RESUMEN
A major limitation of cancer chemotherapy is development of resistance. In this study, we analyzed KB-3-1 cells and adriamycin-selected multidrug resistant sublines KB-A1 and KB-A10 cells for mechanisms of resistance. KB-A10 cells are 10-fold more resistant than KB-A1 cells but have lower P-glycoprotein. Of the known mechanisms of multidrug resistance, topoisomerase II and lung-resistance-related protein were altered between the resistant cell lines. Glutathione-S-transferase activity and multidrug-resistance-related protein levels were higher in the resistant cell lines compared to the sensitive cells but were similar in KB-A1 and KB-A10 cells. Results indicate differential regulation of mechanisms of resistance with stepwise selection.
RESUMEN
BACKGROUND: Acinetobacter baumannii nosocomial outbreaks are common and the microorganism is frequently resistant to multiple antimicrobials. There is little information about Acinetobacter baumannii antimicrobial susceptibility in the northern region of Chile. AIM: To identify different Acinetobacter baumannii biotypes isolated from clinical samples and to determine their antimicrobial susceptibility. MATERIAL AND METHODS: One hundred twenty three Acinetobacter baumannii isolates were studied. The identification and typing of Acinetobacter baumannii was based on phenotypic characteristics. Antimicrobial susceptibility was investigated using agar dilution techniques. RESULTS: Most Acinetobacter baumannii strains were isolated from wounds, urinary and respiratory infections. Seven biotypes were isolated, being biotype 9 the most frequent. Imipenem was the antimicrobial with the higher activity against the microorganism. Amikacin, cefoperazonesulbactam, ampicillinsulbactam and ceftazidime had a moderate activity. There were high resistance levels to ampicillin and older cephalosporins. CONCLUSIONS: Acinetobacter baumannii is emerging as a significant nosocomial pathogen in Chile and shows high resistance rates to multiple antibiotics.