OBJECTIVES:

To isolate and identify antimicrobial-resistant enterobacteria from drinking water in the Midwest region of São Paulo State, Brazil.

MATERIALS AND METHODS:

A total of 3,726 water samples from public supply system and collective wells from 62 municipalities were analyzed. Positive samples for total coliforms and/or Escherichia coli were seeded on MacConkey Agar for isolation and identification. Isolated enterobacteria were evaluated for antimicrobial resistance detection and expanded spectrum β-lactamase production.

RESULTS:

From a total of 67 water samples from 29 municipalities with growth of enterobacteria, 21 (31.34%) were resistant to at least one antimicrobial, seven (10.43%) to two classes of antimicrobials, three (4.47%) to three classes, and one (1.49%) to four classes. The drug with the highest number of resistant bacterial samples was cefoxitin (12), followed by cephalothin (eight), cefotaxime (five), ticarcillin + clavulanate (four), aztreonam (four), nalidixic acid (three), and ampicillin + sulbactam (three). Second generation cephalosporins showed the largest number of resistant bacterial samples (12; 32.43%), followed by penicillins (10; 14.92%), and first generation cephalosporins (8; 25.81%). Three (4.47%) samples were resistant to three classes of antimicrobials and one (1.49%) to four classes.

CONCLUSION:

Drinking water can be a source of spread of resistant and multiresistant Gram-negative bacteria, characterizing a public health problem. Proper water treatment and monitoring of public water supply systems are important to detect antimicrobial resistant bacteria.

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