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Is the Colonisation of Staphylococcus aureus in Pets Associated with Their Close Contact with Owners?

  • Karolina Bierowiec ,

    karolina.bierowiec@up.wroc.pl

    Affiliation Division of Infectious Diseases and Veterinary Administration, Department of Epizootiology with Clinic of Birds and Exotic Animals, Faculty of Veterinary Medicine, Wrocław University of Environmental and Life Sciences, Wrocław, Poland

  • Katarzyna Płoneczka-Janeczko,

    Affiliation Division of Infectious Diseases and Veterinary Administration, Department of Epizootiology with Clinic of Birds and Exotic Animals, Faculty of Veterinary Medicine, Wrocław University of Environmental and Life Sciences, Wrocław, Poland

  • Krzysztof Rypuła

    Affiliation Division of Infectious Diseases and Veterinary Administration, Department of Epizootiology with Clinic of Birds and Exotic Animals, Faculty of Veterinary Medicine, Wrocław University of Environmental and Life Sciences, Wrocław, Poland

Is the Colonisation of Staphylococcus aureus in Pets Associated with Their Close Contact with Owners?

  • Karolina Bierowiec, 
  • Katarzyna Płoneczka-Janeczko, 
  • Krzysztof Rypuła
PLOS
x

Abstract

In human beings and animals, staphylococci constitute part of the normal microbial population. Staphylococcus aureus could be classified as an opportunistic pathogen because the bacteria are noted in clinically healthy individuals, but when the immune system becomes compromised, they can also cause a wide range of infections. The objective of this study was to test the hypothesis that cats who are in close contact with their owners are at the greatest risk of being colonised with S. aureus. Two groups of cats were investigated: single, pet (domestic) cats that do not have outdoor access; and a local population of feral cats living in urban areas. The prevalence of S. aureus in domestic cats was 19.17%, while it’s prevalence in the feral cat population was only 8.3%; which was statistically significant. Analysis of antibiotic resistance, at the genotypic as well as phenotypic level, showed that S. aureus isolates from pet cats were more likely to harbour antibiotic resistant determinants. The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in households was 10.21%, while in feral cats it was only 1.4%. In conclusion, this study has revealed a correlation between close contact with humans and a higher risk of the cats being colonised with S. aureus and harbouring the antibiotic resistant determinants.

Introduction

In humans and animals, staphylococci constitute part of the normal microbial flora. There are several different definitions of what constitutes an animal’s normal bacterial flora. There are the”symbionts”, which benefit themselves and the host; “commensals”, which do not benefit the host but are harmless; and the “opportunists”–typically non-pathogenic microorganisms that act as a pathogen in certain circumstances [1]. According to the aforementioned definitions, Staphylococcus aureus could be classified as an opportunistic pathogen for both humans and animals. Although the bacteria are found in clinically healthy individuals, they can cause a wide range of infections when the immune system becomes compromised or select comorbidities are associated (congestive heart failure, diabetes, pulmonary disease and renal failure) [2, 3].

The composition of normal flora on an organism depends on the species, feed and environment, including population density. Nevertheless, S. aureus is the most frequently isolated coagulase positive Staphylococcus (CPS) from the anterior nares and temporarily from the skin of humans, whereas coagulase negative staphylococci (CNS), mainly Staphylococcus epidermidis, are dominant on the skin [4]. Similarly, for cats CNS are the major species in this tissue and mucosa’s natural flora. The most frequently observed is S. felis, and seldom CPS such as S. pseudointermedius, but in some environments S. aureus is also observed [5].

Investigation of the nasal carriage is used in epidemiology as a marker of S. aureus exposure with an increased risk of infection in humans [6] inter alia, of some skin diseases [7], wound colonisation [8], surgical site infections [9] or respiratory tract infections [10].

In animals, colonisation of the nares with S. aureus is usually used to assess human exposure to livestock or pet- associated S. aureus, mainly methicillin- resistant S. aureus strains (MRSA). The circulation of S. aureus clones vary between hosts, environments and countries. Some lineages are described in which they are well adapted to their respective host whereas others seem to have a broader host range. For example, the majority of isolates from nares in swine belong to lineages CC30 and CC398 [11], but only ST433is host-specific [12]. Originally CC398 was of human origin and now it is adapted to livestock such as pigs, poultry and cattle or other animals: horses and pets. A similar situation was observed in poultry where CC5 was adapted from humans. [13, 14]. In ruminant mastitis isolates are frequently associated with CC8, CC97, CC126, CC130, CC133 and CC705; whereas rabbit infections mostly belong to ST21 [15]. Clonal complexes CC5, CC8, CC22, CC30 and CC45 are more frequently associated with hospital-acquired infections [16]. Two MRSA clones: ST22 and ST239, have dominated globally in hospital settings [17]; while in the community at large mainly ST8 in the United States and ST80 and ST22 in Europe have been found [18]. There is currently no evidence for the pet-adapted S. aureus. Companion animals usually share their environment with humans, which could indicate a reduced opportunity for host adaptation [19]. MRSA lineages isolated from infected companion animals often mirror typical human epidemic strains circulating in the same region: ST22 in the United Kingdom, Germany, Portugal and ST59 in China [20, 21]. In cats and dogs in Germany, the predominant lineages were CC22 and CC5 followed by CC398 and CC8 [22].

The aim of the study was to test the hypothesis that cats that are in close contact with their owners are at the greatest risk of increased colonisation with S. aureus. To assess this assumption, a cohort study was designed, which studied two groups of cats: the first was the pet cat group primarily in contact only with their owners; the second group was comprised of free-living, wild domestic cats living in the city. This study also provides detailed information on S. aureus strains isolated from both groups and on the drug resistance profile of these bacteria to different antibiotic classes using both phenotypic and molecular methods.

Materials and Methods

Study population and sampling procedures

There were two groups of cats examined. The first group, comprised of pet cats, were recruited as part of a randomised control trial that targeted clinically healthy cats sourced from the city of Wrocław area. This group’s primary inclusion criterion was the cat owner’s statement that the pet was kept in Wrocław without outdoor access and that the cat was the only animal present in the household. The second group were free-living cats within the city of Wrocław. These animals did not have contact with humans and were sampled during a trap, neuter and release (TNR) programme for the humane control of the feral cat population by the Department of Reproduction and Clinic of Farm Animals, Faculty of Veterinary Medicine in Wrocław. All the animals that qualified for the surgery in this programme were clinically healthy. The health status of each animal from both groups was assessed by way a diagnostic examination in conjunction with a clinical examination.

Four swabs were taken from each cat in both groups, as follows: from the conjunctival sacs, nares, anus and skin (groin). The material was collected by a veterinary physician and placed into 2 ml of liquid brain-heart infusion bullion (BHI) (Graso Biotech, Poland).

The research outline was submitted to the II Local Ethics Committee for Animal Experiments in Wrocław. Due to the non-invasive procedure of the samples collection, the Ethics Committee qualified the study as research that did not require ethics committee approval.

Sample identification

The tubes with swabs in 2 ml BHI were incubated at 37°C for 24 hours, then one microlitre of BHI was subcultured onto a mannitol salt broth and blood agar (Graso Biotech, Poland). The plates were incubated at 37°C for the next 24 hours. The preliminary identification of isolates was performed according to colony morphology, gram staining and the detection of enzyme production (coagulase tube test; IBSS Biomed, Poland). All the suspected colonies were further identified using molecular methods.

The purification of DNA was conducted using the manual method of phenol/chloroform employing an initial digestion by lysozyme (Sigma-Aldrich, USA) as described previously by Bania et al. [23]. Isolates were confirmed by a polymerase chain reaction using S. aureus nuc gene specific primers, which encode thermonuclease [24]. In addition, 25% of isolates were confirmed as S. aureus using BLAST analysis from the 16S RNA PCR product (http://rdna4.ridom.de). The obtained sequences were identified by comparison with sequences available in the GenBank database, using a BLAST search algorithim (http://blast.ncbi.nlm.nih.gov/Blast.cgi).

Isolates were identified as MRSA by detection of the mecA or mecC gene using PCR [25, 26]. Amplification of the short sequence repeat region of the spa gene was conducted using specific primers [27]. The thermal cycling conditions were set up according to Shopsin et al. [28] and the completed reaction mixtures were sequenced by Macrogen (Netherlands). The sequences were analysed using the Ridom SpaServer (http://spa.ridom.de).

Antibiotic resistance

All the isolates of S. aureus were screened for antibiotic susceptibility using the disc diffusion method and MIC with the E-test. The antimicrobial disc diffusion tests were as follows (μg/disc): penicillin G (10), cefoxitin (30), erythromycin (15), clindamycin (2), gentamicin (10), tetracycline (30), norfloxacin (10), chloramphenicol (30), mupirocin (200), fusidic acid (10), vancomycin (30), tigecycline (15) and linezolid (30) (Mast Diagnostics, UK). The double-disc diffusion test (D-test) was performed on all isolates to detect inducible clindamycin resistance. The interpretation of the test was as follows: a flattening of the inhibition zone around the clindamycin disc near the erythromycin disc indicated that erythromycin had induced clindamycin resistance (iMLSB). Erythromycin and clindamycin resistance characterised the phenotype cMLSB. The phenotype (MSB) was characterised by clindamycin susceptibility and erythromycin resistance, with a negative D-test [29].

The MIC tests (MIC Test Strip, Liofilchem, Italy) were as follows: oxacillin (0.16–256), penicillin (0.016–256), erythromycin (0.016–256), clindamycin (0.016–256), genatmicin (0.064–1024), tetracycline (0.016–256), mupirocin (0.064–1024), fusidic acid (0.016256) vancomycin, tigecycline (0.016–265) and linezolid (0.016–256). Antimicrobial-resistant phenotyping of isolates was performed and interpreted according to the Clinical and Laboratory Standards Institute document M100-S24 [30]. Evidence of tigecycline, mupirocin and fusidic acid were interpreted according to the protocol used in recent studies [3133].

Antimicrobial-resistant genotypes of isolates were identified using PCR. The presence of genes involved in resistance to penicillinase (blaZ), aminoglycosides (aac(6’)Ie-aph(2”)Ia), ß-lactamase (mecA, mecC), glycopeptides (vanA and vanB), macrolide-lincosamide-streptogramins (ermA, ermB and ermC), tetracyclines (tetK, tetL, tetM and tetO), mupirocine (mupA) and fusidic acid (fusB, fusC, fusD) was determined using PCR amplification [25, 26, 3437]. The reaction volume was 25 μL, containing 0.2 μL of each primer, 2.5 μL of DreamTaq green buffer, 1 U of DreamTaq DNA polymerase (Thermo Scientific, Lithuania) and 1 μL of matrix DNA. Electrophoresis was performed on 2% agarose gel with Midori Green (Nippon Genetics Europe, Germany). Selected PCR products were sequenced (Macrogen Netherlands) and analysed using the BLAST method.

Statistical methods

To calculate the prevalence and confidence intervals in both groups of cats, the bootstrap method was used. This was performed by drawing 78 replacement cats (each of which had an equal probability) from a pool of 78 animals in the pet cat group, and 72 cats (with equal probability each) from a pool of 72 animals in the group of free-living domestic cats. This process was performed with 10 000 reiterations.

The characteristics of the cats were compared to scores of S. aureus colonisation and antibiotic resistance. Data were entered into a computerised database and analysed using the Shapiro–Wilk test, the Wilcoxon test, the Kruskal–Wallis test, 2 × 2 contingency tables and bootstrapped chi-square tests. P <0.05 was considered indicative of a statistically significant association. Residue tables were constructed for statistically significant results and used to detect existing relationships between characteristics. A residue table shows the frequency distribution of the values of the dependent variable, given the occurrence of the values of the independent variable. Statistical analyses were carried out using the R Statistical Package (v. 2.11.1).

Results

A total of 150 cats were examined from January 2013 to November 2014 at the Department of Epizootiology and Clinic of Bird and Exotic Animals, Faculty Veterinary Medicine, Wrocław University of Environmental and Life Sciences, Poland. Cats were assigned to two groups: the pet cats without outdoor access (n = 78; 51.3% female and 48.7% male) and feral cats living in the urban area (n = 72; 69.4% female and 30.6% male). The animals were considered positive if S. aureus was isolated from any site (skin, conjunctival sacs, anus or nares). The research included an examination of 32 S. aureus strains from both groups (24 and 8 from pet cats and feral cats respectively). The average prevalence of S. aureus among pet cats and feral cats was determined using the bootstrap method was 19.17% (11.5–28.21%) and 8.3% (2.78–15.28%), respectively. The difference between groups was statistically significant (P = 0.044). S. aureus isolates were identified as a MRSA when the mecA gene was present, regardless of whether the oxacillin MICs were <4 μg/L. The presence of the mecC gene was not identified in any of the investigated isolates. The research included an examination of 11 MRSA strains from both groups (10 and 1 from pet cats and feral cats respectively). The prevalence of MRSA isolates was 10.21% (3.85–17.95%) for pet cats and 1.4% (0–4.17%) for feral cats and the difference between the two groups was statistically significant (P = 0.0112). There was more than one S. aureus isolate identified in 35% of all cats colonised with S. aureus. In all of these cases, S. aureus were isolated from the nares and usually from the conjunctival sacs. The nares turned out to be the most sensitive anatomical location to detect S. aureus colonisation in both groups, as well as for total S. aureus isolates and for MRSA. The combinations of prevalence using different sampling places and a comparison between groups are presented in Figs 1 and 2.

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Fig 1. Prevalence of S. aureus in pet cats and feral cats, including combinations of sampling places.

Sampling places: nares (N); conjunctival sacs (O); anus (P); skin (S). For each combination of sampling places a confidence interval was marked which was calculated using the bootstrap method.

https://doi.org/10.1371/journal.pone.0156052.g001

thumbnail
Fig 2. Prevalence of MRSA in pet cats and feral cats, including combinations of sampling places.

Sampling places: nares (N); conjunctival sacs (O); anus (P); skin (S). For each combination of sampling places a confidence interval was marked which was calculated using the bootstrap method.

https://doi.org/10.1371/journal.pone.0156052.g002

Any genetic determinants of resistance to the following were not detected: vancomicin (vanA and vanB genes), mupirocin (mupA gene) and fusidic acid (fusB, fusC and fusD genes) in both groups. Comparisons of residual results from PCR are presented in Table 1. The results of phenotypic resistance to antibiotics using an E-test are shown in Table 2. There were no phenotypic resistance isolates to mupirocin, linezolid, tigecycline, fusidic acid, vancomycin, norfloxacin and chloramphenicol identified. Only inducible resistance to clindamycin (iMLSB) was observed in one isolate from each group (the pet cat group and feral cat group).

thumbnail
Table 1. Percentage of genetic determinants of the antibiotic resistance among isolates of S. aureus.

https://doi.org/10.1371/journal.pone.0156052.t001

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Table 2. Percentage of antibiotic resistance according MIC test in all isolated S. aureus strains.

https://doi.org/10.1371/journal.pone.0156052.t002

Isolates were characterised into 14 and 6 spa types in the pet cats group and the feral cats respectively. The most frequently observed were t008 (20.83%) in pet cats, and t755 (25%) and t005 (25%) in feral cats. No correlations were observed between spa types and the anatomical location of S. aureus isolation or the affiliation of the cat to any of the investigated groups. The comparison of spa types isolated in both groups is presented in Table 3.

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Table 3. Diversity of spa types and antibiotic resistance patterns in pet cat and feral cat groups.

https://doi.org/10.1371/journal.pone.0156052.t003

Discussion

The possibility of transmitting zoonotic agents between humans and animals has been widely described in scientific literature. For many pathogens, pet animals play a role as a source of zoonotic infections [38]. Our study was designed to confirm that close contact with humans might cause a higher chance of colonisation with S. aureus in pets. From the comparison of the two study groups of cats–exposed and not exposed to contact with humans–we have shown a statistically significant higher prevalence of S. aureus colonisation in cats that have close contact with their human owners.

The natural bacterial flora of skin and mucosa in cats was comprised mainly of CNS such as S. felis and S. simulans [39, 40] From the CPS species, the most dominant are S. pseudointermedius and S. aureus, but the prevalence of these bacteria does vary from study to study. In a study by Hariharan et al. [39], in India, no S. aureus or S. intermedius/pseuintermedius could be found in swabs from feral cats. However, in an English study on feral and pet cats, the prevalence of CPS was comparable in both groups at about 5% [41]. In Iverson et al.’s study [42], the S. aureus prevalence was 17% but there are also reports that have shown a much higher prevalence in healthy cats of around 34–39.6% [43, 44]. Most commonly the research has studied the prevalence of S. aureus in domestic cats and little is known about its prevalence in feral cats. In this study, the prevalence of S. aureus in feral cats was found to be 8.3% and was much lower than that observed in pet cats (19.17%).

Large differences in the colonisation of cats with MRSA strains were also observed. The main factor described in scientific literature that has an influences on the prevalence value was permanent contact with the environment where the colonisation of MRSA from humans was common [45]. The prevalence in pets, which lived with human colonised with MRSA, reported by Moriss et al. was 11.6% [46]. In our study, the MRSA prevalence in pet cats was 10.21%, considerably higher compared to other findings from scientific literature where the MRSA rate was typically lower than 4% [4749]. The households’ residents were not investigated in this study and so it is not known if the owners had an influence on the MRSA colonisation rate in these cats, or if other factors contributed to such a high MRSA prevalence.

Little is known about prevalence of S. aureus in the community of Poland, but in the hospital environment the proportion of MRSA isolates was 22.7% (ranging from 3.7 to 63.1% in individual hospitals) [50]. Relatively high MRSA prevalence may indicate a wide spread of the pathogens also in the community. We found some similarities by comparing previously described spa and MLST types of S. aureus isolated in Polish hospitals and spa types obtained in this study. Spa types such as: t002, t005, t008, t037, t091 and t755 were previously reported in cases of human infections in Poland [51, 52]. Additionally t008, t037, t091 and t189 were detected in a study which dealt with the epidemiology of community-associated Staphylococcus aureus (CA-SA) in Europe [53]. Considering the previous obtained data we can suspect that some S. aureus strains in cats were human in origin, however, further studies are required to better understand this issue.

In previous studies, other such confounding factors of high MRSA prevalence in pets were identified, including: the number of employees working at the veterinary setting where pets was being treated; antibiotic treatment prior to sampling; surgical site of infection; and surgical implants [21, 54]. Some of the pet cats under investigation, according to information obtained from the pet owners, had been previously treated (mainly by an administration of antibiotics); nevertheless, this data was not sufficient to confirm if the previously described confounding factors influencing the high MRSA prevalence.

The prevalence in the feral cats group was significantly lower at 1.4% (one isolate from the nares) in this study. Similarly, the antibiotic resistance in free-living animals was usually reported in other studies as sporadic [39, 55]. The explanation for this fact could be a low probability that chemotherapeutic treatment was conducted in such a population. Furthermore, there are only a few reports about antibiotic resistance in staphylococci isolates from feral cats and these results are divergent. Patel et al. [41] observed there was a higher antibiotic resistance in feral cats compared with pet cats, whereas in Hariharan et al.’s study [39] the antibiotic resistance was minimal. With regard to other feline infectious agents, the feral cats assessed appear to be of no greater risk to human beings or other cats than pet cats [56]. Moreover, our results show that the pet cats group is more likely to be a reservoir of S. aureus with genetic determinants of antibiotic resistance. There were only a few antibiotic resistance genes observed to be harboured by feral cats in this study. All of them are frequently present in staphylococci genomes of a different origin [57]. This is why there is difficulty in determining the origin of those genes in S. aureus that colonised the feral cats under investigation.

In the case of pet cats, there is a high probability that a larger number of determinates of antimicrobial resistance in S. aureus isolates could be connected with a previous treatment of pets and/or owners, or even previous prophylactic visits to a veterinary clinic [5860]. Antibiotic resistant genes to commonly used chemotherapeutics were found in both human and animals isolates, such as: penicillinase, aminoglycosides, ß-lactamase, macrolides and tetracyclines, and it was only to these antibiotics that phenotypic resistance was observed. In the feral cat group, phenotypic resistance was observed to penicillin and erythromycin. Most S. aureus strains under investigation harboured genetic determinants of resistance, without showing resistance to investigated chemotherapeutics using the MIC test. The inconsistency between these results of phenotype and genotype drug susceptibility tests could be explained as differences in resistance gene expression between isolates. In none of the isolates was a phenotypic resistance observed without the genetic determinants, that would suggest the occurrence of other mechanisms of resistance [61].

The percentage of isolates which showed phenotypic resistance was comparable with similar studies conducted on healthy pets [62]; showing that a high percentage of penicillin resistant isolates is particularly common [63]. The pet cat group in this study was found to be more likely colonised with antibiotic resistant bacterial strains than feral cats. Patel et al. [41] described a reverse situation, for which the authors suggested the possibility of acquired resistance in isolates from feral cats’ resident flora via contact with environmental sources of antibiotics, such as medical waste, domestic waste (meat products) or polluted water. This could also be a cause of the appearance of resistant isolates in the healthy feral cats examined in this study and moreover the source of S. aureus strains. To the best of our knowledge, the feral cats had not previously been handled, nor had they received veterinary treatment, which could be the main source of resistance in pet cats. They could also be colonised with resistant isolates or isolates containing genetic determinates of resistance through contact with humans. The feral cats investigated in the study were free living cats residing within the city area, more often than not in cellars, warehouses and bowers. Therefore it is not possible to exclude indirect contact with humans who may have touched the same surfaces. The colonizing with S. aureus strains could also have its origin in livestock by the consumption of raw meat or contaminated pet food. For instance spa type t091, t015, t008 were frequently isolated in pork and poultry meat in Poland [11, 14] and in our study from cats.

There was a widely described evidence of horizontal transfer of S. aureus isolates between humans, animals and the environment habitat [6467]. Thus, with the possibility of interspecies and environmental transfer of the pathogen, particularly pets could become a reservoir of S. aureus for humans. This is especially important in situations when animal owners suffer from remittent S. aureus infections. An ineffective treatment could result from a constant presence of the bacteria in the environment [68, 69]. Therefore, each case of MRSA or multidrug-resistant S. aureus in a human or animal patient could be a clue for doctors or veterinarians to extend the diagnostic interview and eventually perform laboratory research on the residual household residents. Moreover, in households affected by MRSA, there is a need to apply methods that counteract the spread of the bacteria. There are some available protocols used in human medicine [70, 71], but there is still a lack of similar procedures for pets. Regardless, with adherence to some of these rules, the spread and development of antibiotic resistance among S. aureus could be limited. It is not possible (or permitted) to use chemotherapeutics specified for human usage for the decolonisation of S. aureus in pets even in some countries the use of fusidic acid or mupirocin in pets is approved for the treatment of staphylococcal skin infections [72, 73]. There is a report of the successful topical decolonisation of MRSA-positive cat with ciprofloxacin and rifampin [74] which might be recommended for use in veterinary medicine. The standard protocol in counteracting the spread of the pathogen should be an adherence to personal hygiene (especially hand hygiene after handling animals) and frequent disinfection of surfaces. Pets can often clear up colonisation without drug treatment but in some cases, similar to humans, decolonisation could be transient. Therefore long-term hygiene measures in households should be applied [65, 75]. After all, pet cats could be a source of many pathogens for their owners nevertheless there are some benefits such as the presence of pets has been associated with reduction of stress and blood pressure what is associated with reduction of the risk of cardiovascular diseases [76]. Therefore pets as family members should receive the same attention as concerns the sanitising of MRSA colonisation and treatment of infections as humans.

This study is the first to confirm by using empiric research, that close human contact has an influence on the prevalence of S. aureus in cats. It can be assumed that the original direction of S. aureus transmission was from humans to pets. S. aureus was not considered as a true commensal of companion dogs and cats, but as an opportunistic human pathogen, which has only been transferred to them [67, 77]. Still little is known about the colonisation patterns of S. aureus in pets and thus there is a need for additional longitudinal studies. The relative ease with which S. aureus bacteria can transfer and adapt to new hosts is an example of when a ‘One Health’ approach has to be applied to inhibit the spread of the organism and its acquisition of further antibiotic resistance. Future studies should be conducted to determine the frequency of colonisation at different anatomical locations in pets, which could help to standardise sampling procedures and control prevalence in pet animals. Finally, there is also a need to develop protocols to prevent the spread of S. aureus and its transference by bacteria antibiotic resistance in households, as well as in veterinary hospitals.

Acknowledgments

We are indebted to Professor W. Niżański Department of Reproduction and Clinic of Farm Animals, Faculty of Veterinary Medicine, Wrocław University of Environmental and Life Sciences, for giving his approval to sample during a neutering programme for feral cats.

Author Contributions

Conceived and designed the experiments: KB KPJ KR. Performed the experiments: KB. Analyzed the data: KB. Contributed reagents/materials/analysis tools: KB KPJ. Wrote the paper: KB.

References

  1. 1. Sorum H, Sunde M. Resistance to antibiotics in the normal flora of animals. Vet Res. 2001;32(3–4):227–241. pmid:11432415
  2. 2. Oliveira DC, Tomasz A, de Lencastre H. Secrets of success of a human pathogen: molecular evolution of pandemic clones of meticillin-resistant Staphylocloccus aureus. Lancet Infect Dis. 2002;2(3):180–189. pmid:11944188
  3. 3. McKinnell JA, Miller LG, Eells SJ, Cui E, Huang SS. A Systematic Literature Review and Meta-Analysis of Factors Associated with Methicillin-Resistant Staphylococcus aureus Colonization at Time of Hospital or Intensive Care Unit Admission. Infect Control Hosp Epidemiol. 2013;34(10):1077–1086. pmid:24018925
  4. 4. Otto M. Staphylococcus colonization of the skin and antimicrobial peptides. Expert Rev Dermatol. 2010;5(2):183–195. pmid:20473345
  5. 5. Lilenbaum W, Nunes ELC, Azeredo MAI. Prevalence and antimicrobial susceptibility of staphylococci isolated from the skin surface of clinically normal cats. Lett Appl Microbiol. 1998;27(4):224–228. pmid:9812400
  6. 6. Leibler JH, Jordan JA, Brownstein K, Lander L, Price LB, Perry MJ. Staphylococcus aureus Nasal Carriage among Beefpacking Workers in a Midwestern United States Slaughterhouse. Plos One. 2016;11(2).
  7. 7. Johnson RC, Ellis MW, Lanier JB, Schlett CD, Cui T, Merrell DS. Correlation between Nasal Microbiome Composition and Remote Purulent Skin and Soft Tissue Infections. Infect Immun. 2015;83(2):802–811. pmid:25486991
  8. 8. Maia Almeida GC, dos Santos MM, Martins Lima NG, Cidral TA, Nunes Melo MC, Lima KC. Prevalence and factors associated with wound colonization by Staphylococcus spp. and Staphylococcus aureus in hospitalized patients in inland northeastern Brazil: a cross-sectional study. Bmc Infect Dis. 2014;14.
  9. 9. Skramm I, Moen AEF, Aroen A, Bukholm G. Surgical Site Infections in Orthopaedic Surgery Demonstrate Clones Similar to Those in Orthopaedic Staphylococcus aureus Nasal Carriers. J Bone Joint Surg Am. 2014;96A(11):882–888.
  10. 10. Tilahun B, Faust AC, McCorstin P, Ortegon A. Nasal colonization and lower respiratory tract infections with methicillin-resistant Staphylococcus aureus. Am J Crit Care. 2015;24(1):8–12. pmid:25554549
  11. 11. Krupa P, Bystron J, Podkowik M, Empel J, Mroczkowska A, Bania J. Population Structure and Oxacillin Resistance of Staphylococcus aureus from Pigs and Pork Meat in South-West of Poland. BioMed Res Int. 2015;2015:141475. pmid:26064878
  12. 12. Peton V, Le Loir Y. Staphylococcus aureus in veterinary medicine. Infect Genet Evol. 2014;21:602–615. pmid:23974078
  13. 13. Cuny C, Koeck R, Witte W. Livestock associated MRSA (LA-MRSA) and its relevance for humans in Germany. Int J Med Microbiol. 2013;303(6–7):331–337. pmid:23607972
  14. 14. Krupa P, Bystroń J, Bania J, Podkowik M, Empel J, Mroczkowska A. Genotypes and oxacillin resistance of Staphylococcus aureus from chicken and chicken meat in Poland. Poultry Sci. 2014;93(12):3179–3186.
  15. 15. Sharma-Kuinkel BK, Mongodin EF, Myers JR, Vore KL, Canfield GS, Fraser CM, et al. Potential Influence of Staphylococcus aureus Clonal Complex 30 Genotype and Transcriptome on Hematogenous Infections. Open Forum Infect Dis. 2015;2(3):1–14.
  16. 16. Couto N, Belas A, Kadlec K, Schwarz S, Pomba C. Clonal diversity, virulence patterns and antimicrobial and biocide susceptibility among human, animal and environmental MRSA in Portugal. J Antimicrob Chemother. 2015;70(9):2483–2487. pmid:26048876
  17. 17. Jeremiah CJ, Kandiah JP, Spelman DW, Giffard PM, Coombs GW, Jenney AW, et al. Differing epidemiology of two major healthcare-associated meticillin-resistant Staphylococcus aureus clones. Hosp Infect. 2016;92(2):183–190.
  18. 18. Glaser P, Martins-Simoes P, Villain A, Barbier M, Tristan A, Bouchier C, et al. Demography and Intercontinental Spread of the USA300 Community-Acquired Methicillin-Resistant Staphylococcus aureus Lineage. mBio. 2015;7(1).
  19. 19. McCarthy AJ, Lindsay JA, Loeffler A. Are all meticillin-resistant Staphylococcus aureus (MRSA) equal in all hosts? Epidemiological and genetic comparison between animal and human MRSA. Vet Dermatol. 2012;23(4):267–254. pmid:22823579
  20. 20. Harrison EM, Weinert LA, Holden MTG, Welch JJ, Wilson K, Morgan FJE, et al. A Shared Population of Epidemic Methicillin-Resistant Staphylococcus aureus 15 Circulates in Humans and Companion Animals. Mbio. 2014;5(3).
  21. 21. Vincze S, Brandenburg AG, Espelage W, Stamm I, Wieler LH, Kopp PA, et al. Risk factors for MRSA infection in companion animals: Results from a case-control study within Germany. Intern J Med Microbiol. 2014;304(7):787–793.
  22. 22. Vincze S, Stamm I, Kopp PA, Hermes J, Adlhoch C, Semmler T, et al. Alarming Proportions of Methicillin-Resistant Staphylococcus aureus (MRSA) in Wound Samples from Companion Animals, Germany 2010–2012. Plos One. 2014;9(1).
  23. 23. Bania J, Dabrowska A, Bystron J, Korzekwa K, Chrzanowska J, Molenda J. Distribution of newly described enterotoxin-like genes in Staphylococcus aureus from food. Int J Food Microbiol. 2006;108(1):36–41. pmid:16380185
  24. 24. Martín MC, González-Hevia MA, Mendoza MC. Usefulness of a two-step PCR procedure for detection and identification of enterotoxigenic staphylococci of bacterial isolates and food samples. Food Microbiol. 2003;20(5):650–610.
  25. 25. Oliveira DC, de Lencastre H. Multiplex PCR strategy for rapid identification of structural types and variants of the mec element in methicillin-resistant Staphylococcus aureus. Antimicrob Agents Ch. 2002;46(7):2155–2161.
  26. 26. Garcia-Alvarez L, Holden MTG, Lindsay H, Webb CR, Brown DFJ, Curran MD, et al. Meticillin-resistant Staphylococcus aureus with a novel mecA homologue in human and bovine populations in the UK and Denmark: a descriptive study. Lancet Infect Dis. 2011;11(8):595–603. pmid:21641281
  27. 27. Harmsen D, Claus H, Witte W, Rothganger J, Turnwald D, Vogel U. Typing of methicillin-resistant Staphylococcus aureus in a university hospital setting by using novel software for spa repeat determination and database management. J Clin Microbiol. 2003;41(12):5442–5448. pmid:14662923
  28. 28. Shopsin B, Gomez M, Montgomery SO, Smith DH, Waddington M, Dodge DE, et al. Evaluation of protein A gene polymorphic region DNA sequencing for typing of Staphylococcus aureus strains. J Clin Microbiol. 1999;37(11):3556–63. pmid:10523551
  29. 29. Spode Coutinho VdL, Paiva RM, Reiter KC, de-Paris F, Barth AL, Pinheiro Mombach Machado AB. Distribution of erm genes and low prevalence of inducible resistance to clindamycin among staphylococci isolates. Brazil J Infect Dis. 2010;14(6):564–568.
  30. 30. Performance Standards of Antimicrobial Suceptibility Testing; Twenty-Fourth International Suplement. Wayne: Clinical and Laboratory Standards Institute; 2014.
  31. 31. Coutant C, Olden D, Bell J, Turnidge JD. Disk diffusion interpretive criteria for fusidic acid susceptibility testing of Staphylococci by the National Committee for Clinical Laboratory Standards method. Diag Micr Infect Dis. 1996;25(1):9–13.
  32. 32. Malaviolle X, Nonhoff C, Denis O, Rottiers S, Struelens MJ. Evaluation of disc diffusion methods and Vitek 2 automated system for testing susceptibility to mupirocin in Staphylococcus aureus. J Antimicrob Chemother. 2008;62(5):1018–1023. pmid:18765413
  33. 33. Brink AJ, Bizos D, Boffard KD, Feldman C, Grolman DC, Pretorius J, et al. Guideline summary: Appropriate use of tigecycline. S Afr J Surg. 2012;50(1):20–21. pmid:22353316
  34. 34. Rizzotti L, Simeoni D, Cocconcelli P, Gazzola S, Dellaglio F, Torriani S. Contribution of enterococci to the spread of antibiotic resistance in the production chain of swine meat commodities. J Food Protect. 2005;68(5):955–965.
  35. 35. Chen H-J, Hung W-C, Tseng S-P, Tsai J-C, Hsueh P-R, Teng L-J. Fusidic Acid Resistance Determinants in Staphylococcus aureus Clinical Isolates. Antimicrobl AgentsCh. 2010;54(12):4985–4991.
  36. 36. Seah C, Alexander DC, Louie L, Simor A, Low DE, Longtin J, et al. MupB, a New High-Level Mupirocin Resistance Mechanism in Staphylococcus aureus. Antimicrob Agents Ch. 2012;56(4):1916–1920.
  37. 37. Emaneini M, Bigverdi R, Kalantar D, Soroush S, Jabalameli F, Noorazar Khoshgnab B, et al. Distribution of genes encoding tetracycline resistance and aminoglycoside modifying enzymes in Staphylococcus aureus strains isolated from a burn center. Ann Burns Fire Disasters. 2013;26(2):76–80. pmid:24133400
  38. 38. Kruse H, Kirkemo AM, Handeland K. Wildlife as source of zoonotic infections. Emerg Infect Dis. 2004;10(12):2067–2072. pmid:15663840
  39. 39. Hariharan H, Matthew V, Fountain J, Snell A, Doherty D, King B, et al. Aerobic bacteria from mucous membranes, ear canals, and skin wounds of feral cats in Grenada, and the antimicrobial drug susceptibility of major isolates. Comp Immunol Microb Infect Dis. 2011;34(2):129–134.
  40. 40. Patel A, Lloyd DH, Lamport AI. Prevalence of feline staphylococci with special reference to Staphylococcus felis among domestic and feral cats in the south-east of England. Adv Vet Dermatol.4. 2002;4:85–91.
  41. 41. Patel A, Lloyd DH, Lamport AI. Antimicrobial resistance of feline staphylococci in southeastern England. Vet Dermatol. 1999;10(3):257–261.
  42. 42. Iverson SA, Brazil AM, Ferguson JM, Nelson K, Lautenbach E, Rankin SC, et al. Anatomical patterns of colonization of pets with staphylococcal species in homes of people with methicillin-resistant Staphylococcus aureus (MRSA) skin or soft tissue infection (SSTI). Vet Microbiol. 2015;176(1–2):202–208. pmid:25623014
  43. 43. Abraham JL, Morris DO, Griffeth GC, Shofer FS, Rankin SC. Surveillance of healthy cats and cats with inflammatory skin disease for colonization of the skin by methicillin-resistant coagulase-positive staphylococci and Staphylococcus schleiferi ssp schleiferi. Vet Dermatol. 2007;18(4):252–259. pmid:17610491
  44. 44. Lin Y, Barker E, Kislow J, Kaldhone P, Stemper ME, Pantrangi M, et al. Evidence of multiple virulence subtypes in nosocomial and community-associated MRSA genotypes in companion animals from the upper midwestern and northeastern United States. Clin Med Res. 2011;9(1):7–16. pmid:20739580
  45. 45. Coughlan K, Olsen KE, Boxrud D, Bender JB. Methicillin-resistant Staphylococcus aureus in Resident Animals of a Long-term Care Facility. Zoonoses Public Health. 2010;57(3):220–226. pmid:20042067
  46. 46. Morris DO, Lautenbach E, Zaoutis T, Leckerman K, Edelstein PH, Rankin SC. Potential for pet animals to harbor methicillin-resistant Staphylococcus aureus (MRSA) when residing with human MRSA patients. Zoonoses Public Health. 2012;59(4):286–293. pmid:22233337
  47. 47. Kottler S, Middleton JR, Perry J, Weese JS, Cohn LA. Prevalence of Staphylococcus aureus and Methicillin-Resistant Staphylococcus aureus Carriage in Three Populations. J Vet Intern Med. 2010;24(1):132–139. pmid:20002557
  48. 48. Loeffler A, Pfeiffer DU, Lindsay JA, Magalhaes RJS, Lloyd DH. Prevalence of and risk factors for MRSA carriage in companion animals: a survey of dogs, cats and horses. Epidemiol Infect. 2011;139(7):1019–1028. pmid:20943000
  49. 49. Wan MT, Fu SY, Lo YP, Huang TM, Cheng MM, Chou CC. Heterogeneity and phylogenetic relationships of community-associated methicillin-sensitive/resistant Staphylococcus aureus isolates in healthy dogs, cats and their owners. JApp Microbiol. 2012;112(1):205–213.
  50. 50. Luczak-Kadlubowska A, Sulikowska A, Empel J, Piasecka A, Orczykowska M, Kozinska A, et al. Countrywide molecular survey of methicillin-resistant Staphylococcus aureus strains in Poland. J Clin Microbiol. 2008;46(9):2930–2937. pmid:18614662
  51. 51. Kasprzyk J, Piechowicz L, Wiscniewska K, Dziewit L, Bronk M, Swiec K. Differentiation of spa types and staphylococcal cassette chromosome mec (SCCmec) in clinical methicillin-resistant Staphylococcus aureus isolated in medical sites of Gdansk region. Med Dosw Mikrobiol. 2015;67(2):79–88. pmid:26591659
  52. 52. Wisniewska K, Kasprzyk J, Piechowicz L, Bronk M, Swiec K. Spa types and antibiotic resistance of Staphylococcus aureus bloodstream isolates obtained form patients of the University Clinical Center in Gdansk. Med Dosw Mikrobiol. 2013;65(3):139–147. pmid:24432553
  53. 53. Rolo J, Miragaia M, Turlej-Rogacka A, Empel J, Bouchami O, Faria NA, et al. High Genetic Diversity among Community-Associated Staphylococcus aureus in Europe: Results from a Multicenter Study. Plos One. 2012;7(4).
  54. 54. Soares Magalhaes RJ, Loeffler A, Lindsay J, Rich M, Roberts L, Smith H, et al. Risk factors for methicillin-resistant Staphylococcus aureus (MRSA) infection in dogs and cats: a case-control study. Vet Res. 2010;41(5):55. pmid:20423695
  55. 55. Concepcion Porrero M, Mentaberre G, Sanchez S, Fernandez-Llario P, Casas-Diaz E, Mateos A, et al. Carriage of Staphylococcus aureus by Free-Living Wild Animals in Spain. App Environ Microb. 2014;80(16):4865–4870.
  56. 56. Luria BJ, Levy JK, Lappin MR, Breitschwerdt EB, Legendre AM, Hernandez JA, et al. Prevalence of infectious diseases in feral cats in Northern Florida. J Fel Med Surg. 2004;6(5):287–296.
  57. 57. Wendlandt S, Shen J, Kadlec K, Wang Y, Li B, Zhang W-J, et al. Multidrug resistance genes in staphylococci from animals that confer resistance to critically and highly important antimicrobial agents in human medicine. Trends Microbiol. 2015;23(1):44–54. pmid:25455417
  58. 58. Eckholm NG, Outerbridge CA, White SD, Sykes JE. Prevalence of and risk factors for isolation of meticillin-resistant Staphylococcus spp. from dogs with pyoderma in northern California, USA. Vet Dermatol. 2013;24(1):154–161. pmid:23331692
  59. 59. Hamilton E, Kruger JM, Schall W, Beal M, Manning SD, Kaneene JB. Acquisition and persistence of antimicrobial-resistant bacteria isolated from dogs and cats admitted to a veterinary teaching hospital. J Am Vet Med Assoc. 2013;243(7):990–1000. pmid:24050566
  60. 60. Weiss S, Kadlec K, Fessler AT, Schwarz S. Identification and characterization of methicillin-resistant Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus haemolyticus and Staphylococcus pettenkoferi from a small animal clinic. Vet Microbiol. 2013;167(3–4):680–685. pmid:23992797
  61. 61. Resch M, Nagel V, Hertel C. Antibiotic resistance of coagulase-negative staphylococci associated with food and used in starter cultures. Int J Food Microbiol. 2008;127(1–2):99–104. pmid:18625535
  62. 62. Gandolfi-Decristophoris P, Regula G, Petrini O, Zinsstag J, Schelling E. Prevalence and risk factors for carriage of multi-drug resistant Staphylococci in healthy cats and dogs. J Vet Sci. 2013;14(4):449–456. pmid:23820161
  63. 63. Muniz IM, Penna B, Lilenbaum W. Treating Animal Bites: Susceptibility of Staphylococci from Oral Mucosa of Cats. Zoonoses Public Health. 2013;60(7):504–509. pmid:23280142
  64. 64. Heller J, Kelly L, Reid SWJ, Mellor DJ. Qualitative Risk Assessment of the Acquisition of Meticillin-Resistant Staphylococcus aureus in Pet Dogs. Risk Anal. 2010;30(3):458–472. pmid:20136747
  65. 65. Davis MF, Iverson SA, Baron P, Vasse A, Silbergeld EK, Lautenbach E, et al. Household transmission of meticillin-resistant Staphylococcus aureus and other staphylococci. Lancet Infect Dis. 2012;12(9):703–716. pmid:22917102
  66. 66. Walther B, Hermes J, Cuny C, Wieler LH, Vincze S, Abou Elnaga Y, et al. Sharing More than Friendship—Nasal Colonization with Coagulase-Positive Staphylococci (CPS) and Co-Habitation Aspects of Dogs and Their Owners. Plos One. 2012;7(4).
  67. 67. Petinaki E, Spiliopoulou I. Methicillin-resistant Staphylococcus aureus among companion and food-chain animals: impact of human contacts. Clin Microbiol Infect. 2012;18(7):626–634. pmid:22550956
  68. 68. Manian FA. Asymptomatic nasal carriage of mupirocin-resistant, methicillin-resistant Staphylococcus aureus (MRSA) in a pet dog associated with MRSA infection in household contacts. Clin Infect Dis. 2003;36(2):26–28.
  69. 69. Loeffler A, Lloyd DH. Companion animals: a reservoir for methicillin-resistant Staphylococcus aureus in the community? Epidemiol Infect. 2010;138(5):595–605. pmid:20056014
  70. 70. Bradley SF. Eradication or decolonization of methicillin-resistant Staphylococcus aureus carriage: What are we doing and why are we doing it? Clin Infect Dis. 2007;44(2):186–189. pmid:17173214
  71. 71. Larsen J, David MZ, Vos MC, Coombs GW, Grundmann H, Harbarth S, et al. Preventing the introduction of meticillin-resistant Staphylococcus aureus into hospitals. J Glob Antimicrob Res. 2014;2(4):260–268.
  72. 72. Loeffler A, Baines SJ, Toleman MS, Felmingham D, Milsom SK, Edwards EA, et al. In vitro activity of fusidic acid and mupirocin against coagulase-positive staphylococci from pets. J Antimicrob Chemother. 2008;62(6):1301–1304. pmid:18819974
  73. 73. Guardabassi L, Jensen LB, Kruse H.Guide to Antimicrobial Use in Animals. Willey; 2009.
  74. 74. Sing A, Tuschak C, Hoermansdorfer S. Methicillin-resistant Staphylococcus aureus in a family and its pet cat. New Engl J Med. 2008;358(11):1200–1201. pmid:18337614
  75. 75. Cohn LA, Middleton JR. A veterinary perspective on methicillin-resistant staphylococci. J Vet Emerg Crit Car. 2010;20(1):31–45.
  76. 76. Qureshi AI, Memon MZ, Vazquez G, Suri MFK. Cat ownership and the Risk of Fatal Cardiovascular Diseases. Results from the Second National Health and Nutrition Examination Study Mortality Follow-up Study. J Vas Intern Neurol. 2009;2(1):132–135.
  77. 77. Weese JS, van Duijkeren E. Methicillin-resistant Staphylococcus aureus and Staphylococcus pseudintermedius in veterinary medicine. Vet Microbiol. 2010;140(3–4):418–429. pmid:19246166