title: Low prevalence of DHFR and DHPS mutations in Pneumocystis jirovecii strains obtained from a German cohort.
abstract: BACKGROUND
  Pneumocystis pneumonia (PCP) is an opportunistic and potentially life-threatening infection of immunocompromised individuals. A combination of trimethoprim-sulfamethoxazole is widely used for prophylaxis and treatment of PCP. Polymorphisms in the drug targets, the dihydropteroate synthase (DHPS) or the dihydrofolate reductase (DHFR) are presumably a reason for treatment failure.
  
  
  METHODS
  We retrospectively examined the prevalence of DHPS and DHFR mutations in Pneumocystis jirovecii isolates obtained from HIV-infected and non-HIV-infected PCP patients. DHFR and DHPS genes were amplified using semi-nested PCR followed by sequencing. Obtained data were correlated with clinical findings.
  
  
  RESULTS
  Sequencing of the DHPS gene was achieved in 81 out of 128 isolates (63%), the DHFR-gene was successfully sequenced in 96 isolates (75%). The vast majority of DHFR and DHPS sequences were either wild-type or showed synonymous single nucleotide polymorphisms. Only one sample contained a double mutation at DHPS codon 55 and codon 57 which was associated with treatment failure in some studies. No linkage of treatment failure to a DHFR or DHPS genotype was observed. In our cohort, 35 of 95 Patients (37%) were HIV-positive and 60 (63%) were HIV-negative. The overall mortality rate was 24% with a much higher rate among non-HIV patients.
  
  
  CONCLUSIONS
  DHPS and DHFR mutations exist but are infrequent in our cohort. The contribution of gene polymorphisms to treatment failure needs further research. In immunocompromised HIV-negative patients PCP is associated with high mortality rates. Prophylactic treatment is warranted in this patient subset.
authors.affiliation: Department I of Internal Medicine, University Hospital of Cologne, Kerpener Str. 62, 50937, Cologne, Germany.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Suárez
authors.affiliation: Department I of Internal Medicine, University Hospital of Cologne, Kerpener Str. 62, 50937, Cologne, Germany.
authors.forename: Lisa
authors.initials: L
authors.lastname: Roderus
authors.affiliation: Department I of Internal Medicine, University Hospital of Cologne, Kerpener Str. 62, 50937, Cologne, Germany.|Center for Molecular Medicine Cologne, University of Cologne, 50931, Cologne, Germany.
authors.forename: Edeltraud
authors.initials: E
authors.lastname: van Gumpel
authors.affiliation: Department I of Internal Medicine, University Hospital of Cologne, Kerpener Str. 62, 50937, Cologne, Germany.
authors.forename: Norma
authors.initials: N
authors.lastname: Jung
authors.affiliation: Department I of Internal Medicine, University Hospital of Cologne, Kerpener Str. 62, 50937, Cologne, Germany.|German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany.
authors.forename: Clara
authors.initials: C
authors.lastname: Lehmann
authors.affiliation: Department I of Internal Medicine, University Hospital of Cologne, Kerpener Str. 62, 50937, Cologne, Germany.|German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany.
authors.forename: Gerd
authors.initials: G
authors.lastname: Fätkenheuer
authors.affiliation: Department I of Internal Medicine, University Hospital of Cologne, Kerpener Str. 62, 50937, Cologne, Germany.|German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany.
authors.forename: Pia
authors.initials: P
authors.lastname: Hartmann
authors.affiliation: Institute for Medical Microbiology, Immunology and Hygiene, University Hospital of Cologne, Cologne, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Plum
authors.affiliation: Department I of Internal Medicine, University Hospital of Cologne, Kerpener Str. 62, 50937, Cologne, Germany. jan.rybniker@uk-koeln.de.|German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany. jan.rybniker@uk-koeln.de.|Center for Molecular Medicine Cologne, University of Cologne, 50931, Cologne, Germany. jan.rybniker@uk-koeln.de.
authors.forename: Jan
authors.identifier: http://orcid.org/0000-0001-8351-2690
authors.initials: J
authors.lastname: Rybniker
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D004094:Dihydropteroate Synthase / Q000235:genetics* / Q000378:metabolism; D024881:Drug Resistance, Bacterial; D005260:Female; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D005858:Germany; D015658:HIV Infections / Q000382:microbiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D045363:Pneumocystis carinii / Q000187:drug effects / Q000235:genetics*; D011020:Pneumonia, Pneumocystis / Q000382:microbiology*; D012189:Retrospective Studies; D017422:Sequence Analysis, DNA; D013420:Sulfamethoxazole / Q000494:pharmacology; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D014295:Trimethoprim / Q000494:pharmacology
chemical_list: D000890:Anti-Infective Agents; D005656:Fungal Proteins; D014295:Trimethoprim; D013762:Tetrahydrofolate Dehydrogenase; D004094:Dihydropteroate Synthase; D013420:Sulfamethoxazole
keywords: DHFR; DHPS; HIV; PCP; Pneumocyistis jirovecii; Pneumonia; Trimethoprim–sulfamethoxazole