Prevalence and Antimicrobial Resistance of Enterobacteriaceae in Shell Eggs from Small-Scale Poultry Farms and Farmers' Markets.

Public health concerns over the emergence of antimicrobial resistant bacteria have increased recently. The purpose of this study was to investigate the prevalence of antimicrobial resistant Enterobacteriaceae in shell eggs purchased from small poultry farms and farmers' markets. A total of 504 eggs were pooled to make 252 composite samples, consisting of 2 eggs per composite. The microbial quality of shell eggs was determined by standard quantitative, biochemical, and PCR techniques. Susceptibility to 13 antimicrobial agents was determined by the Kirby-Bauer disk diffusion technique, and results were interpreted based on Clinical and Laboratory Standards Institute values. Shell eggs and egg contents were positive for Escherichia coli (11.9 and 5.2%, respectively), Enterobacter (9.1 and 7.9%), and Serratia (11.5 and 4.8%). Salmonella was isolated from 3.6% of egg shells but not from egg contents. Mean (±SD) Enterobacteriaceae levels (4.4 ± 2.0 log CFU per eggshell) on shell eggs from poultry farms was significantly higher (P ≤ 0.05) than that on shell eggs from farmers' markets (2.1 ± 1.3 log CFU per eggshell). Of the 134 isolates recovered, resistance among isolates from farm and market shell eggs to erythromycin was most common (48.5 and 32.8%, respectively) followed by ampicillin (44.8 and 17.2%), and tetracycline (29.9 and 17.2%). The multiple antibiotic resistance index value for E. coli and Pantoea was 0.62, and that for Salmonella and Klebsiella terrigena was 0.08, indicating that Enterobacteriaceae in shell eggs can be resistant to multiple antimicrobial agents. These data reveal that shell eggs from small poultry farms and farmers' markets can harbor antimicrobial resistant pathogenic and commensal bacteria. Thus, failure to properly handle shell eggs poses a potential health hazard to consumers.

Occurrence and antimicrobial resistance of enterococci isolated from organic and conventional retail chicken.

Antibiotic-resistant bacteria existing in agricultural environments may be transferred to humans through food consumption or more multifaceted environmental paths of exposure. Notably, enterococcal infections are becoming more challenging to treat as their resistance to antibiotics intensifies. In this study, the prevalence and antibiotic resistance profiles of enterococci in organic and conventional chicken from retail stores were analyzed. Of the total 343 retail chicken samples evaluated, 282 (82.2%) were contaminated with Enterococcus spp. The prevalence was higher in organic chicken (62.5%) than conventional chicken (37.5%). Enterococcus isolates were submitted to susceptibility tests against 12 antimicrobial agents. Among the isolates tested, streptomycin had the highest frequencies of resistance (69.1 and 100%) followed by erythromycin (38.5 and 80.0%), penicillin (14.1 and 88.5%), and kanamycin (11.3 and 76.9%) for organic and conventional isolates, respectively. Chloramphenicol had the lowest frequency (0.0 and 6.6%, respectively). The predominant species in raw chicken was E. faecium (27.3%), followed by E. gallinarum (6.0%), E. casseliflavus (2.1%), and E. durans (1.4%). These species were also found to be resistant to three or more antibiotics. The data indicated that antibiotic-resistant enterococci isolates were found in chicken whether it was organic or conventional. However, enterococci isolates that were resistant to antibiotics were less common in organic chicken (31.0%) when compared with those isolated from conventional chicken (43.6%). The results of this study suggest that raw retail organic and conventional chickens could be a source of antibiotic-resistant enterococci.

Evaluation of drug-resistant Enterobacteriaceae in retail poultry and beef.

There has been increasing concern on the emergence of multidrug-resistant foodborne pathogens from foods of animal origin, including poultry. The current study aimed to evaluate antibiotic-resistant Enterobacteriaceae from raw retail chicken/turkey parts (thigh, wings, breast, and ground) and beef meat (ground and chunks) in Middle Tennessee. Resistance of the collected Enterobacteriaceae to a panel of antibiotics was determined by the Kirby-Bauer disk diffusion test. Retail meats were also assayed for the presence of Salmonella spp. and Escherichia coli O157:H7. Two hundred thirty-seven samples representing 95.2% of the total of 249 samples tested were positive for Enterobacteriaceae. The level of contamination with Enterobacteriaceae in raw meats ranged from 3.26 log10 cfu/g to 4.94 log10 cfu/g with significant differences in counts among meat types (P < 0.05). Contamination was significantly greater (P < 0.05) in ground beef, beef chucks, ground chicken, chicken breast, and turkey wings (4.92, 4.58, 4.94, 4.75, 4.13 log10 cfu/g, respectively) than ground turkey and chicken wings (3.26 and 3.26 log10 cfu/g, respectively). Klebsiella oxytoca, Serratia spp., E. coli, and Haffnia alvei were most prevalent contaminants at 27.4, 14.3, 12.1, and 11.4%, respectively. Resistance of the Enterobacteriaceae to antimicrobials was most frequent with erythromycin, penicillin, and ampicillin at 100, 89, and 65.8%, respectively. Few (2.7%) of the Enterobacteriaceae were resistant to chloramphenicol. Salmonella spp., E. coli O157:H7, Morganella morganii, Yersinia enterocolitica, and Vibrio parahemolyticus exhibited multiple drug resistance. This investigation demonstrates that raw poultry and beef are potential reservoirs of antibiotic-resistant Enterobacteriaceae.

Prevalence and antimicrobial resistance of Cronobacter sakazakii isolated from domestic kitchens in middle Tennessee, United States.

Cronobacter sakazakii is an emerging opportunistic pathogen that has been implicated in cases of severe meningitis, sepsis, and necrotizing enterocolitis in premature and full-term infants. In this study, the prevalence of C. sakazakii was estimated in selected domestic kitchens in middle Tennessee. Antimicrobial resistance patterns of these C. sakazakii isolates were examined for points of public health significance. A total of 234 contact sites in 78 domestic kitchens were tested for C. sakazakii. Consumers' used dishcloths and cleaning sponges were also tested. Antimicrobial susceptibility of the identified C. sakazakii isolates was determined for 10 antimicrobial drugs by means of the disk diffusion method. C. sakazakii was recovered from 26.9% of domestic kitchens visited. Multidrug resistance was observed; the highest resistance was to penicillin (76.1% of isolates) followed by tetracycline (66.6%), ciprofloxacin (57.1%), and nalidixic acid (47.6%). None of the C. sakazakii isolates were resistant to gentamicin. These results suggest that antibiotic-resistant C. sakazakii could be present at various sites in domestic kitchens.

Prevalence and antimicrobial resistance of pathogenic bacteria in chicken and guinea fowl.

This study was conducted to compare the presence and antimicrobial susceptibility of Campylobacter, Salmonella spp., and other enteric bacteria between chickens and guinea fowls. Birds were reared on enclosed concrete floor housing covered with pine wood shavings litter material. Chicken (n = 40) and guinea fowl (n = 40) carcasses, drinking water (10 mL; n = 40), and litter (10 g; n = 40) were aseptically collected randomly from a poultry farm and analyzed within 1 h of collection. Individual pens served as experimental units and were replicated twice. Campylobacter spp., Salmonella spp., and other enterobactericeae were isolated and identified using standard selective media and biochemical tests. Isolates were tested for sensitivity to tetracycline, ampicillin, streptomycin, kanamycin, nalidixic acid, gentamicin, erythromycin, ciprofloxacin, cefoxitin, and colistin using the Kirby-Bauer disk diffusion test. Campylobacter spp. and Salmonella spp. were isolated from 28 and 35% of whole carcass rinses of chickens and from 18 and 23% of whole carcass rinses of guinea fowl, respectively. Although only Salmonella spp. were recovered from drinking water, both Salmonella and Campylobacter spp. were recovered from litter material. Campylobacter upsaliensis was recovered only in the guinea fowl, whereas Klebsiella oxytoca and Enterobacter sakazakii were recovered only in chickens. Although no antibiotic resistance was determined in Campylobacter upsaliensis, most Campylobacter, Salmonella, and Escherichia coli isolates from both chickens and guinea fowl were resistant to antibiotics such as ampicillin, kanamycin, erythromycin, and nalidixic acid.