[Antibiotic resistance and plasmid profiles of Escherichia coli in healthy human bodies].

OBJECTIVE

To test the antibiotic resistance of 150 Escherichia coli strains isolated from the faeces of healthy people in Shenzhen city.

METHODS

Escherichia coli were isolated and identified through a procedure described in the Microbiology in Preventive Medicine and Inspection Technique. The antimicrobial susceptibility of 150 isolates to 16 antibiotics was determined by the Kirby-Bauer method based on the Performance Standards for Anti-microbial Susceptibility Testing recommended by NCCLS. The plasmid profiles of the resistance strains were analyzed and classified.

RESULTS

Over 35% of the tested strains showed resistance to 6 antibiotics, including Teracycline (63.33%), Nalidixic Acid (49.33%), Sulfamethoxazole (40.67%), Amplocilin (38.67%), Sulfamethoxazole timethoprim (35.33%), and Streptomycin (35.33%). All isolates were susceptible to Cefmelazon and Amikacin. More than 81% isolates resisted to at least one antibiotic, while 58. 67% and 29. 33% of the isolates resisted to more than 2 and 5 antibiotics respectively. Two strains showed resistance to 10 antibiotics.

CONCLUSION

Antibiotic resistance of Escherichia coli strains isolated from healthy people in Shenzhen city is common and serious. The number and size of plasmids in the isolates do not directly contribute to the antibiotic resistance.