title: [Macrolide-lincosamide-streptogramin B (MLSB) resistance phenotypes in clinical Staphylococcus isolates and investigation of telithromycin activity].
abstract: Staphylococci are one of the most common pathogens isolated from nosocomial and community acquired infections. Antibiotics such as clindamycin and erythromycin have been useful options for treating skin and soft-tissue infections caused by staphylococci. However, expression of macrolide-lincosamide-streptogramin B resistance (MLSB) can limit the effectiveness of these drugs. The aims of this study were to investigate the prevalence and phenotypes of MLSB resistance in staphylococcus strains isolated from clinical samples and to determine the telithromycin activity against these isolates. A total of 218 strains [92 Staphylococcus aureus and 126 coagulase-negative staphylococci (CNS)] isolated from different clinical samples (wound, abscess, blood, sterile body fluids, catheter, upper respiratory tract samples) between February 2011 to December 2012 were included in the study. The isolates were identified by using conventional methods and automated bacterial identification system (BD Phoenix 100™ System, Becton Dickinson, USA). Methicillin resistance of the isolates was determined with the use of cefoxitin (30 µg) disk and telithromycin (15 µg) activity was detected by Kirby-Bauer disk diffusion method. MLSB resistance phenotypes were investigated by the D-test method using erythromycin (15 µg) and clindamycin (2 µg) disks. Of 92 S.aureus isolates, 23 were methicillin-resistant (MRSA) and 69 were methicillin-susceptible (MSSA), whereas 78 of 126 CNS isolates were methicillin-resistant (MRCNS) and 48 were methicillin-susceptible (MSCNS). Hundred and seventy-two (79%) isolates were found as erythromycin-resistant, and the rates of erythromycin resistance in MRSA, MSSA, MRCNS and MSCNS strains were 83%, 71%, 95% and 63%, respectively. Inducible type of MLSB resistance (iMLSB type) was observed in 26%, 6%, 51% and 33%; chromosomal resistance (cMLSB type) in 32%, 27%, 27% and 17% and efflux pump connected resistance (MSB type) in 42%, 67%, 22% and 50% of the MRSA, MSSA, MRCNS and MSCNS, respectively. Forty-four (20%) strains were found susceptible to both clindamycin and erythromycin (S type resistance). Resistance due to enzymatic inactivation (L type) was observed only in two of the CNS strains (0.9%), one was methicillin-resistant and the other was susceptible. Total telithromycin resistance was detected as 26.6% (n= 58), while the resistance rates in MRSA, MSSA, MRCNS and MSKNS isolates were 35%, 35%, 28% and 8%, respectively. Telithromycin resistance rate was 34% (58/172) in erythromycin-resistant isolates. However, all erythromycin-susceptible isolates (n= 46) were also susceptible to telithromycin. Telithromycin-resistant isolates frequently exhibited cMLSB phenotype (39/44; 67.2%), followed by MSB (16/72; 27.6%) and iMLSB (3/56; 5.2%). In conclusion, clindamycin is still an effective antibiotic for the treatment of staphylococcal infections in our hospital, however, 34% resistance rate against telithromycin may limit the use of this agent which is an alternative for the treatment of infections caused by clindamycin and erythromycin-resistant strains.
authors: Ataturk Training and Research Hospital, Microbiology Laboratory, Izmir, Turkey. berrinuzun@gmail.com.
authors: Berrin
authors: B
authors: Uzun
authors: Serdar
authors: S
authors: Güngör
authors: Bayram
authors: B
authors: Pektaş
authors: Ayşegül
authors: A
authors: Aksoy Gökmen
authors: Erkan
authors: E
authors: Yula
authors: Funda
authors: F
authors: Koçal
authors: Selçuk
authors: S
authors: Kaya
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial; D006801:Humans; D048628:Ketolides / Q000494:pharmacology*; D055231:Lincosamides / Q000494:pharmacology; D018942:Macrolides / Q000494:pharmacology; D010641:Phenotype; D013203:Staphylococcal Infections / Q000382:microbiology*; D013210:Staphylococcus / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification; D025381:Streptogramin B / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D048628:Ketolides; D055231:Lincosamides; D018942:Macrolides; D025381:Streptogramin B; C106791:telithromycin