Non-fermenter Gram-negative bacilli at a tertiary hospital, South Africa

Abstract

Background: Non-fermenting Gram-negative bacilli (NFGNB) are a significant cause of healthcare-associated infections and are often implicated in nosocomial outbreaks. Non- fermenting Gram-negative bacilli tend to have variable susceptibility patterns that make the choice of empiric therapy difficult and thus treatment must be based on in vitro susceptibility testing of each antimicrobial agent.

Objectives: To describe the epidemiology of the NFGNB isolated from adult patients at Chris Hani Baragwanath Hospital (CHBAH) and to assess their antimicrobial susceptibility patterns in order to guide empiric therapy and inform infection prevention and control practices.

Method: Organisms isolated from sterile sites of adult in-patients between 01 January 2016 to 31 December 2018 were retrospectively analysed.

Results: A total of 2005 NFGNB isolated. Blood cultures were the most common specimen type (91.4%). Acinetobacter species were the most commonly isolated organisms (65.1%), followed by Pseudomonas species (26.5%). The majority of NFGNB were isolated from patients in surgical wards (38.9%) followed by medical wards (35.2%). Most (60%) of the Acinetobacter species were extremely drug resistant. Pseudomonas species were more susceptible than the Acinetobacter species with an overall susceptibility rate of 86% for Pseudomonas species.

Conclusion: The rates of antimicrobial resistance demonstrated among Acinetobacter and Pseudomonas species were high, which illustrates the threat of antimicrobial resistance also seen worldwide. An emergence of NFGNB with intrinsic multidrug resistance (Stenotrophomonas maltophilia and Burkholderia cepacia) was noted. We suggest empiric therapy with a carbapenem sparing regimen of piperacillin-tazobactam in combination with amikacin and that empiric therapy be reviewed annually when cumulative antibiograms are done.

Contribution: Understanding of the distribution and antimicrobial susceptibility patterns of NFGNB at CHBAH.