Colistin resistance mechanisms in Gram-negative bacteria: a Focus on Escherichia coli

Multidrug-resistant (MDR) Escherichia coli strains have rapidly increased worldwide, and effective antibiotic therapeutic options are becoming more restricted. As a polymyxin antibiotic, colistin has a long history of usage, and it is used as a final line of treatment for severe infections by Gram-negative bacteria (GNB) with high-level resistance. However, its application has been challenged by the emergence of E. coli colistin resistance. Hence, determining the mechanism that confers colistin resistance is crucial for monitoring and controlling the dissemination of colistin-resistant E. coli strains. This comprehensive review summarizes colistin resistance mechanisms in E. coli strains and concentrates on the history, mode of action, and therapeutic implications of colistin. We have mainly focused on the fundamental mechanisms of colistin resistance that are mediated by chromosomal or plasmid elements and discussed major mutations in the two-component systems (TCSs) genes and plasmids that transmit the mobilized colistin resistance resistant genes in E. coli strains.

An ethical framework for evaluation of public health plans: a systematic process for legitimate and fair decision-making

OBJECTIVES

Given the increasing threats of communicable and non-communicable diseases, it is necessary for policy-makers and public health (PH) professionals to address ethical issues in health policies and plans. This study aimed to develop a practical framework for the ethical evaluation of PH programs.

STUDY DESIGN

A multidisciplinary team developed an ethical framework to evaluate PH plans from 2015 to 2017.

METHODS

In this study, the multi-method approach was used. First, a list of moral norms in PH policy and practice was drafted and completed in two interactive sessions. Then, the Delphi method was used for consensus about the structural components to be adopted in the framework. After developing the framework, its efficiency was assessed by evaluating Iran's Fourth Strategic Plan for HIV/AIDS Prevention and Control.

RESULTS

The framework was developed in the following three sections: (i) determination of the general moral norms in PH practice and policy; (ii) five steps of evaluation; and (iii) a procedural evaluation step to ensure fair decision-making. The ratio of the ethical points of the PH plan increased by 46% after implementation of the framework, and the frequency of ethical points increased significantly after applying the framework (P = 0.001).

CONCLUSION

The application of the framework for the ethical evaluation of various PH programs ensures a comprehensive and scientific-deliberative decision-making process, while also contributing to the development of the framework.

Integron types, gene cassettes and antimicrobial resistance profile of Acinetobacter baumannii isolated from BAL samples in Babol, north of Iran

Multi-drug resistant isolates of Acinetobacter baumannii have created therapeutic problems worldwide. This current study was intended to determine the Integron types, gene cassettes and antimicrobial resistance profile of A. baumannii isolated from BAL samples in Babol, north of Iran. During a 15-month period, 35 A. baumannii isolates were studied. Different classes of antimicrobial agents were used to determine the resistance ratios. Multiplex-PCR was used to detect different types of integrons and associated gene cassettes. The resistance rates to GM, FEP, AK, TOB, CP, PIP, SAM, IPM, SXT, CTX, CAZ, CL, TIM, MEM, and TZP were 85.7%, 100%, 91.4%, 68.5%, 94.3%, 88.5%, 97.1%, 94.3%, 100%, 100%, 100%, 0.0%, 91.4%, 94.3% and 91.4%, respectively. The distribution analysis of int genes showed that 25.7%, 88.6% and 28.6% of isolates carried the intI, intII and intIII genes, respectively. The prevalence of aadB, dfrA1, bla-OXA₃₀ and aadA1 genes were 94.3%, 77.1%, 40% and 5.7%, respectively. The current study showed that a high level of A. baumannii isolates harbor integrons in our therapeutic center, which may lead to distribution of multiple antimicrobial resistance. The different types of gene cassette arrays in the present study highlight the important role of geographical features in MDR isolates dissemination which could be credited to different profiles of drug consumption in different areas. The findings emphasized that the need for continuous surveillance to prevent distribution of multidrug resistance among A. baumannii strains in Iran.