The modified Hodge test is a useful tool for ruling out klebsiella pneumoniae carbapenemase

Abstract

OBJECTIVE:Enterobacteriaceae bacteria harboring Klebsiella pneumoniae carbapenemase are a serious worldwide threat. The molecular identification of these pathogens is not routine in Brazilian hospitals, and a rapid phenotypic screening test is desirable. This study aims to evaluate the modified Hodge test as a phenotypic screening test for Klebsiella pneumoniae carbapenemase.METHOD:From April 2009 to July 2011, all Enterobacteriaceae bacteria that were not susceptible to ertapenem according to Vitek2 analysis were analyzed with the modified Hodge test. All positive isolates and a random subset of negative isolates were also assayed for the presence of blaKPC. Isolates that were positive in modified Hodge tests were sub-classified as true-positives (E. coli touched the ertapenem disk) or inconclusive (distortion of the inhibition zone of E. coli, but growth did not reach the ertapenem disk). Negative results were defined as samples with no distortion of the inhibition zone around the ertapenem disk.RESULTS:Among the 1521 isolates of Enterobacteriaceae bacteria that were not susceptible to ertapenem, 30% were positive for blaKPC, and 35% were positive according to the modified Hodge test (81% specificity). Under the proposed sub-classification, true positives showed a 98% agreement with the blaKPC results. The negative predictive value of the modified Hodge test for detection was 100%. KPC producers showed high antimicrobial resistance rates, but 90% and 77% of these isolates were susceptible to aminoglycoside and tigecycline, respectively.CONCLUSION:Standardizing the modified Hodge test interpretation may improve the specificity of KPC detection. In this study, negative test results ruled out 100% of the isolates harboring Klebsiella pneumoniae carbapenemase-2. The test may therefore be regarded as a good epidemiological tool.

Molecular characterization of carbapenem-resistant Klebsiella pneumoniae isolates from a university hospital in Brazil

“…The detection of KPC producers is important to understand the epidemiology of hospital infections and could be useful in planning intervention in preventable factors that can reduce the spread of resistance in a hospital setting. However, laboratory detection can be difficult, because routine laboratories usually do not possess molecular diagnostic resources [36]. In this study, MHT and APB showed to be a specific and sensitive phenotypic test for detection of KPC enzymes in regions with great frequency of isolates producing carbapenem resistance.…”

Comparative Evaluation of Different Phenotypic Methods in Detection of Klebsiella pneumoniae Carbapenemase (KPC)

“…10 In the present study, 254 CRKP were further tested for KPC and MBL production by Modified Hodge Test (MHT). Recently CLSI accepted MHT as specific and sensitive phenotypic method for carbapenemase detection 4 With minimum carbapenemase activity, MHT initially aims to recognize and differentiate the presence of carbapenemase production with that of other enzymes. 13 The Carba NP test has many advantages.…”

“…In recent years, K. pneumoniae have become important pathogens in nosocomial infections 2 . An estimated 8% of all nosocomial bacterial infections such as septicemia, pneumonia and urinary tract infections are caused by Klebsiellae, mainly by Klebsiella pneumoniae and Klebsiella oxytoca, primarily affecting immuno compromised patients 3,4 .K. pneumoniae strains that produce extended spectrum β-lactamase enzymes (ESBLs) with…”

Modified Hodge test as screening test for spreading Carbapenemase resistance has become more important

“…We read the article by Cury et al titled ‘‘The modified Hodge test is a useful tool for ruling out Klebsiella pneumoniae carbapenemase” with interest (1). The authors aimed to evaluate the modified Hodge test (MHT) as a phenotypic screening test for Klebsiella pneumoniae carbapenemase (KPC).…”

“…All carbapenemase resistance caused by the resistance genes is detectable using the MHT, for which the sensitivity and specificity of the screening is known to be very good (1,2). However, the weakest aspect of the MHT is specificity.…”