Drug sensitivity of vero toxin-producing Escherichia coli O157:H7 (VTEC O157:H7) isolated from human diarrhea and healthy cows

Abstract

As a part of studies on the source of infection of Vero toxin-producing Escherichia coli (VTEC), O157:H7 strains isolated from human infectious enteritis between 1986 and 1995 and O157:H7 strains isolated from feces of milk cows between 2001 and 2003 were subjected to drug sensitivity test with drugs widely used as therapeutic drugs for various infectious diseases in humans and animals, and the following results were obtained. 1) Drug sensitivity tests with 20 drugs were performed in 52 strains derived human from diarrhea and 100 strains derived from milk cows, and resistance was noted in 115 strains (75.7%): 36 of the 52 human diarrhea-derived strains (69.2%) and 79 of the 100 milk cow-derived strains (79.0%). 2) The human diarrhea-derived strains and milk cow-derived strains were compared with regard to MIC90 of each drug. The antibacterial activity of the drugs was generally higher against the human diarrhea-derived strains than against the milk cow-derived strains. 3) In the 115 strains exhibiting resistance, the most frequent pattern of drug resistance was single drug resistance noted in 80 strains (68.4%), and multidrug resistance was noted in 35 strains (30.4%) consisting of 17 strains with resistance to 3 drugs, 14 strains with resistance to 2 drugs, and 2 strains each with resistance to 4 drugs and 5 drugs. More strains were multidrug-resistant in the milk cow-derived strains.