winter Seems more prevalent in temperate climatesPREVALENCE (IN U.S.): Estimated to be present in one in every five

patients hospitalized for pneumonia (gener-ally a self-limited disease, so its true preva-lence is unknown)

Estimated to cause 7% of all cases of pneu-monia and approximately half the cases in those aged 5 to 20 yr

PREDOMINANT SEX: Equal distributionPREDOMINANT AGE: Most commonly affected: school-age chil-

dren and young adults (ages 5 to 20 yr) Occurs in older adults as well, especially with

household exposure to a young child More severe infections in affected elderly

patientsGENETICS: Familial disposition: None known May be more severe in patients with sickle

cell anemia

Neonatal infection: severe respiratory distress, sometimes requiring intubation, attributed to this disease in infants.

PHYSICAL FINDINGS & CLINICAL PRESENTATION Nonexudative pharyngitis (common) Headache, otalgia common Fever may be mild or not present Rhonchi or rales without evidence of consoli-

dation (common) in lower lung zones Associated with bullous myringitis (nonspe-

cific finding; perhaps no more frequently than in other pneumonias)

Skin rashes in up to one fourth of patients 1. Morbilliform 2. Urticaria 3. Erythema nodosum (unusual) 4. Erythema multiforme (unusual) 5. Stevens-Johnson syndrome (rare)

Muscle tenderness ($50% of the patients) On examination (and confirmed with testing):

1. Mononeuritis or polyneuritis 2. Transverse myelitis 3. Cranial nerve palsies 4. Meningoencephalitis

Lymphadenopathy and splenomegaly Conjunctivitis Table 1-330 summarizes the clinical mani-

festations of Mycoplasma pneumoniae.

ETIOLOGYInfection is spread person-to-person via respi-ratory droplets or secretions with an incubation period of 1 to 4 wk.

Dx DIAGNOSISDIFFERENTIAL DIAGNOSIS Chlamydia (now known as Chlamydophila)

pneumoniae Chlamydophila psittaci Legionella spp. Coxiella burnetii Several viral agents Q fever Streptococcus pneumoniae Pulmonary embolism or infarction

WORKUP Chest x-ray Thorough history and physical examination

Laboratory tests Evaluation guided by symptoms and findings

LABORATORY TESTS White blood cells (WBCs):

1. WBC count #10,000/mm3 in approxi-mately one fourth of patients

2. Differential count nonspecific 3. Leukopenia rare

Cold agglutinins: 1. Detected in approximately half of the pa-

tients 2. Also may be found in:

a. Lymphoproliferative diseases b. Influenza c. Mononucleosis d. Adenovirus infections e. Occasionally, Legionnaires disease

3. Titers typically #1:64 a. May be detectable with bedside testing b. Appear between days 5 and 10 of the

illness (so may be demonstrable when patient is first examined) and disap-pear within 1 mo

Complement fixation testing assay specific for mycoplasm antigens of paired sera (four-fold rise) or a single titer &1:32 in patients with pneumonia and a compatible history: 1. Considered diagnostic in the appropriate

clinical setting 2. Other assays include ELISA, antigen

capture-enzyme immunoassay, and PCR Culture of the organism from specimens

1. Only truly specific test for infection 2. Technically difficult and done reliably by

few laboratories 3. May require weeks to get results

Sputum 1. Often no sputum produced for laboratory

testing 2. When present, Gram-stained specimens

show polymorphonuclear cells without organisms

Infection occasionally complicated by pan-creatitis or glomerulitis

Disseminated intravascular coagulation is a rare complication

Electrocardiographic evidence of pericarditis or myocarditis may be present

IMAGING STUDIES Predilection for lower lobe involvement (up-

per lobes involved in less than a fourth), with radiographic abnormalities frequently out of proportion to those on physical examination (Fig. 1-655)

Small pleural effusions in approximately 30% of patients

Large effusions: rare Infiltrates: patchy, unilateral, and with a seg-

mental distribution, although multilobar in-volvement may be seen

Evidence of hilar adenopathy on chest radio-graphs in 20% to 25%

Rare cases reported: 1. Associated lung abscess 2. Residual pneumatoceles 3. Lobar collapse 4. Hyperlucent lung syndrome

TABLE 1-330 Clinical Manifestations of Mycoplasma Pneumoniae Infection

From Cohen J, Powderly WG: Infectious diseases, ed 2, St Louis, 2004, Mosby.

Respiratory tract Pharyngitis, laryngitis, acute bronchitis, bronchopneumoniaSkin and mucosa Maculopapular and vesicular exanthema, urticaria, purpura, erythema nodosum,

erythema multiforme, Stevens-Johnson syndromeCentral nervous system Meningitis, meningoencephalitis, acute psychosis, cerebellitis, Guillain-Barr

syndrome?Parenchymatous organs Pancreatitis, diabetes mellitus, nonspecific reactive hepatitis, subacute thyroiditis?Miscellaneous Hemorrhagic bullous myringitis, hemolytic anemia, pericarditis, thromboembolism?

Some association remains uncertain.

IDiseases and Disorders

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PTG Pneumonia, Mycoplasma

Rx TREATMENTACUTE GENERAL Rx Therapy: azithromycin 500 mg qd 3 or 500

mg initially, then 250 mg daily for 4 days for adults. For children: 10 mg/kg in one dose on first day, then 5 mg/kg in one dose for 4 days or clarithromycin: 500 mg bid for 10 days in adults, 15 mg/kg per day in two divided doses for 10 days in children. Alternatives include erythromycin (500 mg qid) for adults or 30 to 40 mg/kg per day in four divided doses in children or doxycycline: 2 to 4 mg/kg per day in one or two divided doses for 10

days, maximum daily dose: 100 to 200 mg, but this agent cannot be used in young chil-dren or women of childbearing age. Respira-tory fluoroquinolones such as Levaquin or moxifloxacin are alternative agents for treat-ment in adults but should not be used in young children.

Therapy shortens the duration and severity of symptoms and may hasten radiographic clearing, but the disease is self-limiting.

CHRONIC Rx Effective antimicrobial therapy does not elim-

inate the organism from the respiratory se-cretions, which may be positive for weeks.

Serum antibody response does not necessar-ily provide lifelong immunity.

Chronic symptoms do not occur, although clinical relapses may occur 7 to 10 days after the initial response and may be associated with new areas of infiltration.

DISPOSITION Clinical improvement is almost universal

within 10 days. Infiltrates generally clear within 5 to 8 wk. Rare deaths are likely attributable to underly-

ing medical diseases. Person-to-person spread can be minimized

by avoiding open coughing, especially in en-closed areas.

REFERRAL Not responding to treatment Severe infection Severe extrapulmonary manifestations Multilobe involvement accompanied by respi-

ratory embarrassment (very rare)

! PEARLS & CONSIDERATIONSCOMMENTSX-ray resolution complete by 8 wk in approxi-mately 90% of patients.

FIGURE 1-655 Localized airspace opacification resulting from Mycoplasma pneumoniae. (From Specht N [ed]: Practical guide to diagnostic imaging, St Louis, 1998, Mosby.)

SUGGESTED READINGS

available at www.expertconsult.com

AUTHOR: GLENN G. FORT, M.D., M.P.H.

RELATED CONTENTMycoplasmal Pneumonia (Patient Information)

e.885.e1

SUGGESTED READINGSDaxboeck F: Mycoplasma pneumoniae central nervous system infections, Curr

Opin Neurol 19(4):374-378, 2006. La Scola B et al: Mycoplasma pneumoniae: a rarely diagnosed agent in ventilator-

acquired pneumonia, J Hosp Infect 59(1):74, 2005. Michelow IC et al: Diagnostic utility and clinical significance of naso- and oropha-

ryngeal samples used in a PCR assay to diagnose Mycoplasma pneumoniae infection in children with community-acquired pneumonia, J Clin Microbiol 42(7):3339-3341, 2004.

Waites KG, Talkington DF: Mycoplasma pneumoniae and its role as a human pathogen, Clin Microbiol Rev 17(4):697, 2004.

Pneumonia, Mycoplasma

886 Pneumonia, Pneumocystis jirovecii (carinii) PTG

i BASIC INFORMATIONDEFINITIONPneumocystis jirovecii pneumonia (PJP) is a serious respiratory infection caused by the fun-gal or protozoal organism P. jirovecii (formerly known as P. carinii ).

SYNONYMSPCPPJP

ICD-9CM CODES136.3 Pneumocystis jirovecii (P. carinii)

pneumonia

EPIDEMIOLOGY & DEMOGRAPHICSINCIDENCE (IN U.S.): Seen primarily in the setting of AIDS Approximately 11 cases per 100 patient-

years among HIV-infected patients with CD4 lymphocyte counts $100/mm3

Also seen in other immunocompromised pa-tients with severe cell-mediated immune de-ficiency (congenital T-cell deficiency, acute leukemia, lymphoma, bone marrow or organ transplant deficiency)

Rituximab use has been associated with Pneumocystis pneumonia in HIV-negative pa-tients, most of whom had hematologic can-cers.

PEAK INCIDENCE: Age 20 to 40 yr (parallel to AIDS epidemic)PREDOMINANT SEX: Equal incidence when corrected for HIV statusPREDOMINANT AGE: $2 yr 20 to 40 yrGENETICS: Neonatal infection: Most frequent opportunistic infection among

HIV-infected children, occurring in approxi-mately 30%

Neonatal occurrence unusual

PHYSICAL FINDINGS & CLINICAL PRESENTATION Fever, cough, shortness of breath present in

almost all cases Lungs frequently clear to auscultation, al-

though rales occasionally present Cyanosis and pronounced tachypnea in se-

vere cases Hemoptysis unusual Spontaneous pneumothorax

ETIOLOGY P. jirovecii (formerly P. carinii) recently reclas-

sified as a fungal organism Reactivation of dormant infection Extrapulmonary involvement rare

Dx DIAGNOSISDIFFERENTIAL DIAGNOSIS Other opportunistic respiratory infections:

1. Tuberculosis 2. Histoplasmosis 3. Cryptococcosis

Nonopportunistic infections: 1. Bacterial pneumonia 2. Viral pneumonia 3. Mycoplasmal pneumonia 4. Legionellosis

Occurs virtually exclusively in the setting of profound depression of cellular immunity

WORKUP Chest x-ray Arterial blood gases Because Pneumocystis cannot be cultured,

diagnosis relies on detection of the organism by colorimetric or immunofluorescent stains or PCR.

Sputum examination for cysts of PJP and to exclude other pathogens

Bronchoscopy with bronchoalveolar lavage or lung biopsy for diagnosis if sputum examina-tion is negative or equivocal. Stains such as Gomori methenamine silver stain or toluidine blue O are used to identify the organism.

LABORATORY TESTS Arterial blood gas monitoring Elevated lactate dehydrogenase in majority of

cases HIV antibody test if cause of underlying im-

mune deficiency state is unclear

IMAGING STUDIESDiffuse uptake on gallium scanning of the lungs is suggestive but not diagnostic.

Rx TREATMENTNONPHARMACOLOGIC THERAPY Supplemental oxygen Ventilatory support if needed Prompt thoracotomy if pneumothorax de-

velops

ACUTE GENERAL RxFor confirmed or suspected PJP: Trimethoprim-sulfamethoxazole (15 to 20

mg/kg trimethoprim and 75 to 100 mg/kg sulfamethoxazole qd) PO or IV per day di-vided and given q6 to 8h

Pentamidine (4 mg/kg IV qd) Either regimen with prednisone (40 mg

PO bid): 1. If arterial oxygen pressure $70 mm Hg 2. If arterial-alveolar oxygen pressure differ-

ence #35 mm Hg

3. Dose tapered to 20 mg bid after 5 days and 20 mg qd after 10 days

Therapy continued for 3 wk Alternative therapies available for patients

unable to tolerate conventional therapy: 1. Dapsone/trimethoprim 2. Clindamycin/primaquine 3. Atovaquone

CHRONIC Rx After completion of therapy, lifelong prophy-

laxis should be maintained with trimethoprim-sulfamethoxazole (one single-strength tablet PO qd or double-strength three times weekly).

Patients intolerant of this therapy should be treated with dapsone (50 mg PO qd) plus pyrimethamine (50 mg PO weekly) plus leu-covorin (25 mg PO weekly).

Inhaled pentamidine (300 mg monthly by standardized nebulizer) is less effective and is reserved for patients intolerant to other forms of prophylaxis.

Same approach taken to all HIV-infected pa-tients with CD4 lymphocyte counts $200 to 250/mm3 or $20% of the total lymphocyte count because of their high risk of PJP.

DISPOSITIONAfter completion of therapy, long-term ambula-tory follow-up is mandatory to provide second-ary prevention of PJP (see Chronic Rx above) and management of the underlying immunode-ficiency syndrome.

REFERRAL To pulmonologist for bronchoscopy if diagno-

sis cannot be confirmed by sputum examina-tion

To an infectious disease specialist if case is severe or difficult to manage

! PEARLS & CONSIDERATIONSCOMMENTSAll patients, especially those with severe infec-tion or intolerant of conventional therapy, should be followed by a physician experienced in the management of PJP and, if appropriate, in the long-term management of HIV infection or other underlying disease.

Severe and life-threatening hypoglycemia may occur after 1 or 2 wk after start of IV pent-amidine. Monitor closely and advise the patient of symptoms of hypoglycemia.

SUGGESTED READINGSavailable at www.expertconsult.com

AUTHOR: GLENN G. FORT, M.D., M.P.H.

RELATED CONTENTPneumocystis Pneumonia (Patient Information)

e.886.e1

SUGGESTED READINGSKovacs JA, Masur H: Evolving health effects of pneumocystis, JAMA 301(24):2578-

2585, 2009. Torres HA et al: Influence of type of cancer and hematopoietic stem cell transplan-

tation on clinical presentation of Pneumocystis jirovecii pneumonia in cancer patients, Eur J Clin Microbiol Infect Dis 25(6):382, 2006.

Pneumonia, Pneumocystis jirovecii (carinii)

IDiseases and Disorders

887

P

PTG Pneumonia, Viral

i BASIC INFORMATIONDEFINITIONViral pneumonia is infection of the pulmonary pa-renchyma caused by any of a large number of viral agents. The most important viruses are discussed.

SYNONYMSNonbacterial pneumoniaAtypical pneumonia

ICD-9CM CODES480.8 Viral pneumonia487.0 Viral pneumonia due to influenza

EPIDEMIOLOGY & DEMOGRAPHICSINCIDENCE (IN U.S.): Influenza virus:

1. 10% to 20% of population in temperate zones infected during 1-2 mo epidemics occurring yearly during winter months.

2. Up to 50% infected during pandemics. 3. Pneumonia develops in small percentage

of infected persons. Incidence of other important viral pneumo-

nias is not known precisely.PEAK INCIDENCE: Influenza:

1. Winter months for influenza A2. Year round for influenza B3. Peak of pneumonia seen weeks into the

outbreak of infection Respiratory syncytial virus (RSV) and parain-

fluenza virus:1. Winter and spring

Adenovirus:1. Endemic (military)

Varicella:1. Spring in temperate zones

Measles:1. Year round

Cytomegalovirus (CMV):1. Year round

PREVALENCE (IN U.S.): Often related to immune status of the popula-

tion or presence of an epidemic Normal hosts (estimates):

1. 86% of cases of pneumonia resulting in hospitalization in American adults

2. 16% of pediatric pneumonias managed as outpatients

3. 49% of hospitalized infants with pneu-monia

Important problem in hosts with impaired immunity

PREDOMINANT SEX: None generally Male sex may predispose to more severe

respiratory disease in RSV infectionPREDOMINANT AGE: Influenza:

1. Overall incidence greatest at age 5 yr2. Lower with increasing age3. The most serious sequelae in those with

chronic medical illnesses, especially car-diopulmonary disease

4. Hospitalizations greatest in infants and adults aged #64 yr

RSV and parainfluenza virus:1. Young children (as the major cause of

pneumonia)2. Occurs throughout life

Adenoviruses:1. Young children2. Adults, primarily military recruits

Varicella:1. Approximately 16% of adults (not infected

in childhood) who contract chickenpox2. Acute varicella during pregnancy more likely

to be complicated by severe pneumonia3. 90% of reported varicella pneumonia

cases are in adults (highest incidence ages 20 to 60 yr)

Measles:1. Young adults and older children who re-

ceived a single vaccination (5% failure rate)

2. Measles during pregnancy more likely to be complicated by pneumonia

3. Underlying cardiopulmonary diseases and immunosuppression predispose to seri-ous pneumonia complicating measles

4. Before availability of measles vaccine, 90% of pneumonias in those $10 yr

5. Currently more than one third of U.S. pa-tients #14 yr

6. 3% to 50% of measles cases are compli-cated by pneumonia

CMV:1. Neonatal through adult2. Immunosuppression is key predisposing

factorGENETICS: Familial disposition: Close contact, not genetics, is important in

acquisition Congenital anomalies and immunosuppres-

sion worsen course of RSV pneumoniaCongenital infection: CMV is the most common intrauterine infec-

tion in the U.S. Pneumonia occurs occasionally in infants

with symptomatic congenital infection.Neonatal infection: Severe RSV pneumonia Adenovirus pneumonia

1. 5% to 20% mortality rate 2. Can lead to residual restrictive or obstruc-

tive functional abnormalities Varicella neonatorum

1. Disseminated visceral disease including pneumonia

2. May develop in neonates whose mothers develop peripartum chickenpox

CMV pneumonia 1. Generally fatal 2. Associated with severe cerebral damage

in this population

PHYSICAL FINDINGS & CLINICAL PRESENTATION 1. Influenza:

Fever, cough, or sore throat (reffered to as influenza-like illness [ILI])

Uncomfortable or lethargic appearance Prominent dry cough (rarely hemoptysis) Flushed integument and erythematous

mucous membranes

Rales or rhonchi 2. RSV and parainfluenza:

Fever Tachypnea Prolonged expiration Wheezes and rales

3. Adenoviruses: Hoarseness Pharyngitis Tachypnea Cervical adenitis

4. Measles: Conjunctivitis Rhinorrhea Kopliks spots (white lesions on the buccal

mucosa) Exanthem (maculopapular rash that starts

on the head, then moves down to rest of body)

Pneumonitis a. May occur as a complication in 3% to

4% of adolescents and young adults b. Coincident with rash c. May also develop after apparent re-

covery from measles Fever Dry cough

5. Varicella: Fever Maculopapular or vesicular rash (all lesions

at the same stage) a. Becomes encrusted b. Pneumonia typical 1 to 6 days after

rash appears c. Pneumonia accompanied by cough

and occasionally hemoptysis Few auscultatory abnormalities noted on

examination of the lungs 6. CMV:

Fever Paroxysmal cough Occasional hemoptysis Diffuse adenopathy when pneumonia oc-

curs after transfusion

ETIOLOGYViral infection can lead to pneumonia in both immunocompetent and immunocompromised hosts.

Dx DIAGNOSISDIFFERENTIAL DIAGNOSIS Bacterial pneumonia, which frequently com-

plicates (i.e., can follow or be simultaneous with) viral pneumonia

Other causes of atypical pneumonia: 1. Mycoplasma spp. 2. Chlamydia spp. 3. Coxiella spp. 4. Legionnaires disease

Acute respiratory distress syndrome (ARDS) Physical findings and associated hypoxemia

confused with pulmonary emboli

WORKUP Information about the current prevalent strain

of influenza virus can be obtained from local

888 Pneumonia, Viral PTG

health departments or from the Centers for Disease Control and Prevention.

Influenza and other viruses may be cultured from respiratory secretions during the initial few days of the illness (special media and techniques necessary).

Respiratory viral panels that use PCR-based assays to test for a variety of viruses are ex-tremely sensitive and are becoming the test of choice.

Rapid flu tests have a 50% sensitivity in diag-nosing influenza (a negative test does not mean the patient does not have influenza).

Measles and adenovirus pneumonia are usu-ally diagnosed clinically and can be confirmed with serology.

CMV may be grown in culture or PCR ampli-fied from bronchoalveolar lavage samples. An algorithm for the workup and management of suspected severe influenza pneumonia in the critical care unit is described in Fig. E1-656. Open lung biopsy is required for a definite diagnosis of CMV pneumonia.

LABORATORY TESTS Sputum Gram stain (usually produced in

scanty amounts) typically shows few poly-morphonuclear leukocytes and few bacteria.

White blood cell count may vary from leuko-penic to modest elevation, usually without a leftward shift.

Disseminated intravascular coagulation oc-casionally complicates adenovirus type 7 pneumonia.

Multinucleated giant cells on Tzanck prepa-ration of an unroofed vesicular lesion are useful in diagnosing varicella in a patient with an infiltrate (also found in herpes simplex).

Severe immunosuppression is associated with symptomatic CMV pneumonia (usually reacti-vation of latent infection or in previously sero-negative recipients from the donor).

Hypoxemia may be profound. Cultures may be helpful in identifying super-

infecting bacterial pathogens. When they occur, parapneumonic pleural ef-

fusions are exudative.

IMAGING STUDIES Chest radiographs may demonstrate a spec-

trum of findings from ill-defined, patchy, or generalized interstitial infiltrates, which can be associated with ARDS.

A localized dense alveolar infiltrate suggests a superimposed bacterial pneumonia.

Small calcified nodules may develop as a radiographic residual of varicella pneumonia.

Rx TREATMENTNONPHARMACOLOGIC THERAPYGeneral: Measures to diminish person-to-person trans-

mission Modified bed rest Maintenance of adequate hydration Possible ventilatory support for severe pneu-

monia or ARDS

Influenza: Yearly prophylactic strain-specific influenza

vaccination (only subvirion vaccine should be used in children $13 yr) can be given to prevent infection.

Live, attenuated influenza vaccines adminis-tered by nose drops as effective as injected inactivated viral vaccines.

RSV: Isolation techniques are important in limiting

spread of RSV infections. Immunoglobulins with a high RSV-neutralizing

antibody titer are beneficial in treatment.Adenoviruses: Intestinal inoculation of respiratory adenovi-

ruses has been used to successfully immu-nize military recruits.

Although they produce no disease in recipi-ents, the viruses may be shed chronically and may infect others at a later date.

These vaccines are not available for civilian populations.

Varicella: Live, attenuated varicella vaccine has been

successfully used in clinical trials. Varicella-zoster immune globulin should be

administered within 4 days of exposure to prevent or modify the disease in susceptible persons.

Nonimmunized persons exposed to varicella are potentially infectious between 10 and 21 days after exposure.

Measles: Effective measles vaccine is available:

C The vaccine should be administered at age 15 mo.

C A second dose should be administered at the time of school entry.

Live, attenuated vaccine or gamma-globulin can prevent measles in unvaccinated per-sons if administered early after exposure.

Vitamin A given PO for 2 days reduces mor-bidity and mortality rates from measles in exposed children.

Severe acute respiratory syndrome (SARS) ' associated coronaviruses: No vaccine currently available. Supportive care: ribavirin ineffective, use of

steroids or interferon-alpha of unclear value.

ACUTE GENERAL Rx General: Administer appropriate antibiotics

for bacterial superinfections. Influenza:

C Amantadine and rimantadine for influenza A (not active against influenza B). Early use can speed recovery from small airways dysfunction, but whether it influences the development or course of pneumonia is uncertain.

C The neuraminidase inhibitors oseltamivir and zanamivir are effective if given in the first 48 hours of symptoms of influenza; their efficacy in established influenza pneumonia is unclear.

C Aerosolized ribavirin or amantadine may have a role in severe influenza pneumonia but have not been approved for this indi-cation.

RSV and parainfluenza:C Ribavirin aerosol is effective for severe

RSV pneumonia.C There is no approved antiviral therapy for

parainfluenza virus pneumonia. Adenoviruses: no effective agent; some

case reports of cidofovir use but unproved. Varicella:

C Varicella pneumonia can be treated with IV acyclovir.

C Adults who develop chickenpox should be considered for acyclovir treatment, which may prevent the development of pneu monia.

Measles: no effective antimeasles agent. CMV:

C Acyclovir can prevent CMV infection in re-nal transplant recipients.

C Ganciclovir and foscarnet, with or without CMV hyperimmune globulin, show promise in the treatment of serious CMV infection, including pneumonia, in compromised hosts.

DISPOSITION Supportive therapy is useful. Death is possible during acute illness. Residual functional abnormalities may be

persistent or develop into or predispose to chronic respiratory diseases in later life.

Morbidity and mortality rates after most viral pneumonias are increased by bacterial su-perinfection.

REFERRAL Uncertainty about the diagnosis in a compro-

mised host. Symptoms or findings are progressive. Severe respiratory compromise, diffuse infil-

trates, or the development of ARDS.

! PEARLS & CONSIDERATIONSCOMMENTS Influenza spreads by close contact and by

small droplets transmitted by cough. RSV is effectively transmitted by fomites and

by direct contact (little by aerosol). Varicella is transmitted by direct contact or by

aerosol. Of the three major forms of parainfluenza vi-

ruses (types 1 to 3), type 3 is the most com-mon cause of viral pneumonia; types 1 and 2 primarily cause laryngotracheitis.

Recent evidence indicates that a newly dis-covered virus known as metapneumovirus is a common cause of upper respiratory infections worldwide; this virus can cause pneumonia.

SUGGESTED READINGS

available at www.expertconsult.com

AUTHORS: PHILIP A. CHAN, M.D., and GLENN G. FORT, M.D., M.P.H.

RELATED CONTENTViral Pneumonia (Patient Information)

e.888.e1

Suspected severe influenza: diffusepneumonitis, other critical illness

High probability caseLow probability case

PCR!

PCR!

PCR!PCR"

PCR"

PCR"

Nasopharyngeal swab + tracheal aspiratefor influenza PCR/culture

Oseltamivir 75 mg PO/ng bid, Rx CAPStore sample for serology

Repeat nasopharyngeal +tracheal aspirate (if intubated)

Continue oseltamivirfor 10 days

D/C CAP antibioticsif no bacterial

pathogen identified

Weekly influenza PCR (tracheal ornasopharyngeal aspirate) until negative

PCR or negative cultureWeekly sputum bacterial cultures

D/C oseltamivirContinue CAP antibiotics

for 7-14 daysConvalescent (28 day)influenza serology if no

other pathogen identified

D/C oseltamivirContinue CAP antibiotics

for 7-14 daysConvalescent (28 day)influenza serology if no

other pathogen identified

FIGURE E1-656 Suggested algorithm in the workup and management of suspected severe influ-enza pneumonia in the critical care unit. CAP, Community-acquired pneumonia; D/C, discontinue; PCR, polymerase chain reaction. (From Vincent JL et al: Textbook of critical care, ed 6, Philadelphia, 2011, Saunders.)

SUGGESTED READINGSCheng VC et al: Medical treatment of viral pneumonia including SARS in immuno-

competent adults, J Infect 49(4):262, 2004. Falsey AR, Walsh EE: Viral pneumonia in older adults, Clin Infect Dis 42(4):518,

2006. Hohenthal U et al: Measurement of complement receptor 1 on neutrophils in

bacterial and viral pneumonia, BMC Infect Dis 6:11, 2006. Luyt CE et al: Viral infections in the ICU, Curr Opin Care 14(5):605, 2008. Michelow IC et al: Epidemiology and clinical characteristics of community-ac-

quired pneumonia in hospitalized children, Pediatrics 113(4):701, 2004. Moreno L et al: Development and validation of a clinical prediction rule to distin-

guish bacterial from viral pneumonia in children, Pediatr Pulmonol 41(4):331, 2006.

Tsolia MN et al: Etiology of community-acquired pneumonia in hospitalized school-age children: evidence for high prevalence of viral infections, Clin Infect Dis 39(5):681, 2004.

Werno AM et al: Human metapneumovirus in children with bronchiolitis or pneu-monia in New Zealand, J Paediatr Child Health 40(9-10):549, 2004.

Pneumonia, Viral