Resistance to the antimicrobial agents of bacteria isolated from non-sterile pharmaceuticals.

The in vitro antimicrobial resistance of 391 bacterial strains isolated from 389 samples of oral and topical medicaments was examined. The numbers of strains isolated (and percentage of samples that present them) were: 234 Bacillus (32.1%), 79 Staphylococcus (13.6%), 46 Micrococcus (11.3%), nine Pseudomonas (1.5%), eight Acinetobacter (1.5%), five Enterococcus (1.2%), three Alcaligenes (0.8%), two Escherichia and Enterobacter (0.5%), one each Providencia, Serratia and Streptococcus (0.2%). Gram-positive bacteria were isolated from topical and oral medicaments and Gram-negative rods were detected only in topical medicaments. The 97.4% of Bacillus strains were resistant to lincomycin and B. cereus was resistant to beta-lactam and trimethoprim-sulphamethoxazole. Staphylococcus spp. showed a high percentage of resistant strains to ampicillin (51.8%), tetracycline (40.5%) and trimethoprim-sulphamethoxazole (48.1%). Staphylococcus epidermidis had the highest number of multiresistant strains. The 23.9% of Micrococcus strains were resistant to colistin. Enterococcus and Streptococcus strains showed multiresistance to penicillin G, aminoglycosides and erythromycin. The 61.5% of Gram-negative rod strains showed multiresistance to beta-lactam antibiotics and erythromycin; Pseudomonas spp. were the most resistant.