Heteroduplex Typing of Clinical Isolates of Acinetobacter from Intensive Care Units in a Tertiary Health Care Centre and their Antibiogram

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Background Acinetobacter is an important hospital pathogen whose role is implicated in various disease conditions especially in patients confined to hospital intensive care units. Differentiation of isolates is essential to identify the source and to understand the spread which in turn helps to prevent infections. HDA being a sensitive reliable and rapid method a large number of isolates can be typed using this method. Therefore we have adapted this technique to differentiate between clinical isolates of Acinetobacter. Aims Heteroduplex analysis to type clinical isolates of Acinetobacter. Methodology 570 clinical isolates of Acinetobacter from different ICUs were analysed. Antibiogram was performed using VITEK system. DNA extraction was done by phenol-chloroform method. Acinetobacter PCR was performed by targeting 397 bp hyper variable region of rpoB gene. The Heteroduplex assay was performed by mixing the amplicons of test strains and that of in-house standard strain. The formation of Heteroduplexes was determined by polyacrylamide gel electrophoresis. Results Out of 570 clinical isolates 212 37.19 isolates were typed into one of the 25 HD types. Remaining 358 62.81 isolates did not form Heteroduplex with in-house standard. No significant variation was seen in the Antibiogram of different Heteroduplex types. Conclusion Heteroduplex analysis provides a simple and accurate method to analyse the strain diversity of Acinetobacter isolates. Epidemiological typing and source tracing of the pathogens cab be done using HD typing. The technique has potential to be applied for other organisms. Various gene targets in the same pathogen may be explored for better precision.