SP31-2 Zoonotic transmission of difficult-to-treat pathogens in Cambodia: let's look for the pigs?

Abstract

most probably is a descendant from human MSSA which through a host jump and selective forces became MRSAwith a natural reservoir in animals. These MRSA are now increasingly transmitting back to humans, causing infections primarily in people working with pigs or their families but also to people without direct contact to pigs. Transmission and smaller outbreaks have been described both from hospitals and nursinghomes, however, human tohuman transmission still seems to be significantly less than for “human MRSA”. This difference in transmission pattern may be linked to loss of genes ... of the human immune system including Scn. Recapture of such genes may, however, change this situation which may change the problem from being mainly occupational health related to be a health issue for the general population. Although MRSA including CC398 has been found in meat, there is no sign of food being a significant factor in the transmission of MRSA CC398 from animals to humans. Skin and soft tissue infections dominate the clinical picture reflecting that this primarily is seen among otherwisehealthy persons; however, serious infections including endocarditis have also been described. The SCCmec casettes of MRSA CC398 are often large, composite with carriage of resistance genes against antibiotics and/or heavy metals within the cassette. Nearly all LA-MRSA isolates are resistant to tetracycline, but apart from that a striking diversity in antibiograms has been seen. mecC [initially named mecA(LGA251)] containing isolates primarily from dairy cattle but also from humans were described in 2011. The isolates belong to lineages primarily described in cows and a recent study has provided evidence that the direction of transmission is from animals to humans. This gene is located in a novel staphylococcal cassette chromosome mec element, designated type-XI SCCmec, it is only 70% identical to mecA homologues. These isolates are readily picked up by cefoxitin but molecular commercial assays are not yet able to detect these isolates which have consequences for choice of methodology for detection of MRSA.