Analysis of antimicrobial resistance and class 1 integrons among strains from upper respiratory tract of healthy adults.

OBJECTIVE

The distribution and characterization of integrons among opportunistic pathogens from nasopharynx of healthy adults.

METHODS

A total of 1,019 nasopharyngeal samples from healthy adults were collected; bacteria were identified by API system; antibiotic susceptibility were tested by K-B method; class 1, 2 and 3 integrons were examined by degenerate primers of the genetic content of integrons were analyzed by PCR and DNA sequencing.

RESULTS

Out of the 1,019 cases, 743 (72.9%) opportunistic pathogens were isolated. The top five commons organism identified were Coagulase-negative staphylococcus (n=404), Staphylococcus aureus (n=109), Haemophilus influenzae (n=74), Streptococcus pneumoniae (n=49) and Klebsiella pneumoniae (n=32). Eight (25.0%) isolates of K. pneumoniae produced the ESBLs. The isolated rates of S. aureus and H. influenzae were decreased with aging. 6.3% (2/32) K. pneumoniae isolates and 16.7% (1/8) Proteus isolates carried class 1 integrons. Among intI1-positive strains, sequencing analysis revealed that one of the integron positive K. pneumoniae isolates harbored gene cassette aadA5-dfrA17. Proteus isolates harbored gene cassette aadA2-dhfrXII.

CONCLUSIONS

The results stressed the need for continued surveillance of bacteria from the asymptomatic carriers.