Carriage of Methicillin-Resistant Staphylococcus aureus by Wild Urban Norway Rats (Rattus norvegicus)

Abstract

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.

Effects of Culling onLeptospira interrogansCarriage by Rats

“…Other vectorborne (e.g., fleaborne Rickettsia spp. [ 14 ]) or environmentally acquired (e.g., methicillin-resistant Staphylococcus aureus [ 15 ]) rat-associated pathogens might not be as easily influenced by culling. Future studies should determine the duration of effects induced by lethal control because effects on L. interrogans prevalence may wane with time.…”

What Is the Origin of Livestock-Associated Methicillin-Resistant Staphylococcus aureus Clonal Complex 398 Isolates from Humans without Livestock Contact? An Epidemiological and Genetic Analysis

“…Since living in areas with a high density of pigs (6) and private farm visits (27) were risk factors for livestock-associated MRSA carriage, modes of indirect transmission are most likely through contamination of areas in which people live and interact. Considering the survival of S. aureus bacteria in the environment and subsequent spread by air over large distances (7), transmission by air is a possibility (28), as well as transmission by vectors such as rodents (29). Nevertheless, transmission by human-to-human contact cannot be ruled out: of the six MUO CC398 carriers investigated by extended questionnaire in this study, one MUO CC398 carrier had had contact with a MRSA carrier (who or which MRSA type was unknown) outside the family or household, while another had visited a farm without contact to animals.…”

Methicillin‐resistant Staphylococcus aureus in urban Norway rat (Rattus norvegicus) populations: Epidemiology and the impacts of kill‐trapping

“…Trapping was carried out from June 2016–January 2017 in Vancouver's Downtown Eastside (N4917′/W1236′), where MRSA had been previously identified in local rat and human populations (Al‐Rawahi et al, ; Himsworth, Miller, et al, ). There were twelve study‐sites (randomly assigned as one of five interventions or seven controls), each consisting of three city‐blocks connected by continuous alleys (Figure ).…”

“…A hypothesis‐testing model‐building approach was used. Covariates (sex, sexual maturity, length, mass, bite wounds) potentially linked with both rat trappability (Davis, ; Himsworth, Jardine, Parsons, Feng, & Patrick, ) and pathogen status (Costa et al, ; Easterbrook et al, ; Glass et al, ; Himsworth, Miller, et al, ) were included in the model as confounders if they changed the effect of the intervention by at least 10%. Statistics were carried out in RStudio (Version 1.0.136, 2009–2016) using the lme4 package for regression (Bates, Mächler, Bolker, & Walker, ).…”

“…Urban Norway rats ( Rattus norvegicus ) can carry MRSA (Himsworth, Miller, et al, ). Because there are few studies on MRSA carriage by rats, numerous knowledge gaps remain (Himsworth, Miller, et al, ; Kato et al, ; Khalaf, Ayyal, Khalaf, & Karim, ). For example, previous studies have not assessed the duration of carriage.…”