Phylogenetic analysis of livestock oxacillin-resistant Staphylococcus aureus

Reverse zoonotic disease transmission (zooanthroponosis): a systematic review of seldom-documented human biological threats to animals

Background

Research regarding zoonotic diseases often focuses on infectious diseases animals have given to humans. However, an increasing number of reports indicate that humans are transmitting pathogens to animals. Recent examples include methicillin-resistant Staphylococcus aureus, influenza A virus, Cryptosporidium parvum, and Ascaris lumbricoides. The aim of this review was to provide an overview of published literature regarding reverse zoonoses and highlight the need for future work in this area.

Methods

An initial broad literature review yielded 4763 titles, of which 4704 were excluded as not meeting inclusion criteria. After careful screening, 56 articles (from 56 countries over three decades) with documented human-to-animal disease transmission were included in this report.

Findings

In these publications, 21 (38%) pathogens studied were bacterial, 16 (29%) were viral, 12 (21%) were parasitic, and 7 (13%) were fungal, other, or involved multiple pathogens. Effected animals included wildlife (n = 28, 50%), livestock (n = 24, 43%), companion animals (n = 13, 23%), and various other animals or animals not explicitly mentioned (n = 2, 4%). Published reports of reverse zoonoses transmission occurred in every continent except Antarctica therefore indicating a worldwide disease threat.

Interpretation

As we see a global increase in industrial animal production, the rapid movement of humans and animals, and the habitats of humans and wild animals intertwining with great complexity, the future promises more opportunities for humans to cause reverse zoonoses. Scientific research must be conducted in this area to provide a richer understanding of emerging and reemerging disease threats. As a result, multidisciplinary approaches such as One Health will be needed to mitigate these problems.

Occurrence of Methicillin Resistant and Enterotoxigenic Staphylococcus aureus in Traditional Cheeses in the North West of Iran

Traditional dairy products are potential sources of a variety of microorganisms which participate in food poisoning. Staphylococcus aureus is a conspicuous example of toxigenic bacteria causative for food-borne diseases. Moreover, resistance to methicillin is a prominent index in food hygiene studies. In the present study, we have aimed at characterization and identification of enterotoxigenic methicillin resistant S. aureus (MRSA) isolated from traditional cheeses in Azerbaijan region in the northwest of Iran during 2012. A number of phenotypical and molecular assays were utilized for screening of S. aureus. Subsequently, the prevalence of the genes responsible for the five staphylococcal enterotoxins (SEA-SEE) and also methicillin resistance gene was assessed. The outcomes of phenotypical methods were in conformity with those of the molecular procedures. The results indicated that 16% of cheese samples were contaminated by S. aureus. 110 isolates were authenticated by both phenotypical and molecular methods. All of the mentioned isolates were positive for coa, nuc, and 16S rDNA primers. 21% of these isolates were mecA positive and 60.8% of these MRSA were positive for SEs. Regarding the frequent outbreaks of enterotoxigenic MRSA, new hygiene policies and management practices should be considered to increase food safety and avoid extra treatment costs.

Incidence and characterisation of methicillin-resistant Staphylococcus aureus (MRSA) from nasal colonisation in participants attending a cattle veterinary conference in the UK

We sought to determine the prevalence of nasal colonisation with methicillin-resistant Staphylococcus aureus among cattle veterinarians in the UK. There was particular interest in examining the frequency of colonisation with MRSA harbouring mecC, as strains with this mecA homologue were originally identified in bovine milk and may represent a zoonotic risk to those in contact with dairy livestock. Three hundred and seven delegates at the British Cattle Veterinarian Association (BCVA) Congress 2011 in Southport, UK were screening for nasal colonisation with MRSA. Isolates were characterised by whole genome sequencing and antimicrobial susceptibility testing. Eight out of three hundred and seven delegates (2.6%) were positive for nasal colonisation with MRSA. All strains were positive for mecA and none possessed mecC. The time since a delegate's last visit to a farm was significantly shorter in the MRSA-positive group than in MRSA-negative counterparts. BCVA delegates have an increased risk of MRSA colonisation compared to the general population but their frequency of colonisation is lower than that reported from other types of veterinarian conference, and from that seen in human healthcare workers. The results indicate that recent visitation to a farm is a risk factor for MRSA colonisation and that mecC-MRSA are rare among BCVA delegates (<1% based on sample size). Contact with livestock, including dairy cattle, may still be a risk factor for human colonisation with mecC-MRSA but occurs at a rate below the lower limit of detection available in this study.

Genetically divergent methicillin-resistant Staphylococcus aureus and sec-dependent mastitis of dairy goats in Taiwan

Background

Widespread in the environment, Staphylococcus spp. infect animals and humans as normal flora or pathogens. By extending our recent report of multi-drug resistant (MDR) S. aureus in dairy goats, this study investigated the staphylococcal infection and characterized the MDR-S. aureus and methicillin-resistant S. aureus (MRSA) isolates collected from goats in 2008 to elucidate the appearance of MRSA in goats and the mastitis associated staphylococcus enterotoxin (SE) types. A total of 555 samples were collected from six goat parts and three environmental sources among four dairy goat farms in southern Taiwan. Coagulase-positive and negative Staphylococcus spp. (CPS and CNS, respectively) were also identified. Furthermore, predominant SE genes of nine enterotoxin genes sea through sej along with antimicrobial resistance and genetic variations were determined.

Results

In total, 137 staphylococcal strains were identified and found predominantly in milk, and in the vagina, anus, and nasal cavity. The most prevalent species was S. lentus, followed by S. aureus, S. epidermidis, and S. xylosus. Enterotoxin genes were not identified in any CNS isolates, however sec and see were identified only in S. aureus associated with mastitis in goat. In compared to the isolates from 2006 to 2007, 27 S. aureus isolates from 2008 were found to be more resistant to ampicillin, cephalothin, oxacillin, oxytetracycline, penicillin G, and tetracycline. Eleven MRSA isolates were identified and belonged to SCCmec type III (nine isolates) as the major type and SCCmec type II (two isolates). These MRSA isolates revealed pulse-field gel electrophoresis (PFGE) pattern A (five isolates), C (one isolate), and D (one isolate) of human isolates. The other two isolates without pulsotypes belonged to ST59.

Conclusion

The prevalence and infection sites of CNS differed from those of CPS. Genetic analyses indicated that genetic divergence, possible zoonotic transfer of MRSA, and the involvement of sec as important virulence factors for of S. aureus that lead to mastitis in goats.

Colonization and transmission of methicillin-resistant Staphylococcus aureus ST398 in nursery piglets

A transmission experiment was performed to evaluate the spread of methicillin-resistant Staphylococcus aureus (MRSA) ST398 in nursery piglets. Reproduction ratios (R(0)) in three experimental groups were found to vary between 3.92 and 52.54, indicating that after introduction, MRSA ST398 will spread easily among weaned piglets, with a tendency to become established.

Emergence and spread of cfr-mediated multiresistance in staphylococci: an interdisciplinary challenge

In staphylococci, methylation of A2503 of 23S rRNA leads to resistance against several classes of antibiotics (oxazolidinones, phenicols, streptogramin compounds, lincosamidins and pleuromutilins). The corresponding resistance gene cfr is located on plasmid(s) and is transferable within and between staphylococcal species including Staphylococcus aureus. It first emerged in coagulase-negative staphylococci, later in Central Europe also in S. aureus ST9 and in methicillin-resistant S. aureus ST398, which have their main reservoir in pigs, and meanwhile also in nosocomial coagulase-negative staphylococci from Southern Europe and the USA, and furthermore in nosocomial methicillin-resistant S. aureus in Spain. Timely detection and targeted prevention of further dissemination in both human and veterinary medicine is warranted for preserving the activity linezolid as an important antibiotic for treatment of staphylococcal infections.

Community-associated methicillin-resistant Staphylococcus aureus: epidemiology and clinical consequences of an emerging epidemic

Staphylococcus aureus is an important cause of skin and soft-tissue infections (SSTIs), endovascular infections, pneumonia, septic arthritis, endocarditis, osteomyelitis, foreign-body infections, and sepsis. Methicillin-resistant S. aureus (MRSA) isolates were once confined largely to hospitals, other health care environments, and patients frequenting these facilities. Since the mid-1990s, however, there has been an explosion in the number of MRSA infections reported in populations lacking risk factors for exposure to the health care system. This increase in the incidence of MRSA infection has been associated with the recognition of new MRSA clones known as community-associated MRSA (CA-MRSA). CA-MRSA strains differ from the older, health care-associated MRSA strains; they infect a different group of patients, they cause different clinical syndromes, they differ in antimicrobial susceptibility patterns, they spread rapidly among healthy people in the community, and they frequently cause infections in health care environments as well. This review details what is known about the epidemiology of CA-MRSA strains and the clinical spectrum of infectious syndromes associated with them that ranges from a commensal state to severe, overwhelming infection. It also addresses the therapy of these infections and strategies for their prevention.

Methicillin-resistant Staphylococcus aureus (MRSA) in food production animals

Until recently, reports on methicillin-resistant Staphylococcus aureus (MRSA) in food production animals were mainly limited to occasional detections in dairy cattle mastitis. However, since 2005 a MRSA clone, CC398, has been reported colonizing pigs, veal calves and broiler chickens and infecting dairy cows. Many aspects of its prevalence in pigs remain unclear. In other livestock, colonizing capacity and reservoir status still require elucidation. MRSA CC398 has also been detected in meat, but, as for other MRSA, the risk this poses is somewhat unclear. Currently, the most worrying aspect of MRSA CC398 appears to be its capacity to spread to humans. This might complicate MRSA control measures in human healthcare, urging research into risk factors and transmission routes. Although infections with MRSA CC398 are much less reported than carriage, more investigation into its pathogenic potential is required. Moreover, the origin and evolution of this clone remain unknown.

Emergence of methicillin-resistant Staphylococcus aureus (MRSA) in different animal species

The emergence of methicillin-resistant Staphylococcus aureus (MRSA) in animals such as horses, pet animals and productive livestock has raised questions of a probable human origin and in more general of host specificity of S. aureus. Particular clonal lineages are obviously specific for humans (e.g. ST15, ST25, ST45) and other for ruminants (e.g. ST151). MRSA associated with veterinary nosocomial infections (e.g. ST8 and ST254 in horses, ST22 in small animals) very likely have their origin in health care facilities. MRSA ST398 which became first known from widespread colonization in industrially raised pigs seems to have a limited host specificity and is able to colonize and to cause infections in various hosts. Mechanisms of host adaptation and their genomic background are poorly understood so far.