Update on Pneumocystis carinii f. sp. hominis typing based on nucleotide sequence variations in internal transcribed spacer regions of rRNA genes

Genetic Polymorphisms of Pneumocystis jirovecii in HIV-Positive and HIV-Negative Patients in Northern China

Pneumocystis jirovecii is an opportunistic fungus that can cause severe and potentially fatal Pneumocystis pneumonia (PCP) in immunodeficient patients. In this study, we investigated the genetic polymorphisms of P. jirovecii at eight different loci, including six nuclear genes (ITS, 26S rRNA, sod, dhps, dhfr and β-Tub) and two mitochondrial genes (mtLSU-rRNA and cyb) in three PCP cases, including two patients with HIV infection and one without HIV infection in Shanxi Province, P.R. China. The gene targets were amplified by PCR followed by sequencing of plasmid clones. The HIV-negative patient showed a coinfection with two genotypes of P. jirovecii at six of the eight loci sequenced. Of the two HIV-positive patients, one showed a coinfection with two genotypes of P. jirovecii at the same two of the six loci as in the HIV-negative patient, while the other showed a single infection at all eight loci sequenced. None of the three drug target genes (dhfr, dhps and cyb) showed mutations known to be potentially associated with drug resistance. This is the first report of genetic polymorphisms of P. jirovecii in PCP patients in Shanxi Province, China. Our findings expand our understanding of the genetic diversity of P. jirovecii in China.

Pneumocystis jirovecii genetic diversity in a Spanish tertiary hospital

Pneumocystis jirovecii is associated with non-noxious colonization or severe pneumonia in immunocompromised hosts. Epidemiological investigations have been hampered by the lack of a standardized typing scheme. Thus, only partial molecular data on Spanish P. jirovecii cases are available. Recently a new ISHAM consensus multilocus sequence typing scheme (MLST) targeting β-TUB, mt26S, CYB, and SOD with a publicly accessible database has been launched to overcome this problem.The molecular epidemiology of P. jirovecii from immunocompromised patients either colonized (n = 50) or having pneumonia (n = 36) seen between 2014 and 2018 at a single center in Barcelona, Spain, was studied. The new ISHAM consensus MSLT scheme was used to investigate the local epidemiology and identify possible unnoticed outbreaks. Mutations in the DHPS gene, not included in the scheme but giving information about potential sulpha treatment failure, were also studied. The study assigned 32 sequence types (ST) to 72.2% pneumonia and 56% colonization cases. The most frequent STs were ST21 (18.5%), ST22 (14.8%), and ST37(14.8%). For non-unique STs, ST3, ST30 and ST31 were found only in pneumonia cases, whereas ST27 was associated exclusively to colonization's. Despite 38 patients sharing similar STs, only two were involved in a potential cross transmission event. No DHPS mutations were identified. The new consensus typing scheme was useful to ascertain the molecular epidemiology of P. jirovecii in our center revealing a high genetic diversity and the potential association of specific STs to colonization and pneumonia cases.

LAY SUMMARY

A newly described MLST scheme aims at providing a standardized tool to study and compare Pneumocystis jirovecii epidemiology. A high diversity amongst P. jirovecii isolates from patients in Barcelona, Spain, and a potential association between specific STs and infection/colonization were identified.

Consensus Multilocus Sequence Typing Scheme for Pneumocystis jirovecii

Pneumocystis jirovecii is an opportunistic human pathogenic fungus causing severe pneumonia mainly in immunocompromised hosts. Multilocus sequence typing (MLST) remains the gold standard for genotyping of this unculturable fungus. However, the lack of a consensus scheme impedes a global comparison, large scale population studies and the development of a global MLST database. To overcome this problem this study compared all genetic regions (19 loci) currently used in 31 different published Pneumocystis MLST schemes. The most diverse/commonly used eight loci, β-TUB, CYB, DHPS, ITS1, ITS1/2, mt26S and SOD, were further assess for their ability to be successfully amplified and sequenced, and for their discriminatory power. The most successful loci were tested to identify genetically related and unrelated cases. A new consensus MLST scheme consisting of four genetically independent loci: β-TUB, CYB, mt26S and SOD, is herein proposed for standardised P. jirovecii typing, successfully amplifying low and high fungal burden specimens, showing adequate discriminatory power, and correctly identifying suspected related and unrelated isolates. The new consensus MLST scheme, if accepted, will for the first time provide a powerful tool to investigate outbreak settings and undertake global epidemiological studies shedding light on the spread of this important human fungal pathogen.

Isolation and molecular identification of Aspergillus flavus and the study of its potential for malathion biodegradation in water

In spite of the fact that pesticides enhanced the quality and yield of the agricultural production however do have certain serious effects on the environment. This study was carried out for isolation and molecular identification of microorganisms from water for malathion biodegradation in aquatic system. PCR analysis was used for identification of the isolated fungus. The growth kinetics of A. flavus in the presence of malathion under different environmental factors (pH, temperature and malathion concentration) were evaluated. Furthermore, the degradation kinetics of malathion by A. flavus in aqueous media under different environmental factors was evaluated. The isolated microorganism was identified as A. flavus with respect to it relation to the data from the gene bank and the lowest nucleotide diversity value between the tested isolate and A. flavus. The identified isolate grew successfully in a media supplemented with malathion much faster than without it. Hundred percent of malathion initial concentration was degraded within 36 days of incubation with A. flavus. The temperature of 30 °C, pH value of 7 and malathion initial concentration of 5 mg/l were the optimum conditions of A. flavus for growth and degradation of malathion. Bioremediation of malathion residues in water using A. flavus isolate are promising and considered the first report.

Genotyping of Pneumocystis jirovecii by Use of a New Simplified Nomenclature System Based on the Internal Transcribed Spacer Regions and 5.8S rRNA Gene of the rRNA Operon

Genotyping based on internal transcribed spacer 1 (ITS1) and ITS2 of the rRNA operon has played an important role in understanding the transmission and epidemiology of Pneumocystis jirovecii, one of the major opportunistic pathogens in individuals with AIDS and other immunocompromised individuals. The widespread use of this typing system has resulted in several problems, including inconsistent genotype nomenclatures, difficult data transferability, and complicated interpretation of the length variation in multiple homopolymeric tracts. The aim of this study was to establish a new, simplified genotype nomenclature system for P. jirovecii based on the ITS1 and ITS2 sequences. We first analyzed the complete ITS1, 5.8S rRNA gene, and ITS2 sequences (termed ITS1-5.8S-ITS2) in 27 recent P. jirovecii isolates from China and identified 18 unique genotypes. Subsequently, we performed a comprehensive classification of more than 400 ITS1- and ITS2-related sequences from GenBank and an in-depth evaluation of the length variation of multiple homopolymeric tracts within ITS1-5.8S-ITS2. Integration of the results from these analyses led to a new, simplified genotype nomenclature system including 62 unique ITS1-5.8S-ITS2 genotypes, simply designated types 1 through 62. This new system offers several advantages over traditional ITS1- and ITS2-based typing systems, including a simpler analysis and interpretation process, a higher discriminative power, and no limitation in assigning potential new genotypes. This new system is expected to facilitate the standardization of P. jirovecii genotyping and easy data exchanges across different laboratories.

Therapy and Management of Pneumocystis jirovecii Infection

The rates of Pneumocystis pneumonia (PcP) are increasing in the HIV-negative susceptible population. Guidance for the prophylaxis and treatment of PcP in HIV, haematology, and solid-organ transplant (SOT) recipients is available, although for many other populations (e.g., auto-immune disorders) there remains an urgent need for recommendations. The main drug for both prophylaxis and treatment of PcP is trimethoprim/sulfamethoxazole, but resistance to this therapy is emerging, placing further emphasis on the need to make a mycological diagnosis using molecular based methods. Outbreaks in SOT recipients, particularly renal transplants, are increasingly described, and likely caused by human-to-human spread, highlighting the need for efficient infection control policies and sensitive diagnostic assays. Widespread prophylaxis is the best measure to gain control of outbreak situations. This review will summarize diagnostic options, cover prophylactic and therapeutic management in the main at risk populations, while also covering aspects of managing resistant disease, outbreak situations, and paediatric PcP.

A Molecular Window into the Biology and Epidemiology of Pneumocystis spp

Pneumocystis, a unique atypical fungus with an elusive lifestyle, has had an important medical history. It came to prominence as an opportunistic pathogen that not only can cause life-threatening pneumonia in patients with HIV infection and other immunodeficiencies but also can colonize the lungs of healthy individuals from a very early age. The genus Pneumocystis includes a group of closely related but heterogeneous organisms that have a worldwide distribution, have been detected in multiple mammalian species, are highly host species specific, inhabit the lungs almost exclusively, and have never convincingly been cultured in vitro, making Pneumocystis a fascinating but difficult-to-study organism. Improved molecular biologic methodologies have opened a new window into the biology and epidemiology of Pneumocystis. Advances include an improved taxonomic classification, identification of an extremely reduced genome and concomitant inability to metabolize and grow independent of the host lungs, insights into its transmission mode, recognition of its widespread colonization in both immunocompetent and immunodeficient hosts, and utilization of strain variation to study drug resistance, epidemiology, and outbreaks of infection among transplant patients. This review summarizes these advances and also identifies some major questions and challenges that need to be addressed to better understand Pneumocystis biology and its relevance to clinical care.

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.

Investigation of nosocomial pneumocystis infections: usefulness of longitudinal screening of epidemic and post-epidemic pneumocystis genotypes

BACKGROUND

Twenty-five patients, of whom 22 were renal transplant recipients, developed Pneumocystis jirovecii infections at the nephrology department of Reims University Hospital (France) from September 2008 to October 2009, whereas only four sporadic cases had been diagnosed in this department over the 14 previous years.

AIM

This outbreak was investigated by analysing patient encounters and P. jirovecii types.

METHODS

A transmission map was drawn up. P. jirovecii typing at DHPS, ITS and mtLSU rRNA sequences was performed in the patients of the cluster (18 patients with Pneumocystis pneumonia (PCP) and seven colonized patients), 10 unlinked control patients (six PCP patients and four colonized patients), as well as 23 other patients diagnosed with P. jirovecii (nine PCP patients and 14 colonized patients) in the same department over a three-year post-epidemic period.

FINDINGS

Eleven encounters between patients harbouring the same types were observed. Three PCP patients and one colonized patient were considered as possible index cases. The most frequent types in the cluster group and the control group were identical. However, their frequency was significantly higher in the first than in the second group (P < 0.01). Identical types were also identified in the post-epidemic group, suggesting a second outbreak due to the same strain, contemporary to a disruption in prevention measures.

CONCLUSIONS

These results provide additional data on the role of both PCP and colonized patients as infectious sources. Longitudinal screening of P. jirovecii types in infected patients, including colonized patients, is required in the investigation of the fungus's circulation within hospitals.

Lifelong Prophylaxis With Trimethoprim-Sulfamethoxazole for Prevention of Outbreak of Pneumocystis jirovecii Pneumonia in Kidney Transplant Recipients

Background

Outbreaks of Pneumocystis jirovecii pneumonia (PCP) in kidney transplant recipients are frequently reported worldwide. However, the general guidelines propose only short-term prophylaxis with trimethoprim-sulfamethoxazole after kidney transplantation. We experienced 3 PCP outbreaks in the last 10 years despite providing the recommended prophylaxis. The purpose of this study was to find a prophylaxis regimen that could successfully prevent future PCP outbreaks in immunosuppressed kidney transplant recipients.

Methods

Occurrence of PCP at our hospital since 2004 was reviewed. A total of 48 cases were diagnosed from July 2004 through December 2014. Genotypes of P. jirovecii were determined in these cases.

Results

Three PCP outbreaks by 3 different genotypes of P. jirovecii in each outbreak occurred with 2-year intervals in last 10 years. Molecular analysis showed that each intraoutbreak was caused by identical P. jirovecii, whereas interoutbreaks were caused by different genotypes. Although short-term prophylaxis was provided to all kidney recipients after each outbreak after identification of a single PCP case, additional outbreaks were not prevented because the universal prophylaxis had already been completed when new case of PCP emerged.

Conclusions

The contagious nature of P. jirovecii allows easy development of outbreaks of PCP in immunosuppressed kidney transplant recipients. Although the universal short-term prophylaxis is effective in controlling ongoing outbreak, lifelong prophylaxis of kidney transplant recipients should be considered to prevent new outbreaks.

Diagnosis and management of Pneumocystis jirovecii infection

INTRODUCTION

Pneumocystis jirovecii is a ubiquitous fungus, which causes pneumonia in humans. Diagnosis was hampered by the inability to culture the organism, and based on microscopic examination of respiratory samples or clinical presentation. New assays can assist in the diagnosis and even aid with the emergence of resistant infections. Areas covered: This manuscript will provide background information on Pneumocystis pneumonia (PcP). Diagnosis, from radiological to non-microbiological (e.g. Lactate dehydrogenase) and microbiological investigations (Microscopy, PCR, β-D-Glucan) will be discussed. Recommendations on prophylactic and therapeutic management will be covered. Expert commentary: PcP diagnosis using microscopy is far from optimal and false negatives will occur. With an incidence of 1% or less, the pre-test probability of not having PcP is 99% and testing is suited to excluding disease. Microscopy provides a high degree of diagnostic confidence but it is not infallible, and its lower sensitivity limits its application. Newer diagnostics (PCR, β-D-Glucan) can aid management and improve performance when testing less invasive specimens, such as upper respiratory samples or blood, alleviating clinical pressure. Combination testing may allow PcP to be both diagnosed and excluded, and molecular testing can assist in the detection of emerging resistant PcP.

Pneumocystis Carinii Pneumonia in Adult Non-HIV Disorders

Pneumocystis carinii pneumonia (PCP) remains a serious infection in the immunocompromised host (in the absence of HIV infection) and presents significant management and diagnostic challenges to ICU physicians. Non-HIV PCP is generally abrupt in onset, and follows a fulminate course with high rates of hospitalization, ICT admission, respiratory failure, and requirement for intubation. Mortality is generally high, especially if mechanical ventilation is required. Non-invasive ventilatory support may be considered, although the rapid progression to respiratory failure often necessitates intubation at the time of presentation. Bronchoscopy is often required to establish the diagnosis, and empirical antimicrobial treatment specifically targeted to P. carinii should be initiated while awaiting confirmation. Adjunctive corticosteroids may accelerate recovery, although their use has not yet been established in non-HIV PCP. For the ICU physicians to diagnose PCP, the non-specific presentation of an acute febrile illness and respiratory distress with diffuse pulmonary infiltrates requires a high clinical index of suspician, familiarity with clinical conditions associated with increased risk for PCP, and a low threshold for bronchoscopy to establish the diagnosis.

Pneumocystis pneumonia outbreak among renal transplant recipients at a North American transplant center: Risk factors and implications for infection control

BACKGROUND

Pneumocystis pneumonia is a severe opportunistic fungal infection. Outbreaks among renal transplant recipients have been reported in Europe and Japan, but never in North America.

METHODS

We conducted a retrospective case-control study among adult renal transplant recipients at a Canadian center, using a 3:1 matching scheme. Ten cases and 30 controls were matched based on initial transplantation date, and all patients received prophylaxis with trimethoprim-sulfamethoxazole for 1 year posttransplantation.

RESULTS

The median time between transplantation and infection was 10.2 years, and all patients survived. Compared with controls, case patients had statistically lower estimated glomerular filtration rate (29.3 mL/min vs 66.3 mL/min; P = .028) and lymphopenia (0.51 × 10(9)/L vs 1.25 × 10(9)/L; P = .002). Transmission mapping revealed significant overlap in the clinic and laboratory visits among case vs control patients (P = .0002). One hundred percent of patients (4 out of 4) successfully genotyped had the same strain of Pneumocystis jirovecii.

CONCLUSIONS

Our study demonstrated an outbreak of pneumocystis more than 10 years following initial transplantation, despite using recommended initial prophylaxis. We identified low estimated glomerular filtration rate and lymphopenia as risk factors for infection. Overlapping ambulatory care visits were identified as important potential sources of infection transmission, suggesting that institutions should re-evaluate policy and infrastructure strategies to interrupt transmission of respiratory pathogens.

Management of Pneumocystis jirovecii Pneumonia in Kidney Transplantation to Prevent Further Outbreak

The outbreak of Pneumocystis jirovecii pneumonia (PJP) among kidney transplant recipients is emerging worldwide. It is important to control nosocomial PJP infection. A delay in diagnosis and treatment increases the number of reservoir patients and the number of cases of respiratory failure and death. Owing to the large number of kidney transplant recipients compared to other types of organ transplantation, there are greater opportunities for them to share the same time and space. Although the use of trimethoprim-sulfamethoxazole (TMP-SMX) as first choice in PJP prophylaxis is valuable for PJP that develops from infections by trophic forms, it cannot prevent or clear colonization, in which cysts are dominant. Colonization of P. jirovecii is cleared by macrophages. While recent immunosuppressive therapies have decreased the rate of rejection, over-suppressed macrophages caused by the higher levels of immunosuppression may decrease the eradication rate of colonization. Once a PJP cluster enters these populations, which are gathered in one place and uniformly undergoing immunosuppressive therapy for kidney transplantation, an outbreak can occur easily. Quick actions for PJP patients, other recipients, and medical staff of transplant centers are required. In future, lifelong prophylaxis may be required even in kidney transplant recipients.

Genotyping of Pneumocystis jirovecii isolates from human immunodeficiency virus-negative patients in China

Pneumocystis jirovecii is a fungus that causes Pneumocystis pneumonia in immuno-compromised patients. To analyze the genetic diversity of P. jirovecii in HIV-negative patients in China, respiratory specimens were obtained from 105 patients who tested PCR-positive for the presence of the P. jirovecii mitochondrial large subunit ribosomal RNA (mtLSU rRNA) between 2011 and 2013. P. jirovecii isolates were genotyped based on the upstream conserved sequence (UCS) of the major surface glycoprotein (MSG) gene and the internal transcribed spacer (ITS) of nuclear rRNA operon. Eighty-one of the 105 isolates showed a positive PCR for the UCS region. We identified six different patterns comprising two, three, four, or five UCS repeats, including 1, 2, 3 (69.14%), 1, 2, 3, 3 (22.22%), 1, 2 (3.7%), 1, 1, (2.47%), 2, 2, 3, 3 (1.23%), and 1, 1, 2, 3, 3 (1.23%). In regard to the ITS region, 58 of the 105 isolates were cloned and sequenced successfully. Six known ITS1 alleles (A, B, DEL1, E, N, and SYD1), two new alleles (designated as BTM3 and BTM4), six known ITS2 alleles (a, b, i, g, h and O) and one new allele (designated as btm6) were observed. A total of 19 P. jirovecii ITS haplotypes were identified. The most frequent type was Bi (25.9%), followed by Ai (13.8%), Eb (10.3%), and SYD1g (6.9%). Among the 58 specimens examined, 49 (84.5%) were found to contain a single type of P. jirovecii, while 9 (15.5%) contained multiple genotypes. A total of 34 allelic profiles were observed in 58 isolates when the two loci were combined with each other. A Fisher's exact test revealed that there was no statistically significant (P=0.330) association between the most frequent UCS and ITS genotypes. An analysis of the phylogenetic relationship between different patient groups identified two major groups based on the sequence variations of concatenated UCS and ITS sequences in 49 isolates. Our results demonstrated the high genetic variability of P. jirovecii in HIV-negative patients in China.

Dihydropteroate synthase gene mutation rates in Pneumocystis jirovecii strains obtained from Iranian HIV-positive and non-HIV-positive patients

The dihydropteroate sulfate (DHPS) gene is associated with resistance to sulfa/sulfone drugs in Pneumocystis jirovecii. We investigated the DHPS mutation rate in three groups of Iranian HIV-positive and HIV-negative patients by polymerase chain reaction-restricted fragment length polymorphism analysis. Furthermore, an association between P. jirovecii DHPS mutations and strain typing was investigated based on direct sequencing of internal transcribed spacer region 1 (ITS1) and ITS2. The overall P. jirovecii DHPS mutation rate was (5/34; 14.7%), the lowest rate identified was in HIV-positive patients (1/16; 6.25%) and the highest rate was in malignancies patients (3/11; 27.3%). A moderate rate of mutation was detected in chronic obstructive pulmonary disease (COPD) patients (1/7; 14.3%). Most of the isolates were wild type (29/34; 85.3%). Double mutations in DHPS were detected in patients with malignancies, whereas single mutations at codons 55 and 57 were identified in the HIV-positive and COPD patients, respectively. In this study, two new and rare haplotypes were identified with DHPS mutations. Additionally, a positive relationship between P. jirovecii strain genotypes and DHPS mutations was identified. In contrast, no DHPS mutations were detected in the predominant (Eg) haplotype. This should be regarded as a warning of an increasing incidence of drug-resistant P. jirovecii strains.

AIDS-related Pneumocystis jirovecii genotypes in French Guiana

The study described Pneumocystis jirovecii (P. jirovecii) multilocus typing in seven AIDS patients living in French Guiana (Cayenne Hospital) and seven immunosuppressed patients living in Brest, metropolitan France (Brest Hospital). Archival P. jirovecii specimens were examined at the dihydropteroate synthase (DHPS) locus using a PCR-RFLP technique, the internal transcribed spacer (ITS) 1 and ITS 2 and the mitochondrial large subunit rRNA (mtLSUrRNA) gene using PCR and sequencing. Analysis of typing results were combined with an analysis of the literature on P. jirovecii mtLSUrRNA types and ITS haplotypes. A wild DHPS type was identified in six Guianese patients and in seven patients from metropolitan France whereas a DHPS mutant was infected in the remaining Guianese patient. Typing of the two other loci pointed out a high diversity of ITS haplotypes and an average diversity of mtLSUrRNA types in French Guiana with a partial commonality of these haplotypes and types described in metropolitan France and around the world. Combining DHPS, ITS and mtLSU types, 12 different multilocus genotypes (MLGs) were identified, 4 MLGs in Guianese patients and 8 MLGs in Brest patients. MLG analysis allows to discriminate patients in 2 groups according to their geographical origin. Indeed, none of the MLGs identified in the Guianese patients were found in the Brest patients and none of the MLGs identified in the Brest patients were found in the Guianese patients. These results show that in French Guiana (i) PCP involving DHPS mutants occur, (ii) there is a diversity of ITS and mtLSUrRNA types and (iii) although partial type commonality in this territory and metropolitan France can be observed, MLG analysis suggests that P. jirovecii organisms from French Guiana may present specific characteristics.

Molecular epidemiology of Pneumocystis jiroveci in human immunodeficiency virus-positive and -negative immunocompromised patients in The Netherlands

Pneumocystis jiroveci infections can cause pneumocystis pneumonia (PCP) or lead to colonization without signs of PCP. Over the years, different genotypes of P. jiroveci have been discovered. Genomic typing of P. jiroveci in different subpopulations can contribute to unravelling the pathogenesis, transmission and spread of the different genotypes. In this study, we wanted to determine the distribution of P. jiroveci genotypes in immunocompetent and immunocompromised patients in The Netherlands and determine the clinical relevance of these detected mutations. A real-time PCR targeting the major surface glycoprotein gene (MSG) was used as a screening test for the presence of P. jiroveci DNA. Samples positive for MSG were genotyped based on the internal transcribed spacer (ITS) and dihydropteroate synthase (DHPS) genes. Of the 595 included bronchoalveolar lavage fluid samples, 116 revealed the presence of P. jiroveci DNA. A total of 52 of the 116 samples were ITS genotyped and 58 DHPS genotyped. The ITS genotyping revealed 17 ITS types, including two types that have not been described previously. There was no correlation between ITS genotype and underlying disease. All ITS- and DHPS-genotyped samples were found in immunocompromised patients. Of the 58 DHPS-genotyped samples, 50 were found to be WT. The other eight samples revealed a mixed genotype consisting of WT and type 1. The majority of the latter recovered on trimethoprim-sulfamethoxazole suggesting no clinical relevance for this mutation.

Finding your way through Pneumocystis sequences in the NCBI gene database

Pneumocystis sequences can be downloaded from GenBank for purposes as primer/probe design or phylogenetic studies. Due to changes in nomenclature and assignment, available sequences are presented with a variety of inhomogeneous information, which renders practical utilization difficult. The aim of this study was the descriptive evaluation of different parameters of 532 Pneumocystis sequences of mitochondrial and ribosomal origin downloaded from GenBank with regard to completeness and information content. Pneumocystis sequences were characterized by up to four different names. Official changes in nomenclature have only been partly implemented and the usage of the "forma specialis", a special feature of Pneumocystis, has only been established fragmentary in the database. Hints for a mitochondrial or ribosomal genomic origin could be found, but can easily be overlooked, which renders the download of wrong reference material possible. The specification of the host was either not available or variable regarding the used language and the localization of this information in the title or several subtitles, which limits their applicability in phylogenetic studies. Declaration of products and geographic origin was incomplete. The print version of this manuscript is completed by an online database which contains detailed information to every accession number included in the meta-analysis.

Genetic diversity of Histoplasma capsulatum strains isolated from Argentina based on nucleotide sequence variations in the internal transcribed spacer regions of rDNA

The internal transcribed spacer (ITS) regions of rDNA genes of 49 Histoplasma capsulatum (48 from clinical samples and one from soil) isolates were examined. Nucleotide sequence heterogeneity within this region was useful for phylogenetic classification of H. capsulatum and species identification. Thus, in 45 of 49 isolates we observed higher percentages of identity in the nucleotide sequences of ITS regions when the isolates studied herein were compared with those reported in our country in the South America B clade. Phylogenetic analyses of rDNA sequences corresponding to the 537 bp of the ITS region obtained from H. capsulatum isolates assigned South America type B clade (45 isolates), North America type 1 and Asia clade (2 isolates each one). H. capsulatum strains isolated from soil and from patients living in Argentina (45 of 49) clustered together with the H. capsulatum isolates of the South America B clade. The high level of genetic similarity among our isolates suggests that almost one genetic population is present in the microenvironment. Isolates described as H. capsulatum var. capsulatum or var. farciminosum (2 isolates) did not form a monophyletic group and were found in the Asia clade. Subsequent studies are needed to properly identify these isolates.

Pneumocystis jirovecii haplotypes at the internal transcribed spacers of the rRNA operon in French HIV-negative patients with diverse clinical presentations of Pneumocystis infections

Pneumocystis jirovecii, a transmissible fungus, is the causative agent of pulmonary infections. Its genomic diversity has appeared in reports from around the world but data on P. jirovecii genotypes in France are still limited. This study describes the typing of P. jirovecii isolates from 81 HIV-negative patients monitored at Brest University Hospital, Brittany, France, 40 of whom developed Pneumocystis pneumonia (PcP), and remaining 41 patients were colonized by the fungus. The isolates were assayed at the internal transcribed spacer (ITS)1 and ITS2 under improved amplification conditions to avoid in vitro ITS recombination. P. jirovecii ITS haplotypes were identified in 56/81 patients (31 PcP patients and 25 patients who were colonized) which revealed a high diversity in that 27 different haplotypes were identified. Eg was the most frequent haplotype (31/56, 55.3%), followed by Ec and Ai (5/56, 8.9% each). In contrast, Ne, usually the second most frequent haplotype in Europe and the USA, was observed in only 2/56 patients (3.6%). Mixed infections were detected in 18/56 patients (32.1%; 12 PcP patients and six who were colonized). No significant differences were observed in haplotype diversity, frequency of peculiar haplotypes, and mixed infection occurrence, between the two patient populations. The study, conducted with the largest HIV-negative patient population investigated so far, shows that ITS typing remains an efficient method for characterizing P. jirovecii among human populations, whatever their clinical presentation of Pneumocystis infections.

Sequencing and characterization of the complete mitochondrial genomes of three Pneumocystis species provide new insights into divergence between human and rodent Pneumocystis

Pneumocystis jirovecii is an important opportunistic pathogen associated with AIDS and other immunodeficient conditions. Currently, very little is known about its nuclear and mitochondrial genomes. In this study, we sequenced the complete mitochondrial genome (mtDNA) of this organism and its closely related species Pneumocystis carinii and Pneumocystis murina by a combination of sequencing technologies. Our study shows that P. carinii and P. murina mtDNA share a nearly identical number and order of genes in a linear configuration, whereas P. jirovecii has a circular mtDNA containing nearly the same set of genes but in a different order. Detailed studies of the mtDNA terminal structures of P. murina and P. carinii suggest a unique replication mechanism for linear mtDNA. Phylogenetic analysis supports a close association of Pneumocystis species with Taphrina, Saitoella, and Schizosaccharomyces, and divergence within Pneumocystis species, with P. murina and P. carinii being more closely related to each other than either is to P. jirovecii. Comparative analysis of four complete P. jirovecii mtDNA sequences in this study and previously reported mtDNA sequences for diagnosing and genotyping suggests that the current diagnostic and typing methods can be improved using the complete mtDNA data. The availability of the complete P. jirovecii mtDNA also opens the possibility of identifying new therapeutic targets.

A comparison of capillary electrophoresis and direct sequencing in upstream conserved sequence region analysis of Pneumocystis jirovecii strains

The major surface glycoprotein (MSG) of Pneumocystis jirovecii is the most abundant surface protein and appears to play a critical role in the pathogenesis of pneumocystosis. The expressed MSG gene is located immediately downstream of a region called the upstream conserved sequence (UCS). The UCS contains a region of tandem repeats that vary in number and sequence. In the present study, we have used capillary electrophoresis and direct sequencing to detect the variability in the repeat units of UCS. By direct sequencing the PCR products from samples of 13 patients, we have identified three types of repeat units which consisted of 10 nt and three different patterns in the UCS region with three and four repeats: 1, 2, 3 (84.6 %); 1, 2, 3, 3 (8.2 %); and a new genotype 2, 2, 3, 3 (8.2 %). The same samples were analysed by capillary electrophoresis. Three samples (23 %) contained a mixture of two or three different patterns of UCS repeats. In conclusion, quantifying the number of repeat units in the UCS by capillary electrophoresis provides a potential new method for the rapid typing of P. jirovecii and the detection of mixed infection.

Outbreaks and clustering of Pneumocystis pneumonia in kidney transplant recipients: a systematic review

From 1980 onwards, an increasing number of outbreaks of Pneumocystis pneumonia (PCP) among kidney transplant recipients have been reported. The cause of these outbreaks is unclear and different explanations have been provided. We performed a systematic review to provide a comprehensive overview of the epidemiologic characteristics as well as the involved clinical risk factors. A total of 15 peer-reviewed English language articles published from 1980 onward were included. Outbreak settings were all marked by absence of adequate chemoprophylaxis, frequent inter-patient contacts and lack of isolation measures taken during hospitalization of PCP cases. PCP-associated mortality rates significantly decreased from a weighted mean of 38% before 1990 to 19% and 13% in the following two decades. Clinical risk factors for PCP in outbreak settings were largely similar to non-outbreak settings. Genotyping by multilocus sequence typing (MLST) or comparison of the internal transcribed spacer (ITS) regions 1 and 2 showed that the outbreaks are most frequently caused by a predominant or a single Pneumocystis strain. Pooled epidemiological data and genotyping results strongly support the theory that interhuman transmission of Pneumocystis occurred. No seasonal trend was noted. The results emphasize the need for chemoprophylaxis in kidney transplant recipients despite a low baseline incidence of PCP in this population, and support the current CDC recommendation with regard to isolation of patients with PCP during hospitalization.

Clinical characteristics of Pneumocystis pneumonia in non-HIV patients and prognostic factors including microbiological genotypes

Background

The number of patients with non-HIV Pneumocystis pneumonia (PCP) is increasing with widespread immunosuppressive treatment. We investigated the clinical characteristics of non-HIV PCP and its association with microbiological genotypes.

Methods

Between January 2005 and March 2010, all patients in 2 university hospitals who had been diagnosed with PCP by PCR were enrolled in this study. Retrospective chart review of patients, microbiological genotypes, and association with 30-day mortality were examined.

Results

Of the 82 adult patients investigated, 50 patients (61%) had inflammatory diseases, 17 (21%) had solid malignancies, 12 (15%) had hematological malignancies, and 6 (7%) had received transplantations. All patients received immunosuppressive agents or antitumor chemotherapeutic drugs. Plasma (1→3) β-D-glucan levels were elevated in 80% of patients, and were significantly reduced after treatment in both survivors and non-survivors. However, β-D-glucan increased in 18% of survivors and was normal in only 33% after treatment. Concomitant invasive pulmonary aspergillosis was detected in 5 patients. Fifty-six respiratory samples were stored for genotyping. A dihydropteroate synthase mutation associated with trimethoprim-sulfamethoxazole resistance was found in only 1 of the 53 patients. The most prevalent genotype of mitochondrial large-subunit rRNA was genotype 1, followed by genotype 4. The most prevalent genotype of internal transcribed spacers of the nuclear rRNA operon was Eb, followed by Eg and Bi. Thirty-day mortality was 24%, in which logistic regression analysis revealed association with serum albumin and mechanical ventilation, but no association with genotypes.

Conclusions

In non-HIV PCP, poorer general and respiratory conditions at diagnosis were independent predictors of mortality. β-D-glucan may not be useful for monitoring the response to treatment, and genotypes were not associated with mortality.

A limited number of ITS haplotypes defines the diversity of Pneumocystis jirovecii strains in Sweden

The infectious fungus Pneumocystis jirovecii remains an important cause of pneumonia (PCP) in the immunocompromised host. To study the biodiversity of P. jirovecii in Sweden the internal transcribed spacers (ITS) of the rDNA locus were amplified, cloned and sequenced from a set of diagnostic respiratory specimens obtained from 64 patients with P. jirovecii infection during the years 1996-2003. The analysis of 408 cloned sequences from amplified products resulted in the identification of 10 ITS1 and 12 ITS2 established genotypes. Twelve ITS haplotypes (combinations of ITS1 and ITS2) were identified of which nine were found to recur during the time span of the study. Haplotype Eg was the most common, followed by Ne, Bi and Eb. A new ITS2 genotype denoted v was identified in specimens from four patients. There was no association between ITS haplotype and patient age, sex, underlying disease or geographical origin. Shannon and Simpson index analysis revealed no difference in diversity in Sweden compared to other countries studied and no changes in diversity were found during the study period in Sweden. Criteria were defined to enable the discrimination of genuine ITS types and a more accurate assessment of the previously overestimated genetic diversity of P. jirovecii populations. A model depicting the phylogenetic and genealogic relationships in a revised set of global types of this fungus is presented.

Phylogenetic status of Pneumocystis from corticosteroid-treated gerbils

Pneumocystis spp. infect the lungs of multiple mammalian species and cause disease in immunosuppressed individuals. The Pneumocystis isolates that have been studied to date fall into two major clades, those from primates and those from rodents. Within each of these clades, different species have been described on the basis of host specificity and differences in sequence and morphology. Here, we demonstrate that dexamethasone immunosuppression consistently results in histologically apparent lung infection in gerbils (28/35 animals). Sequence analysis of the 18S, 5.8S and internal transcribed spacer regions of the rDNA and a portion of the mitochondrial large subunit rDNA demonstrated that this gerbil Pneumocystis is grouped with other rodent Pneumocystis spp., but is distinct from them. Our results suggest that gerbil Pneumocystis differs sufficiently from Pneumocystis species found in other rodents to be considered a separate species.

Pneumocystis jirovecii multilocus gene sequencing: findings and implications

Pneumocystis jirovecii pneumonia (PcP) remains a major cause of respiratory illness among immunocompromised patients, especially patients infected with HIV, but it has also been isolated from immunocompetent persons. This article discusses the application of multilocus genotyping analysis to the study of the genetic diversity of P. jirovecii and its epidemiological and clinical parameters, and the important concepts achieved to date with these approaches. The multilocus typing studies performed until now have shown that there is an important genetic diversity of stable and ubiquitous P. jirovecii genotypes; infection with P. jirovecii is not necessarily clonal, recombination between some P. jirovecii multilocus genotypes has been suggested. P. jirovecii-specific multilocus genotypes can be associated with severity of PcP. Patients infected with P. jirovecii, regardless of the form of infection they present with, are part of a common human reservoir for future infections. The CYB, DHFR, DHPS, mtLSU rRNA, SOD and the ITS loci are suitable genetic targets to be used in further epidemiological studies focused on the identification and characterization of P. jirovecii haplotypes correlated with drug resistance and PcP outcome.

Restriction fragment length polymorphism typing demonstrates substantial diversity among Pneumocystis jirovecii isolates

Better understanding of the epidemiology and transmission patterns of human Pneumocystis should lead to improved strategies for preventing Pneumocystis pneumonia (PCP). We have developed a typing method for Pneumocystis jirovecii that is based on restriction fragment length polymorphism (RFLP) analysis after polymerase chain reaction amplification of an approximately 1300 base-pair region of the msg gene family, which comprises an estimated 50-100 genes/genome. The RFLP pattern was reproducible in samples containing >1000 msg copies/reaction and was stable over time, based on analysis of serial samples from the same patient. In our initial analysis of 48 samples, we found that samples obtained from different individuals showed distinct banding patterns; only samples obtained from the same patient showed an identical RFLP pattern. Despite this substantial diversity, samples tended to cluster on the basis of country of origin. In an evaluation of samples obtained from an outbreak of PCP in kidney transplant recipients in Germany, RFLP analysis demonstrated identical patterns in samples that were from 12 patients previously linked to this outbreak, as well as from 2 additional patients. Our results highlight the presence of a remarkable diversity in human Pneumocystis strains. RFLP may be very useful for studying clusters of PCP in immunosuppressed patients, to determine whether there is a common source of infection.

Clinical significance and phylogenetic relationship of novel Australian Pneumocystis jirovecii genotypes

Pneumocystis jirovecii is an important opportunistic pathogen in immunocompromised patients. Molecular typing is employed to study this pathogen, as no culture system exists. No Australian P. jirovecii strains have been previously studied. Direct sequencing, targeting the internal transcribed spacer (ITS) regions of the nuclear rRNA operon, the mitochondrial large-subunit rRNA (mt LSU rRNA), and the dihydropteroate synthase (DHPS) gene, was performed on 68 Australian samples, collected between 2001 and 2007. Seven novel Australian ITS haplotypes (a composite of the ITS1 and ITS2 regions) were identified (SYD1m, SYD1g, Isyd2, Esyd3, Osyd4, Ag, and Hc). A dendrogram of published ITS haplotypes revealed that of the seven novel haplotypes, three (SYD1m, SYD1g, and Osyd4) are closely related to the haplotype Eg. Applying statistical parsimony, an Australian haplotype network was constructed which identified Eg as the ancestral haplotype, with two unresolved loops encountered. This suggests that the ITS lacks the resolution required for evolutionary analysis. Only two mt LSU rRNA genotypes were detected, with genotype 1 predominating. Mutant DHPS genotypes were present in 13% (8/60) of the samples. The novel haplotype Isyd2 was associated with less severe disease than the other Australian haplotypes. In contrast, patients with mutant DHPS genotypes were more likely to have severe disease, require invasive ventilation, and have a poor outcome than patients with wild-type DHPS genotypes. In conclusion, genetic clinical correlates continue to be found for Pneumocystis pneumonia; however, they remain controversial and warrant further study.

Molecular phylogeny of pneumocystis based on 5.8S rRNA gene and the internal transcribed spacers of rRNA gene sequences

To clarify the phylogenetic relationships and species status of Pneumocystis, the 5.8S rRNA gene and the internal transcribed spacers (ITS, 1 and 2) of Pneumocystis rRNA derived from rat, gerbil and human were amplified, cloned and sequenced. The genetic distance matrix of six Pneumocystis species compared with other fungi like Taphrina and Saccharomyces indicated that the Pneumocystis genus contained multiple species including Pneumocystis from gerbil. The phylogenetic tree also showed that Pneumocystis from human and monkey formed one group and four rodent Pneumocystis formed another group. Among the four members, Pneumocystis wakefieldiae was most closely related to Pneumocystis murina and Pneumocystis carinii, and was least related to gerbil Pneumocystis.