In vitro activity of Colistin against carbapenem resistant isolates of Acinetobacter species

Abstract

The emergence of multidrug-resistant (MDR) Acinetobacter baumannii clones worldwide and the high morbidity and mortality associated with infections caused by these strains present a challenge to clinicians.The number of multidrug-resistant Acinetobacter baumannii, which is an opportunistic pathogen that may cause pneumonia, bacteremia, infection in burn wounds, meni-ngitis, and urinary tract infections, has been increased globally in the past 5 years, and it isregarded as one of the most difficult nosocomially acquired gram-negative pathogens to treat and control. Acinetobacter baumannii is increasingly recognized as an important pathogen in both immunocompromised and hospitalized patients infected by contact with contaminated equipments.Furthermore, patients infected with A. baumannii are often already critically ill or immune-compromised, and the associated mortality is significant. The study was conducted at the Central Microbiology Laboratory, including 50 carbapenem resistant Acinetobacter spp. The isolates were initially identified according to the routine protocols followed at the Micro-biology Laboratory. Subculture on MaCconkey agar platestoobtainfreshisolates. Determination of Minimal inhi-bitory concentration (MIC) by E-test strips(Epsilometer test) for colistin and tigecycline was done. And finally in vitro determination of the effect of combination between colistin and tigecyclineforAcinetobacter isolates resistant to colistin. The results revealed high susceptibility of carbapenem resistant Acinetobacter spp. for colistin using E-test, indifference of the combination between colistin and tigecycline using E-test, significant correlation between DD and E-test for tigecycline and non significant correlation for colistin .