Carriage of methicillin-resistant Staphylococcus aureus by wild urban Norway rats (Rattus norvegicus).
Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of multi-drug-resistant infections in people, particularly indigent populations. MRSA can be transmitted between people and domestic animals, but the potential for transmission between people and commensal pests, particularly rodents, had not been investigated. The objective of this study was to identify the presence and characterize the ecology of MRSA in rats (Rattus spp.) from in an impoverished, inner-city neighborhood. Oropharyngeal swabs were collected from rats trapped in 33 city blocks and one location within the adjacent port. Bacterial culture was performed and MRSA isolates were characterized using a variety of methods, including whole-genome sequencing (WGS). The ecology of MRSA in rats was described using phylogenetic analysis, geospatial analysis, and generalized linear mixed models. MRSA was identified 22 of 637 (3.5%) rats tested, although prevalence varied from 0 - 50% among blocks. Isolates belonged to 4 clusters according to WGS, with the largest cluster (n = 10) containing isolates that were genetically indistinguishable from community-acquired USA300 MRSA strains isolated from people within the study area. MRSA strains demonstrated both geographic clustering and dispersion. The odds of an individual rat carrying MRSA increased with increased body fat (OR = 2.53, 95% CI = 1.33-4.82), and in the winter (OR = 5.29, 95% CI = 1.04-26.85) and spring (OR = 5.50, 95% CI = 1.10-27.58) compared to the fall. The results show that urban rats carried the same MRSA lineages occurring in local human and/or animal populations, supporting recent transmission from external sources. MRSA carriage was influenced by season, most likely as a result of temporal variation in rat behavior and rat-human interactions.
School of Population and Public Health, University of British Columbia, Vancouver, British Columbia, Canada ; Animal Health Centre, British Columbia Ministry of Agriculture, Abbotsford, British Columbia, Canada.
Chelsea G
CG
Himsworth
Animal Health Centre, British Columbia Ministry of Agriculture, Abbotsford, British Columbia, Canada.
Ruth R
RR
Miller
Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
Vincent
V
Montoya
Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada ; British Columbia Centre for Disease Control, Vancouver, British Columbia, Canada.
Linda
L
Hoang
Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada ; St. Paul's Hospital, Vancouver, British Columbia, Canada.
Marc G
MG
Romney
Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada ; Children's and Women's Health Centre of British Columbia, Vancouver, British Columbia, Canada.
Ghada N
GN
Al-Rawahi
Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada ; British Columbia Centre for Excellence in HIV/AIDS, St. Paul's Hospital, Vancouver, British Columbia, Canada.
Thomas
T
Kerr
Department of Pathobiology, University of Guelph, Guelph, Ontario, Canada.
Claire M
CM
Jardine
School of Population and Public Health, University of British Columbia, Vancouver, British Columbia, Canada.
David M
DM
Patrick
Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada ; British Columbia Centre for Disease Control, Vancouver, British Columbia, Canada.
Patrick
P
Tang
Department of Pathobiology, University of Guelph, Guelph, Ontario, Canada.
J Scott
JS
Weese
D000818:Animals; D015415:Biomarkers / Q000378:metabolism*; D002170:Canada / Q000453:epidemiology; D002353:Carrier State / Q000382:microbiology*; D004269:DNA, Bacterial / Q000235:genetics; D004463:Ecology; D020869:Gene Expression Profiling; D062305:Geographic Mapping; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity; D020411:Oligonucleotide Array Sequence Analysis; D009960:Oropharynx / Q000382:microbiology*; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012376:Rodent Diseases / Q000453:epidemiology* / Q000382:microbiology*; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*
D015415:Biomarkers; D004269:DNA, Bacterial; D012333:RNA, Messenger