The presence of methicillin-resistant Staphylococcus aureus on large pig breeding farms in Croatia

Prevalence and characteristics of methicillin-resistant staphylococci in goats on the island of Tenerife, Spain

The aim of this study was to determine the prevalence of methicillin-resistant Staphylococcus (MRS) in healthy goats on the Island of Tenerife, Spain, as well as to identify the phenotypic and genotypic characteristics of the strains found. A cross-sectional prevalence study was conducted. A total of 158 goats from 15 different farms were sampled between September 2017 and January 2018. The percentage of positive samples of methicillin-resistant Staphylococcus aureus (MRSA) was 15.8% (25/158) and that of methicillin-resistant coagulase-negative staphylococci (MRCoNS) was 6.9% (11/158). All MRSA isolates from goats belonged to one clonal group showing Multi-Locus Sequence type 398. All strains studied (n = 36) were resistant to non-carbapenem beta-lactam antibiotics and susceptible to teicoplanin, linezolid, vancomycin, rifampicin, quinupristin-dalfospristin and mupirocine. In MRSA isolates, the highest percentage of resistance obtained, besides beta-lactam non-carbapenem antibiotics, was to trimethoprim-sulphamethoxazole and, in the case of MRCoNS isolates, to phosphomycin and erythromycin. A total of 12 resistance patterns were obtained, presenting differences between patterns obtained for MRSA and MRCoNS, with 7 different patterns for MRSA and 5 for MRCoNS. We therefore consider it essential to expand the epidemiological study of these strains of animal origin, as well as to increase surveillance and control measures at all stages of the food chain.

Livestock-associated Staphylococcus aureus on Polish pig farms

BACKGROUND

Livestock-associated Staphylococcus aureus (LA-SA) draws increasing attention due to its particular ability to colonize farm animals and be transmitted to people, which in turn leads to its spread in the environment. The aim of the study was to determine the dissemination of LA-SA on pig farms selected throughout Poland, characterize the population structure of identified S. aureus, and assess the prevalence of LA-SA carriage amongst farmers and veterinarians being in contact with pigs.

METHODS AND FINDINGS

The study was conducted on 123 pig farms (89 farrow-to-finish and 34 nucleus herds), located in 15 out of 16 provinces of Poland. Human and pig nasal swabs, as well as dust samples were analyzed. S. aureus was detected on 79 (64.2%) farms from 14 provinces. Amongst these farms LA-SA-positive farms dominated (71/79, 89.9%, 95% CI [81.0%, 95.5%]). The prevalence of LA-MRSA-positive farms was lower than LA-MSSA-positive (36.6% of LA-SA-positive farms, 95% CI [25.5%, 48.9%] vs. 74.6%, 95% CI [62.9%, 84.2%]). In total, 190 S. aureus isolates were identified: 72 (38%) MRSA and 118 (62%) methicillin-susceptible S. aureus (MSSA), of which 174 (92%) isolates were classified to three livestock-associated lineages: CC398 (73%), CC9 (13%), and CC30/ST433 (6%). All CC398 isolates belonged to the animal clade. Four LA-MRSA clones were detected: ST433-IVa(2B) clone (n = 8, 11%), described to the best of our knowledge for the first time, and three ST398 clones (n = 64, 89%) with the most prevalent being ST398-V(5C2&5)c, followed by ST398-V(5C2), and ST398-IVa(2B). Nasal carriage of LA-SA by pig farmers was estimated at 13.2% (38/283), CC398 carriage at 12.7% (36/283) and ST398-MRSA carriage at 3.2% (9/283), whereas by veterinarians at 21.1% (8/38), 18.4% (7/38) and 10.5% (4/38), respectively.

CONCLUSIONS

The prevalence of LA-MRSA-positive pig farms in Poland has increased considerably since 2008, when the first MRSA EU baseline survey was conducted in Europe. On Polish pig farms CC398 of the animal clade predominates, this being also reflected in the prevalence of CC398 nasal carriage in farmers and veterinarians. However, finding a new ST433-IVa(2B) clone provides evidence for the continuing evolution of LA-MRSA and argues for further monitoring of S. aureus in farm animals.

MRSA in Croatia: prevalence and management

Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are associated with increased morbidity, mortality and length of hospital stay. MRSA is a major pathogen in hospitals and an important pathogen in community infections with few severe and fatal cases. However, MRSA causes the majority of skin and soft tissue infections in the US. The burden of community MRSA is much smaller in Europe, but there are reports of livestock-associated MRSA (LA-MRSA) isolated from pigs and cattle causing significant infections in the people who are connected to these farms. MRSA has been present in Croatia for more than 45 years, and it exerts a different impact on health-care infections. A remarkable increase in MRSA percentage was noted in primarily sterile samples in 2002 (37%) in comparison to 2001 (31%). This percentage remained quite high until 2008, when the first signs of a reduced trend were observed. The lowest percentage was 22% in 2012.

Prevalence and molecular characteristics of methicillin-resistant Staphylococcus aureus strains isolated in a multicenter study of nursing home residents in Croatia

BACKGROUND

Residents of nursing homes (NHs) are often hospitalized and could present a potential reservoir for methicillin-resistant Staphylococcus aureus (MRSA). The aim of the study was to determine the prevalence for MRSA carriage in residents and staff in Croatian NHs and to characterize MRSA strains using genotyping techniques.

METHODS

A cross-sectional study was performed among 877 residents and staff of 7 NHs representing 3 major Croatian regions. Nasal swabs from residents and staff and other samples from residents with invasive devices were obtained. Identified isolates were submitted to susceptibility testing and genotyping with SCCmec typing, S aureus protein A (spa) locus typing, and pulsed-field gel electrophoresis (PFGE).

RESULTS

The overall prevalence of MRSA colonization was 7.1% (95 confidence interval, 5.4%-8.8%), ranging from 0% to 28.8%. Four MRSA isolates were found in NH staff. All MRSA isolates were negative for Panton-Valentine leukocidin-encoding genes. SCCmec type II was found in 32 MRSA strains; SCCmec IV, in 27 strains; SCCmec I, in 3 strains. The predominant spa type was t008, found in 49 strains; PFGE analysis revealed 2 major clonal groups.

CONCLUSIONS

MRSA strains were found to be colonizing residents and staff of 7 NHs in Croatia. Our study demonstrates the spread of 2 clones within and among Croatian NHs. The data presented here provide an important baseline for future surveillance of MRSA in NH.

From pig to pork: methicillin-resistant Staphylococcus aureus in the pork production chain

Methicillin-resistant Staphylococcus aureus (MRSA) is a major global public health concern and could be a food safety issue. Recurrent reports have documented that pig herds are an important reservoir for MRSA, specifically the livestock-associated sequence type 398. The high prevalence of MRSA in pig primary production facilities and the frequent detection of MRSA of the same types in pork and pig meat products raise the question of underlying mechanisms behind the introduction and transmission of MRSA along the pork production chain. A comprehensive review of current literature on the worldwide presence of livestock-associated MRSA in various steps of the pork production chain revealed that the slaughter process plays a decisive role in MRSA transmission from farm to fork. Superficial heat treatments such as scalding and flaming during the slaughter process can significantly reduce the burden of MRSA on the carcasses. However, recontamination with MRSA might occur via surface treating machinery, as a result of fecal contamination at evisceration, or via increased human handling during meat processing. By optimizing processes for carcass decontamination and avoiding recontamination by effective cleaning and personal hygiene management, transmission of MRSA from pig to pork can be minimized.

Transmission Dynamics of Methicillin-Resistant Staphylococcus aureus in Pigs

From the mid-2000s on, numerous studies have shown that methicillin-resistant Staphylococcus aureus (MRSA), renowned as human pathogen, has a reservoir in pigs and other livestock. In Europe and North America, clonal complex (CC) 398 appears to be the predominant lineage involved. Especially worrisome is its capacity to contaminate humans in close contact with affected animals. Indeed, the typical multi-resistant phenotype of MRSA CC398 and its observed ability of easily acquiring genetic material suggests that MRSA CC398 strains with an increased virulence potential may emerge, for which few therapeutic options would remain. This questions the need to implement interventions to control the presence and spread of MRSA CC398 among pigs. MRSA CC398 shows a high but not fully understood transmission potential in the pig population and is able to persist within that population. Although direct contact is probably the main route for MRSA transmission between pigs, also environmental contamination, the presence of other livestock, the herd size, and farm management are factors that may be involved in the dissemination of MRSA CC398. The current review aims at summarizing the research that has so far been done on the transmission dynamics and risk factors for introduction and persistence of MRSA CC398 in farms.