Multidrug resistance and identification of genes associated with carbapenemases production in Klebsiella pneumoniae isolated from clinical and subclinical bovine mastitis

Abstract

Klebsiella pneumoniae (K. pneumoniae) is an opportunistic enterobacteria found in environment and in the intestinal tract of animals and humans, related to enteric and extra-enteric infections. Among livestock, K. pneumoniae and Escherichia coli are most important pathogen of clinical bovine mastitis from environmental origin. Mammary infections by this pathogens are predominant in rainfall periods. In cattle, the severity of clinical mastitis can be classified into three levels: mild (score 1), moderate (score 2) and severe (score 3). Cases of score 1 are characterized by changes exclusivelly in milk of affected quarter, whereas changes in milk and clinical signs of inflammation in mammary gland are classified as score 2. I addition, changes in milk, mammary gland, and systemic signs (with occasional death of animais by endotoxic shock), are grouped as score 3. However, these classification have no been investigated in clinical cases of mastitis caused by K. pneumoniae. The multidrug resistance of bacteria to conventional antimicrobials is an emergent concern to animals and humans, including by K. pneumoniae. Currently, studies focused on enzymes that confer resistance of K. pneumoniae to conventional antimicrobials, particularly from carbapenemases group, are considered an emergent concern. The enzyme carbapenemase is produced by K. pneumoniae and is used as a marker of antimicrobial resistance. The isolates carbapenemase-positive harbour mainly the genes blaKPC, blaNDM, and blaOXA-48. In this context, the aim of present study is to investigate the phenotypic characterization of multiple antimicrobial resistance index (using disk diffusion method) and molecular detection of genes associated with resistance to the carbapenemic group (blaKPC, blaNDM, and blaOXA-48) in K. pneumoniae isolates obtained from clinical bovine mastitis from diferente levels of severity.