Levels of Different Microbial Groups on Inert Surfaces of Poultry Slaughterhouses: Identification Using Matrix-Assisted Laser Desorption Ionization Time-of-Flight and Detection of Extended-Spectrum Beta-Lactamase- and Carbapenemase-Producing Enterobacteria.

Knowledge of the microbiota present in food processing environments is a significant advance that will allow for better evaluation of the risk of food contamination and a better design of the procedures for sanitization. The levels of microbial group indicators of hygienic quality were determined in different areas of the slaughter lines of two poultry slaughterhouses in the northwest of Spain (22 surfaces in each slaughterhouse were studied). The average microbial levels (cfu/cm) were 2.15 × 10 ± 4.26 × 10 (total aerobic counts, TAC), 1.99 × 10 ± 5.00 × 10 (psychrotrophic microorganisms), 3.10 × 10 ± 1.37 × 10 (enterobacteria), 3.96 × 10 ± 2.55 × 10 (coliforms), 1.80 × 10 ± 7.79 × 10 (enterococci), and 1.12 × 10 ± 3.35 × 10 (vancomycin-resistant enterococci, VRE). TAC and psychrotrophic microorganisms were the most abundant groups in all samples ( < 0.05). The counts of both microbial groups were higher ( < 0.05) in samples of Slaughterhouse A than in those of Slaughterhouse B. Microbial loads for the rest of the bacteria were not influenced by the slaughterhouse sampled ( > 0.05). All 44 samples showed TAC and psychrotrophic microorganisms. Colonies of the rest of the microbial groups were only found in 26 samples (59.1% of the total). The isolates (one from each sample) were identified with MALDI-TOF and PCR. Gram-negative bacteria (all ) were isolated in 23 samples, and Gram-positive bacteria were isolated in 16 (9 spp., 2 spp. and VRE, 3 VRE, 1 spp. and spp., and 1 spp.). The resistance of the strains to 11 ( spp.) or 17 () antibiotics was determined (disk diffusion, CLSI), finding an average of 2.05 ± 2.06 resistances per strain (3.46 ± 2.27 if reduced susceptibility reactions are included). A total of 37.3% of the isolates had a gene for resistance to beta-lactam antibiotics (, , , or ). The high prevalence of resistant bacteria and resistance genes highlights the need to establish measures to control the spread of antibiotic resistance in poultry slaughterhouses. The findings of this work could contribute to the design of more effective sanitation procedures.