Peripheral Blood Smear Bacillemia CHRISTINE LAWRENCE,M.D.,§HELDON T. EROWN,M.D., LAWRENCE F. FREUNDLICH,M.S. %mx,NewYork

T he presence of large numbers of bacteria on pe- ripheral blood smear is uncommon even in pa-

tients who have positive blood culture results [l]. In a systematic study of cases in which peripheral blood leukocytes were seen to contain bacteria, Smith [2] noted a nearly certain fatal outcome in patients in whom organisms were found in more than 15 cells/ mm3. During the past four years, we have seen two patients with remarkably large numbers of bacteria in their peripheral polymorphonuclear leukocytes (PMNs), involving 54 and 13 percent of these cells, respectively. The extraordinary numbers of leuko- cytes that contained bacilli in our patients were 7,700 and 2,060/mm3, respectively-that is, bacillemia 500 and 130 times greater than the bacillemia Smith found to be associated with almost certain death. Neverthe- less, both of our patients survived.

CASE REPORTS Patient 1

This 24-year-old, previously healthy, Hispanic man was hospitalized after two to three days of sore throat, chills, fever, and abdominal pain. At age 16, he under- went splenectomy after trauma. He had not received Pneumovax. He appeared “toxic,” and had a tempera- ture of 104”F, blood pressure of 120/80 mm Hg, and a respiratory rate of 30/minute. A few petechiae were seen on his torso and he had right upper abdominal tenderness. The chest radiograph was clear. His hemo- globin level was 13.4 g/d], and the white blood cell count was 1’7,800/mm3 with a left shift. The platelet count was 130,000/mm3 and the prothrombin time (PT) 22 seconds (control, 12 seconds); a repeat PT measurement a few hours later was 34 seconds. The serum urea nitrogen level was 22 mg/dl and the creati- nine value was 2.1 mg/dl. His urine was unremarkable. The spinal fluid was unremarkable and culture-nega- tive. He was suspected of having pneumococcal sepsis with early evidence of disseminated intravascular co- agulation (DIC). Because of the thrombocytopenia, a hematology consultation was requested. The Wright- stained peripheral blood smear showed bacilli in 54 percent of the polymorphonuclear leukocytes (Figure 1 and Table I).

The patient was treated initially with parenteral penicillin, nafcillin, gentamicin, and oral erythromy- tin. Twenty-four hours after admission, Wright- stained blood smears still revealed abundant intact rods in the PMNs. The bacilli were gram-negative, so treatment with chloramphenicol was begun. At this time, the blood cultures did not appear to show

From the Departments of Medicine and Laboratory Medicine, Bronx Munic- inal Hosoital Center and the Albert Einstein College of Medicine. Bronx. New York. Requests for reprints should be addressed-to Dr. Chnstine Lawrence, Department of Medicine, Bronx Municipal Hospital Center, Pelham Park- way South and Eastchester Road, Bronx, New York 10461. Manuscript submitted January 13, 1988, and accepted in revised form April 4. 1988.

growth. On the second hospital day, his platelet count reached a nadir of 20,000/mm3.

By the third hospital day, two of four sets of blood culture bottles were positive for gram-negative rods, predominantly in anaerobic culture. These were iden- tified as Bacteroides distasonis [3] on the seventh hos- pital day. Antibiotic therapy was then changed to me- tronidazole and cefoxitin, although the patient’s condition was clinically improved. Despite an exten- sive evaluation, no source for this patient’s Bacteroides sepsis was found. On follow-up evaluation five years later, he was in good health. Results of routine screen- ing tests to assess immunocompetence were normal.

Patient 2 This 55-year-old Hispanic man was hospitalized af-

ter three days of vomiting blood and passing a tarry stool. He appeared mildly ill, and had a temperature of 98.6”F, a blood pressure of 110/80 mm Hg, and heart rate of 108 beats/minute. The physical examination showed no abnormalities except for positive results of guaiac tests on his stool and gastric aspirate. The he- moglobin level was 12.2 g/dl, white blood cell count 18,900/mm3 with a left shift, and platelet count 17,000/mm3; the PT was 15.8 seconds (control, 11.8 seconds) and the partial thromboplastin time (PTT) was 58.1 seconds (control, 29.9 seconds). The gastroin- testinal bleeding was attributed to thrombocytopenia and recent aspirin use. The serum urea nitrogen level was 54 mg/dl and creatinine value was 1.7 mg/dl.

On admission, he was seen by a hematologist for his thrombocytopenia and abnormal coagulation test re- sults. Although toxicity was not observed, intracellu- lar bacilli were seen in 13 percent of the peripheral blood PMNs (Figure 1 and Table I) and were gram- positive. Culture samples were then obtained and he was treated with ampicillin, gentamicin, and clinda- mycin. The finding of a 1:20 titer of fibrin split prod- ucts suggested a diagnosis of low-grade DIC despite a fibrinogen level of 570 mg/dl. The gastrointestinal bleeding stopped within 24 hours. The aspirin inges- tion, thrombocytopenia, and DIC were believed to ad- equately explain his bleeding. No bacilli were seen on peripheral smear after 36 hours. His PT and PTT were normal. His platelet count rose steadily to 2X&000/ mm3 by the sixth hospital day. The blood cultures appeared sterile until the 10th hospital day, when blind subculture on sheep’s blood agar showed growth of gram-positive rods. The source of this patient’s sep- sis was not found and he was discharged on the 12th hospital day. At 14 days, the initial blood cultures revealed growth in all of four bottles, both aerobic and anaerobic, each with the same gram-positive organism identified as Corynebacterium CDC type G2 by the New York City Board of Health Laboratory [4].

Six months later, he was in good health. Results of routine screening tests were unremarkable. Evalua- tion of immunocompetence was notable for a moder- ately reactive tuberculin skin test and the absence of

July 1988 The American Journal of Medicine Volume 85 111

BLOOD SMEAR BACILLEMIA / LAWRENCE ET AL

Figure 1. Polymorphonuclear leukocyte from Patient 1 (left) and Patient 2 (right) with engulfed bacilli.

antibody to the human immunodeficiency virus (HIV).

Blood cultures in both Patients 1 and 2 were checked daily to detect any evidence of growth, includ- ing turbidity, hemolysis, gas production, or colony for- mation. In addition, all aerobic cultures were routinely subcultured within the first 18 hours of incubation. Anaerobic cultures were subcultured if there was any sign of microbial growth.

COMMENTS Both of these patients had what would be consid-

ered by Smith [2] to be lethal bacillary sepsis. Both patients survived, the first after a severe illness thought to be infectious, and the second after an ill- ness not originally thought to be infectious. In both cases, the thrombocytopenia was presumably secon-

TABLE I

Severity of Bacillemia on Peripheral Blood Smears

Patient 1 Patient 2

PMNs infected/mm3 7,700 2,060

PMNs with bacilli* 54% 13% Bacilli/cell

o-3 65% 64% 4-23 35% 36%

Bands with bacilli* 6% 0% Ba;!;/cell

100% 0%

Monocytes with bacillit 0% 0%

*I Five hundred mature PMNs and 500 bands were counted. +Three monocytes were counted in Patient 1 and 20 monocytes were counted in Patient 2.

dary to sepsis. In each patient, the hematologist noted on admission a remarkably high density of organisms in the peripheral blood, with as many as 20 bacilli per PMN (Figure 1 and Table I). The presence of intracel- lular bacteria and the diagnostic utility of examining peripheral blood smears for them in cases of suspected sepsis have received considerable attention in the lit- erature [2,5]. Since the initial report of Humphrey [6], attempts at improving the sensitivity and speed of diagnosing bacteremia by examination of blood buffy- coat smears have periodically met with enthusiasm [7], but its value has been generally discounted [8].

It is puzzling why there was such high-grade infesta- tion of the blood PMN leukocytes with these two spe-

cies of bacilli without much apparent destruction of the bacteria (Figure 1) and, in Patient 2, without the characteristic clinical signs of sepsis. The presence of intracellular organisms in the granulocytes excludes abnormalities of chemotaxis or phagocytosis and sug- gests a defect in bactericidal mechanisms. Of previous- ly described hereditary [9] and acquired [lO,ll] abnor- malities of PMN function, only Patient l’s history of splenectomy appears relevant. The predisposition of splenectomized patients toward infection and high- grade bacteremia with such encapsulated organisms as Streptococcus pneumoniae, Haemophilus influenzae, and less commonly Bacteroides fragilis is well known [12]. B. distasonis has not generally been of concern in these patients and some studies suggest that its lack of encapsulation may partly explain the relatively low pathogenicity of this organism when compared with other encapsulated species of Bacteroides [13].

Whether or not properties of the infecting organ- isms may have contributed to prolonged intracellular carriage of bacilli in these two cases is open to specula- tion. There have been several clinical [14-161 and ex-

112 July 1988 The American Journal of Medicine Volume 85

BLOOD SMEAR BACILLEMIA ,’ LAWRENCE ET AL

perimental[17] studies of functional defects of neutro- phils in response to infection. Acquired, transient bactericidal defects against Staphylococcus aureus have been well documented in one report [18]. How- ever, there are no convincing demonstrations of func- tional bactericidal abnormalities as a general response to infection.

In 1983, Austin and Hil.l[19] described a 40-year-old man who had a porcine prosthetic mitral and aortic valve replacement five years prior to development of fatal endocarditis. Eight of nine blood cultures showed growth of “diphtheroids,” the first after seven days’ incubation, subsequently identified as Corynebacteri- urn CDC group G2 141. Ours is the second report of septicemia with Corynebacterium CDC group G2 in a non-immunocompromised host. This finding supports the increasingly frequent recognition of “diphthe- raid”-appearing organisms as clinically important pathogens [20,21].

In Patient 1, the persistence on blood smear of intra- cellular bacilli 24 hours after antibiotics were started led to a significant and possible lifesaving modifica- tion of the therapeutic regimen with clearing of the bacillemia. In Patient 2, the unexpected finding of bacilli on blood smear led to a diagnosis of sepsis and DIC and prompt institution of antibiotics. Microbio- logic confirmation of infection took three and 10 days in the two respective cases whereas identification of the organism took seven and 45 days, so that informa- tion obtained from cultures did not significantly influ- ence treatment. The findings in our two patients with what would be considered fatal bacillemia [2] re-em- phasize the great value of the peripheral blood smear, especially in patients with DIC and thrombocytope- nia.

REFERENCES 1. Bennett IL, Beeson PB: Bacteremia: a consideration of some experimental and clinical aspects. Vale J Biol Med 1954; 26: 241-262.

2. Smith H: Leukocytes containing bacteria in plain blood films from patients wrth septicemia. Australas Ann Med 1966; 15: 210-221. 3. Holdeman LV, Kelley RW, Moore WEC: Anaerobic gram-negatrve straight, curved, and helical rods. Family 1: Bacteroidaceae. Prrbram, 1933, lOAL. In: Krieg NR, Holt JG, eds. Bergey’s manual of systematic bacteriology, vol 1. Baltimore: Williams and Wilkins, 1984; 602-662. 4. Hollis DG, Weaver RE: Gram-positrve organisms: a guide to identification. Atlan- ta: Centers for Disease Control, 1981; 4. 5. Torres J, Bisno AL: Hyposplenism and pneumococcemia: visualization of Diplo coccuspneumoniae in the peripheral blood smear. Am J Med 1973; 55: 851-855. 6. Humphrey AA: Use of the huffy layer in the rapid diagnosis of septicemia. Am J Clin Pathol 1944; 14: 358-362. 7. Brooks GF, Pribble AH, Beaty HN: Early diagnosis of bacteremia by buffycoat examinations. Arch Intern Med 1973; 132: 673-675. 8. Plordes JJ: The diagnosis of infectious diseases. In: Petersdorf RG, Adams RD, Braunwald E, lsselbacher KJ, Martin JB, Wilson JD, eds. Harrison’s principles of internal medicine, 10th ed. New York: McGraw-Hill, 1983; 848. 9. Plordes JJ: The diagnosis of infectious diseases. In: Braunwald E. lsselbacher KJ. Petersdorf RG. Wilson JD, Martin JB. Fauci AS, eds. Harrison’s principles of internal medicine, 11th ed. New York: McGraw-Hill, 1987; 459-463. 10. Ambruso DR, Johnston RB: Defects of phagocytefunction. In: Chandra RK, ed. Primary and secondary immunodeficiency disorders. New York: Churchill Living- stone, 1983; 133-148. 11. Baehner RL: Neutrophil dysfunction associated with states of chronic and recurrent infection. Pediatr Clin North Am 1980; 27: 377-401. 12. Likhite W: Immunological impairment and susceptibility to infection after sple- nectomy. JAMA 1976; 236: 1376-1377. 13. Polk BF, Kasper DL: Bacteroides fragifis subspecies in clinical isolates. Ann Intern Med 1977; 86: 569-571. 14. Koch C: Acquired defect in the bacteriocidal function of neutrophil granulo- cytes during bacterial infections. Acta Pathol Microbial Stand [B] 1974; 82: 439- 447. 15. Solberg CO, Hellum KB: Neutrophilgranulocytefunction in bacterial infections. Lancet 1972; II: 727-730. 16. Weinstein RJ, Young LS: Neutrophil function in gram-negative rod bacteremia: the interaction between phagocytic cells, infecting organisms, and humoral fac- tors. J Clin Invest 1976; 58: 190-199. 17. Quie PG: Perturbation of the normal mechanisms of intraleukocytic killing of bacteria. J Infect Dis 1983; 148: 189-193. 18. Messner RP, Reed WP, Palmer DL, Bolin RB. Davis AT, Quie PG: A transient defect in bacteriocidal caoacitv. Clin lmmunol lmmunooathol 1973: 1: 523-532. 19. Austin GE, Hill ED: Enboca;ditis due to Corynebac~erium CDC group G2 (let- ter). J Infect Dis 1983; 147: 1106. 20. Lipsky BA, Goldberger AC, Tompkins LS, Plordes JJ: Infections caused by non- diphtheria corynebacteria. Rev Infect Dis 1982; 4: 1220-1235. - 21. Young VM, Meyers WF, Moody MR, Schimpff SC: The emergence of coryne- form bacteria as a cause of nosocomial infections in compromised hosts. Am J Med 1981; 70: 646-650.

July 1988 The American Journal of Medicine Volume 85 113