Extended-spectrum beta-lactamase producing Enterobacteriaceae in companion animals

Abstract

Extended-spectrum beta-lactamases (ESBL) are bacterial enzymes, capable of degrading beta-lactam antibiotics through hydrolysis. Beta-lactam antibiotics act on bacterial cell walls, where the beta-lactam ring is incorporated in the peptidoglycan layer causing an imbalance of this layer which leads to disruption of the bacterial cell wall. Beta-lactamases hydrolyse the beta-lactam ring, making beta-lactam antibiotics ineffective. In contrast to beta-lactamases which target 1st and 2nd generations of cephalosporins and penicillins, targets of extended-spectrum beta-lactamases include 3rd and 4th generations of cephalosporins. ESBL function can be inhibited by clavulanic acid. ESBLs are mainly seen in Enterobacteriaceae isolates. The aim of this project is to elucidate the role of companion animals in ESBL epidemiology. Four studies were carried out in the scope of this project to gain knowledge about the significance of ESBL-producing Enterobacteriaceae in dog and cat populations, and to examine the role of companion animals in relation to humans, other animals and the environment. Chapter 2 describes a longitudinal study in dogs, addressing colonisation dynamics, colonisation rates and dominant ESBL types to estimate the significance of ESBL-producing Enterobacteriaceae in dogs and the risk for exposure of ESBL-producing Enterobacteriaceae to dog owners. Chapter 3 describes a similar longitudinal study in cats, also addressing colonisation dynamics, colonisation rates and dominant ESBL types, to estimate the significance of ESBL-producing Enterobacteriaceae in cats, the difference in ESBL colonisation between dogs and cats and the risk for exposure of ESBL-producing Enterobacteriaceae to cat owners. In order to investigate the role of companion animals in ESBL epidemiology, the interaction of companion animals with their surroundings in relation to spread of ESBL-producing Enterobacteriaceae should be addressed. Chapter 4 describes environmental contamination with ESBL-producing Enterobacteriaceae in operating theatres of veterinary clinics after admittance of ESBL-positive companion animals, to assess the risk for exposure of ESBL-producing Enterobacteriaceae to susceptible animals. To further address the risk of exposure of ESBL-producing Enterobacteriaceae to companion animals, risk factors associated in relation to ESBL-carriage or ESBL-shedding should be determined. Chapter 5 describes a case-control study investigating the prevalence of ESBL-producing Enterobacteriaceae in cats with a raw-food diet, compared to a control group.