MRSA Strains in Nepalese Rhesus Macaques (Macaca mulatta) and Their Environment

Abstract

This study looked at 227 saliva samples from Rhesus macaques (Macaca mulatta) and 218 samples from the surrounding environments. From these samples, MRSA isolates were collected from Rhesus saliva samples (n = 13) and environmental samples (n = 19) near temple areas in Kathmandu, Nepal. For comparison, selected MRSA isolates (n = 5) were obtained from patients with wound infections from a Kathmandu hospital. All isolates were characterized using Abbott StaphyType® DNA microarrays. Eighteen isolates (62%) from monkeys (n = 4; 31%) and environmental samples (n = 14; 74%), were CC22-MRSA-IV. Most (n = 16) of them carried both, the PVL locus and toxic shock toxin gene (tst1), an unusual combination which is the same as in previously characterized strain from Nepalese macaques and pigs. The five human isolates also belonged to that strain type. Eight monkey MRSA isolates were CC361-MRSA-IV. One MRSA from a monkey and one from an environmental sample, were CC88-MRSA-V. Other environmental MRSA included one each, CC121-MRSA-VT, and CC772 -MRSA-V. Two were CC779-MRSA-VT, potentially a novel clone. All MRSA carried the blaZ gene. The aacA–aphD, dfrA, and erm (C) genes were very common in isolates from all sources. One macaque MRSA carried the resistance genes aphA3 and sat, neither previously identified in primate MRSA isolates. This current study suggests that humans could be a potential source of the MRSA in the macaques/environment and transmission may be linked to humans feeding the primates and/or living in close proximity to each other.

Staphylococcus aureus and Methicillin Resistant S. aureus in Nepalese Primates: Resistance to Antimicrobials, Virulence, and Genetic Lineages

“…Both clones have been identified in other United States primate facilities as well as commercial facilities [1,3 and unpublished observations]. The isolates were characterized by PCR, multilocus sequence typing (MLST), whole genome sequencing, single -nucleotide polymorphism [SNP] analysis, pulsed-field gel electrophoresis (PFGE) and microarray-based assays [ 2 , 3 , 4 ]. The data suggested an importation of the MRSA strains together with the primates from outside rather than an introduction by local staff members [ 2 , 3 ].…”

“…to determine if either ST188 or ST3268 were carried by these primates as well. We did two studies in Nepal characterizing MRSA isolates cultured from wild rhesus macaques ( Macaca mulatta ) saliva samples [ 4 , 5 ]. The animals were living in and around temple areas of the Kathmandu valley in Nepal, where human–macaque interaction is common.…”

“…ST239-MRSA-III is a hospital-associated strain that spread globally for the last five decades. CC22-MRSA-IV comprises several related strains with different SCC mec IV subtypes and toxin genes profiles [ 4 , 5 , 6 ]. This includes EMRSA-15, which is a common and widespread strain in hospital and community settings especially in Western Europe.…”

“…The data from the previous work led us to hypothesize that humans were a likely source of the CC22-MRSA and CC239-MRSA isolates in the wild Nepalese macaques. In the second study, we collected saliva samples from Macaca mulatta as well as environmental samples from five surrounding areas, including the Bajrayogini temple site outside the Kathmandu valley [ 4 ] ( Figure 1 ). Thirteen MRSA were isolated from primates, 19 were isolated from the environment, and 5 were taken, for comparison, from humans.…”

“…Sixteen (89%) carried both the PVL and the tst-1 gene, which is an unusual combination that according to the microarray profiles is the same as in the previously characterized strains from both Nepalese macaques and pigs [ 5 ]. Most of the strains from both the primates and environment are known from earlier studies to be associated with humans [ 4 , 5 ].…”