Abstract:
Background: Urinary tract infections (UTIs) are a major problem all around the world. Most of
the UTIs are caused by Gram-negative bacilli (GNB). Carbapenem drugs are the last line of
defense against UTIs caused by GNB. Determining the prevalence of carbapenem resistance
GNB-causing UTIs is essential, as they have become resistant to a range of antibiotics.
Objectives: To evaluate the presence of carbapenemase-producing GNB (CP-GNB) and to
identify the antibiotic susceptibility patterns of GNB-causing UTIs at the National Hospital,
Colombo, Sri Lanka
Methods: This study included 142 GNB isolates (urine). Gram staining was performed to identify
GNB isolates taken from Cystine Lactose Electrolyte deficient medium. Oxidase test was done to
differentiate Pseudomonas aeruginosa from Enterobacteriaceae. Antibiotic susceptibility patterns
were identified by the Disc diffusion method. Carbapenemase production was determined by
carbapenem inactivation method (mCIM). The data were analyzed using SPSS version 29.0.2.0.
Chi-square method and descriptive statistics were used.
Results: Out of 142 GNB isolates, the commonest were Enterobacteriaceae, 125 (88.03%). The
other 17 (11.97 %) isolates were P. aeruginosa. Among total GNB isolates, 27.46% were positive
for mCIM test, and 64.09% were negative for mCIM. Out of total Enterobacteriaceae, 30 (24.0%)
were mCIM positive, 10 (8.0%) were mCIM intermediate, 85 (68.0%) were mCIM negative. Out
of total P. aeruginosa, 9 (52.94%) were mCIM positive, 2 (11.76%) were mCIM intermediate and
6 (35.30%) were mCIM negative. They also showed significant resistance to cefuroxime (30 µg),
cefpodoxime (10 µg), Amoxicillin-clavulanic acid (30 µg), and ciprofloxacin (5 µg) (p<0.001).
The mCIM-negative isolates showed significant resistance towards nalidixic acid (30 µg), and
ciprofloxacin (5 µg) (p<0.001).
Conclusion: CP-GNB showed significant resistance to several routinely used antibiotics
