A standardised approach to the treatment and management of significant acinetobacter species infection at academic complex hospitals in KwaZulu-Natal.

Abstract

Introduction: Carbapenem-resistant Acinetobacter species (Acinetobacter spp.) are increasingly recognised as important pathogens, whose resistance patterns present a high-risk global challenge. However, there is limited scientific data and a lack of a standardised approach to help the clinician select optimal therapy in local setting. This study aimed to provide a standardised approach for the management of significant Acinetobacter spp. infection based on phenotypic and genotypic characterisation of local isolates, as well as clinical characteristics and outcomes of patients at academic complex hospitals in KwaZulu-Natal. Objectives: The significance of Acinetobacter spp. infections and the most effective drug combinations for optimal therapy were determined. Acinetobacter spp. isolates were phenotypically and genotypically characterised. This was followed by the development of a standard management guideline for local use, based on the data obtained in the different objectives. Methods: The research consisted of a retrospective and prospective observational and experimental laboratory component. The laboratory component included synergy testing of colistin, susceptibility to antimicrobial agents in use at local hospitals, polymerase chain reaction and sequencing for analysis of the resistant genes related to carbapenem, colistin and amikacin. Phenotypic, genotypic, and clinical characterisation were utilised to develop a standardised management approach of significant Acinetobacter spp. infection. Results: Acinetobacter spp. was identified as a significant cause of sepsis and mortality among patients in a surgical intensive care unit (ICU). Cases of multidrug-resistant (MDR) and extensively drug-resistant (XDR) Acinetobacter spp. increased over seven years, together with the emergence of pandrug-resistant (PDR) isolates. The results of synergy testing of colistin combinations with amikacin, carbapemens (imipemen, meropenem), ciprofloxacin, tazocin, linezolid, rifampicin and vancomycin against Acinetobacter spp. was highly diverse and speciesdependent. Characterisation of Acinetobacter spp. isolates showed that oxacillinase β-lactamase (OXA-23)-producing MDR isolates correlated with their antibiogram. Pulsed field gel electrophoresis (PFGE) showed horizontal transfer between seven clusters, each containing two patients each, totalling 14 patients. However, the PFGE typing revealed a diverse collection of MDR Acinetobacter spp. clones, and that isolates from not more than two patients were related. This suggests, therefore, that no outbreak had occurred based on the PFGE typing interpretation. Further genetic investigation revealed that the aphA6 gene were associated with amikacin resistance and IpxA gene may be associated with colistin resistance in our local setting. Conclusion: The results highlighted the importance of antibiotic stewardship in the treatment of Acinetobacter spp. infection. Individual-specific antibiograms are recommended as the best 2 approach for treatment in KwaZulu-Natal (KZN) and synergy testing should be performed for individualised direct therapy. The clinical and microbiological indicators of significant infection are crucial when establishing the decision to treat. The study provided a valuable standardised approach, including a flow chart of criteria for sepsis and colonisation; a standardised algorithm for the management; and synergy test at academic complex hospitals, Medical Microbiology laboratory, National Health Laboratory Service (NHLS) in KZN.