Healthcare-associated infections caused by chlorhexidine-tolerant Serratia marcescens carrying a promiscuous IncHI2 multi-drug resistance plasmid in a veterinary hospital

Abstract

The bacterium Serratia marcescens can cause opportunistic infections in humans and in animals. In veterinary settings, the diversity, reservoirs and modes of transmission of this pathogen are poorly understood. The phenotypes and genotypes of Serratia spp. isolated from dogs, cats, horses, a bird and a rabbit examined at an Australian veterinary hospital between 2008 and 2019 were characterised. The isolates were identified as S. marcescens (n = 15) or S. ureilytica (n = 3) and were placed into four distinct phylogenetic groups. Nine quasi-clonal isolates associated with post-surgical complications in different patients displayed high levels of resistance to the antimicrobials fluoroquinolones, cephalosporins, aminoglycosides, and to the disinfectant chlorhexidine. A Serratia sp. with a similar resistance profile was also isolated from chlorhexidine solutions used across the Hospital, suggesting that these infections had a nosocomial origin. A genomic island encoding a homolog of the Pseudomonas MexCD-OprJ biocide efflux system was detected in the chlorhexidine-tolerant Serratia. The nine multi-drug resistant Serratia isolates also possessed a Ser-83-Ile mutation in GyrA conferring fluoroquinolone resistance, and carried a large IncHI2 conjugative plasmid encoding antimicrobial and heavy metal resistances. This replicon was highly similar to a plasmid previously detected in a strain of Enterobacter hormaechei recovered from the Hospital environment. IncHI2 plasmids are commonly found in Enterobacteriaceae, but are rarely present in Serratia spp., suggesting that this plasmid was acquired from another organism. A chlorhexidine-tolerant Serratia isolate which lacked the IncHI2 plasmid was used in mating experiments to demonstrate the transfer of multi-drug resistance from a E. hormaechei donor. This study illustrates the importance of environmental surveillance of biocide-resistance in veterinary hospitals.

Genotypic analyses of IncHI2 plasmids from enteric bacteria

“…Of the colistin resistant isolates in their study and the current study, mcr-1.1 was detected on IncHI2 plasmids in E. coli across multiple years 51 . These papers represent a small fraction of the IncHI2 literature focused on the characterization of these important resistance genes from the plasmids in bacteria from varied geographical locations, host sources and time periods, highlighting the global spread of IncHI2 plasmids 23 , 52 – 54 .…”

Diminishing the Pathogenesis of the Food-Borne Pathogen Serratia marcescens by Low Doses of Sodium Citrate

“…Once established, Serratia , a well-known food pathogen, can form biofilms on food and surfaces, which can make the bacteria more resistant to cleaning and disinfection [ 84 , 85 ]. Critically, Serratia can cause infections in humans, particularly in individuals with compromised immune systems [ 2 , 10 , 86 ]. Anti-virulence agents are compounds that target specific virulence factors in bacteria, rather than targeting the bacteria themselves [ 39 , 87 ].…”

“…Serratia marcescens is a Gram-negative bacterium that can be found in a variety of environments, including soil, water, and food [ 1 , 2 ]. It is often considered as an indicator of poor sanitation and hygiene practices.…”

“…S. marcescens is an opportunistic pathogen that easily adapts to shifting physicochemical conditions, showing a considerable capability of surviving and thriving in diverse environments, such as disinfectant solutions, making it a major nosocomial pathogen which is often isolated from urinary tract, respiratory tract, soft tissue, ocular, and septic infections [ 1 , 8 , 9 , 10 , 11 ]. The S. marcescens adaptation and survival in diverse environments can be traced to a number of genetic factors, including chromosomally-encoded porins and efflux systems that contribute to the resistance to several antibiotics [ 2 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ].…”

Molecular Detection of Serratia Marcescens Isolated From Different Clinical Cases in Wasit Province, Iraq

“…Serratia marcescens is a rod-shaped Gram-negative bacterium that belongs to the family Enterobacteriaceae (Allen et al, 2022). It is a facultative anaerobic bacterium that can grow in the presence and absence of oxygen at temperatures 30-37°C (Ferreira et al, 2018;Kljakić et al, 2021).…”