Staphylococcus aureus and MRSA colonisation in pigs and humans
Staphylococcus aureus (S. aureus) is a commensal
and opportunistic pathogen that infect humans, companion animals and livestock.
S. aureus causes a number of diseases
ranging from mild community skin infections to severe life-threatening such as infective
endocarditis, osteomyelitis, bacteraemia, pneumonia, septicaemia in the
hospitals as well as having great impact on economic and animal welfare in
animal husbandry. Of particular interest is methicillin resistance
staphylococcus aureus (MRSA) because of limited treatment available.
first reported in livestock in 1972 in milk from Belgium cows with mastitis1 and followed by sporadic report in livestock and
companion animals such as chicken2, pets3, cattle and swine. In 2004, new clone of MRSA in
pigs which is associated with livestock CC398 was reported in Netherland and
several countries especially in Europe have reported and pig exposure has been
identified as a significant risk factor for MRSA colonization in humans. In
Asian countries, ST9 is frequently isolated from livestock. Major concern is
whether there is transmission of MRSA between humans and animals.
transmission and persistence of LA-MRSA and human-associated clones in humans
and pigs seems not to be fully understood. The transfer of resistant bacteria
from farm animals to farmers has been detected in several instances. Voss et al
demonstrated that there is >760 fold for MRSA to be detected in pig farmers
among the patients admitted in the Dutch hospital. Similar study demonstrated
that the nasal S. aureus colonisation in pigs farmers was 44.6% compared to
24.1% controls even in healthy populations. This might be because close contact
might facilitate cross inter-species transmission especially when animals are infested
with heavy loads of antimicrobial agents and also the ability of CC398 to
survive in the environment.
a limited epidemiological studies of MRSA prevalence, colonization levels and
molecular typing in animals are available. In addition to that, genetic
relatedness of human and animal MRSA clones using high discriminatory power
such as whole genome sequencing has not been investigated. High diversity in
terms of religion, cultures and
ethnicities as well as high number of animals which are in close contact with
humans make it necessary to know epidemiology and population structures of not
only MRSA but also MSSA strains in Africa.