Abstract : Introduction: Infections and mortality associated with multidrug- resistant Gram-negative bacilli (MDR
GNB) have dramatically increased in all parts of the world. The present study was conducted to screen the
burden of Gram negative multidrug resistance in our tertiary care hospital and to pave a stepping stone for
the infection control team to tackle the problem effectively.
Materials and Methods: A total of 300 non-repetitive MDR GNB isolates from the specimens received in
our diagnostic Microbiology lab oratory for a period of one year were screened phenotypically for Extended
spectrum b -lactamases (ESBL), AmpC betalactamases and Carbapenemases. Colistin and Tigecycline
susceptibility E-test were also performed randomly on some carbapenemase producing organisms.
Results: Among the 300 MDR GNB isolates, ESBL and AmpC producers were 56% and 24% respectively.
E.coli was the most common organism with ESBL (73%) and AmpC (46%) resistance mechanisms.
Carbapenemase producers were 14.6% with predominant isolate being Acinetobacter spp (40%). Among
the risk factors, 13% patients had immunosuppressive conditions like diabetes, 31% had insitu urinary
catheters, 57.7% and 29.4% had prior antibiotic usage and hospitalisations respectively. Twenty five
carbapenemase producing MDR GNB tested for Colistin MIC were in the susceptible range. 71% of
Acinetobacter spp tested for Tigecycline showed resistant MIC values.
Conclusion: Multidrug resistance has a significant adverse impact on clinical outcomes of patients &
leads to higher costs due to consumption of health-care resources. Adherence to simple measures like hand
hygiene & careful attention to barrier precautions can help in preventing the spread of these infections to a
Keywords: MDR GNB, ESBL, AmpC betalactamases, Carbapenemases.