Susceptibility to chlorhexidine and mupirocin among methicillin-resistant Staphylococcus aureus clinical isolates from a teaching hospital.

Despite the widespread use of chlorhexidine (CHX) to prevent infection, data regarding the in vitro action of CHX against methicillin-resistant Staphylococcus aureus (MRSA) are limited. Clinical isolates from Hospital das Clinicas, Sao Paulo, Brazil, identified during 2002/2003 and 2012/2013 were studied to describe the susceptibility to CHX and mupirocin, molecular characteristics, and virulence profile of MRSA. Susceptibility test to Mupirocin was performed by the disk diffusion method and to CHX by the agar dilution technique. PCR for virulence genes, mecA gene and Staphylococcal Cassette Chromosome mec (SCCmec) types were investigated as well. Mupirocin- and CHX-resistant isolates were sequenced using the IlluminaTM plataform. Two hundred and sixteen MRSA clinical isolates were evaluated: 154 from infected and 62 from colonized patients. Resistance to mupirocin was observed in four isolates assigned as SCCmec type III and STs (ST05; ST239 and ST105) carrying mupA and blaZ, two of them co-harboring the ileS gene. Only one isolate assigned as SCCmec type III was resistant to CHX (MIC of 8.0 µg.mL-1) and harbored the qacA gene. Resistance to chlorhexidine and mupirocin were found in isolates carrying qacA and mupA in our hospital. Since these genes are plasmid-mediated, this finding draws attention to the potential spread of resistance to mupirocin in our hospital.

Outbreak of IMP-producing carbapenem-resistant Enterobacter gergoviae among kidney transplant recipients.

OBJECTIVES: The objective of this study was to investigate a prolonged outbreak of carbapenem-resistant Enterobacter gergoviae (CREG) involving kidney transplant recipients (KTRs) between 2009 and 2014. METHODS: A case-control study was undertaken. Controls (n = 52) were selected from CREG-negative KTRs. Surveillance cultures for CREG were collected weekly. Colonization was defined as isolation of CREG from surveillance samples or from clinical specimens, with no evidence of infection. We also investigated infection control practices at the facility. RESULTS: Of 26 identified cases, 13 had had no known contact with another CREG-positive patient before the first positive culture. Seven patients (27%) developed infection. The site most often colonized was the urinary tract. During the study period two clusters were identified, one in 2009 and another in 2013-14. DNA sequencing revealed blaIMP-1 in all CREG tested. No environmental or hand cultures tested positive for CREG. An audit of infection control practices detected flaws in the handling and cleaning of urinary tract devices. Multivariate analysis identified advanced age, ureteral stent use, retransplantation and male gender as risk factors for CREG acquisition. CONCLUSIONS: An outbreak among KTRs caused by an unusual species of MDR bacteria may have resulted from a common source of contamination related to urinary tract devices.