Prevalence and antimicrobial susceptibility profiles of Staphylococcus spp. isolated from broilers in Croatia

Staphylococcal infections can be a serious public health problem for farm workers and other persons in contact with poultry, due to their ability to cause a wide range of infections in other animal species and humans. In addition, the presence of pathogenic bacteria in the intestines of poultry can lead to contamination of poultry products. Coagulase-positive (CoPS) and coagulase-negative (CoNS) staphylococci, which are potentially involved in staphylococcal infections in humans, have been associated with poultry. The best-known CoPS is Staphylococcus aureus (S. aureus). The aim of this study was to evaluate the prevalence of Staphylococcus spp. in broilers on commercial farms in Croatia, and to determine their antimicrobial susceptibility profiles. Staphylococcus spp. strains isolated from cloacal swabs of apparently healthy broiler flocks in Croatia were analysed, and a relatively high Staphylococcus infection rate was detected, with a total percentage of isolated Staphylococcus strains of 38%. Among these, 3/100 (3%), 5/100 (5%), 3/100 (3%), 2/100 (2%) were S. aureus, and three CoNS: S. sciuri, S. simiae and S. lentus, respectively. The majority of isolated strains were resistant to penicillin (88.8%), clindamycin (85%), cefoxitin (78%), trimethoprim/sulfamethoxazole (65%), ciprofloxacin (53%), erythromycin (40%) and tetracycline (25%). The highest susceptibility of isolated strains was to chloramphenicol (95%) and gentamicin (89%). All S. aureus, S. lentus and S. simiae isolates were multi-drug-resistant strains that exhibited resistance to three or more antimicrobials, while S. sciuri isolates were resistant to two of the tested antimicrobials.