Mechanisms of Antibiotic Resistance inEscherichia coliIsolates Obtained from Healthy Children in Spain

Abstract

Antibiotic resistance and mechanisms involved were studied in Escherichia coli isolates from fecal samples of healthy children. Fifty fecal samples were analyzed, and one colony per sample was recovered and identified by biochemical and molecular tests. Forty-one E. coli isolates were obtained (82%). MIC testing was performed by agar dilution with 18 antibiotics, and the mechanisms of resistance were analyzed. Ampicillin resistance was detected in 24 isolates (58.5%), and blaTEM, blaSHV, and blaOXA type genes were studied by PCR and sequencing. The following beta-lactamases were detected (number of isolates): TEM (20), SHV-1 (1), and OXA-30 (1). The number of aminoglycoside-resistant isolates detected was as follows: streptomycin (15), tobramycin (1), gentamicin (1), and kanamycin (4). The aac(3)-IV gene was detected in the only gentamicin-resistant isolate. Nine (22%) and 2 (5%) isolates showed nalidixic acid (NALR) and ciprofloxacin resistance (CIPR), respectively. Mutations in GyrA and ParC proteins were shown in both NAL(R)-CIP(R) isolates and were the following: (1) GyrA (S83L + D87N), ParC (S801); and (2) GyrA (S83L + A84P), ParC (S80I + A108V). A single mutation in the S83 codon of the gyrA gene was found in the remaining seven NAL(R)-CIP(S) isolates. Tetracycline resistance was identified in 21 isolates (51%) and the following resistance genes were found (number of isolates): tetA (12), tetB (5), and tetD (1). Chloramphenicol resistance was detected in five isolates (12%). These results show that the intestinal tract of healthy children constitutes a reservoir of resistant bacteria and resistance genes.

High resistance to tetracycline and ciprofloxacin in bacteria isolated from poultry farms in Ibadan, Nigeria

“…Previous studies have shown that the efflux tetA and tetB are the commonest tetracycline resistance genes generally observed in E. coli [28,29]. The tet genes occurrence are frequent on mobile genetic elements e.g.…”

Tetracycline Resistance in Escherichia coli and Persistence in the Infantile Colonic Microbiota

“…Accordingly, tet(A) and tet(B), both of which encode efflux mechanisms, have been identified previously as the most common tetracycline resistance genes in E. coli of both human and animal origin (7,16).…”

“…Tetracycline is never given to children, due to its effect on growing bones and teeth (29). Tetracycline is not used to treat E. coli infections in humans, but resistance to tetracycline is still common in E. coli (4,7), which suggests that resistance has been selected by a bystander effect on commensal E. coli, during treatment of other pathogens in humans or animals. Bacterial resistance to tetracycline is most commonly mediated by energy-dependent pumping of tetracycline out of the bacterial cell.…”

Antibiotic susceptibility of microbiota members Escherichia coli strains isolated from stool samples of patients attended Kırıkkale Yüksek İhtisas Hospital in ten months

“…In a different study in the United States conducted with cervicovaginal and rectal E. coli isolates they found no differences between antimicrobial susceptibility and resistance rates of these isolates and determined to antimicrobial resistance rate to ampicillin as 39.50% (14). Ampicillin resistance rates of fecal flora E. coli isolates are determined in Germany 16.70% in Serbia 42.00% in Korea 43.70% in Spain 58.50% and in Mexico 100% (15)(16)(17)(18)(19).…”