Carriage of Methicillin-resistant Staphylococcus aureus in a Colony of Rhesus (Macaca mulatta) and Cynomolgus (Macaca fascicularis) Macaques

An Epidemiologic Study of Bacterial Culture and Antibiotic Susceptibility Analyses in Captive Macaques and Marmosets at the Wisconsin National Primate Research Center

Antimicrobial resistance (AMR) represents a growing public health threat that arises at the interface between animal, human, and environmental health. Although the pathways promoting the development of AMR are well characterized in human health settings, data within the veterinary medical world are less abundant, particularly from fields focusing on nontraditional species, such as nonhuman primates (NHPs). The purpose of this study was to describe trends in sample submission for bacterial culture, characterize patterns of microbial growth and any changes in AMR and susceptibility over time, and inform best practices for veterinary antimicrobial stewardship in a captively-housed, indoor NHP colony. Electronic health records from the Wisconsin National Primate Research Center were analyzed across a 10-y period using SAS Studio. There was an increasing pattern of sample submissions for culture and susceptibility analyses, with no corresponding increases in resistance to relevant antibiotics for potential zoonotic pathogens, such as Escherichia coli or Shigella species. Trends are suggestive of appropriate antimicrobial stewardship practices that were responsive to the medical needs of Wisconsin National Primate Research Center animals, as well as the needs of the larger research community at the University of Wisconsin-Madison. These findings can inform veterinary professionals working with NHPs and contribute to the growing body of literature surrounding AMR in nontraditional species.

Identification of Vancomycin Resistance in Methicillin-resistant Staphylococcus aureus in two macaque species and decolonization and long-term prevention of recolonization in Cynomolgus Macaques (Macaca fascicularis)

Methicillin-resistant Staphylococcus aureus (MRSA) is a S. aureus strain with resistance to beta-lactam antibiotics, making it a global human and veterinary health concern. Specifically, immunosuppressed patients have a remarkably higher risk of clinical MRSA infections with significantly increased rates of prolonged clinical recovery, morbidity, and mortality. The current treatment of choice for MRSA is vancomycin. Importantly, we report the first known vancomycin-resistant S. aureus (VRSA) carriers in a cohort of Mauritian cynomolgus macaques (CM) imported to the Oregon National Primate Research Center (ONPRC), with a MRSA carrier rate of 76.9% (10/13 animals). All MRSA isolates also demonstrated resistance to vancomycin with prevalence of vancomycin-intermediate Staphylococcus aureus (VISA) at 30% (3/10 MRSA-positive CMs) and VRSA at 70% (7/10 MRSA-positive CMs). Additionally, we identified VRSA in a rhesus macaque (RM) housed within the same room as the VRSA-positive CMs and identified a MRSA/VISA carrier rate of 18.8% in RMs (3/16 positive for both MRSA and VISA) in unexposed recently assigned animals directly from the ONPRC RM breeding colony. Considering that the MRSA and VRSA/VISA-positive CMs future study aims included significant immunosuppression, MRSA/VRSA/VISA decolonization treatment and expanded "MRSA-free" practices were employed to maintain this status. We report the first controlled study using in-depth analyses with appropriate diagnostic serial testing to definitively show an MRSA decolonization therapy (90% success rate) and expanded barrier practice techniques to successfully prevent recolonization (100%) of a cohort of CMs MRSA-free (up to 529 days with a total of 4,806 MRSA-free NHP days).

Bacterial Genotype, Carrier Risk Factors, and an Antimicrobial Stewardship Approach Relevant To Methicillin-resistant Staphylococcus Aureus Prevalence in a Population of Macaques Housed in a Research Facility

Methicillin-resistant Staphylococcus aureus (MRSA) remains a significant problem for human and animal health and can negatively affect the health status of macaques and other nonhuman primates (NHP) in research colonies. However, few publications provide guidance on the prevalence, genotype, or risk factors for macaques with MRSA and even fewer on how to effectively respond to MRSA once identified in a population. After having a clinical case of MRSA in a rhesus macaque, we sought to determine the MRSA carrier prevalence, risk factors, and genotypes of MRSA in a population of research NHPs. Over a 6-wk period in 2015, we collected nasal swabs from 298 NHPs. MRSA was isolated from 28% (n = 83). We then reviewed each macaque's medical record for a variety of variables including animal housing room, sex, age, number of antibiotic courses, number of surgical interventions, and SIV status. Analysis of these data suggests that MRSA carriage is associated with the room location, age of the animal, SIV status, and the number of antibiotic courses. We used multilocus sequence typing and spa typing on a subset of MRSA and MSSA isolates to determine whether the MRSA present in NHPs was comparable with common human strains. Two MRSA sequence types were predominant: ST188 and a novel MRSA genotype, neither of which is a common human isolate in the United States. We subsequently implemented antimicrobial stewardship practices (significantly reducing antimicrobial use) and then resampled the colony in 2018 and found that MRSA carriage had fallen to 9% (26/285). These data suggest that, as in humans, macaques may have a high carrier status of MRSA despite low clinically apparent disease. Implementing strategic antimicrobial stewardship practices resulted in a marked reduction in MRSA carriage in the NHP colony, highlighting the importance of limiting antimicrobial use when possible.

Investigation of methicillin-resistant Staphylococcus aureus, methicillin-susceptible Staphylococcus aureus, and Staphylococcus argenteus from wild long-tailed macaques (Macaca fascicularis) at Kosumpee Forest Park, Maha Sarakham, Thailand

Background and Aim

In the past, the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) infections in both humans and animals has increased across Thailand. Staphylococcus argenteus has been associated with infections among humans, exotic pets, and livestock. Both species have been identified in non-human primate species from geographically diverse locations but not from non-human primates in Thailand. This study aimed to determine the presence of MRSA/methicillin-susceptible S. aureus (MSSA) and S. argenteus isolates collected from buccal swab samples in Macaca fascicularis at Kosumpee Forest Park (KFP), Maha Sarakham, Northeast Thailand.

Materials and Methods

Aseptic buccal swab samples were collected from 30 free-ranging macaques in November 2018. All isolates were tested using multiple biochemical tests and S. aureus latex slide agglutination test. Presumptive S. aureus isolates were tested for the presence of the mecA gene using polymerase chain reaction (PCR) assays. The isolates were phenotypically determined to be resistant to a β-lactam antibiotic using the disk diffusion method with a 30 mg cefoxitin disk. The isolates were analyzed by PCR for the non-ribosomal peptide synthetase (NRPS) gene to distinguish S. argenteus from S. aureus.

Results

Fifteen macaques (50%) were colonized with S. aureus and 21 isolates were characterized. Three of the macaques carried both the MRSA and MSSA isolate. One animal carried both MRSA and S. argenteus isolate, and one animal carried only S. argenteus. The NRPS gene analysis confirmed that 2 isolates (9.52%) were S. argenteus and 19 isolates (90.48%) were S. aureus [five MSSA and 14 MRSA].

Conclusion

This study is the first to identify MRSA/MSSA and S. argenteus in wild free-ranging M. fascicularis from Thailand at the KFP in Maha Sarakham. This study is also the first report on the occurrence of S. argenteus carriage in M. fascicularis from Thailand.

Antimicrobial prophylaxis does not improve post-surgical outcomes in SIV/SHIV-uninfected or SIV/SHIV-infected macaques (Macaca mulatta and Macaca fascicularis) based on a retrospective analysis

Surgical antimicrobial prophylaxis is indicated when performing contaminated surgeries, when specific surgical implants are placed, and for prolonged surgical procedures. Unnecessary prophylactic antibiotics are often utilized for macaque surgeries, despite medical and veterinary guidelines. In this study we compared complication rates in macaques receiving peripheral lymph node (PLN) and laparoscopic biopsies, with and without antimicrobial prophylaxis. A majority of animals were SIV or SHIV infected at the time of surgery, so we also compared post-operative complication rates based on infection status. We found no significant difference in PLN biopsy complication rates for animals that received antimicrobial prophylaxis versus those that did not. Animals who underwent laparoscopic procedures and received prophylactic antibiotics had a higher complication rate than those who did not receive them. Complication rates did not differ significantly for SIV/SHIV infected versus uninfected animals for both laparoscopic biopsy procedures and PLN biopsy procedures. SIV/SHIV infected animals that underwent PLN biopsies had no significant difference in complication rates with and without antimicrobial prophylaxis, and SIV/SHIV infected animals receiving prophylactic antibiotics for laparoscopic biopsies had a higher complication rate than those that did not. This study suggests that perioperative prophylactic antibiotics have no role in the management of SIV/SHIV-infected and uninfected macaques undergoing clean, minimally invasive surgeries. Additionally, we recommend eliminating unnecessary antibiotic use in study animals due to their potential confounding impacts on research models and their potential to promote antimicrobial resistance.

Hiding in plain sight - Wildlife as a neglected reservoir and pathway for the spread of antimicrobial resistance: A narrative review

Antimicrobial resistance represents a global health problem, with infections due to pathogenic antimicrobial resistant bacteria (ARB) predicted to be the most frequent cause of human mortality by 2050. The phenomenon of antimicrobial resistance has spread to and across all ecological niches, and particularly in livestock used for food production with antimicrobials consumed in high volumes. Similarly, hospitals and other healthcare facilities are recognized as significant “hotspots” of ARB and antimicrobial resistance genes (ARGs); however, over the past decade, new and previously overlooked ecological niches are emerging as hidden reservoirs of ARB/ARGs. Increasingly extensive and intensive industrial activities, degradation of natural environments, burgeoning food requirements, urbanization, and global climatic change have all dramatically affected the evolution and proliferation of ARB/ARGs, which now stand at extremely concerning ecological levels. While antimicrobial resistant bacteria and genes as they originate and emanate from livestock and human hosts have been extensively studied over the past 30 years, numerous ecological niches have received considerably less attention. In the current descriptive review, the authors have sought to highlight the importance of wildlife as sources/reservoirs, pathways and receptors of ARB/ARGs in the environment, thus paving the way for future primary research in these areas.

Association of Primate Veterinarians' Guidelines for the Judicious Use of Antimicrobials

The Association of Primate Veterinarians (APV) recognizes that antimicrobials are commonly prescribed for prophylactic, therapeutic, and experimental management of nonhuman primates (NHP). While clinicians should use antimicrobials to treat documented cases of illness, the decision to prescribe antimicrobials must take into account the increasing resistance of bacterial populations, leading to decreasing efficacy of critical pharmaceuticals in both human and veterinary medicine. The intent of this document is to provide guidance to veterinarians, research staff, and institutional animal care and use committees (IACUCs) on the use of antimicrobials in NHP.

Evaluation of Topical Lysostaphin as a Novel Treatment for Instrumented Rhesus Macaques (Macaca mulatta) Infected with Methicillin-Resistant Staphylococcus aureus

Lytic enzymes are novel antimicrobial agents that degrade bacterial cell walls, resulting in cell rupture and death. We tested one enzyme, the bacteriocin lysostaphin, for treatment of nonhuman primates (Macaca mulatta) with persistent methicillinresistant Staphylococcus aureus (MRSA) infection of their cranial implant margins. The goal of this study was to determine if topical lysostaphin, either alone or as an adjunct therapy, could eliminate MRSA. Lysostaphin had in vitro lytic activity against all 4 previously identified NHP MRSA clones, as well as against 12 MRSA isolates of the same clonal type (MLST ST3862 and spa type t4167) before and after treatment, with no resistance discovered. In an in vivo pilot study, a 2-d application of lysostaphin alone reduced MRSA in the implant margins by 3-logs during treatment of one animal; however, MRSA titers had returned to control levels by 1 wk after treatment. In the main study, all animals (n = 4) received 10 d of systemic antibiotic treatment and both the animals and their environment (cages, equipment, room) underwent 5-d of decontamination. The experimental animals (n = 2) received 5 doses of topical lysostaphin (15 mg, every other day) applied onto their implant margins. Daily cultures showed that MRSA counts decreased significantly (≤ 25 colony-forming units/mL; P < 0.05). However, sampling of the cranial implant margin 7 d after last treatment showed that MRSA counts had returned to control levels. Our study suggests that lysostaphin, coupled with other treatment modalities, can decrease MRSA infection short-term but do not completely eradicate MRSA in the long-term. This reappearance of MRSA may be due to cross-contamination or reinfection from other infected areas, an inability of the treatment to reach all colonized areas, or insufficient dosing or length of treatment. Topical lysostaphin may be more useful clinically for superficial nonimplant associated wounds in which the lytic enzyme has better access to the infected tissue.