Antibiotic Resistance and Phylogenetic Characterization of Acinetobacter baumannii Strains Isolated from Commercial Raw Meat in Switzerland

Abstract

The spread of antibiotic-resistant bacteria through food has become a major public health concern because some important human pathogens may be transferred via the food chain. Acinetobacter baumannii is one of the most life-threatening gram-negative pathogens; multidrug-resistant (MDR) clones of A. baumannii are spreading worldwide, causing outbreaks in hospitals. However, the role of raw meat as a reservoir of A. baumannii remains unexplored. In this study, we describe for the first time the antibiotic susceptibility and fingerprint (repetitive extragenic palindromic PCR [rep-PCR] profile and sequence types [STs]) of A. baumannii strains found in raw meat retailed in Switzerland. Our results indicate that A. baumannii was present in 62 (25.0%) of 248 (CI 95%: 19.7 to 30.9%) meat samples analyzed between November 2012 and May 2013, with those derived from poultry being the most contaminated (48.0% [CI 95%: 37.8 to 58.3%]). Thirty-nine strains were further tested for antibiotic susceptibility and clonality. Strains were frequently not susceptible (intermediate and/or resistant) to third- and fourth-generation cephalosporins for human use (i.e., ceftriaxone [65%], cefotaxime [32%], ceftazidime [5%], and cefepime [2.5%]). Resistance to piperacillin-tazobactam, ciprofloxacin, colistin, and tetracycline was sporadically observed (2.5, 2.5, 5, and 5%, respectively), whereas resistance to carbapenems was not found. The strains were genetically very diverse from each other and belonged to 29 different STs, forming 12 singletons and 6 clonal complexes (CCs), of which 3 were new (CC277, CC360, and CC347). RepPCR analysis further distinguished some strains of the same ST. Moreover, some A. baumannii strains from meat belonged to the clonal complexes CC32 and CC79, similar to the MDR isolates responsible for human infections. In conclusion, our findings suggest that raw meat represents a reservoir of MDR A. baumannii and may serve as a vector for the spread of these pathogens into both community and hospital settings.

Effect of storage temperature on bacterial diversity in chicken skin

“…Acinetobacter is present on healthy human skin and microbiota (Lupo et al . ) but it is also responsible for diseases in several birds, including chickens (Liu et al . ).…”

Bacteria from Animals as a Pool of Antimicrobial Resistance Genes

“…Interestingly, recent reports have also underlined the presence of colistin and polymyxin B resistant A. baumannii and other Acinetobacter spp. isolates in meat (chicken, turkey, beef and pork) [169,170]. Resistance to polymyxins in A. baumannii is mediated by mutations in the genes pmrA and/or pmrB [168].…”

Clinical and Pathophysiological Overview of Acinetobacter Infections: a Century of Challenges

“…Such strains have harbored extensive antibiotic resistance repertoires. Furthermore, A. baumannii strains harboring extensive antibiotic resistance have contaminated commercial food, including meat, vegetables, and various types of livestock, suggesting multiple environmental routes of transmission into human populations (3,(17)(18)(19). However, non-baumannii Acinetobacter spp.…”