The fusidic acid (FUS) resistance determinants fusB, fusC, fusD and fusF in coagulase-negative staphylococci (CoNS) clinical isolates were examined. Among 208 FUS-resistant isolates, the fusB gene was the most common resistance determinant in each species, except in Staphylococcus hominis subsp. hominis or in species carrying intrinsic fusD or fusF. In S. hominis subsp. hominis, the fusC gene was the major determinant responsible for FUS resistance. To understand the genetic context of fusC in S. hominis subsp. hominis, 31 fusC-positive S. hominis subsp. hominis isolates were examined. Among these isolates, 14 carried SCCfusC, 3 carried an SCC476-like element and 7 carried a new SCC structure (SCC3390). As shown by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) analyses, the S. hominis subsp. hominis clinical isolates showed limited clonality. Taken together, SCCfusC has been found in S. hominis subsp. hominis, Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus capitis subsp. ureolyticus and Staphylococcus aureus, suggesting its wide distribution and spread among different species of staphylococci.
Anti-Bacterial Agents/pharmacology , Drug Resistance, Bacterial/genetics , Fusidic Acid/pharmacology , Gene Transfer, Horizontal/genetics , Methicillin-Resistant Staphylococcus aureus/drug effects , Methicillin-Resistant Staphylococcus aureus/genetics , Staphylococcus hominis/genetics , Bacterial Proteins/genetics , Humans , Methicillin-Resistant Staphylococcus aureus/isolation & purification , Microbial Sensitivity Tests , Multilocus Sequence Typing , Staphylococcus capitis/drug effects , Staphylococcus capitis/genetics , Staphylococcus capitis/isolation & purification , Staphylococcus epidermidis/drug effects , Staphylococcus epidermidis/genetics , Staphylococcus epidermidis/isolation & purification , Staphylococcus haemolyticus/drug effects , Staphylococcus haemolyticus/genetics , Staphylococcus haemolyticus/isolation & purification , Staphylococcus hominis/drug effects , Staphylococcus hominis/isolation & purification , Taiwan
We analyzed the occurrence and mechanisms of fusidic acid resistance present in staphylococci isolated from 59 healthy volunteers. The fingers of the volunteers were screened for the presence of staphylococci, and the collected isolates were tested for resistance to fusidic acid. A total of 34 fusidic acid resistant staphylococcal strains (all were coagulase-negative) were isolated from 22 individuals (22/59, 37.3%). Examination of the resistance genes revealed that acquired fusB or fusC was present in Staphylococcus epidermidis, Staphylococcus capitis subsp. urealyticus, Staphylococcus hominis subsp. hominis, Staphylococcus warneri and Staphylococcus haemolyticus. Resistance islands (RIs) carrying fusB were found in S. epidermidis and S. capitis subsp. urealyticus, while staphylococcal chromosome cassette (SCC)-related structures harboring fusC were found in S. hominis subsp. hominis. Genotypic analysis of S. epidermidis and S. hominis subsp. hominis indicated that the fus elements were disseminated in diverse genetic strain backgrounds. The fusC elements in S. hominis subsp. hominis strains were highly homologous to SCCfusC in the epidemic sequence type (ST) 239/SCCmecIII methicillin-resistant S. aureus (MRSA) or the pseudo SCCmec in ST779 MRSA. The presence of acquired fusidic acid resistance genes and their genetic environment in commensal staphylococci suggested that the skin commensal staphylococci may act as reservoir for fusidic acid resistance genes.
Drug Resistance, Bacterial/genetics , Fusidic Acid/pharmacology , Genes, Bacterial , Skin/microbiology , Staphylococcus/genetics , Adolescent , Base Sequence , Genotype , Hand , Humans , Molecular Sequence Data , Species Specificity , Staphylococcus/drug effects
