2.2. Antimicrobial sensitivity and string test

The bacterial strain was subjected to antimicrobial sensitivity testingusingVitek2®, (BioMérieux, France) AST-N280 card, Kirby-Bauer disk diffusion and micro-broth dilution methods, representing a standard antibiotics test panel (Himedia, Mumbai India; Table 1). Antibiotics including tobramycin, ceftazidime ​+ ​avibactam, cefotaxime, ertapenem, cefoperazone ​+ ​sulbactam, meropenem, ciprofloxacin, amikacin, cefuroxime-axetil, nitrofurantoin, nalidixic acid, doxycycline, trimethoprim ​+ ​sulfamethoxazole, cefuroxime, ceftriaxone, cefepime, imipenem, colistin, piperacillin ​+ ​tazobactam, ofloxacin, gentamycin, netilmicin, tigecycline, amoxcillin ​+ ​clavulanic acid, norfloxacin, and ampicillin were used for antibiotic susceptibility profiling of the clinical isolate. Less than five disks were used per Mueller-Hinton agar (Himedia, India) plate with a test organism lawn for the agar disk diffusion method, or the Kirby Bauer method for antimicrobial susceptibility testing. The inhibition zone was measured as per the manufacturer's guidelines. Reports from the Vitek2®sytem were also used to identify the antibiotic susceptibility profile of the test isolate. In addition, hypermucoviscosity was measured by using the string test method to ascertain the virulence nature of the clinical isolate. The string test involves streaking the selected strain onto Muller Hinton agar and grown at 37 ​°C overnight. With the help of an inoculation loop, the colony was touched and pulled to produce a thin string between colony and loop. If a thin string up to 5 ​mm height is observed, it denotes hypermucoviscosity [30].

Antimicrobial sensitivity test results with Vitek2® system.

Test strain K. pneumoniae was resistant to all classes of antibiotics and combinations available for treating Infections. ∗R- Resistant; S-Sensitive; MIC- Minimum inhibitory concentration (mg/l).