Comparative Evaluation of CHROMagar COL-APSE, MicroScan Walkaway, ComASP Colistin, and Colistin MAC Test in Detecting Colistin-resistant Gram-Negative Bacteria

Abstract

colistin has become a critical antibiotic for fatal Gram-negative infections owing to the proliferation of multidrug-resistant carbapenemase-producing bacteria. Thus, cheaper, faster, efficient and easier-touse colistin diagnostics are required for clinical surveillance, diagnoses and therapeutics. the sensitivity, specificity, major error (ME), very major error (VME), categorial agreement, essential agreement, turnaround time (TAT), average cost, and required skill for four colistin resistance diagnostics viz., cHRoMagar coL-APSE, ComASP Colistin, MicroScan, and Colistin MAC Test (CMT) were evaluated against broth microdilution (BMD) using 84 Gram-negative bacterial isolates. A multiplex PCR (M-PCR) was used to screen all isolates to detect the presence of the mcr-1 to mcr-5 genes. A 15-point grading scale was used to grade the tests under skill, ease, processing time etc. mcr-1 was detected by both M-pcR and cMt in a single E. coli isolate, with other pcR amplicons suggestive of mcr-2,-3 and-4 genes being also observed on the gel. The sensitivity and specificity of CHROMagar COL-APSE, MicroScan, and ComASP Colistin, were 82.05% and 66.67%, 92.31% and 76.92%, and 100% and 88.89% respectively. The MicroScan was the most expensive at a cost (per sampe tested) of R221.6 ($15.0), followed by cHRoMagar coL-APSE (R118.3; $8.0), M-PCR (R75.1; $5.1), CMT (R20.1; $1.4) and ComASP Colistin (R2.64; $0.2). CHROMagar was the easiest to perform, followed by ComASP Colistin, M-PCR, MicroScan, cMt and BMD whilst M-pcR and MicroScan required higher skill. the comASp colistin was the best performing diagnostic test, with low VME and ME, making it recommendable for routine colistin sensitivity testing in clinical laboratories; particularly, in poorer settings. It is however limited by a TAT of 18-24 hours. Subsequent to the exponential dissemination of extended-spectrum β-lactamases (ESBLs) in Gram-negative bacteria (GNB) and the increased use of carbapenems to treat infections unresponsive to the penicillins and cephems (cephalosporins and cephamycins), carbapenemase-producing and carbapenem-resistant GNB are becoming common worlwide 1,2. Thus, carbapenems, which are last-resort antibiotics, are being replaced by colistin, a polymyxin that was discovered many years ago but shelved over nephrotoxicity and neurotoxicity concerns 2,3. Resistance to colistin, due to its increased use to treat carbapenem-resistant GNB, has also emerged 2-4. Beginning from 2016, colistin resistance, which hitherto was mediated my chromosomal mutations, was found to be also mediated by plasmid-borne mcr genes 5,6. The high fatalities caused by colistin and/or carbapenem-resistant GNB infections have led to their being categorised as high-priority pathogens by the WHO 7,8. The clinical importance of colistin-resistant GNB (CR-GNB) necessitates an efficient diagnostic protocol for quickly and efficiently detecting them to preempt further escalation and mortalities 9 .

Genomic and Resistance Epidemiology of Gram-Negative Bacteria in Africa: a Systematic Review and Phylogenomic Analyses from a One Health Perspective

“…The backbone to efficient diagnosis and treatment of infections is rapid, effective, simple, and inexpensive diagnostics and skilled laboratory scientists ( 66 – 68 ). Without appropriate diagnostics, the etiology of many infectious diseases, the genotype/clone of the infecting organism, and its resistance mechanisms cannot be known, and a proper therapeutic choice cannot be made ( 66 – 68 ). This describes the situation in many African countries, making several preventable infections emerge subtly into large-scale outbreaks ( 67 , 68 ).…”

“…Without appropriate diagnostics, the etiology of many infectious diseases, the genotype/clone of the infecting organism, and its resistance mechanisms cannot be known, and a proper therapeutic choice cannot be made ( 66 – 68 ). This describes the situation in many African countries, making several preventable infections emerge subtly into large-scale outbreaks ( 67 , 68 ). As shown in Table S7 , simpler phenotypic diagnostic tests with a longer turnaround time of at least 24 h were more commonly used in Africa while complex, skill-requiring, and expensive tests like whole-genome sequencing and Vitek were hardly used.…”

Global evolutionary epidemiology and resistome dynamics of Citrobacter species, Enterobacter hormaechei, Klebsiella variicola, and Proteeae clones

“…This resistome repertoire was also seen in K. variicola , C. freundii , P. rettgeri P. mirabilis , P. stuartii , and M. morganii , to a relatively lesser degree in a descending order (Supporting Information Table S4). This is a worrying observation as colistin, carbapenems and tigecycline are last resort antibiotics used to treat fatal bacterial infections (Osei Sekyere et al ., 2016; Osei Sekyere et al ., 2020c; Mmatli et al, 2020). In most cases, these antibiotics are used in combination with fosfomycin, fluoroquinolones and aminoglycosides to treat carbapenem‐resistant Enterobacterales (CRE) infections (Osei Sekyere et al ., 2016; Osei Sekyere et al ., 2020c).…”

“…This is a worrying observation as colistin, carbapenems and tigecycline are last resort antibiotics used to treat fatal bacterial infections (Osei Sekyere et al ., 2016; Osei Sekyere et al ., 2020c; Mmatli et al, 2020). In most cases, these antibiotics are used in combination with fosfomycin, fluoroquinolones and aminoglycosides to treat carbapenem‐resistant Enterobacterales (CRE) infections (Osei Sekyere et al ., 2016; Osei Sekyere et al ., 2020c). Evidently, the presence of all these resistance mechanisms to these antibiotics, could make these species PDR and automatically qualify them as critical priority pathogens per the WHO criteria (Asokan et al ., 2019; Rello et al ., 2019).…”

eliability of phenotypic methods for detection of colistin resistance among carbapenem-resistant Acinetobacter baumannii clinical isolates from Egypt

“…6,8 Over the past five years, besides the automated platforms, new screening and culture-based diagnostics methods used for detecting mcr-1-positive and polymyxin-resistant Gram-negative bacteria were studied, depending on their sensitivity, specificity, their relative cost, time and relative skill required. [17][18][19] Some novel manual diagnostics tests are: MIC Test strip® (MTM) (Liofilchem), MICRONAUT MIC-Strip® (MERLIN Diagnostika), Commercial Rapid Polymyxin NP (RPNP), SensiTest™Colistin (Liofilchem), Zeta potential (±EDTA) alteration and others. Although these methods showed good specificity and sensitivity and required a low relative skills to be performed, they are still expensive to be used in our country in the routine work.…”