Pneumocystis jirovecii and Cystic Fibrosis in Brittany, France

Practical Guidance for Clinical Microbiology Laboratories: Updated guidance for processing respiratory tract samples from people with cystic fibrosis

SUMMARYThis guidance presents recommendations for clinical microbiology laboratories for processing respiratory samples from people with cystic fibrosis (pwCF). Appropriate processing of respiratory samples is crucial to detect bacterial and fungal pathogens, guide treatment, monitor the epidemiology of cystic fibrosis (CF) pathogens, and assess therapeutic interventions. Thanks to CF transmembrane conductance regulator modulator therapy, the health of pwCF has improved, but as a result, fewer pwCF spontaneously expectorate sputum. Thus, the collection of sputum samples has decreased, while the collection of other types of respiratory samples such as oropharyngeal and bronchoalveolar lavage samples has increased. To optimize the detection of microorganisms, including Pseudomonas aeruginosa, Staphylococcus aureus, Haemophilus influenzae, and Burkholderia cepacia complex; other less common non-lactose fermenting Gram-negative bacilli, e.g., Stenotrophomonas maltophilia, Inquilinus, Achromobacter, Ralstonia, and Pandoraea species; and yeasts and filamentous fungi, non-selective and selective culture media are recommended for all types of respiratory samples, including samples obtained from pwCF after lung transplantation. There are no consensus recommendations for laboratory practices to detect, characterize, and report small colony variants (SCVs) of S. aureus, although studies are ongoing to address the potential clinical impact of SCVs. Accurate identification of less common Gram-negative bacilli, e.g., S. maltophilia, Inquilinus, Achromobacter, Ralstonia, and Pandoraea species, as well as yeasts and filamentous fungi, is recommended to understand their epidemiology and clinical importance in pwCF. However, conventional biochemical tests and automated platforms may not accurately identify CF pathogens. MALDI-TOF MS provides excellent genus-level identification, but databases may lack representation of CF pathogens to the species-level. Thus, DNA sequence analysis should be routinely available to laboratories for selected clinical circumstances. Antimicrobial susceptibility testing (AST) is not recommended for every routine surveillance culture obtained from pwCF, although selective AST may be helpful, e.g., for unusual pathogens or exacerbations unresponsive to initial therapy. While this guidance reflects current care paradigms for pwCF, recommendations will continue to evolve as CF research expands the evidence base for laboratory practices.

Metagenomics Applied to the Respiratory Mycobiome in Cystic Fibrosis

Cystic fibrosis (CF) is a genetic disorder characterized by chronic microbial colonization and inflammation of the respiratory tract (RT), leading to pulmonary exacerbation (PEx) and lung damage. Although the lung bacterial microbiota has been extensively studied, the mycobiome remains understudied. However, its importance as a contributor to CF pathophysiology has been highlighted. The objective of this review is to provide an overview of the current state of knowledge regarding the mycobiome, as described through NGS-based studies, in patients with CF (pwCF).Several studies have demonstrated that the mycobiome in CF lungs is a dynamic entity, exhibiting a lower diversity and abundance than the bacterial microbiome. Nevertheless, the progression of lung damage is associated with a decrease in fungal and bacterial diversity. The core mycobiome of the RT in pwCFs is mainly composed of yeasts (Candida spp., Malassezia spp.) and molds with lower abundance. Some fungi (Aspergillus, Scedosporium/Pseudallescheria) have been demonstrated to play a role in PEx, while the involvement of others (Candida, Pneumocystis) remains uncertain. The "climax attack" ecological model has been proposed to explain the complexity and interplay of microbial populations in the RT, leading to PEx and lung damage. NGS-based studies also enable the detection of intra- and interkingdom correlations between fungi and bacteria. Further studies are required to ascertain the biological and pathophysiological relevance of these correlations. Finally, with the recent advent of CFTR modulators, our understanding of the pulmonary microbiome and mycobiome in pwCFs is about to change.

Fungal Colonization of the Airways of Patients with Cystic Fibrosis: the Role of the Environmental Reservoirs

Filamentous fungi frequently colonize the airways of patients with cystic fibrosis and may cause severe diseases, such as the allergic bronchopulmonary aspergillosis. The most common filamentous fungi capable to chronically colonize the respiratory tract of the patients are Aspergillus fumigatus and Scedosporium species. Defining the treatment strategy may be challenging, the number of available drugs being limited and some of the causative agents being multiresistant microorganisms. The knowledge of the fungal niches in the outdoor and indoor environment is needed for understanding the origin of the contamination of the patients. In light of the abundance of some of the causative molds in compost, agricultural and flower fields, occupational activities related to such environments should be discouraged for patients with cystic fibrosis (CF). In addition, the microbiological monitoring of their indoor environment, including analysis of air and dust on surfaces, is essential to propose preventive measures aiming to reduce the exposure to environmental molds. Nevertheless, some specific niches were also identified in the indoor environment, in relation with humidity which favors the growth of thermotolerant molds. Potted plants were reported as indoor reservoirs for Scedosporium species. Likewise, Exophiala dermatitidis may be spread in the kitchen via dishwashers. However, genotype studies are still required to establish the link between dishwashers and colonization of the airways of CF patients by this black yeast. Moreover, as nothing is known regarding the other filamentous fungi associated with CF, further studies should be conducted to identify other potential specific niches in the habitat.

Fungal microbiota dynamics and its geographical, age and gender variability in patients with cystic fibrosis

OBJECTIVES

In cystic fibrosis (CF), there is a predisposition to bronchial colonization by potentially pathogenic microorganisms, such as fungi. Our aims were to describe the dynamics of respiratory mycobiota in patients with CF and to evaluate the geographic, age and gender variability in its distribution.

METHODS

Cohort study in which 45 patients with CF from four hospitals in three Spanish cities were followed up during a 1-year period, obtaining spontaneous sputum samples every 3 to 6 months. Fungal microbiota were characterized by Internal Transcribed Spacer sequencing and Pneumocystis jirovecii was identified by nested PCR in a total of 180 samples.

RESULTS

The presence of fungi were detected in 119 (66.11%) of the 180 samples and in 44 (97.8%) of the 45 patients: 19 were positive and 1 negative throughout all follow-ups and the remaining 25 presented alternation between positive and negative results. A total of 16 different genera were identified, with Candida spp. (50/180, 27.78%) and Pneumocystis spp. (44/180, 24.44%) being the most prevalent ones. The distribution of fungal genera was different among the evaluated centres (p < 0.05), by age (non-adults aged 6-17 years vs. adults aged ≥18 years) (p < 0.05) and by gender (p < 0.05).

DISCUSSION

A high prevalence of fungal respiratory microbiota in patients with CF was observed, whose dynamics are characterized by the existence of multiple cycles of clearance and colonization, reporting the existence of geographic, age and gender variability in the distribution of fungal genera in this disease.

Pneumocystis jirovecii among patients with cystic fibrosis and their household members

We conducted a pilot study of patients with cystic fibrosis (CF) to assess intra-family transmission of P. jirovecii and compare it with data on other prevalent pathogens such as P. aeruginosa and S. pneumoniae, in which respiratory transmission has already been documented. Oral swab samples from 10 patients with CF and 15 household members were collected at baseline and 2 weeks later. P. aeruginosa and S. pneumoniae were assessed using standardized culture methods and PCR, and P. jirovecii was assessed using real and nested PCR, genotyping the positive samples by direct sequencing. P. aeruginosa cultures were positive for 7/10 (70%) of patients with CF at baseline and was identified by PCR in 8/10 (80%) of cases at baseline and 2 weeks later. S. pneumoniae cultures were negative for all patients, but the microorganism was identified by PCR in two cases. P. jirovecii was detected by real time and nested PCR in 5/10 (50%) of the patients at the two time points. In the household members, P. aeruginosa and P. jirovecii were identified in 7/15 (46.7%), and S. pneumoniae was identified in 8/15 (53,3%). The concordance of positive or negative pairs of patients with CF and their household members was 33.3% (5/15) for P. aeruginosa, 46.7% (7/15) for S. pneumonia and 93.3% (14/15) for P. jirovecii. The concordance for P. jirovecii genotypes among five pairs with available genotype was 100%. This study suggests for the first time the possible transmission of Pneumocystis in the home of patients with CF, indicating that patients and their household members are reservoirs and possible sources of infection.

LAY SUMMARY

This study suggests for the first time the possible transmission of Pneumocystis in the family environment of patients with cystic fibrosis, indicating that patients and their household members are reservoirs and possible sources of this infection.

Pneumocystis jirovecii in Patients With Cystic Fibrosis: A Review

Pneumocystis pneumonia (PCP) remains the most frequent AIDS-defining illness in developed countries. This infection also occurs in non-AIDS immunosuppressed patients, e.g., those who have undergone an organ transplantation. Moreover, mild Pneumocystis jirovecii infections related to low pulmonary fungal burden, frequently designated as pulmonary colonization, occurs in patients with chronic pulmonary diseases, e.g., cystic fibrosis (CF). Indeed, this autosomal recessive disorder alters mucociliary clearance leading to bacterial and fungal colonization of the airways. This mini-review compiles and discusses available information on P. jirovecii and CF. It highlights significant differences in the prevalence of P. jirovecii pulmonary colonization in European and Brazilian CF patients. It also describes the microbiota associated with P. jirovecii in CF patients colonized by P. jirovecii. Furthermore, we have described P. jirovecii genomic diversity in colonized CF patients. In addition of pulmonary colonization, it appears that PCP can occur in CF patients specifically after lung transplantation, thus requiring preventive strategies. In other respects, Pneumocystis primary infection is a worldwide phenomenon occurring in non-immunosuppressed infants within their first months. The primary infection is mostly asymptomatic but it can also present as a benign self-limiting infection. It probably occurs in the same manner in CF infants. Nonetheless, two cases of severe Pneumocystis primary infection mimicking PCP in CF infants have been reported, the genetic disease appearing in these circumstances as a risk factor of PCP while the host-pathogen interaction in older children and adults with pulmonary colonization remains to be clarified.

Pneumocystis primary infection in infancy: Additional French data and review of the literature

Data on features of Pneumocystis primary infection in infancy are still fragmented. To study Pneumocystis primary infection, 192 infants who were monitored for acute pulmonary disease or fever over a 40-month period were retrospectively investigated. P. jirovecii detection on archival nasopharyngeal aspirates was performed using a qPCR assay. Factors associated with P. jirovecii were assessed using univariate and multivariate analyses. P. jirovecii genotypes in infants and a control group of adults contemporaneously diagnosed with Pneumocystis pneumonia were identified using unilocus, bilocus, and multilocus sequence typing (MLST). P. jirovecii was detected in 35 infants (18.2%). The univariate analysis pointed out four factors: viral infection (P = .035, OR [IC 95], 2.2 [1.1–4.7]), lower respiratory tract infection (P = .032, OR [IC 95], 2.5 [1.1–5.9]), absence of hospital discharge after birth (P = .003, OR (IC 95), 0.1 (0.02–0.5]), and the 63–189-day group (P < .001, OR [IC 95], 42.2 [5.4–332]). The multivariate analysis confirmed these two latter factors (P = .02, OR [IC 95], 0.1 [0.02–0.72]; P = .005, OR [IC 95], 11.5 [2.1–63.5]). Thus, P. jirovecii acquisition mostly takes place in the community. A comparison of these data with those of previously published studies showed that median and interquartile range of positive-infant ages were close to those observed in Chile, Denmark, and Peru, highlighting similar characteristics. Common unilocus or bilocus genotypes were identified in infants and adults, whereas no MLST genotypes were shared. Therefore, a common reservoir made up of infected infants and adults is still hypothetical. Finally, primary infection is a worldwide phenomenon occurring at the same time in childhood regardless of geographical location, rather than an incidental event.

Molecular diagnosis of Pneumocystis pneumonia in immunocompromised patients

PURPOSE OF REVIEW

Pneumocystis pneumonia (PCP) is a frequent opportunistic infection associated with a high mortality rate. PCP is of increasing importance in non-HIV immunocompromised patients, who present with severe respiratory distress with low fungal loads. Molecular detection of Pneumocystis in broncho-alveolar lavage (BAL) has become an important diagnostic tool, but quantitative PCR (qPCR) needs standardization.

RECENT FINDINGS

Despite a high negative predictive value, the positive predictive value of qPCR is moderate, as it also detects colonized patients. Attempts are made to set a cut-off value of qPCR to discriminate between PCP and colonization, or to use noninvasive samples or combined strategies to increase specificity.

SUMMARY

It is easy to set a qPCR cut-off for HIV-infected patients. In non-HIV IC patients, a gain in specificity could be obtained by combining strategies, that is, qPCR on BAL and a noninvasive sample, or qPCR and serum beta-1,3-D-glucan dosage.

Detection of Pneumocystis jirovecii by quantitative real-time PCR in oral rinses from Pneumocystis pneumonia asymptomatic human immunodeficiency virus patients

Pneumocystis pneumonia (PCP) is a potentially life-threatening fungal infection usually seen in immunocompromised patients. Pneumocystis jirovecii can be easily detected from oral rinse samples in HIV patients with suspected PCP. In this study, a quantitative real-time PCR assay was used to establish the frequency of detection of P. jirovecii in oral rinses from HIV patients without respiratory symptoms or suspicion of PCP. Two saline oral rinses were collected from 100 ambulant HIV patients and from 60 COPD patients (comparator group). Four HIV patients were positive for P. jirovecii. In three patients, the first sample was positive and in one the second one was positive. One of these patients was on PCP prophylaxis and had a CD4⁺ count of 76 cells/mm³. The mean CD4⁺ count for all patients was 527 cells/mm³. All qRT-PCR test results for the COPD patients were negative. No patient developed PCP at six months follow-up. The qRT-PCR assay can be used to detect P. jirovecii DNA in oral rinse samples from HIV patients without evident clinical symptoms, however the oral carriage of this fungus was rare in our cohort of patients. In conclusion, although rare, a positive oral rinse P. jirovecii result may reflect colonisation, in particular in patients with HIV. This needs to be kept in mind when using oral rinses and qRT-PCR in the diagnosis of P. jirovecii infection.

A Multidisciplinary Approach to Pretransplant and Posttransplant Management of Cystic Fibrosis-Associated Liver Disease

Approximately 5%-10% of patients with cystic fibrosis (CF) will develop advanced liver disease with portal hypertension, representing the third leading cause of death among patients with CF. Cystic fibrosis with advanced liver disease and portal hypertension (CFLD) represents the most significant risk to patient mortality, second only to pulmonary or lung transplant complications in patients with CF. Currently, there is no medical therapy to treat or reverse CFLD. Liver transplantation (LT) in patients with CFLD with portal hypertension confers a significant survival advantage over those who do not receive LT, although the timing in which to optimize this benefit is unclear. Despite the value and efficacy of LT in selected patients with CFLD, established clinical criteria outlining indications and timing for LT as well as disease-specific transplant considerations are notably absent. The goal of this comprehensive and multidisciplinary report is to present recommendations on the unique CF-specific pre- and post-LT management issues clinicians should consider and will face.

The myriad challenges of respiratory fungal infection in cystic fibrosis

Fungal infection in cystic fibrosis (CF) is a recognized challenge, with many areas requiring further investigation. Consensus definitions exist for allergic bronchopulmonary aspergillus in CF, but the full scope of clinically relevant non-allergic fungal disease in CF-asymptomatic colonization, transient or chronic infection localized to endobronchial mucus plugs or airway tissue, and invasive disease-is yet to be clearly defined. Recent advances in mycological culture and non-culture identification have expanded the list of both potential pathogens and community commensals in the lower respiratory tract. Here we aim to outline the current understanding of fungal presence in the CF respiratory tract, risk factors for acquiring fungi, host-pathogen interactions that influence the role of fungi from bystander to pathogen, advances in the diagnostic approaches to isolating and identifying fungi in CF respiratory samples, challenges of classifying clinical phenotypes of CF patients with fungi, and current treatment approaches. Development and validation of biomarkers characteristic of different fungal clinical phenotypes, and controlled trials of antifungal agents in well-characterized target populations, remain central challenges to surmount and goals to be achieved.