Antimicrobial-resistant bacteria in free-living marine mammals; detection of Klebsiella pneumoniae subspecies pneumoniae producing the carbapenemase OXA-48 indicates likely anthropogenic marine microbial pollution.. Carbapenemase OXA-48 in Klebsiella pneumoniae from free-living marine mammals

The occurrence of bacteria resistant to antimicrobials in free-living marine mammals which have not previously been treated with antimicrobials has been reported previously. The beta-lactamase enzyme OXA-48 has spread widely in recent years in Enterobacteriaceae associated with man, disseminated primarily on incompatibility group L/M plasmids. OXA-48 confers resistance to carbapenems, important antimicrobials for treating highly-resistant bacterial infections in humans. This enzyme has rarely been detected in bacteria from animals. Furthermore, the use of carbapenem compounds is not permitted in food-producing animals in Europe and to our knowledge has not been reported in food-producing animals globally. Here we report the detection of Klebsiella pneumoniae subspecies pneumoniae carrying the blaOXA-48 gene on an incompatibility group L/M plasmid from an infection in a free-living wild common seal Phoca vitulina. Evidence is accruing that marine mammals may be infected with bacteria originating from anthropogenic sources (human sewage) contaminating the environment. Our findings provide significant additional evidence, demonstrating that an epidemic plasmid occurring in bacteria predominantly associated with man has been detected in bacteria infecting a marine mammal. Surveillance of the bacteria causing infections in wild seals, determining the susceptibility of these bacteria to antimicrobials and their genotype has therefore provided a useful indicator for assessing this type of marine bacterial contamination.