Pleuritis and suppurative pneumonia associated with a hypermucoviscosity phenotype of Klebsiella pneumoniae in California sea lions (Zalophus californianus)

The aim of this study is to document the isolation of a hypermucoviscosity (HMV) phenotype of Klebsiella pneumoniae from 25 cases of suppurative pneumonia and pleuritis and two cases of abscesses in California sea lions (Zalophus californianus) from the central California coast, representing the first report of this zoonotic pathogen from the marine environment and only the second report in non-humans. Animals died 2 h to 4 days after first being observed sick on beaches. Clinical signs varied from dyspnoea to coma. Gross post-mortem examination of 25 cases revealed fibrinous pleuritis, copious pus in the pleural cavity and suppurative bronchopneumonia. K. pneumoniae isolates obtained from lung and pleural swabs and the hepatic and subcuticular abscesses were highly mucoid on blood agar culture media and were positive to the “string test”. Twenty-one of the 27 isolates were examined by PCR and all were positive for rmpA and K2wyz and negative for K1magA genes. Although pneumonia and pleuritis have previously commonly been observed in marine mammals, their association with pure cultures of a zoonotic bacteria, K. pneumoniae HMV phenotype, has not. This report provides further evidence of the role marine mammals play as sentinels of health risks to humans from coastal waters.