Pneumocystis carinii infection. Update and review

Late-onset Pneumocystis jirovecii pneumonia post-allogeneic stem cell transplantation after time-dependent discontinuation of prophylaxis

INTRODUCTION

Pneumocystis jirovecii pneumonia (PJP) is a rare complication of hematopoietic stem cell transplantation (HSCT). Primary prophylaxis for 6-12 months post-HSCT is the standard approach. However, there is no consensus regarding the optimal duration of prophylaxis.

METHODS

We identified patients who developed PJP more than 1-year post-HSCT. All patients had previously received 12 months of PJP prophylaxis. PJP was diagnosed based on clinical findings and the detection of P. jirovecii in bronchoalveolar lavage (BAL) using polymerase chain reaction (PCR). The CD4+ T-cell percentage was determined using flow cytometry. Data expressed as median (interquartile range).

RESULTS

Ten patients developed PJP at 17.5 months (16-24 months) post-HSCT. PJP diagnosis occurred 5.5 months (3-15 months) after discontinuing prophylaxis. Eight patients received anti-thymocyte globulin (ATG) as graft versus host disease (GVHD) prophylaxis. At diagnosis, only one patient had lymphopenia; all patients had CD4+ T-lymphocyte counts ≥0.2 × 109 /L (median 0.337 × 109 /L). Three patients had concomitant bacterial infections. The clinical presentation was mild; only three required hospitalization, none of them required intensive care and there were no deaths.

CONCLUSION

There is a need to develop risk-adapted prophylactic strategies in the contemporary era using ATG-based GVHD prophylaxis.

Meta-Analysis and Systematic Literature Review of the Genus Pneumocystis in Pet, Farm, Zoo, and Wild Mammal Species

A systematic literature search on Pneumocystis in 276 pet, farm, zoo, and wild mammal species resulted in 124 publications originating from 38 countries that were analyzed descriptively and statistically, for which inclusion and exclusion criteria were exactly defined. The range of recorded Pneumocystis prevalence was broad, yet in half of the citations a prevalence of ≤25% was documented. Prevalence was significantly dependent on the method used for Pneumocystis detection, with PCR revealing the highest percentages. Pet animals showed the lowest median Pneumocystis prevalence, followed by farm, wild, and zoo animals. In contrast, pet and farm animals showed higher proportions of high-grade infection levels compared to zoo and wild mammals. Only in individual cases, all of them associated with severe Pneumocystis pneumonia, was an underlying immunosuppression confirmed. Acquired immunosuppression caused by other diseases was frequently discussed, but its significance, especially in highly immunosuppressive cases, needs to be clarified. This meta-analysis supported a potential influence of the social and environmental factors of the host on Pneumocystis transmission in wildlife, which must be further elucidated, as well as the genetic diversity of the fungus.

Efficacy of initial caspofungin plus trimethoprim/sulfamethoxazole for severe PCP in patients without human immunodeficiency virus infection

BACKGROUND

The number of pneumocystis pneumonia (PCP) cases is increasing in immunocompromised patients without human immunodeficiency virus infection (HIV), causing serious morbidity with high mortality. Trimethoprim/sulfamethoxazole (TMP/SMZ) monotherapy has limited effectiveness in the treatment of PCP. Clinical data on whether initial caspofungin plus TMP/SMZ for this disease is superior to monotherapy in non-HIV-infected patients are limited. We aimed to compare the clinical effectiveness of these regimens for severe PCP in non-HIV patients.

METHODS

A retrospective study reviewed 104 non-HIV-infected patients with confirmed PCP in the intensive care unit between January 2016 and December 2021. Eleven patients were excluded from the study because TMP/SMZ could not be used due to severe hematologic disorders or clinical data were missing. All enrolled patients were divided into three groups according to different treatment strategies: Group 1 received TMP/SMZ monotherapy, Group 2 received caspofungin combined with TMP/SMZ as first-line therapy, and Group 3 initially received TMP/SMZ monotherapy and later received caspofungin as salvage therapy. The clinical characteristics and outcomes were compared among the groups.

RESULTS

A total of 93 patients met the criteria. The overall positive response rate of anti-PCP treatment was 58.06%, and the overall 90-day all-cause mortality rate was 49.46%. The median APACHE II score was 21.44. The concurrent infection rate was 74.19%, among whom 15.05% (n = 14) of those patients had pulmonary aspergillosis, 21.05% (n = 20) had bacteremia, and 23.65% (n = 22) had CMV infections. The patients who received initial caspofungin combination with TMP/SMZ had the best positive response rate (76.74%) compared to others (p = 0.001). Furthermore, the group that received initial caspofungin combined with TMP/SMZ had a 90-day all-cause mortality rate (39.53%) that was significantly different from that of the shift group (65.51%, p = 0.024), but this rate showed no statistically significant difference compared with that in the monotherapy group (48.62%, p = 0.322). None of the patients had serious adverse events from caspofungin therapy.

CONCLUSIONS

For non-HIV-infected patients with severe PCP, initial combination therapy with caspofungin and TMP/SMZ is a promising first-line treatment option compared with TMP/SMZ monotherapy and combination therapy as salvage therapy.

A comprehensive clinical guide for Pneumocystis jirovecii pneumonia: a missing therapeutic target in HIV-uninfected patients

INTRODUCTION

Pneumocystis jirovecii is an opportunistic, human-specific fungus that causes Pneumocystis pneumonia (PCP). PCP symptoms are nonspecific. A patient with P. jirovecii and another lung infection faces a diagnostic challenge. It may be difficult to determine which of these agents is responsible for the clinical symptoms, preventing effective treatment. Diagnostic and treatment efforts have been made more difficult by the rising frequency with which coronavirus 2019 (COVID-19) and PCP co-occur.

AREAS COVERED

Herein, we provide a comprehensive review of clinical and pharmacological recommendations along with a literature review of PCP in immunocompromised patients focusing on HIV-uninfected patients.

EXPERT OPINION

PCP may be masked by identifying co-existing pathogens that are not necessarily responsible for the observed infection. Patients with severe form COVID-19 should be examined for underlying immunodeficiency, and co-infections must be considered as co-infection with P. jirovecii may worsen COVID-19's severity and fatality. PCP should be investigated in patients with PCP risk factors who come with pneumonia and suggestive radiographic symptoms but have not previously received PCP prophylaxis. PCP prophylaxis should be explored in individuals with various conditions that impair the immune system, depending on their PCP risk.

First Molecular Detection of Pneumocystis spp. in the Golden Jackal (Canis aureus)

Forty-six golden jackals (Canis aureus) were collected between November 2020 and February 2021 in five counties of Serbia. Lung samples were screened for the presence of Pneumocystis DNA by pan-Pneumocystis PCR on the mtLSU rRNA gene obtaining PCR products of 370 bp in length. Pneumocystis DNA was detected in the lungs from 6/46 (13.04%) golden jackals. Four were females and two were males; four were classified as adults and two as subadults. Positive samples were confirmed in 4/5 investigated counties. No gross pathologic lung lesions were observed in this study. The sequences of Pneumocystis spp. from golden jackals were identical to one another and showed the highest similarity with Pneumocystis spp. sequences of dogs (98% nucleotide identity). The genetic variation was comparable to Pneumocystis spp. of raccoon dogs (95-97% nucleotide identity), red foxes (91-95% nucleotide identity), ferrets (86% nucleotide identity), and another Pneumocystis type in dogs (P. canis Ck2, 81% nucleotide identity) was higher. Golden jackals may be carriers and may play a nonnegligible role in the spread of Pneumocystis spp. Although this finding cannot be directly related to any clinical manifestation or pathologic lesions, a possible role in the exacerbation of different pulmonary disorders should be considered.

Fungal diseases at the medical front door

Fungal diseases are an increasingly recognized cause of mortality worldwide and often pose diagnostic challenges. This article focuses on common fungal diseases as they may present in the acute medical unit, looking at the initial investigation and management of four common diseases: Pneumocystis jirovecii pneumonia, cryptococcal meningitis, candidaemia and allergic bronchopulmonary aspergillosis. There is an increase in morbidity and mortality if these conditions are not correctly diagnosed and thus appropriate therapy is delayed. A better understanding of the initial investigation and management of these conditions will improve the outcome of patients with fungal diseases presenting to the 'medical front door'.

Single-center outbreak of Pneumocystis jirovecii pneumonia in heart transplant recipients

BACKGROUND

Pneumocystis jirovecii pneumonia (PJP) outbreaks are described in solid organ transplant recipients. Few reports suggest interhuman transmission with important infection control implications. We described a large PJP outbreak in heart transplant (HTx) recipients.

METHODS

Six cases of PJP occurred in HTx recipients within 10 months in our hospital. Demographics, clinical characteristics, treatment and outcomes were described. To identify contacts among individuals a review of all dates of out-patient visits and patient hospitalizations was performed. Cross exposure was also investigated using genotyping on PJ isolates.

RESULTS

At the time of PJP-related hospitalization, patients' mean age was 49 ± standard deviation 4 years, median time from HTx was 8 (25%-75% interquartile range [Q1-Q3] 5-12) months and none of the cases were on prophylaxis. At PJP-related admission, 5 patients had CMV reactivation, of whom 4 were on antiviral preemptive treatment. Median in-hospital stay was 30 (Q1-Q3, 28-48) days; and 2 cases required intensive care unit admission. All patients survived beyond 2 years. Transmission map analysis suggested interhuman transmission in all cases (presumed incubation period, median 90 [Q1-Q3, 64-91] days). Genotyping was performed in 4 cases, demonstrating the same PJ strain in 3 cases.

CONCLUSIONS

We described a large PJP cluster among HTx recipients, supporting the nosocomial acquisition of PJP through interhuman transmission. Based on this experience, extended prophylaxis for more than 6 months after HTx could be considered in specific settings. Further work is required to understand its optimal duration and timing based on individual risk factor profiles and to define standardized countermeasures to prevent and limit PJP outbreaks.

Lung Infections

A review of pulmonary infections of all types with diagnostic and morphological features.

Pneumocystosis in dogs: meta-analysis of 43 published cases including clinical signs, diagnostic procedures, and treatment

We evaluated 43 published cases of dogs with confirmed Pneumocystis infection regarding the value of clinical parameters indicating the presence of the disease as well as tools for the detection of the pathogen. The assessed parameters included clinical signs, laboratory findings, results of thoracic radiography, autopsy, histopathology, methods for the detection of Pneumocystis, as well as medical therapy. Pneumocystosis was diagnosed most often in certain breeds (Cavalier King Charles Spaniel, Miniature Dachshund) with a predisposition for impaired immunity. The median age of the dogs was 1 y. Chronic therapy-resistant respiratory signs, such as tachypnea, dyspnea, and cough, along with leukocytosis, neutrophilia, and hypogammaglobulinemia, were the most frequently described clinical and clinicopathologic abnormalities. Pneumocystosis can be masked by coinfections with other respiratory pathogens, and the successful detection of Pneumocystis organisms is of major relevance. Several detection methods have been used in the past, but only a few provide reliable results. In 2017, the cytologic evaluation of Giemsa-stained bronchoalveolar lavage samples is generally used, even if sensitivity is only moderate. More reliable results can be achieved using special stains or sensitive molecular techniques. Fast and reliable detection of Pneumocystis is the essential basis for appropriate treatment and higher survival chances for dogs.

The incidence, mortality and timing of Pneumocystis jiroveci pneumonia after hematopoietic cell transplantation: a CIBMTR analysis

Pneumocystis jiroveci pneumonia (PJP) is associated with high morbidity and mortality after hematopoietic stem cell transplantation (HSCT). Little is known about PJP infections after HSCT because of the rarity of disease given routine prophylaxis. We report the results of a Center for International Blood and Marrow Transplant Research study evaluating the incidence, timing, prophylaxis agents, risk factors and mortality of PJP after autologous (auto) and allogeneic (allo) HSCT. Between 1995 and 2005, 0.63% allo recipients and 0.28% auto recipients of first HSCT developed PJP. Cases occurred as early as 30 days to beyond a year after allo HSCT. A nested case cohort analysis with supplemental data (n=68 allo cases, n=111 allo controls) revealed that risk factors for PJP infection included lymphopenia and mismatch after HSCT. After allo or auto HSCT, overall survival was significantly poorer among cases vs controls (P=0.0004). After controlling for significant variables, the proportional hazards model revealed that PJP cases were 6.87 times more likely to die vs matched controls (P<0.0001). We conclude PJP infection is rare after HSCT but is associated with high mortality. Factors associated with GVHD and with poor immune reconstitution are among the risk factors for PJP and suggest that protracted prophylaxis for PJP in high-risk HSCT recipients may improve outcomes.

A case report of pulmonary coinfection of Strongyloides stercoralis and Pneumocystis jiroveci

A case of pulmonary coinfection by Strongyloides stercoralis and Pneumocystis jiroveci has been detected in an AIDS patient treated in the Respiratory Intensive Care Unit of the Muñiz Hospital. At diagnosis, the patient presented cough with mucopurulent expectoration, dyspnea, fever, bilateral pulmonary infiltrates on the chest X-ray, negative bacilloscopy for acid fast bacteria and a CD4(+) T lymphocytes count of 52 cells/µL. The microbiological diagnosis was achieved by microscopic observation of the respiratory secretions obtained by bronchoalveolar lavage, while the wet mount examination revealed rhabditiform and filariform larvae of the nematode and foamy exudates, pathognomonic of the pulmonary pneumocystosis. It was the unique case of this association among about 3 000 samples performed in our laboratory in the last 10 years and diagnosed by microscopy. Other complementary stains (a rapid modification of Grocott, Kinyoun and Giemsa) were applied to the smears after the diagnosis of mycotic and parasitary infections achieved by fresh microscopy. Both physicians and microbiologists should take into account the possible coexistence of respiratory pathogens in immunocompromised patients, such as those with AIDS.

Inflammation

Inflammation was described as early as 3000 BC in an Egyptian papyrus [1] and is still a common problem despite continuous advancements in prevention and treatment methods. The delineation of the site and extent of inflammation are crucial to the clinical management of infection and for monitoring the response to therapy [2].

Antimicrobial activity of aurein 2.5 against yeasts

Fungal infections with multiple resistance to conventional antifungals are increasingly becoming a medical problem, and there is an urgent need for new antifungal compounds with novel mechanisms of action. Here, we show that aurein 2.5, a naturally occurring peptide antibiotic, displays activity against the fungal strains: Rhodotorula rubra and Schizosaccharomyces pombe (MICs < 130 μM). The peptide adopted high levels of membrane-interactive α-helical structure (> 65%) in the presence of lipid membranes derived from these organisms and showed strong propensities to penetrate (π ≥ 13 mN m(-1) ) and lyse them (> 70%). Based on these data, we suggest that aurein 2.5 kills yeasts via membranolytic mechanisms and may act as a template for the development of therapeutically useful antifungal agents.

Epidemiological characteristics of pulmonary pneumocystosis and concurrent infections in pigs in Jeju Island, Korea

Epidemiological characteristics of swine pulmonary Pneumocystis (P.) carinii and concurrent infections were surveyed on Jeju Island, Korea, within a designated period in 172 pigs submitted from 54 farms to the Department of Veterinary Medicine, Jeju National University. The submitted cases were evaluated by histopathology, immunohistochemistry, PCR/RT-PCR, and bacteriology. P. carinii infection was confirmed in 39 (22.7%) of the 172 pigs. Histopathologically, the lungs had moderate to severe lymphohistioctyic interstitial pneumonia with variable numbers of fungal organisms within lesions. Furthermore, porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV-2) co-infection was a common phenomenon (12.8%, 20.5%, and 48.7% were positive for PRRS, PCV-2, or both, respectively, as determined by PCR/RT-PCR). Infection was much more concentrated during winter (December to March) and 53.8% of the infected pigs were 7- to 8-weeks old. In addition, three pigs showed co-infection with bacteria such as Pasteurella multocida and Streptococcus suis. The results of the present study suggest that the secondary P. carinii infection is common following primary viral infection in swine in Korea. They further suggest that co-infection of P. carinii might be enhanced by the virulence of primary pathogens or might have synergistic effects in the pigs with chronic wasting diseases.

Evaluation of the current management protocols for prophylaxis against Pneumocystis jiroveci pneumonia and other opportunistic infections in patients living with HIV/AIDS

Opportunistic infections (OIs) are a leading cause of mortality and morbidity in patients living with HIV/AIDS. Data on the proper administration of prophylactic regimes for the prevention of OIs in such patients are scarce. A total of 205 confirmed HIV-infected patients were enrolled in the study from the inpatient wards and outpatient services. The treatment given to them for the prevention of Pneumocystis carinii (jiroveci) pneumonia was compared with the established guidelines and the proportions of those receiving proper treatment were calculated. Primary prophylaxis was seen to be satisfactory in the case of P. carinii (jiroveci) pneumonia. The prophylaxis was not given properly for tuberculosis and other common OIs. Secondary prophylaxis was up to the mark. Prophylaxis in AIDS patients seems to be a major problem area and a lot of efforts need to be directed toward it since patients suffering from AIDS are bound to have a downhill course despite provision of all available treatment options.

A new method for the detection of Pneumocystis jirovecii using flow cytometry

Pneumocystis jirovecii is an opportunistic pathogen responsible for severe pneumonia in immunocompromised patients. Its diagnosis has been based upon direct microscopy either by classic staining (Gomori Grocott) or by epifluorescence microscopy (immunofluorescence staining, IFS), both of which are time-consuming and low on sensitivity. Our aim was to develop a flow cytometric (FC) protocol for the detection of P. jirovecii on respiratory samples. In our study, 420 respiratory samples were analysed in parallel by IFS and FC, and compared from clinical diagnosis to its resolution upon specific anti-Pneumocystis therapy. The optimum specific antibody concentration for FC analysis was determined to be 10 microg/ml, without any cross-reactions to bacteria or fungi. All positive cases detected by IFS were positive by FC; however, FC classified eight samples to be positive which were classified as negative by routine technique. These samples were obtained from patients with respiratory symptoms who responded favourably to Pneumocystis-specific therapy and were subsequently considered to be true-positives. Using clinical diagnosis as a reference method, FC showed 100% sensitivity and specificity, whereas IFS showed 90.9% sensitivity and 100% specificity. According to our results, a new diagnostic approach is now available to detect P. jirovecii in respiratory samples.

Epidemiology of invasive mycoses in North America

The incidence of invasive mycoses is increasing, especially among patients who are immunocompromised or hospitalized with serious underlying diseases. Such infections may be broken into two broad categories: opportunistic and endemic. The most important agents of the opportunistic mycoses are Candida spp., Cryptococcus neoformans, Pneumocystis jirovecii, and Aspergillus spp. (although the list of potential pathogens is ever expanding); while the most commonly encountered endemic mycoses are due to Histoplasma capsulatum, Coccidioides immitis/posadasii, and Blastomyces dermatitidis. This review discusses the epidemiologic profiles of these invasive mycoses in North America, as well as risk factors for infection, and the pathogens' antifungal susceptibility.

Fact or fiction: does the non-HIV/AIDS immunosuppressed patient need Pneumocystis jiroveci pneumonia prophylaxis? An updated literature review

BACKGROUND

Pneumocystis jiroveci pneumonia (PJP) is a potentially fatal fungal infection occurring in immunocompromised patients.

OBJECTIVE

To determine whether PJP prophylaxis is required in the non-human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) immunocompromised patient and, if so, the optimal prophylactic therapy.

METHODS

A thorough literature review, with the appropriate MeSH terms, was conducted using PubMed, Medline, and The Cochrane Database. A number of cases describing PJP in patients with various systemic diseases and immunosuppressive medications, along with a Cochrane review, were highlighted.

RESULTS

Although there are a number of case reports in the literature, the only collagen vascular disease with an increased incidence of PJP is Wegener granulomatosis. Oral trimethoprim-sulfamethoxazole continues to be the prophylaxis of choice for PJP.

CONCLUSION

There is currently no evidence to recommend PJP prophylaxis in the non-HIV/AIDS immunocompromised population. If physicians do decide to use prophylaxis, they should always weigh the benefits with the potential risks. Further studies are needed to better quantify the risks of PJP with immunosuppressive medications.

Oral atovaquone for the treatment of severe Pneumocystis jirovecii pneumonia in a patient with glucose-6-phosphate dehydrogenase deficiency

We present a case of severe Pneumocystis jirovecii pneumonia and coexisting cytomegalovirus infection in a glucose-6-phosphate dehydrogenase (G6PD) enzyme deficient woman with anaplastic astrocytoma on temozolomide and corticosteroid therapy. She was successfully treated with oral atovaquone and ganciclovir. Atovaquone represents a safe alternative in severe Pneumocystis infection when trimethoprim-sulfamethoxazole (co-trimoxazole) is contraindicated.

Respiratory infections in immunocompromised patients

PURPOSE OF REVIEW

Immunosuppressive states and therapies are becoming common in clinical practice. Recent advances and trends in bacterial, fungal, viral and parasitic pulmonary infections in immunosuppressed patients are described.

RECENT FINDINGS

Pulmonary infections can jeopardize the prognosis of immunosuppressed patients. The number of patients infected with multidrug-resistant bacteria or opportunistic pathogens like rapid-growing environmental mycobacteria, Strongyloides stercoralis or Rhodococcus equi is increasing with the increased numbers of immunosuppressed patients due to HIV/AIDS and the potent immunosuppressive therapies used in solid-organ and haematopoietic transplantations, cancer and systemic illnesses. The slow development of more effective antibiotics underlines the necessity of preventive measures, development of rapid detection tests for pathogens and appropriate treatment regimens to avoid development of further resistance.

SUMMARY

Adequate prophylaxis, clinical suspicion, microbiological and molecular investigations, drug susceptibility-based antibiotic treatment and new drug development are strategies required to face up to the challenge of pulmonary infections in immunodepressed patients.

Pneumocystis jiroveci Pneumonia

Pneumocystis pneumonia (PCP) is one of the most common pulmonary infections in persons with impaired cell-mediated immunity, and particularly those infected with human immunodeficiency virus (HIV).1–7 Pneumocystis was first described in the lungs of guinea pigs, during experiments on American trypanosomiasis by Carlos Chagas8 in 1909 and by Antonio Carinii9 in 1910. Both considered the cysts of Pneumocystis as part of the trypanosome’s life cycle. Shortly afterward the Delanoes10 found identical forms in the lungs of rats that had not been infected with trypanosomes and recognized the organism as a separate species. The name Pneumocystis carinii, was given to this organism as a generic name (Greek:pneumon, “lung”; kystis, “cyst”), honoring Carinii.11

Interaction of Pneumocystis carinii with dendritic cells and resulting host responses to P. carinii

To assess the interaction of Pneumocystis carinii with dendritic cells (DCs), and the consequences of the response of the host immune system to P. carinii antigens when DC are pulsed with P. carinii, murine DC were pulsed with P. carinii, and the resultant P. carinii host responses assessed in vitro and in vivo. P. carinii interacted with murine bone marrow-derived DC in vitro in part via mannose receptors. DC pulsed with P. carinii did not demonstrate increased expression of the cell surface markers MHC II, CD40, CD54, CD80 (B7.1), and CD86 (B7.2). The release of interleukin (IL)-4 was increased, but there was no increase in the release of interleukin (IL)-12p40, IL-10, tumor necrosis factor-alpha, IL-6, and nitrite compared with naive DC. In vivo administration of DC pulsed with P. carinii induced a P. carinii-specific response, generating CD4+ cells that proliferated and released IL-4, but not interferon-gamma, in response to P. carinii-pulsed DC in vitro. In vivo administration of DC pulsed with P. carinii also induced P. carinii-specific immunoglobulin (Ig)G1, IgG2a, and IgG2b, but not IgG3, antibodies in serum, and lung lavage fluid. Finally, CD4+ depleted mice immunized with DC pulsed with P. carinii demonstrated suppression of lung growth of P. carinii after intratracheal challenge with P. carinii at 3 and 16 weeks after immunization. These observations provide insight into DC-P. carinii interactions, and support the concept that a vaccine that includes DC pulsed with P. carinii can mount a humoral and T helper 2-type cellular response to P. carinii sufficient to suppress the growth of P. carinii in the lung.

Aromatic diamidines as antiparasitic agents

Parasitic infections are widespread in developing countries and frequently associated with immunocompromised patients in developed countries. Consequently, such infections are responsible for a significant amount of human mortality, morbidity and economic hardship. A growing consensus has identified the urgent need for the development of new antiparasitic compounds, mostly due to the large number of drug-resistant parasites and the fact that currently available drugs are expensive, highly toxic, require long treatment regimens and frequently exhibit significantly reduced activity towards certain parasite strains and evolutive stages. In this context, the activity of aromatic diamidines has been explored against a widespread range of micro-organisms, and the authors' present aim is to review the current status of chemotherapy with these compounds against human parasitic infections.

Utility of reflex gomori methenamine silver staining forPneumocystis jirovecii on bronchoalveolar lavage cytologic specimens: A review

Pneumocystis jiroveci (Pj; formerly Pneumocystis carinii) is an opportunistic pathogen causing life-threatening pneumonia (Pneumocystis pneumonia) in immunosuppressed individuals. Its diagnosis is dependent on identification in bronchoalveolar lavage (BAL) specimens. Gomori's methenamine silver nitrate (GMS) stain has been advocated to highlight the organisms in BAL specimens. This study was performed to determine the utility of reflex GMS staining on all BAL specimens for identifying Pj.All BAL specimens from years 2000 to 2004 were processed as cytospins and stained with Papanicolaou (Pap) and GMS stains. A total of 2,984 BAL specimens were identified. A total of 116 (3.9% of total BAL) BAL specimens were diagnostic of Pj. The diagnostic specimens were grouped as follows: 103 (88.8% of total positive cases) Pj identified with both Pap and GMS staining; 11 (9.5% of total positive cases) Pj identified only with Pap staining; and 2 (1.7% of total positive cases) Pj identified only with GMS staining. In conclusion, the prevalence of Pj in BAL specimens is 3.9%, which can be attributed to improved management of immunocompromised patients. Performing reflex GMS staining on all BAL specimens does not improve the diagnostic identification of Pj since the majority (98.3%) of diagnoses can be rendered on Pap stained slides. A cost analysis for GMS staining on 2,879 GMS-negative BAL specimens was estimated at $143,950. Thus, from diagnostic and cost benefit perspectives, GMS staining can be recommended only on cases where Pap stain is negative, and the clinical presentation is consistent with Pneumocystis pneumonia.