SOME STRANGE FINDINGS: NON-INTERPRETABLE PATTERNS IN MODIFIED HODGE TEST

• Published in: Journal of evolution of medical and dental sciences Vol. 2; no. 43; pp. 8302 - 8304
• Main Authors: Konar, Jayashree, Bhattacharyya, Indrani
• Format: Journal Article
• Language: English
• Published: Akshantala Enterprises Private Limited 28.10.2013
• Subjects: Beta lactamases; Carbapenems; Identification and classification; Physiological aspects
• ISSN: 2278-4748; 2278-4802
• DOI: 10.14260/jemds/1457

Many clinically relevant species of Gram-negative bacilli are often resistant to β-lactam antibiotics even to carbapenems. According to CLSI guideline 2013, Carbapenemase producers are screened by zone size <21mm to Meropenem or Etrapenem and phenotypically confirmed by Modified f test. The test of Hodge et al was modified by substituting Escherichia coli for penicillin-susceptible Staphylococcus aureus ATCC 25923, and 10-µg Imipenem disk for a 10-U Penicillin disk. While looking for the Carbapenemase producing strains, some astonishing, unexplainable facts were revealed in this study. Meropenem-resistant test strains were screened (zone diameter in Modified Kirby-Bauer technique < 21mm) & for phenotypic confirmation of Carbapenemase production, modified Hodge test was performed. Thereafter the test strains were examined for production of Metallo β Lactamase using Imipenem (10 µg) disk and combination of Imipenem and EDTA, followed by test for Bacteriocin production. Two Acinetobacter and one Pseudomonas aeruginosa strains were found to produce a Star like outward distortion. They did not produce Metallo β lactamase. Moreover, screening test for bacteriocin production was also found to be negative. The strains resistant to Carbapenem antibiotics but nonproducers of metallo β lactamase and/or Bacteriocins, have left behind a head twister for us.