Abstract :
Background and Objectives: Resistance to therapeutic drugs poses problems in hospital settings as well
as in the community since most of the bacteria exhibit multi drug resistance pattern. The resistance is
mostly conferred by ESBL and Amp Cb -lactamase production in gram negative bacilli. Thus, identification
of Amp C is required to bring improvement in the management of patients suffering from infections
in hospitals. There is lack of information on documentation of Amp C b -lactamases, thus the present
retrospective study was undertaken to assess the method of identification and documentation Amp C
b - lactamases among gram negative isolates and their antibiogram from hospitalized patients in BTGH,
Gulbarga and also to analyse the changes in antiobiotic susceptibility trend over the years.
Materials and Methods: A total of 250 Gram negative consecutive and non-repetitive isolates obtained
from various clinical samples were screened for Amp C b -lactamase and ESBL production by modified
double disk approximation method (MDDM). The screen positive isolates were subjected to Amp C b -
lactamase detection by modified 3 – dimensional extract test. All these isolates were also subjected to
antibiotic sensitivity testing.
Results: Of all the gram negative isolates, 55.2% were found resistant to third generation cephalosporins,
out of which 47.8% were ESBL producers. A total of 23.2% isolates were found to be Cefoxitin resistant,
60.3% of which were Amp C producers. Most of the Amp C producing organisms showed sensitivity to
Imipenem, Amikacin and Ciprofloxacin.
Conclusion: In the present study, the AmpC type b – lactamase were seen to be produced mostly in
Klebsiella pneumonia which can be attributed to a combined type of drug resistance mechanisms by AmpC
and ESBL production prevalent in these organisms.
Keyword :
Extended spectrum beta lactamases (ESBL), AmpC beta lactamases,
Modified double disk approximation method (MDDM), Double disk synergy test (DDST),
Modified 3 – dimensional test.