A cluster of carbapenemase-producing Enterobacter cloacae complex ST171 at a tertiary care center demonstrating an ongoing regional threat.

BACKGROUND: In Minnesota and North Dakota, a clonal strain of blaKPC-3-producing Enterobacter cloacae complex has been reported with increasing frequency. METHODS: Between July 2015 and February 2016, 13 carbapenem-resistant E. cloacae complex isolates were identified at our institution. Five blaKPC-positive isolates were identified by polymerase chain reaction and underwent pulsed-field gel electrophoresis and whole genome sequencing. Medical records of these patients were reviewed. RESULTS: All 5 case-isolates belonged to sequence type 171 and were blaKPC-3-positive. Three pulsed-field gel electrophoresis patterns with >90% similarity were identified in the 5 case-isolates. We identified overlaps in time and location between case patients. Plasmid types and resistance genes were nearly identical between the isolates. Whole genome sequencing showed isolates A, B, and D to be closely related with <10 core single-nucleotide polymorphisms differences. Isolates C and E were also closely related to each other, but more distantly to A, B, and D; all belonged to the clonal lineage of the major circulating E. cloacae complex strain in Minnesota and North Dakota. Despite having overlapping hospital stays, isolates for patients C and D were not identical. CONCLUSIONS: Isolates A and D were nearly identical, indicating possible transmission during hospitalization. Transmission of the other isolates may have occurred elsewhere. This report highlights the importance of using both epidemiologic and molecular data to track the spread of carbapenemase-producers.

Efficacy of concurrent application of chlorhexidine gluconate and povidone iodine against six nosocomial pathogens.

BACKGROUND: Chlorhexidine gluconate (CHG) and povidone iodine (PI) are rarely used concurrently despite a lack of evidence regarding functional incompatibility of these agents. METHODS: CHG and PI, alone and combined, were evaluated against Staphylococcus aureus (methicillin-susceptible S aureus [MSSA] and methicillin-resistant S aureus [MRSA]), Staphylococcus epidermidis (MRSE), Acinetobacter baumannii, Pseudomonas aeruginosa, and Escherichia coli using checkerboard microbroth dilution techniques. Minimum bactericidal concentration (MBC) was the concentration (percent wt/vol) that reduced bacterial burden ≥ 5-log(10) colony-forming units/mL at 2 hours when compared with bacterial densities in growth controls. Fractional bactericidal concentration indexes (FBCIs) were calculated to determine CHG and PI compatibility. Additionally, tissue plugs from freshly excised porcine vaginal mucosa were infected with S aureus (MSSA), treated for 2 hours with CHG 3%, PI 5%, or CHG 3% and PI 5% combined and then viable bacteria on the tissue plugs enumerated. RESULTS: In broth, CHG demonstrated dose-dependent bactericidal activity, whereas PI activity was all-or-none. All isolates studied were similarly susceptible to CHG (MBCs: 0.0078% ± 0.0019%, 0.0069% ± 0.0026%, 0.0024% ± 0.0005%, 0.0024% ± 0.0005%, 0.0059% ± 0.0%, and 0.0029% ± 0.0%, respectively). The MBCs of PI were identical (0.625%) for all isolates. Overall, FBCI calculations showed indifference. Treatment of MSSA-infected porcine tissue for 2 hours demonstrated that the CHG-PI combination was superior to either antiseptic alone. CONCLUSION: FBCIs, determined in broth culture, indicate that combining CHG and PI had no negative impact on antisepsis. Moreover, data from an ex vivo porcine mucosal infection model suggest a potential benefit when combining the 2 antiseptic agents.