Evaluation of Performance of Filmarray and Microscan Technologies in Identification of Blood stream infection pathogens and their Antibiotic Resistance

Abstract

Bloodstream infection (BSI) is a major cause of mortality with rates of 53% in sub-Saharan Africa. BSI is marked by the presence of bacterial and/or fungal microorganisms in the blood, which elicit an immunological response. The major pathogens responsible for BSI in both children and adults worldwide are bacteria, and fungi. These infections require quick, reliable and accurate diagnosis to aid in a more precise antimicrobial therapy to the patient. This study was carried out to identify primary BSI pathogens using FilmArray® (FA®) and MicroScan WalkAway 40 Plus® (MS®) technologies. The performance of these technologies was compared with culture based plus Analytical profile index (API) technique used as the gold standard using blood samples from patients attending Kisii and Homa Bay county referral hospitals. FA® technology identified the following BSI pathogens; Enterococcus faecium, Staphylococcus aureus, Streptococcus pneumoniae, Enterobacter cloacae, Acinetobacter baumanii, Pseudomonas aeruginosa, Salmonella typhi, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Candida albicans, Candida krusei, and Candida parapsilosis. MS identified the following BSI pathogens to species level Enterococcus faecium, Staphylococcus aureus, Staphylococcus capitis, Staphylococcus mutants, Staphylococcus epidermidis, Staphylococcus auricularis, Staphylococcus saprophyticus, Staphylococcus hominis, Staphylococcus lugudensis, Staphylococcus sciuri, Staphylococcus intermedius, Streptococcus pneumoniae, Streptococcus anginosus, Streptococcus bovis, Enterobacter cloacae, Acinetobacter baumanii, Pseudomonas aeruginosa, Salmonella typhi, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Candida albicans, Candida krusei, and Candida parapsilosis. The culture and API identified the following BSI microorganisms; Enterococcus faecium, Staphylococcus aureus, Staphylococcus capitis, Staphylococcus simulans, Staphylococcus epidermidis, Staphylococcus auricularis, Staphylococcus saprophyticus, Staphylococcus hominis, Staphylococcus lugudensis, Staphylococcus sciuri, Staphylococcus intermedius, Streptococcus pneumoniae, Enterobacter cloacae, Acinetobacter baumanii, Pseudomonas aeruginosa, Salmonella typhi, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Candida albicans, Candida krusei, and Candida parapsilosis. The sensitivity and specificity of the three technologies were determined. The FA technology was able to identify Enterobacter cloacae with higher sensitivity of (100%, 4/4) than the MS technology and API which identified (50%, 2/4), this shows FA had higher sensitivity in identification of Enterobacter cloacae. The overall specificity of FA, MS and API was 99.04% (95% CI: 96.59-99.88%), sensitivity of 98.68% (95% CI: 95.33-99.84%). The MS had overall specificity of 98.56% (95% CI: 95.86-99.70%), sensitivity of 98.68% (95% CI: 95.30-99.84%). The FA technology had limitation in identifying Staphylococcus capitis, Staphylococcus simulans, Staphylococcus epidermidis, Staphylococcus auricularis, Staphylococcus saprophyticus, Staphylococcus hominis, Staphylococcus lugudensis, Staphylococcus sciuri, Staphylococcus intermedius, Streptococcus anginosus, and Streptococcus bovis, these organisms are not in the FA data base and they are majorly skin contaminants, also FA had limitation in identifying gram positive rods these are also not in its data base. MS and API had limitation in identifying some Enterobacteria cloacae However, FA had advantage of identifying resistant genes, these are mecA (methicillin), vanA/B (vancomycin) and KPC (carbapenems). FA also identifies coinfection of more than one pathogen. MS and API had advantage of expanded database allowing it to identify more BSI pathogens than FA. In this study there were no resistance genes detected from the identified BSI pathogens, However, these were demonstrated using control isolates across the technologies under test; Enterococcus faecium, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus haemolyticus, Salmonella typhi and Escherichia coli. The FA and MS technology have not been used in public hospitals and have not been evaluated locally, further evaluation using a larger number of samples is recommended. FA and MS can be a good tool in rapid identification of blood stream infection which culminates in reduction of hospital stay and cost with better management of patients and reduction of misuse of drugs.