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Multidrug resistance among Acinetobacter baumannii isolates from Iran: changes in antimicrobial susceptibility
Abbas Bahador1, Reza Raoofian, Mohammad Taheri
11 Department of Microbiology, School of Medicine, Tehran University of Medical Sciences , Tehran, Iran .
Background And Aim:
Widespread multidrug-resistant Acinetobacter baumannii (MDR-AB) strains have limited therapeutic options for treating intensive care unit (ICU) patients with MDR-AB infection in Iran. We aimed to evaluate MDR-AB diversity and antimicrobial susceptibility in Tehran (Iran) to address the need for feasible and effective control approaches against severe MDR-AB infections.
Methods:
We used amplified fragment length polymorphism (AFLP) and minimum inhibitory concentration (MIC) determinations to compare genotypic diversity and susceptibility patterns of 100 MDR-AB isolates from ICU patients in two medical centers in Tehran (Iran), from 2006 to 2011.
Results:
Within 5 years, drastic genotypic changes occurred among MDR-AB isolates, and resistance to antimicrobials increased 0-30%. In 2011, 6-100% of isolates were resistant to every agent tested. All isolates remained susceptible to either minocycline or tobramycin, however, MIC50 concentrations against these agents increased. Novel international clone (IC) variants (not IC I-III types) comprised 36% MDR-AB isolates in 2011.
Conclusions:
The MDR-AB population in Tehran is rapidly changing toward growing resistance to various antimicrobials, including colistin and tigecycline. Although increasing resistance to last-resort antimicrobials is alarming, simultaneous susceptibility of all MDR-AB isolates to some conventional antibiotics highlights the merits of investigating their synergistic activity against extended-spectrum and pandrug resistant A. baumannii. Integrating the novel Iranian MDR-AB IC variants into epidemiologic clonal and susceptibility profile databases can help global efforts toward the control of MDR-AB pandemic.
Insights
Multidrug-resistant Acinetobacter baumannii (MDR-AB) in Iran shows increasing antimicrobial resistance and genetic diversity. However, some conventional antibiotics remain effective, suggesting potential for combination therapies against these severe infections.
Area of Science:
- Infectious Diseases
- Microbiology
- Antimicrobial Resistance
Background:
- Multidrug-resistant Acinetobacter baumannii (MDR-AB) poses a significant threat to intensive care unit (ICU) patients in Iran.
- Limited therapeutic options exist for treating MDR-AB infections, necessitating research into effective control strategies.
Purpose of the Study:
- To evaluate the genotypic diversity and antimicrobial susceptibility patterns of MDR-AB isolates in Tehran, Iran.
- To inform the development of feasible and effective control approaches against severe MDR-AB infections.
Main Methods:
- Amplified fragment length polymorphism (AFLP) was used to assess genotypic diversity.
- Minimum inhibitory concentration (MIC) determinations were performed to evaluate antimicrobial susceptibility.
- 100 MDR-AB isolates from ICU patients in Tehran (2006-2011) were analyzed.
Main Results:
- Significant genotypic changes and a 0-30% increase in antimicrobial resistance were observed in MDR-AB isolates over five years.
- In 2011, isolates exhibited high resistance rates to tested agents, with 6-100% resistance.
- All isolates remained susceptible to minocycline or tobramycin, although MIC50 values increased. Novel international clone (IC) variants comprised 36% of isolates in 2011.
Conclusions:
- The MDR-AB population in Tehran is evolving towards increased resistance, even to last-resort drugs like colistin and tigecycline.
- Simultaneous susceptibility to certain conventional antibiotics suggests potential for synergistic therapies against extensively drug-resistant (XDR) and pandrug-resistant (PDR) A. baumannii.
- Integrating novel Iranian MDR-AB IC variants into global databases can aid in controlling the MDR-AB pandemic.
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