ANTIMICROBIAL RESISTANCE PATTERN AMONG NON-FERMENTING GRAM NEGATIVE BACILLI ISOLATED FROM CLINICAL SAMPLES IN A TERTIARY CARE HOSPITAL IN INDIA.

Background: Non-fermenting gram negative bacilli have emerged as important pathogens and their isolation is increasing among hospital acquired infections. Many are innately resistant to most antibiotics and often multidrug resistant posing difficulty in treatment. Aim: The aim of the study was to determine the prevalence of Non-fermenting gram negative bacilli isolated from various clinical samples and to evaluate their antimicrobial resistance pattern. Materials and methods: This was a retrospective study of Non-fermenting gram negative bacilli isolated from clinical samples over a 2-year period from July 2015 to June 2017. Non-fermenting gram negative bacilli were grown on Blood agar and MacConkey agar and identified by standard methods including gram staining, motility and appropriate biochemical tests. Antimicrobial susceptibility testing was done by Kirby Bauer disc diffusion method as per Clinical and Laboratory Standards Institute guidelines and resistance pattern was studied. Results: A total of 323 Non-fermenting gram negative bacilli were isolated from 10819 samples with Pseudomonas being the most common species followed by Acinetobacter species. Pseudomonas species showed high resistance to Piperacillin-Tazobactum (60.6%). Acinetobacter species have shown higher resistance to Meropenem (42.1%) and Ceftazidime (73.7%). Conclusion: Acinetobacter species have emerged as highly resistant microorganisms causing infections especially in the Intensive Care Unit settings. However resistance to Colistin was not seen.


ISSN: 2320-5407
Int. J. Adv. Res. 6(4), 1084-1088 1085 intravenous catheters and prior antibiotic therapy in a seriously ill patient in a hospital. 1 They exhibit high intrinsic resistance to many antibiotics at levels attainable in body tissues and as a result of liberal and empirical use of antibiotics most of these organisms have in recent times acquired resistance to many routinely used antibiotics.

Aims and objects:-1.
To determine the prevalence of Non-fermenting Gram negative bacilli isolated from various clinical samples 2. To evaluate their antimicrobial resistance pattern

Material and methods:-
This retrospective study was done at the department of Microbiology, Regional Institute of Medical Sciences, Imphal over a two year period from July 2015 to June 2017. The study participants were patients who were referred to our department for culture and antibiotic susceptibility testing from various locations including outpatient department (OPD), inpatient department or clinical wards and Intensive care units (ICU) and were found to be culture positive for non-fermenters. Clinical specimens such as sputum, pus, urine, blood, catheter tip and other body fluids sent for culture and sensitivity testing were inoculated on Blood agar and MacConkey agar and incubated aerobically at 37°C for 18-24 hours. Organisms showing growth were identified using standard identification methods and appropriate biochemical tests. Characters assessed include colony morphology, gram staining, motility, oxidase, catalase, indole, urease, nitrate reduction, citrate utilization and oxidation-fermentation reaction of glucose. 1 Few species were confirmed by automated Vitek 2 Compact system (Biomerieux).
Antibiotic susceptibility testing to Imipenem, Meropenem, Piperacillin-Tazobactam, Ceftazidime, Ceftazidime-Clavulanate, Cefepime, Gentamicin, Ciprofloxacin, Trimethoprim-sulfamethoxazole and Colistin was performed with the help of the Kirby-Bauer disc diffusion method using commercially available antibiotic discs (HiMedia) on Mueller-Hinton agar. Briefly, a 0.5 McFarland standard inoculum of a pure culture of the organism is prepared and a lawn culture is plated onto Mueller-Hinton agar. Antibiotic discs were placed onto the agar and the plates were incubated for 18-24 hours. 1 Interpretation was done according to the Clinical and Laboratory Standards Institute guidelines. 13
Among the Pseudomonas species, 34.7% were isolated from sputum, 26.6% from urine, 22.6% from pus, 12.6% from tracheal aspirate and 0.5% from blood. Majority of Acinetobacter species were isolated from urine (31.6%) followed by sputum (28.3%), pus (18.3%), tracheal aspirate (10.8%) and blood (5.8%). One isolate each for Stenotrophomonas maltophilia and Chryseobacterium indologenes were isolated from urine. Two species belonging to Burkholderia cepacia complex were isolated from blood (Table 1).   1087 Pseudomonas species was the most common non-fermenter followed by Acinetobacter species and this is in concordance with most of other studies. 5,11 Resistance to antibiotics among the NFGNB may vary widely from place to place even within a given geographical area but those isolated from the hospital settings are often multidrug resistant. Because of these variations a surveillance of the nosocomial pathogens for resistant organisms in a particular hospital set up is needed in order to guide appropriate selection of empirical therapy and to develop an antibiotic policy. 3,10 In our study higher resistance to antibiotics among the non-fermenters was seen in the Intensive care units as these settings often harbor highly resistant pathogenic strains. Among the Pseudomonas species high level of resistance was seen for Piperacillin-Tazobactam (60.6%) and is probably due to the frequent use of this drug for empirical therapy. Low levels of resistance were observed for Cefepime (12.1%), Ciprofloxacin (18.2%) and Ceftazidime (24.2%) in contrast to other studies who reported 60-70% resistance to these antibiotics. 5,11 Resistance to Gentamicin, though not very pronounced, was seen to be increasing in comparison to in-patient and outpatient. Acinetobacter species isolated from ICUs were highly resistant to most antibiotics like Ceftazidime, Meropenem, Co-trimoxazole and Gentamicin a similar finding reported by many researchers. 3,5 These glucose non-fermenters have the ability to develop resistance rapidly to almost all available antibiotics and make them particularly dangerous in hospital settings. Resistance to Piperacillin-Tazobactam (31.6%) was much higher than those of inpatient and outpatient departments. Imipenem resistance was seen in 15.8% among ICUs and 20.6% among inpatient isolates with an overall resistance of 14.2%. Though Imipenem resistance in our study was lesser in comparison to studies by Taneja et al and Juyal et al who reported higher overall resistance of 36.4% and 30.54% respectively, 3,12 but emerging resistance to this group of drug is of major concern because these are considered as drugs of last resort.
Therefore studying and analyzing resistance to antibiotics among NFGNB is important for every healthcare setting, as infections caused by such strains can significantly increase the morbidity especially among the high risk patients due to their resistance to multiple antibiotics. These organisms by virtue of their adaptation in the hospital environment can also transfer resistance to other susceptible bacteria by horizontal gene transfer. 3

Conclusion:-
NFGNB are important bacteria causing a wide range of infections and nosocomial outbreaks. Increasing resistance to multiple antibiotics among NFGNB especially in health care facilities is of particular concern especially to Carbapenem group of drugs. It has been observed that Intensive care units are notorious for harboring such highly resistant microorganisms. Unhygienic practices in hospital, especially contaminated hands of health care workers, and warm hospital environment promote colonization by these multidrug resistant organisms. Hence proper and rational use of antibiotics and improved infection control measures coupled with surveillance will be of utmost importance to prevent and halt the progress of antimicrobial resistance among NFGNB in the healthcare setting.