Prevalence of Gram Negative Infections by Acinetobacter and Pseudomonas Severely Resistant to Antibiotic Susceptibility Based on Minimum Growth Inhibitor Concentration

Introduction: Currently, we are witnessing the formation of various species of gram-negative microorganisms, including Enterobacteriaceae, Pseudomonas aeruginosa and acinetobacter, resistant to antibiotics such as MDR, XDR and PDR. This study is important to confirm microbial resistance to an antimicrobial agent and also to monitor the activity of new antimicrobial agents. Regarding XDR gram-negative microorganisms isolated from samples, it was considered necessary to determine MIC.

Methods: Patients suspected of various infections with septicemia diagnosed in different wards of the Firoozgar Hospital were enrolled. The quantitative value of minimum growth inhibitor concentration (MIC) was determined for infections caused by highly resistant gram-negative bacteria (acinetobacter and Pseudomonas species) (XDR) reported by antibiogram disk.

Results: sample size was 117, of which 41.9% were female and 58.1% were male. Regarding Colistin, 80% of the cultures were resistant and 12% were intermittent; this value was 52% in the MIC test. Regarding tigecycline, 100% of the acinetobacter samples were susceptible to this antibiotic. Most of cultures which had antibiotic resistance were acinetobacter (61.4%) and pseudomonas (39.6%).

Discussion: Acinetobacter baumannii is susceptible to tigecycline. Emergence of multi-drug resistance in Pseudomonas aeruginosa and A. baumannii is a major concern in the world, because several drugs, except polymyxins, are available to treat these infections. A significant resistance was found in MIC to Colistin (31.1%). Thus, there is resistance to Colistin, which is one of the last lines of antibiotic treatment.

Conclusion: This study shows an increase in percentage resistance of these bacteria to antibiotics. This trend is a worrying process for antibiotic treatment of diseases.