Epidemiological investigation into the possible exchange of SCCmec between staphylococci in different ecosystems

This project aimed to study epidemiology and genetic diversity of methicillin resistant Staphylococcus aureus (MRSA) and methicillin resistant Staphylococcus sciuri (MRSS). Indeed, while S. aureus is recognized as a pathogen potentially responsible of nosocomial infection in humans or mastitis in bovines, S. sciuri is one of the most ancient species in the genus Staphylococcusmainly and considered as a harmless environmental species though it has also been recovered from some cases of infections in humans and animals. In this project we followed two surveys in Belgium over MRSA in poultry in 2011 and in healthy bovines in 2012. During these surveys, two isolation methods have also be compared. One of these isolation methods uses two enrichment broths and is proposed by the EFSA though considered as not very sensitive. The alternative method is very similar to the first one except that only one enrichment broth is used. Additionally to this, MRSS have been isolated during the survey in poultry. Additionally to this, investigation on the prevalence of methicillin resistant Staphylococcus sciuri (MRSS) in poultry and in farm animals has been performed. Our results show the importance of methicillin resistant Staphylococci in livestock though with different estimated prevalence depending on the farm animal and the age group. We have also shown the high prevalence of MRSS in food producing animals. Indeed MRSS prevalence in poultry outnumbered the prevalence of MRSA. While MRSA was shown to appear occasionally in chicken, MRSS were more common. MRSA prevalence differs also among origin. Indeed, the prevalence estimated during the bovine survey was much higher than that of poultry. This prevalence was also depending on the age group of the animals. Whereas no significant difference could be highlighted between the prevalence in broilers and layers, the prevalence of MRSA in dairy and meat cows was significantly lower compared to veal calves. Furthermore, our results showed that, such as S. aureus, S. sciuri is often found to be multi-resistant to antibiotics and as such, it may serve as a reservoir for antimicrobial resistance or eventually virulence genes. Indeed, since MRSA and MRSS are commonly found in farm animals, they might share a common gene pool. However, some differences in the antimicrobial resistance profile were noted. While MRSA were mostly resistant to tetracycline and trimethoprim; MRSS were more resistant to fusidic acid, tiamulin and quinupristin/dalfopristin. However, trimethoprim and clindamycin resistance was high in both species. Furthermore, resistance to ciprofloxacin and chloramphenicol was low in MRSS and all isolates were sensitive to vancomycin in both cases. Genetic diversity of both MRSA and MRSS was also assessed. In contrast to S. sciuri, there are well defined molecular tools available for S. aureus characterization allowing a better understanding of its behavior in different animal populations and of the population structure of this species. Spa-typing and MLST showed the presence of a broad range of different MRSA types in bovines although the livestock-associated (LA)-MRSA ST398 was the most common. However, unexpectedly, non ST398 MRSA has also been found both in bovines and in poultry. This type was determined as ST239 which is a common hospital acquired (HA)-MRSA. This support the hypothesis of a spill-over and spill-back between animals and humans that was set in this project. However, all these tools are not available for S. scuri and our studies had to rely on SCCmec typing and PFGE for subtyping of the population. SCCmec typing in MRSA and MSSA was different, while MRSA mostly harbor SCCmec type IV and V, MRSS carried mostly SCCmec type III and a non-typable cassette. In poultry, these cassettes seemed to be associated to the animal origin since the non-typable SCCmec was mostly found in layers while the type III was mainly recovered in broilers. This repartition was also supported by the PFGE profiles since two major clusters appeared in the dendrogram and corresponded to the origin (broilers or layers) and to the SCCmec type. This study showed that, even if some diversity was observed in the profiles, some strains were common to different farm which indicates a possible strain sharing between farms in the same country

Epidemiology and molecular characterization of methicillin-resistant Staphylococcus aureus nasal carriage isolates from bovines

Background: Staphylococcus aureus is a common bacterium usually found on skin and mucous membranes of warm blooded animals. Resistance in S. aureus has been increasingly reported though depending on the clonal lineage. Indeed, while hospital acquired (HA)-methicillin resistant S. aureus (MRSA) are typically multi-resistant, community associated (CA)-MRSA are by large more susceptible to many antibiotics. Although S. aureus isolated from animals are often susceptible to most antibiotics, multi-resistant livestock associated (LA)-MRSA have been recovered from bovine mastitis. In this study, we investigated the prevalence and types of MRSA present in the nose of healthy bovines of different age groups and rearing practices. Since no validated methods for MRSA isolation from nasal swabs were available, we compared two isolation methods. Molecular characterization was performed by means of spa-typing, MLST, SCCmec typing and microarray analysis for the detection of antimicrobial resistance and virulence genes. Results: MRSA between herd prevalence in bovines was estimated at 19.8%. There was a marked difference between rearing practices with 9.9%, 10.2% and 46.1% of the dairy, beef and veal calve farms respectively being MRSA positive. No significant difference was observed between both isolation methods tested. Most isolates were ST398 spa type t011 or closely related spa types. Few ST239 spa type t037 and t388 and ST8 spa type t121 were also found. SCCmec types carried by these strains were mainly type IV(2B), IV(2B&5) and type V. Type III and non-typeable SCCmec were recovered to a lesser extent. All isolates were multi-resistant to at least two antimicrobials in addition to the expected cefoxitin and penicillin resistance, with an average of resistance to 9.5 different antimicrobials. Isolates selected for microarray analysis carried a broad range of antimicrobial resistance and virulence genes. Conclusion: MRSA were mainly present in veal farms, compared to the lower prevalence in dairy or beef farms. Multi-resistance in these strains was high. Though mainly CC398 spa t011 was found, the genetic diversity was higher than what was found for pigs in Belgium. CC8 strains, a typically human lineage but also recently found also in association with bovines, has been retrieved here also

Why do workers of Myrmica ruginodis (Hymenoptera, Formicidae) navigate by relying mainly on their vision ?

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Characterization of methicillin-resistant Staphylococcus sciuri isolates from industrially raised pigs, cattle and broiler chickens

This study aimed at assessing the epidemiology and genetic diversity of methicillin-resistant Staphylococcus sciuri (MRSS) from different farm animal species. Nasal swabs were collected from 200 pigs, 100 dairy cows, 100 beef cows, 150 veal calves and 200 broilers. Colonies were isolated on selective media containing cefoxitin and the mecA gene was detected by PCR. Antimicrobial resistance was determined by broth microdilution. The genetic diversity was assessed by PFGE and resistance and virulence genes were detected by microarray analysis. The total MRSS prevalence at the animal level was estimated at 9.5%, varying from similar to 10% in veal (13.3%), broilers (12.5%) and dairy cows (10.0%) to 6.5% in pigs and 3.0% in beef cows. mecA was detected in all isolates. SCCmec elements of type III and non-typeable ones were seen most frequently. More than 90% of isolates were non-wild-type (NWT) for gentamicin, penicillin, tiamulin, clindamycin and quinupristin/dalfopristin. The frequency of NWT isolates for fusidic acid and trimethoprim ranged between 78% and 87%. PFGE analysis allowed distinction between two major clusters. Most isolates tested by microarray carried erm and tet genes. Virulence genes were also detected, including an isa gene encoding an immune-evasion factor and the hsdS2 gene encoding a site-specific deoxyribonuclease. This study shows that multiresistant MRSS is carried by different farm animal species. Although some animals shared the same strain, PFGE showed different patterns, indicating high diversity among the MRSS isolates recovered. The absence of clusters associated with a certain animal species suggests low host specificity

Characterization of methicillin-resistant Staphylococcus aureus from healthy carrier chickens

Methicillin-resistant Staphylococcus aureus (MRSA) has long been recognized as an important pathogen in human medicine leading to hospital and community-acquired infections. However, it is now also considered a growing problem in veterinary medicine, although causing little or no disease. Although MRSA has already been detected in livestock including poultry, little is known about the epidemiology of MRSA in broiler and layer chickens. We therefore investigated 372 poultry farms in Belgium. We also compared the isolation method recommended by the European Food Safety Authority using two enrichment steps with an isolation method using only one enrichment step. Isolated MRSA was characterized by means of antimicrobial resistance profiling, spa typing, multi-locus sequence typing, and SCCmec typing. MRSA prevalence was 0.8% using the double broth enrichment method, while using the single broth enrichment method it was 1.8%. Five MRSA strains belonged to the livestock-associated (LA) MRSA ST398 (four with spa type t011 and one with t899), and three to the hospital-acquired MRSA ST239 spa type t037. The ST239 strains carried SCCmec type III while those belonging to ST398 carried SCCmec type IV or V. All isolates showed additional resistance to erythromycin and tetracycline apart from the expected resistance to cefoxitin and penicillin. All strains were susceptible to linezolid, mupirocin and vancomycin. In conclusion, a higher sensitivity for the isolation of LA-MRSA was obtained using only one enrichment step. While the typical LA-MRSA ST398 was present at low prevalence in poultry, human-associated strains have also been found

Genotyping and antimicrobial resistance of Staphylococcus aureus isolates from diseased turkeys

Staphylococcus aureus is a highly versatile pathogen in a large number of domestic animals, including avian species. To gain deeper insight into the epidemiology and diversity of S. aureus associated with articular disease in domestic turkeys, isolates were collected from infected foot joints of turkeys in Brittany (France). A total of 34 isolates were recovered and characterized by means of antimicrobial resistance, staphylococcal protein A typing, macrorestriction pulsed-field gel electrophoresis and micro-array analysis. Thirty isolates were identified as clonal complex (CC) 398 and methicillin-susceptible S. aureus (MSSA), one was identified as a methicillin-resistant S. aureus (MRSA) CC398 isolate, and the remaining were also MSSA and belonged to CC5, CC101, and CC121. Eleven different antimicrobial resistance patterns were detected, with most isolates resistant to penicillin and tetracycline. Based on all typing methods used, the 34 isolates could be divided into 22 different strains. Results on selected isolates, genotyped using microarrays, indicated a high homogeneity among pathogenic MSSA isolates from turkeys. Moreover, all isolates, except the unique MRSA isolate, carried specific phi Av prophage avian-niche-specific genes, demonstrating the versatility of S. aureus to adapt to the specific ecological poultry niche

Characterization of methicillin-resistant non-Staphylococcus aureus staphylococci carriage isolates from different bovine populations.

This study aimed at investigating bovine non-Staphylococcus aureus staphylococci for their role as a potential reservoir for methicillin resistance.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe