Trend of extensively drug-resistant Acinetobacter baumannii and the remaining therapeutic options: a multicenter study in Tehran, Iran over a 3-year period.
Comprehensive data on drug-resistant patterns of Acinetobacter baumannii isolates in developing countries is limited. We conducted a multihospital study to assess the rate and trend of drug-resistant phenotypes in Ac. baumannii using standardized definitions and to determine the remaining therapeutic options against resistant phenotypes. The 401 nonduplicate isolates were collected from six hospitals which are geographically distributed across Tehran, Iran over a 3-year period. Following PCR of blaOXA-51-likegene, susceptibility testing was performed against nine antimicrobial agent categories. Three hundred and ninety (97%) isolates were resistant to least two carbapenems; carbapenem-resistant Ac. baumannii. The majority of isolates (366, 91·3%) were extensively drug resistant (XDR) and the rest of the isolates were classified as multidrug resistant (26, 6·8%) and susceptible (9, 2·2%). The rate of XDR-AB slightly decreased from 93·8% in 2011 to 89·8% in 2013. A considerable decrease in resistance to doxycycline, minocycline and tigecycline was demonstrated. The XDR-AB isolates showed susceptibility to gentamicin (10·4%), tobramycin (23%), ampicilin-sulbactam (30·1%), minocycline (32·8%), tigecycline (10·7%), doxycycline (21·6%), colistin (100%) and polymixin B (100%). We demonstrated the rising trend of resistance to all antibiotic categories except tetracyclines and folate pathway inhibitors. We found that the treatment options against XDR-AB are extremely limited and each treatment alternative including even old, but safe, antibiotics might be considered.


CONCLUSIONS
The high frequency of drug-resistant phenotypes including carbapenem-resistant Acinetobacter baumannii, multidrug-resistant, and extensively resistant has been demonstrated in Ac. baumannii isolates tested here. As the antibiotic resistance pattern of isolates varies in different geographical regions, this study can provide comprehensive information about the antibiotic resistance profile of Ac. baumannii isolates in Tehran. In addition, the resistance profiles could be effectively considered by clinicians to manage antibiotic therapy. This work also emphasizes on the prudent use of antibiotics and the monitoring of antibiotic susceptibility trend and rate.
Division of Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
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Jasemi
Division of Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.|Food Microbiology Research Center, Tehran University of Medical Sciences, Tehran, Iran.
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Douraghi
Division of Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
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Adibhesami
Department of Epidemiology and Biostatistics, Tehran University of Medical Sciences, Tehran, Iran.
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Zeraati
Department of Microbiology, Reference Health Laboratories, Ministry of Health, Tehran, Iran.
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Rahbar
Department of Pathology, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran.
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Boroumand
Division of Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
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Aliramezani
Division of Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
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Ghourchian
Department of Infectious Diseases, Pediatrics Infectious Diseases Research Center, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran.
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Mohammadzadeh
D000151:Acinetobacter Infections / Q000188:drug therapy / Q000382:microbiology*; D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D015780:Carbapenems / Q000627:therapeutic use; D003091:Colistin / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial; D006801:Humans; D007492:Iran; D008826:Microbial Sensitivity Tests; D008911:Minocycline / Q000031:analogs & derivatives / Q000627:therapeutic use; D013407:Sulbactam / Q000627:therapeutic use; D000078304:Tigecycline; D014031:Tobramycin / Q000627:therapeutic use
D000900:Anti-Bacterial Agents; D015780:Carbapenems; D000078304:Tigecycline; D008911:Minocycline; D013407:Sulbactam; D014031:Tobramycin; D003091:Colistin

Acinetobacter baumannii
; antibiotic resistance; carbapenem-resistant Ac. baumannii; colistin; extensively drug-resistant Ac. baumannii; multidrug-resistant; nosocomial pathogen; resistant phenotypes