Detection of methicillin-resistant Staphylococcus aureus in Iberian pigs

Abstract

Aims: Iberian pigs are bred in Spain for the production of high‐value dry‐cured products, whose export volumes are increasing. Animals are typically reared outdoors, although indoor farming is becoming popular. We compared carriage of methicillin‐resistant Staphylococcus aureus (MRSA) in Iberian pigs, raised indoors and outdoors, with intensively farmed Standard White pigs. Methods and Results: From June 2007 to February 2008, 106 skin swabs were taken from Iberian pigs and 157 samples from SWP at slaughterhouses in Spain. We found that Iberian pigs carried MRSA, although with a significantly lower prevalence (30/106; 28%) than SWP (130/157; 83%). A higher prevalence of indoor Iberian pigs compared with animals reared under outdoor conditions was not significant; however, all but one positive indoor Iberian pig samples were detected from one slaughterhouse. Overall, 16 different spa types were identified, with t011 predominating in all three animal populations. A subset of isolates was characterized by MLST. Most of these belonged to ST398. MRSA isolates from Iberian pigs presented a higher susceptibility to antibiotics than those isolated from SWP. Conclusions: Despite limited contact with humans, pigs raised outdoors are colonized by an MRSA population that genetically overlaps with that of intensively farmed pigs, although antimicrobial resistance is lower. Significance and Impact of the Study: To our knowledge, this is the first detection of MRSA in food animals raised in free‐range conditions.

Prevalence of colonization by methicillin-resistant Staphylococcus aureus ST398 in pigs and pig farm workers in an area of Catalonia, Spain

“…Moreover, in La Rioja (Northern Spain), Gómez-Sanz described a prevalence of 21 and 49% in fattening and suckling pigs, respectively, in this case at the slaughterhouse level [34]. Another study showed that 28% of Iberian pigs were colonized; these animals have little contact with pig farmers [35]. Furthermore, in our study we observed that pig farmers working in farms with pig populations are carriers of MRSA ST398.…”

From Pig to Pork: Methicillin-Resistant Staphylococcus aureus in the Pork Production Chain

“…Denmark (1), Germany (10,54,99), Italy (9), Switzerland (51,80), Spain (48,84), and The Netherlands (30) have reported prevalences of MRSA-positive pigs of 1.3 to 64.7%. Other investigations have been conducted on Tenerife (73) and in Asia (7,23,64).…”

“…Most of the porcine MRSA strains at European abattoirs belonged to spa types tOll, t034 and tl08. The latter strain was primarily identified by Dutch and Spanish investigations, accounting for 37.5% (30) and 11% (48,84) of all isolates, respectively, spa type t899 was predominat ing in Italian abattoirs and could be found in 49% of the MRSA-positive slaughter pig herds. In addition, 47% of the positive herds carried non-CC398 strains (CC1, CC9 and CC97) (9).…”

Livestock-Associated MRSA and Its Current Evolution

“…Currently, CC398 includes 43 sequence types [34], but the major MRSA sequence type colonizing pigs is ST398. Other STs described in pigs are ST541, ST1965, ST1966, ST1967, and ST1968 [16,35,36]. However, it has been shown that there is a specific subgroup of human ST398 strains, different from LA-MRSA ST398 [37], that can be readily differentiated by SNP detection and the presence or absence of scn and tet(M) [38].…”