BackgroundMupirocin has been used for the treatment of skin infections and eradication of nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA). The increased use of this antibiotic has been accompanied by outbreaks of MRSA that are resistant to mupirocin.ObjectiveThis study aims to determine the prevalence, genotype and antimicrobial susceptibility of mupirocin-resistant MRSA from 4 Korean hospitals.MethodsA total 193 MRSA clinical isolates were collected from four university hospitals. Antimicrobial susceptibility tests, including mupirocin, and pulsed-field gel electrophoresis (PFGE) pattern analysis were performed.ResultsOverall, 27 of the 193 (14.1%) MRSA isolates were resistant to mupirocin. All of the (A) hospital isolates showed high-level (HL) mupirocin resistance and the low-level (LL) mupirocin resistant strains were from three other hospitals. The PFGE patterns of 16 mupirocin-resistant isolates were divided into 5 clusters (1-5), and the nine HL mupirocin-resistant isolates belonged to cluster 1. Both the HL and LL mupirocin-resistant MRSA isolates were susceptible to vancomycin and rifampin, but they were resistant to ciprofloxacin, clindamycin and tetracycline. The erythromycin and fusidic acid resistance rates were different between the HL and LL resistant isolates.ConclusionHL mupirocin-resistant isolates that could transfer this resistance to other bacteria were detected and these isolates were clonally related. The emergence of mupirocin resistant isolates emphasizes the importance of using antibiotics judiciously and carefully monitoring the prevalence of mupirocin resistance.

The prevalence, genotype for antibiotic resistance and antibiotic susceptibility of vancomycin resistant enterococci (VRE) were determined. And molecular typings of the Enterococcus faecium isolates were analyzed. Prevalence of VRE in chickens, healthy children and intensive care unit (ICU) patients was 41.6%, 7.9%, and 20.4%, respectively. Forty out of 54 isolates from chicken intestines, and 9 out of 11 from ICU patients were identified as Enterococcus faecium. Eleven out of 13 isolates from non-hospitalized young children were E. gallinarium. Twelve strains of E. faecalis were isolated from chicken intestines. The gene for the antibiotic resistance in E. faecium, and E. faecalis was vanA, while that in E. gallinarium was vanC1. E. faecium isolates were resistant to most of antibiotics except ampicillin and gentamicin. Molecular typing of the E. faecium strains obtained by pulse field gel electrophoresis and repetitive sequence-based PCR suggest that VRE transmit horizontally from poultry to humans, especially young children, via the food chains in Korea.

Campylobacter jejuni isolates from diarrhea patients and chickens in 2008 in Iksan, Korea were tested for biochemical characteristics, and for possession of genes hipO, mutated gyrA, and cdtB. Among the chickens tested 52% carried C. jejuni. All 28 patient isolates and 48 chickens isolates had typical biochemical characteristics, except for nalidixic acid resistance. All isolates from patients and chickens were resistant to ciprofloxacin, and had mutated gyrA gene indicating good correlation of the two tests. Analysis of pulsed-field gel electrophoresis (PFGE) pattern of SmaI-restricted DNA of 53 isolates showed 14 clusters. Twenty-eight patient isolates and two chicken isolates (57%) showed an identical pattern (cluster 9). Chicken isolates C37 and C48 (cluster 2), C31 and C33 (cluster 3), C29, C34, C35, and C36 (cluster 4), and C43, C44 (cluster 6) had identical patterns. All patient isolates, compared to 87% and 80% of chicken isolates, were susceptible to amikacin and chloramphenicol, respectively. Antibiotics with the lowest MIC 90 were imipenem, gentamicin, and erythromycin, whereas, those with the highest were ampicillin and tetracycline. In conclusion, C. jejuni carriage rate of chickens in Iksan, Korea, was high, all 28 isolates from patients and two from chickens were an identical clone, whereas isolates from patients and remaining chickens were different clones with only 62% similarity, all isolates had hipO and cdtB genes, and all isolates were resistant to ciprofloxacin.