Tetracycline Resistance Associated with tet Genes or Integrons among Enterobacter cloacae Strains Isolated from Patients with Urinary Tract Infections

This study aimed to evaluate the prevalence of tet genes and Class I and 2 integrons in Enterobacter cloacae strains isolated from patients with urinary tract infections (UTIs).

A total of 50 E. cloacae isolates were collected. Antimicrobial susceptibility pattern and tetracycline MIC were determined. The presence of tet genes (tetA, tetB, tetC, tetD) and Class 1 and 2 integrons and the content of Class 1 integron were determined.

Tetracycline MIC pattern classified 36 % of the E. cloacae isolates as resistant. The most common tet gene was tetC (22%), followed by tetD, tetA, and tetB.  Class 1 integron was detected in 64% of the isolates. Class 1 integron content analysis showed two variable gene cassettes (aadA1 and aadA5/dfrA17 genes). The frequency of aadA5/dfrA17 was 18.75%, which was more common than aadA1 gene (6.25%).

The most important genetic markers for tetracycline resistance in E. cloacae isolates were tetC and Class 1 integron. Harboring Class 1 integron and resistance to streptomycin and ciprofloxacin were significantly correlated.