Abstract
BackgroundHospital intensive care units (ICUs) are known reservoirs of multidrug resistant nosocomial bacteria. Targeted environmental monitoring of these organisms in health care facilities can strengthen infection control procedures. A routine surveillance of extended spectrum beta-lactamase (ESBL) producers in a large Australian veterinary teaching hospital detected the opportunistic pathogen Enterobacter hormaechei in a hand washing sink of the ICU. The organism persisted for several weeks, despite two disinfection attempts. Four isolates were characterized in this study.MethodsBrilliance-ESBL selective plates were inoculated from environmental swabs collected throughout the hospital. Presumptive identification was done by conventional biochemistry. Genomes of multidrug resistant Enterobacter were entirely sequenced with Illumina and Nanopore platforms. Phylogenetic markers, mobile genetic elements and antimicrobial resistance genes were identified in silico. Antibiograms of isolates and transconjugants were established with Sensititre microdilution plates.ResultsThe isolates possessed a chromosomal Tn7-associated silver/copper resistance locus and a large IncH12 conjugative plasmid encoding resistance against tellurium, arsenic, mercury and nine classes of antimicrobials. Clusters of antimicrobial resistance genes were associated with class 1 integrons and IS26, IS903 and ISCR transposable elements. The blaSHV-12, qnrB2 and mcr-9.1 genes, respectively conferring resistance to cephalosporins, quinolones and colistin, were present in a locus flanked by two IS903 copies. ESBL production and enrofloxacin resistance were confirmed phenotypically. The isolates appeared susceptible to colistin, possibly reflecting the inducible nature of mcr-9.1.ConclusionsThe persistence of this strain in the veterinary hospital represented a risk of further accumulation and dissemination of antimicrobial resistance, prompting a thorough disinfection of the ICU. The organism was not recovered from subsequent environmental swabs, and nosocomial Enterobacter infections were not observed in the hospital during that period. This study shows that targeted routine environmental surveillance programs to track organisms with major resistance phenotypes, coupled with disinfection procedures and follow-up microbiological cultures are useful to control these risks in sensitive areas of large veterinary hospitals.
Highlights
Hospital intensive care units (ICUs) are known reservoirs of multidrug resistant nosocomial bacteria
Kamathewatta et al Antimicrob Resist Infect Control (2020) 9:163 with major resistance phenotypes, coupled with disinfection procedures and follow-up microbiological cultures are useful to control these risks in sensitive areas of large veterinary hospitals
Persistence of a multidrug resistant strain of Enterobacter hormaechei in a sink Four extended spectrum beta-lactamase (ESBL) producing Enterobacter sp. were isolated on selective media from environmental swabs collected in a veterinary teaching hospital ICU over a period of approximately one month
Summary
Hospital intensive care units (ICUs) are known reservoirs of multidrug resistant nosocomial bacteria. A routine surveillance of extended spectrum beta-lactamase (ESBL) producers in a large Australian veterinary teaching hospital detected the opportunistic pathogen Enterobacter hormaechei in a hand washing sink of the ICU. Investigations into nosocomial infections outbreaks caused by Enterobacterales, Pseudomonas and Acinetobacter, have revealed that contaminated hand washing sinks in intensive care units were an important source of these microorganisms [4,5,6,7,8]. The genomic analysis of the bacteria isolated through these surveillance programs provides useful information on the origin and potential spread of antibiotic resistance genes. This knowledge can be used to improve infection control procedures. A successful decontamination protocol was implemented in the hospital to eliminate the organism from the sink in response to these findings
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