[Coliform bacteria in rinsed beer mugs--identification with the API 20 E system and resistance behavior]

653 11 beer mugs rinsed mechanically by conveyor belt dishwashing machines and 182 mugs cleaned in open vats were investigated for their content of faecal and total coliforms. Ten and more faecal coliform germs could be detected in 4.7% of the mechanically rinsed tankards and in 12.1% of those cleaned in open vats. Respectively, ten and more total coliforms were found in 30.3% and in 67.6%. Altogether 213 coliform strains as defined by the German drinking water regulation were characterised biochemically by the API 20 E-system and by their susceptibility to 15 antimicrobial agents. A total of 19 different species from eight genera could be differentiated, whereas 12 strains were unidentifiable by the applied system. Klebsiella oxytoca was the most frequently encountered germ, followed by Enterobacter cloacae, K. pneumoniae and Ent. sakazakii. 59 of the 213 strains were fully susceptible to all antibiotics used. 44 strains, however, revealed complete or moderate resistance against three and more agents. These results indicate that unhygienic dishwashing procedures may play a decisive role in the epidemiology of clinically relevant and multiresistant germs.