Community-genotype strains of methicillin-resistant Staphylococcus aureus with high-level mupirocin resistance in a neonatal intensive care unit.

The aim of this study was to investigate the genotypes of mupirocin-resistant methicillin-resistant Staphylococcus aureus (MR-MRSA) isolates in our neonatal intensive care unit (NICU) and their potential source. One hundred one MRSA isolates obtained from 59 inborn and 42 outborn infants were identified and their antimicrobial susceptibility determined. Using pulse-field gel electrophoresis (PFGE) analysis, MR-MRSA isolates obtained from the neonatal patients in the NICU were compared with those from adult hospitalized in the same hospital and with community-associated MRSA (CA-MRSA) isolates recovered from different hospitals in Korea. Overall, 47% of CA-MRSA and 79% of healthcare-associated MRSA isolates exhibited high-level mupirocin resistance (HLMR). Forty-five percent of the outborn infants were considered to have CA-MRSA at the time of admission to our NICU. Most HLMR-MRSA isolates from neonates were grouped into a single cluster by PFGE analysis, and which included CA-MRSA isolates with HLMR recovered from outborn infants who were already colonized when they were transferred to our NICU. They belonged to the same PFGE group as the community-genotype strains isolated from different hospitals in Korea. HLMR-MRSA isolates from adults patients were classified as different clones. None of the attending staff in the NICU were nasal carriers. Community-genotype strains of MRSA with HLMR may be imported to our NICU through obstetrics clinics and contribute to MRSA colonization or infection in facilities with a high rate of admission of outborn infants.

Park SH ，Kim SY ，Lee JH ，Park C ，Lee DG ... -  《-》

Emergence of community-associated methicillin-resistant Staphylococcus aureus strains in the neonatal intensive care unit: an infection prevention and patient safety challenge.

Methicillin-resistant Staphylococcus aureus (MRSA) infections cause significant morbidity and mortality in neonatal intensive care units (NICUs). We characterized the clinical and molecular epidemiology of MRSA strains colonizing NICU patients. Nasal MRSA isolates (n = 250, from 96 NICU patients) recovered through active surveillance from 2009 to 2014 were characterized with staphylococcal cassette chromosome mec (SCCmec) typing and detection of mupA (marker of high-level mupirocin resistance) and qacA/B (marker associated with chlorhexidine resistance). Factors associated with community-associated (CA-) or healthcare-associated (HA-) MRSA were evaluated. The overall prevalence of MRSA nasal colonization was 3.9%. Of 96 neonates in our retrospective cohort, 60 (63%) were colonized with CA-MRSA strains and 35 (36%) were colonized with HA-MRSA strains. Patients colonized with HA-MRSA were more likely to develop MRSA infections than patients colonized with CA-MRSA (13/35, 37% versus 8/60, 13%; p 0.007), although the interval from colonization to infection was shorter in CA-MRSA-colonized infants (median 0 days, range -1 to 4 versus HA-MRSA-colonized infants, 7 days, -1 to 43; p 0.005). Maternal peripartum antibiotics were associated with CA-MRSA colonization (adjusted odds ratio (aOR) 8.7; 95% CI 1.7-45.0); intubation and surgical procedures were associated with HA-MRSA colonization (aOR 7.8; 95% CI 1.3-47.6 and aOR 6.0; 95% CI 1.4-24.4, respectively). Mupirocin- and chlorhexidine-resistant MRSA was isolated from four and eight patients, respectively; carriage of a mupirocin-resistant strain precluded decolonization. CA-MRSA strains are prominent in the NICU and associated with distinct risk factors. Given community reservoirs for MRSA acquisition and transmission, novel infection prevention strategies are needed.

Reich PJ ，Boyle MG ，Hogan PG ，Johnson AJ ，Wallace MA ，Elward AM ，Warner BB ，Burnham CA ，Fritz SA ... -  《-》

Effect of mupirocin decolonization on subsequent methicillin-resistant Staphylococcus aureus infection in infants in neonatal intensive care units.

Huang YC ，Lien RI ，Lin TY 《-》

Emergence of community-associated methicillin-resistant Staphylococcus aureus strains as a cause of healthcare-associated bloodstream infections in Korea.

Park SH ，Park C ，Yoo JH ，Choi SM ，Choi JH ，Shin HH ，Lee DG ，Lee S ，Kim J ，Choi SE ，Kwon YM ，Shin WS ... -  《-》

Molecular epidemiology of plasmid-mediated high-level mupirocin resistance in methicillin-resistant Staphylococcus aureus in four Spanish health care settings.

Mupirocin is used for the decolonization of methicillin-resistant Staphylococcus aureus (MRSA). High-level mupirocin resistance (Hi-Mup(R)) is of concern, having been associated with therapeutic failure. Our main objective was to assess the emergence and mode/s of spread of Hi-Mup(R) in the MRSA population recovered between 2002 and 2009 in four health care settings in the Pontevedra province, northwest Spain. Five hundred and fifty consecutive clinical MRSA isolates were obtained and screened for antimicrobial susceptibility. Isolates were stratified into multidrug-resistant (MDR) and non-MDR. High-level mupirocin resistant MRSA were characterized by genotyping and plasmid analysis. Thirty-one MRSA (5.6%) exhibited Hi-Mup(R). No association was detected between Hi-Mup(R) and MDR but isolates displaying Hi-Mup(R) were more likely to be resistant to gentamicin and tobramycin. Four main MRSA clones were identified: ST125/t067/PFGE A, ST36/t018/PFGE D, ST8/t008/PFGE B, and ST72/t148 or t3092/PFGE B. Each isolate carried the Hi-Mup(R)ileS2-encoding gene on plasmids and ten plasmid types were distinguished based on unique IS257-ileS2 configurations. Some plasmid types were successfully disseminated among the MRSA clones. Remarkably, six plasmid types were acquired by the predominant genotype ST125/t067/PFGE A. In conclusion, molecular characterization of MRSA isolates combined with the rapid typing of ileS2-encoding plasmids through determination of IS257-ileS2 configurations have proved to be a powerful strategy to address the molecular epidemiology of Hi-Mup(R). The transmission of a diverse set of ileS2-carrying plasmids promoted the emergence of the resistance, with a limited role of clonal expansion in its dispersion.

Pérez-Roth E ，Potel-Alvarellos C ，Espartero X ，Constela-Caramés L ，Méndez-Álvarez S ，Alvarez-Fernández M ... -  《-》