Genetic Variation among Pneumocystis carinii hominis Isolates in Recurrent Pneumocystosis

Keely, Scott P.; Stringer, James R.; Baughman, Robert P.; Linke, Michael J.; Walzer, P D; Smulian, A. George

doi:10.1093/infdis/172.2.595

Cited by 174 publications

(103 citation statements)

References 10 publications

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“…The ITS1 and ITS2 regions evolve more rapidly than the functional domains that they flank and are therefore potentially more useful at demonstrating differences among closely related populations of organisms (4). The ITS region has also been used to examine differences in P. carinii isolates from different parts of the world (13) and from patients with recurrent episodes of PCP (10,23). The high level of variation in the ITS genes compared to those in other genes used for typing (e.g., the mitochondrial large-subunit [mt LSU] rRNA gene) demonstrates the utility of this genetic locus in epidemiologic studies and in the detection of genetic diversity.…”

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Genetic Diversity of Pneumocystis carinii f. sp. hominis Based on Variations in Nucleotide Sequences of Internal Transcribed Spacers of rRNA Genes

Nimri¹,

Moura²,

Huang

et al. 2002

J Clin Microbiol

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A variety of genes have been used to type Pneumocystis carinii. In the present study, nucleotide sequence variations in the ITS1 and ITS2 internal transcribed spacer (ITS) regions of the rRNA genes were used to type Pneumocystis carinii f. sp. hominis DNA obtained from the lungs of 60 human immunodeficiency virus-infected individuals. These regions were amplified by PCR, cloned, and sequenced. Multibase polymorphisms were identified among samples. Several new genotypes are reported on the basis of the nucleotide sequence variations at previously unreported positions of both the ITS1 and the ITS2 regions. Twelve new ITS1 sequences were observed, in addition to the nine sequence types reported previously. The most common was type E, which was observed in 60.5% of the samples. The sequence variations in the ITS1 region were mainly located at positions 5, 12, 23, 24, 45, 53, and 54. Sixteen new ITS2 types were also identified, in addition to the 13 types reported previously. The most common was type g (26.6%). The sequences of the ITS2 regions in most specimens were different from the previously published sequence at bases 120 and 166 through 183. The most common variations observed were deletions at positions 177 through 183. The presence of more than one sequence type in some patients (60%) suggested the occurrence of coinfection with multiple P. carinii strains. The genetic polymorphism observed demonstrates the degree of diversity of Pneumocystis strains that infect humans. Furthermore, the high degree of polymorphism suggests that these genes are evolving faster than other genes. Consequently, the sequence information derived is useful for purposes such as examination of the potential of person-to-person transmission and recurrent infections but perhaps not for other genotyping applications that rely on more stable genetic loci.Pneumocystis carinii is an opportunistic pathogen that causes potentially fatal pneumonia in immunocompromised or immunosuppressed patients. Despite the decrease in the incidence of the disease in human immunodeficiency virus HIV-infected patients (3), P. carinii pneumonia (PCP) continues to be a common AIDS-defining illness associated with significant mortality in both adults (8%) (3) and children (30%) (19).Although recent research has clarified our understanding of certain biological aspects of the organism, no standard method for the typing of P. carinii has emerged. Pure isolates of the organism are difficult to obtain in large amounts due to the lack of a standardized method of in vitro cultivation of humanderived P. carinii. Standard methods of typing have similarly been slow to develop (24).Despite evidence of genetic variations among human P. carinii isolates (12,20), the degree of diversity among strains that infect humans still lacks clarification. The existence of multiple strains of P. carinii that infect humans was first demonstrated by examination of the restriction fragment length polymorphisms (RFLPs) of P. carinii genomes from three patients (21). However, RFLP analyses...

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Genetic Diversity of Pneumocystis carinii f. sp. hominis Based on Variations in Nucleotide Sequences of Internal Transcribed Spacers of rRNA Genes

Nimri¹,

Moura²,

Huang

et al. 2002

J Clin Microbiol

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“…Most cases are supposedly due to the reactivation of latent infections, but recent studies indicate the possibility of de novo introduction from human or environmental reservoirs (6,8).…”

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“…Sequence analysis of some genetic loci demonstrated a marked heterogeneity of P. carinii isolated from humans or other mammalian species (6,10,11,14,15,16,19,21). Coinfection with different strains of P. carinii in the same host has also been demonstrated (1,5,11,15,20).…”

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Genetic Diversity of Pneumocystis carinii Isolated from Human Immunodeficiency Virus-Positive Patients in Turin, Italy

et al. 2001

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By DNA sequence analysis we identified two new strain types and five novel sporadic variations among 25 isolates of Pneumocystis carinii f. sp. hominis obtained from 19 human immunodeficiency virus-positive patients. Of these, 13 were infected with a single strain and 6 were coinfected. Fifteen different combination types were identified among the 18 strains for which complete molecular typing was accomplished

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“…Research employing molecular techniques has also shown evidence of reinfection. By examining patients who have suffered from pneumocystosis several times, different genetic types of P. jirovecii were isolated at subsequent stages of the disease (Keely et al 1995). Furthermore, it has been noted that the genetic pattern of Pneumocystis isolated from infected people is not similar to the pattern characteristic for isolates collected at their place of birth, but is more often in accordance with the pattern characteristic for the place in which the person resided at the time of collection of the specimen (Beard et al 2000).…”

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confidence: 99%

The occurrence of Pneumocystis jirovecii in people from three different age groups of Warsaw (Poland) community

Gołąb

Sadkowska-Todys

Szkoda

et al. 2008

Acta Parasitologica

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The three age groups of people from Warsaw: children, young adults and elderly people were examined for the prevalence of infection with Pneumocystis jirovecii. Nested PCR was used to amplify fragment of mitochondrial large subunit rRNA of the fungus in samples of oropharyngeal swabs. Nineteen (12.8%) of the 148 examined samples were positive for DNA of P. jirovecii. The samples collected from children were more often positive than the samples from young adults (p = 0.003) or from both groups of adults (p = 0.0029). Moreover, among adults (n = 99) proportion of infected women (n = 6; 12.5%) was significantly higher than men (n = 1; 2%). Results of the research confirm the high prevalence of Pneumocystis infection in children and indirectly point out to children as a possible source of infection for older people.

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Genetic Variation among Pneumocystis carinii hominis Isolates in Recurrent Pneumocystosis

Cited by 174 publications

References 10 publications

Genetic Diversity of Pneumocystis carinii f. sp. hominis Based on Variations in Nucleotide Sequences of Internal Transcribed Spacers of rRNA Genes

Genetic Diversity of Pneumocystis carinii f. sp. hominis Based on Variations in Nucleotide Sequences of Internal Transcribed Spacers of rRNA Genes

Genetic Diversity of Pneumocystis carinii Isolated from Human Immunodeficiency Virus-Positive Patients in Turin, Italy

The occurrence of Pneumocystis jirovecii in people from three different age groups of Warsaw (Poland) community

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