Modification and evaluation of the Carba NP test by use of paper strip for simple and rapid detection of carbapenemase-producing Enterobacteriaceae.
Carbapenemase-producing Enterobacteriaceae (CPE) isolates have now emerged worldwide. We therefore modified the phenotypic Carba NP test by use of a filter paper strip for easily and rapidly identifying CPE in routine laboratory. A collection of 56 CPE and carbapenemase-producing Pseudomonas spp. isolates (including 28 NDM-1, 11 IMP-14a, 1 IMP-1, 1 IMP-4, 1 IMP-9, 1 IMP-15, 4 VIM-2, 1 VIM-1, 1 IMP-14a with VIM-2, 3 OXA-48, 3 OXA-181 and 1 KPC-2 producers) and 41 non-CPE isolates (including 19 ESBL, 7 pAmpC, 3 AmpC, 9 ESBL with pAmpC and 3 non-ESBL & non-AmpC producers) as confirmed by the PCR methods were tested by the paper strip method using pharmaceutical imipenem/cilastatin as a substrate. Bacterial colonies of each isolate were applied directly on filter paper strips dropped with either imipenem-phenol red (test strip) or phenol red solution alone (control strip). The reaction was read within 5 min. This test failed to detect 3 OXA-181, 2 OXA-48 and 3 IMP-14a producers (85.7 % sensitivity), whereas no false positives were seen (100 % specificity). Further evaluation of the paper strip test in 267 CPE screening-positive isolates from three hospitals by their medical technologists showed 92.0 % sensitivity (100 % for NDM producers) and 100 % specificity compared with the PCR methods. Because of its ease, rapidness and cost effective, the paper strip test has a potential for routine CPE testing in low-resource laboratories particularly in areas with high prevalence of NDM enzymes, leading to appropriate antimicrobial therapy and infection control strategy.
Medical Sciences Programme, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, 40002, Thailand.
Arpasiri
A
Srisrattakarn
Centre for Research and Development of Medical Diagnostic Laboratories, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, 40002, Thailand.
Aroonlug
A
Lulitanond
Centre for Research and Development of Medical Diagnostic Laboratories, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, 40002, Thailand.
Chotechana
C
Wilailuckana
Centre for Research and Development of Medical Diagnostic Laboratories, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, 40002, Thailand.
Nicha
N
Charoensri
Clinical Microbiology Unit, Srinagarind Hospital, Khon Kaen University, Khon Kaen, 40002, Thailand.
Lumyai
L
Wonglakorn
Clinical Microbiology Laboratory, The Queen Sirikit National Institute of Child Health, Bangkok, 10400, Thailand.
Sirikan
S
Piyapatthanakul
Clinical Microbiology Laboratory, Nan Hospital, Nan, 55000, Thailand.
Ampai
A
Supajeen
Centre for Research and Development of Medical Diagnostic Laboratories, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, 40002, Thailand. aroonwad@kku.ac.th.
Aroonwadee
A
Chanawong
D001426:Bacterial Proteins / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D001431:Bacteriological Techniques / Q000379:methods; D015780:Carbapenems / Q000494:pharmacology; D015377:Cilastatin / Q000378:metabolism; D000077728:Cilastatin, Imipenem Drug Combination; D004338:Drug Combinations; D004755:Enterobacteriaceae / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification*; D004756:Enterobacteriaceae Infections / Q000382:microbiology; D057075:Enzyme Assays / Q000379:methods* / Q000592:standards; D006801:Humans; D015378:Imipenem / Q000378:metabolism; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011549:Pseudomonas / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification; D011934:Reagent Strips; D001618:beta-Lactamases / Q000032:analysis* / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D015780:Carbapenems; D004338:Drug Combinations; D011934:Reagent Strips; D015377:Cilastatin; D015378:Imipenem; D000077728:Cilastatin, Imipenem Drug Combination; D001618:beta-Lactamases; C063912:carbapenemase; C108449:oxacillinase
Carbapenem resistance; Imipenemase; Klebsiella pneumoniae carbapenemase; New Delhi metallo-β-lactamase; Oxacillinase-48; Verona imipenemase