Characterization and determination of antimicrobial susceptibility of microorganisms contaminating ultrasound probes in Kenyatta National Hospital

Abstract

Background Patients subjected to ultrasound probes are at risk of microbial contamination including Staphylococcus aureus strains resistant to methicillin. This has been linked to cross-contamination from one patient to another which has been greatly attributed to the disinfection and sterilization techniques applied to these probes. Identification, characterization and antimicrobial susceptibility determination of microorganism isolated from probes will inform about the risk of transmission of potentially pathogenic bacteria with the use of ultrasound probes, which is becoming common in clinical practice. The information can contribute to the design of evidence-based comprehensive strategies for prevention of hospital-acquired infections. Broad Objective To characterize and determine the antimicrobial susceptibility of microorganisms contaminating ultrasound probes used at Kenyatta National Hospital radiology department between August and October 2019. Methodology This was a cross-sectional study carried out at Kenyatta National Hospital Radiology Department. A total of 271 swabs were consecutively collected before and after an ultrasound session over a period of three months. Growth on Blood agar and MacConkey agar was evaluated for colonial morphology and gram stain. Species identification and antimicrobial susceptibility was done using VITEK - 2 System according to Clinical and Laboratory Standards Institute M100 guideline. Percentages of the total organisms isolated and percentages of select organisms that were resistant to the individual drugs was computed using IBM SPSS Statistics version 21. Results A total of 271 swabs were collected from ultrasound probes before and after patient had received clinical services. Among these, 58% had bacterial growth. Staphylococcus epidermidis (67%, 105/156) and S. saprophyticus (19%, 19/156) were the most predominant species isolated. Burkholderia cepacia (4) and Sphingomonas paucimobilis (1) were the only gram negative bacteria isolated. Low resistance levels (0-40%) to piperacillin, amikacin, ceftriaxone, ceftazidime and ciprofloxacin was observed. Additionally we observed high resistance rate (75-100%) to aminoglycosides, cephalosporin and penicillin tested. Conclusion The ultrasound probes were contaminated with bacteria however much of the bacteria isolated are known skin colonizers. There is therefore the need for adequate disinfection procedures to be carried before and after every scanning session.