title: Characterization of Staphylococcus aureus Strains Isolated from Czech Cystic Fibrosis Patients: High Rate of Ribosomal Mutation Conferring Resistance to MLS(B) Antibiotics as a Result of Long-Term and Low-Dose Azithromycin Treatment.
abstract: Staphylococcus aureus is one of the most frequent pathogens infecting the respiratory tract of patients with cystic fibrosis (CF). This study was the first to examine S. aureus isolates from CF patients in the Czech Republic. Among 100 S. aureus isolates from 92 of 107 observed patients, we found a high prevalence of resistance to macrolide-lincosamide-streptogramin B (MLS(B)) antibiotics (56%). More than half of the resistant strains (29 of 56) carried a mutation in the MLS(B) target site. The emergence of MLS(B) resistance and mutations conferring resistance to MLS(B) antibiotics was associated with azithromycin treatment (p=0.000000184 and p=0.000681, respectively). Methicillin resistance was only detected in 3% of isolates and the rate of resistance to other antibiotics did not exceed 12%. The prevalence of small-colony variant (SCV) strains was relatively low (9%) and eight of nine isolates with the SCV phenotype were thymidine dependent. The study population of S. aureus was heterogeneous in structure and both the most prevalent community-associated and hospital-acquired clonal lineages were represented. Of the virulence genes, enterotoxin genes seg (n=52), sei (n=49), and sec (n=16) were the most frequently detected among the isolates. The PVL genes (lukS-PV and lukF-PV) have not been revealed in any of the isolates.
authors.affiliation: 1 Department of Medical Microbiology, 2nd Faculty of Medicine, Charles University in Prague and Motol University Hospital , Prague, Czech Republic .
authors.forename: Jan
authors.initials: J
authors.lastname: Tkadlec
authors.affiliation: 1 Department of Medical Microbiology, 2nd Faculty of Medicine, Charles University in Prague and Motol University Hospital , Prague, Czech Republic .
authors.forename: Eva
authors.initials: E
authors.lastname: Vařeková
authors.affiliation: 2 Department of Experimental Biology, Faculty of Science, Masaryk University, Brno , Czech Republic .
authors.forename: Roman
authors.initials: R
authors.lastname: Pantůček
authors.affiliation: 2 Department of Experimental Biology, Faculty of Science, Masaryk University, Brno , Czech Republic .
authors.forename: Jiří
authors.initials: J
authors.lastname: Doškař
authors.affiliation: 2 Department of Experimental Biology, Faculty of Science, Masaryk University, Brno , Czech Republic .
authors.forename: Vladislava
authors.initials: V
authors.lastname: Růžičková
authors.affiliation: 2 Department of Experimental Biology, Faculty of Science, Masaryk University, Brno , Czech Republic .
authors.forename: Tibor
authors.initials: T
authors.lastname: Botka
authors.affiliation: 3 Department of Pneumology, 2nd Faculty of Medicine, Charles University in Prague and Motol University Hospital , Prague, Czech Republic .
authors.forename: Libor
authors.initials: L
authors.lastname: Fila
authors.affiliation: 1 Department of Medical Microbiology, 2nd Faculty of Medicine, Charles University in Prague and Motol University Hospital , Prague, Czech Republic .
authors.forename: Oto
authors.initials: O
authors.lastname: Melter
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use*; D017963:Azithromycin / Q000627:therapeutic use*; D003428:Cross Infection / Q000382:microbiology; D003550:Cystic Fibrosis / Q000382:microbiology*; D018153:Czech Republic; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D006801:Humans; D008134:Long-Term Care; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D009154:Mutation / Q000235:genetics; D012270:Ribosomes / Q000235:genetics*; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics*; D013936:Thymidine / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D017963:Azithromycin; D013936:Thymidine