In The Name of God

Pneumocystis pneumonia in COVID-19 patients

1

Tahereh shokohi, PhD.

• Professor in Medical Mycology

• Invasive Fungi Research Centre (IFRC), Communicable diseases Institutes/Department of

Medical Mycology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran.

OUTLINE

What is Pneumocystis jirovecii pneumonia ?

Risk factors of PCP

COVID-19 × pneumocystis

Common clinical features

Different types of specimen

Different methods for Pneumocystis jirovecii pneumonia

Conclusion

2

3

This figure were uploaded by Andre Luis Souza dos Santos Content may be subject to copyright

What is Pneumocystis jirovecii pneumonia ?

4

Pneumocystis pneumonia (PCP), also known as Pneumocystis jirovecii pneumonia

(PJP), is a form of pneumonia that is caused by the yeast-like fungus Pneumocystis

jirovecii.

Pneumocystis is commonly found in the lungs of healthy people, but being a source of

opportunistic infection, it can cause lung infections in immunocompromised.

It is especially seen in people with HIV/AIDS (who account for 30-40% of PCP

cases), those using medications that suppress the immune system, and people with

cancer, autoimmune or inflammatory conditions, and chronic lung disease.

5

Risk factors of PCP

The following group are at risk for PCP :

Persons with HIV infection whose CD4+ cells fall below 200/µL

Persons with primary immune deficiencies

Persons receiving long-term immunosuppressive regimens

Persons with hematologic and nonhematologic malignancies

Persons with severe malnutrition

6

COVID-19 × pneumocystis

SARS-CoV-2 infection led to :

A state of functional immune suppression related to CD4+ lymphopenia, which predisposes to the activation and

proliferation of the pneumocystis, with the breakout of pneumocystis pneumonia.

Also, COVID-19 patients could develop acute respiratory distress syndrome (ARDS), requiring steroids and

immunomodulatory therapies, well-known predisposing factors for developing Pneumocystis pneumonia

7

Common clinical features

Because COVID-19 and Pneumocystis pneumonia may present common clinical features, this fungal infection is often

undiagnosed

Pneumocystis pneumonia (PCP) has considerable clinical overlap with SARS-CoV-2 pneumonia, as both diseases may have :

A sub-acute

presentation,

With dry cough

and dyspnea,

profound

hypoxemia

Bilateral

multifocal

ground-glass

infiltrates

LymphopeniaAn elevated lactate

dehydrogenase

(LDH)

Silva, Laura et al.(2020). Fungal Infections in COVID-19-Positive Patients: a Lack of Optimal Treatment Options. Current Topics in Medicinal Chemistry. 20.

10.2174/156802662022200917110102

8

The higher mortality rate is likely a result of delayed diagnosis and delayed

initiation of appropriate treatment.

The prevalence of PJP in covid patients was once thought to be much

lower, but have shown that the lower reported incidence is likely a failure to

accurately diagnose PJP.

An accurate diagnosis requires access to modern medical care, which is not

available worldwide.

The prognosis of PJP is worse in patients who present with concurrent

pulmonary disease, in patients who develop pneumothorax, and in patients

who require mechanical ventilation.

Diagnosis of Pneumocystis jirovecii pneumonia(sampling)

A. Invasive Procedures

A,1. Bronchoalveolar lavage (BAL) fluid is recommended as the best specimen as it yields good negative predictive value ( A-II: ).

► Bronchoalveolar lavage (BAL) is the most common invasive procedure used to diagnose P jiroveci pneumonia (PJP). It has a

diagnostic yield that exceeds 90% (and may be higher if multiple lobes are sampled). BAL yields a lower sensitivity in patients

receiving aerosolized pentamidine, in which case a transbronchial biopsy may be performed in conjunction with BAL.

► Obtain BAL if PJP is strongly suspected and the induced sputum sample findings are negative. BAL may be used in patients

who are unable to cooperate with an induced sputum sample (eg, because of altered mental status). BAL may be less useful in

cases of suspected PJP relapse. Consultation with a pulmonologist is required for BAL. Lung biopsy

A,2, Open lung biopsy is the most invasive procedure and yields 100% sensitivity and specificity because it provides the greatest

amount of tissue for diagnosis. However, this procedure is reserved for rare cases when bronchoscopy findings are nondiagnostic.

9

Diagnosis of Pneumocystis jirovecii pneumonia(sampling)

B. Non-invasive specimens

Non-invasive specimens can be suitable alternatives ( B-II: ),

B.1. Sputum P jirovecii PCR testing may be a viable alternative to invasive testing. This could be a more timely method for sample

collection and would provide a safer alternative to bronchoscopic evaluation in patients who already have respiratory failure.

o Further studies comparing the sensitivity, specificity, and positive and negative predictive values for each sample type are needed.

10

Diagnosis of Pneumocystis jirovecii pneumonia(sampling)

B.1.1. Induced sputum (by inhalation of a hypertonic saline solution)

• Sputum induction is the quickest and least-invasive method for definitively diagnosing PJP.

• The sensitivity of sputum induction varies widely (< 50% to >90%) and depends on proficiency in using the

technique and the experience of the laboratory. Specificity is high (99%-100%).

• This study may be less sensitive in patients without HIV infection, as the immunodeficiency caused by HIV

infection typically leads to a greater alveolar load of Pneumocystis organisms.

B.1.2. Expectorated sputum has a very low sensitivity and should not be submitted for diagnosis. Pneumocystis antigen

detection assays on sputum may also be helpful but may have a low sensitivity.

11

12

Diagnosis of Pneumocystis jirovecii pneumonia

(staining)

The occurrence of COVID-19 and Pneumocystis coinfection cases

has previously been reported based on laboratory diagnosis and

seems to be underestimated in clinical practice

P. jirovecii replicates asexually by binary fission of trophic forms

(formerly trophozoites) and sexually, resulting in the formation of

an ascus (formerly cyst) containing eight ascospores.

13

Diagnosis of Pneumocystis jirovecii

pneumonia(staining)

• Since P. jirovecii is not cultivable in vitro, the

diagnosis of PCP has long relied on microscopic

detection of trophic forms and cysts using different

stains[Giemsa(GS),toluidineblueO(TBO),calcofluor

white (CW) and Gomori methenamine silver

(GMS)].

Trophozoites in BAL

material

Cysts in BAL material

13

VS

Diagnosis of Pneumocystis jirovecii pneumonia (staining)

Gomori methenamine silver (GMS) staining

Pneumocystis jiroveciCalcofluor white staining of Pneumocystis jiroveci

14

Diagnosis of Pneumocystis jirovecii pneumonia (Immunofluorescence)

These stains were supplanted in the mid-1990s by direct or indirect IF using anti-P.jirovecii monoclonal antibodies.

Immunofluorescence assays (direct& indirect) are recommended as the most sensitive microscopic method (recommendation

A-II: ).

• Use mainly anti-cyst antibodies

• More rarely, a mixture of anti-cyst and anti-trophic form antibodies

• The sensitivity of IF, irrespective of the technique used(direct or indirect), was better than conventional

staining(recommendation A-II).

• Since a 1:10 ratio exists between asci and trophic forms, we recommend the use of a combination of two stains, one to

detect ‘cysts’(anti-cyst IF assay is the most sensitive, compared with conventional staining using TBO, CW or GMS) and

another to detect ‘trophozoites’ (GS) (A-III).

• The combination of techniques allows detection of both forms and evaluation of the ascus/trophic form ratio

15

II. Real-time PCR(Quantitative PCR) is recommended for

the routine diagnosis of PCP ( A-II: ), and may be useful in

distinguishing between colonization and active infection

Bronchoalveolar lavage (BAL) fluid is recommended as

the best specimen as it yields good negative predictive

value ( A-II: ).

Non-invasive specimens can be suitable alternatives ( B-

II:),

PCP cannot be ruled out in case of a negative PCR result

( A-II: ).

Diagnosis of Pneumocystis jirovecii pneumonia

(QPCR)

16

Diagnosis of Pneumocystis jirovecii pneumonia (BDG)

Detecting β-d-glucan (BDG) in serum can contribute to the diagnosis but not the follow-

up of PCP ( A-II: ).

BDG is particularly relevant given concerns about healthcare transmission associated

with performing bronchoscopy in these patients.

A negative serum β-D-Glucan (BDG) result can exclude PCP in a patient at risk ( A-II: ),

whereas a positive test result may indicate other fungal infections.

β-D-Glucan is a cell-wall component of many fungi, including Candida, Aspergillus, and

Pneumocystis (but not the Zygomycetes).

It has been shown to be a sensitive test to detect PJP in a meta-analysis of 13 studies

assessing the sensitivity, specificity, and overall accuracy of the test.

A negative serum BDG result is sufficient for excluding PJP only in patients with HIV

infection.

In non-HIV cases, the results should be interpreted in parallel with clinical and radiologic

findings. 17

Diagnosis of Pneumocystis jirovecii pneumonia (LDH)

A lactic dehydrogenase (LDH) study is performed as part of the initial workup.

LDH levels are usually elevated (>220 U/L) in patients with P jiroveci pneumonia (PJP). They are

elevated in 90% of patients with PJP who are infected with HIV.

The study has a high sensitivity (78%-100%); its specificity is much lower because other disease

processes can result in an elevated LDH level.

LDH levels appear to reflect the degree of lung injury. They should decline with successful treatment.

Consistently elevated LDH levels during treatment may indicate therapy failure and a worse prognosis

18

Take Home Massages

In patients affected by COVID-19 pneumonia, even if recovered, a PJP must be

always ruled out if a worsening of respiratory failure and/or a typical CT scan

suggests a secondary infection, especially if the patient has COVID-related risk

factors for PJP development. Moreover, although negative beta-D-glucan tests

have a high negative predictive value in diagnosing PJP, this case confirms that

in atypical immunosuppressed population the negativity of serum beta-D-

glucan may be insufficient to rule out PJP diagnosis.

19

20