Background: Acinetobacter species have been increasingly recognized as a major pathogen implicated in hospital-acquired and healthcare-associated infections worldwide. With the increasing incidence of Carbapenem resistance, the other alternative, Colistin retains susceptibility but issues of appropriate dosing, toxicities, and resistance remain. Minocycline an old tetracycline, with high lipophilicity, high tissue penetration, long half life, good oral bioavailability, no serious side effects and the ability to be used in combinations when monotherapy fails, has been found to be an effective alternative therapy for MDR Acinetobacter associated infections.

Aims & Objectives: To determine the activity of tetracycline group of drugs against Acinetobacter species.

Result: A total of 300 Acinetobacter species were included in this study of which 61.7% were carbapenem resistant isolates, 59.3 % were multi-drug resistant Acinetobacter spp. Acinetobacter spp simultaneously resistant to carbapenems, fluoroquinolones and beta -lactams were defined as MDR in our study. Majority of isolates were sensitive to polymixin B (95%), minocycline (67.3%) and tigecycline (78%). Tigecycline was the second most effective antibiotic after Colistin, followed by minocycline. Out of the 10 strains which were resistant to Colistin as well as tigecycline,  the only other effective antibiotic was Minocycline (7/10).

Discussion: Tigecycline was the second most active isolate following Colistin, but most of the isolates in the study were from blood culture and pulmonary sites, where the activity of tigecycline remains doubtful. Minocycline thus theoretically appears to be the second most active agent. With the pharmacokinetic and pharmacodynamic advantages of minocycline and its ability to act in combination with colistin at half the dosage, it turns out to be a useful alternative for the institution of empirical therapy, followed by the monotherapy if proven to be culture sensitive, or combination can be considered when culture resistant, followed by oral therapy in cases of MDR Acinetobacter infections.

Keywords: Acinetobacter baumannii, MDR, minocycline

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Dr Simit Kumar

Associate Professor, Dept of Microbiology, R.G.Kar Medical College, Kolkata

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