Original article / research
Year : 2022 Month : July-September Volume : 11 Issue : 3 Page : MO17 - MO19

Antibiotic Sensitivity Pattern of Non Fermentative Gram Negative Bacilli in a Tertiary Care Hospital, Kakinada, Andhra Pradesh, India
Neerajakshi Reddi, Gaddiparthi Israel
1. Assistant Professor, Department of Microbiology, Rangaraya Medical College, Kakinada, Andhra Pradesh, India. 2. Assistant Professor, Department of Microbiology, Rangaraya Medical College, Kakinada, Andhra Pradesh, India.
 
Correspondence Address :
Dr. Neerajakshi Reddi,
Assistant Professor, Department of Microbiology, Rangaraya Medical College,
Kakinada-533001, Andhra Pradesh, India.
E-mail: drneerajakshi@gmail.com
 
ABSTRACT
: Non Fermentative Gram Negative Bacilli (NFGNB), which are saprophytic in nature, have emerged as important pathogens. They have been associated with infections such as septicaemia, meningitis, pneumonia, Urinary Tract Infection (UTI) and surgical site infections. They exhibit resistance to beta lactams and also to other groups of antibiotics and carbapenems.

Aim: To identify and isolate NFGNB from various clinical samples and to know their antimicrobial susceptibility pattern.

Materials and Methods: The present study was a cross-sectional study done in the Department of Microbiology, Rangaraya Medical College, Kakinada, Andhra Pradesh, India, from July 2018 to August 2019. The study was done on 204 clinical samples that were inoculated on different growth media. The non fermenters were identified by conventional methods and isolates that were not identified, were subjected to automated system (MicroScan autoSCAN-4 system). The susceptibility testing was done by Kirby-Bauer disc diffusion method. Data was entered in Microsoft Excel sheet 10 and all analysis was performed by Statistical Package for the Social Sciences (SPSS) 24.0.

Results: A total of 100 NFGNB were isolated from 204 clinical samples. Pseudomonas aeruginosa (P. aeruginosa) was the most common non-fermenter (49%), followed by Acinetobacter baumannii (A. baumannii) (19%), P. fluorescens (17%), Acinetobacter lwoffii (A. lwoffii) (4%), Alcaligenes faecalis (A. faecalis) (4%), Burkholderia cepacia (B. cepacia) (3%), Pseudomonas putida (P. putida) (2%) and Stenotrophomonas maltophilia (S. maltophilia) (2%). The NFGNB showed good sensitivity to imipenem (97%), amikacin (53%) , and 92% resistance to cefipime, 75%, 73%, 49%, and 48%, resistance to ceftazidime, ticarcillin, ciprofloxacin, piperacillin, respectively.

Conclusion: P. aeruginosa and A. baumannii were the common NFGNB isolated in the present study from surgical site infections, urinary tract infections, bacteraemia, and ventilator associated pneumonia. The different species of NFGNB have shown a varied sensitivity pattern. All NFGNB showed higher rate of resistance to cefipime and ceftazidime and good sensitivity to imipenem, and amikacin.
Keywords : Acinetobacter baumannii, Imipenem, Nosocomial pathogens, Pseudomonas aeruginosa, Resistance pattern
 
INTRODUCTION
The NFGNB are a diverse group of non spore forming aerobic bacilli that either do not utilise glucose or utilise it oxidatively and occur as saprophytes in the environment and some also found as commensals in the human gut. About 15% of NFGNB are known to be isolated among bacterial isolates from a clinical microbiology laboratory (1). They can tolerate harsh environmental conditions and shows marked drug resistance to antimicrobial agents and so frequently described as hospital acquired pathogens (2). Commercial systems like MicroScan, Rapid NF Plus, API Rapid NFT, Vitek system, Remel systems are used to identify non fermenting bacilli for faster and accurate diagnosis of NFGNB infections (3). The NFGNB are intrinsically resistant to commonly using antibiotics and are known to produce Extended Spectrum ?-lactamases (ESBL) and Metallo ?-lactamases (MBL) (4). Risk factors are immunosuppression, neutropenia, mechanical ventilation, cystic fibrosis, indwelling catheters, invasive diagnostic and therapeutic procedures (5). In recent years, due to the liberal and empirical use of antibiotics, they have emerged as important healthcare-associated pathogens. They have been associated with infections like septicaemia, meningitis, pneumonia, urinary tract infections and surgical site infections (6). They are highly prevalent in moist environmental conditions (7). This group of bacteria was earlier considered to be colonisers but are now frequently isolated from different clinical specimens and are responsible for a wide range of human infections especially in immunocompromised individuals (8).

Infections produced by NFGNB may be endogenous and exogenous in origin (9).This heterogenous group includes Pseudomonas spp., Acinetobacter spp. Alkaligens spp. Stenotrophomonas maltophilia, Burkholderia cepacia complex (10). They are often resistant to disinfectants and can spread from patient to patient (11). The NFGNB are emerging as an important cause of blood stream infections (12). They have been commonly found on the skin of healthcare workers, ventilator machines, humidifiers and mattresses (13).

Multidrug resistance in NFGNB is progressively increasing, so there is a need to identify NFGNB and monitoring their susceptibility pattern for the proper management of infections caused by them to avoid unnecessary usage of antibiotics and emergence of drug resistant strains. Hence, the aim of the present study was to identify and isolate NFGNB from various clinical samples and to determine their antimicrobial susceptibility pattern with Kirby-Bauer disc diffusion method from patients admitted to Government General Hospital, a tertiary care hospital, Kakinada, Andhra Pradesh, India.
 
MATERIAL AND METHODS
The NFGNB are a diverse group of non spore forming aerobic bacilli that either do not utilise glucose or utilise it oxidatively and occur as saprophytes in the environment and some also found as commensals in the human gut. About 15% of NFGNB are known to be isolated among bacterial isolates from a clinical microbiology laboratory (1). They can tolerate harsh environmental conditions and shows marked drug resistance to antimicrobial agents and so frequently described as hospital acquired pathogens (2). Commercial systems like MicroScan, Rapid NF Plus, API Rapid NFT, Vitek system, Remel systems are used to identify non fermenting bacilli for faster and accurate diagnosis of NFGNB infections (3). The NFGNB are intrinsically resistant to commonly using antibiotics and are known to produce Extended Spectrum ?-lactamases (ESBL) and Metallo ?-lactamases (MBL) (4). Risk factors are immunosuppression, neutropenia, mechanical ventilation, cystic fibrosis, indwelling catheters, invasive diagnostic and therapeutic procedures (5). In recent years, due to the liberal and empirical use of antibiotics, they have emerged as important healthcare-associated pathogens. They have been associated with infections like septicaemia, meningitis, pneumonia, urinary tract infections and surgical site infections (6). They are highly prevalent in moist environmental conditions (7). This group of bacteria was earlier considered to be colonisers but are now frequently isolated from different clinical specimens and are responsible for a wide range of human infections especially in immunocompromised individuals (8).

Infections produced by NFGNB may be endogenous and exogenous in origin (9).This heterogenous group includes Pseudomonas spp., Acinetobacter spp. Alkaligens spp. Stenotrophomonas maltophilia, Burkholderia cepacia complex (10). They are often resistant to disinfectants and can spread from patient to patient (11). The NFGNB are emerging as an important cause of blood stream infections (12). They have been commonly found on the skin of healthcare workers, ventilator machines, humidifiers and mattresses (13).

Multidrug resistance in NFGNB is progressively increasing, so there is a need to identify NFGNB and monitoring their susceptibility pattern for the proper management of infections caused by them to avoid unnecessary usage of antibiotics and emergence of drug resistant strains. Hence, the aim of the present study was to identify and isolate NFGNB from various clinical samples and to determine their antimicrobial susceptibility pattern with Kirby-Bauer disc diffusion method from patients admitted to Government General Hospital, a tertiary care hospital, Kakinada, Andhra Pradesh, India.
 
RESULTS
A total of 100 NFGNB were isolated from 204 clinical samples with an isolation rate of 49%. Out of 204 different clinical samples 156 (76.5%) gram negative bacilli were isolated. In remaining 48 (23.5%) samples, 11 (22.9%) samples showed no growth, and 37 (77.1%) samples showed polymicrobial infection. Out of 156 (76.5%) gram negative bacilli, 126 (80.8%) were non lactose fermenters and 30 (19.2%) were lactose fermenters. Out of 100, 40 isolates were found from surgical wards. Higher number of NFGNB were isolated in age group of 41-60 years 41 (41%). 32 (47.1%) Pseudomonas spp and 2 (75%) A. faecalis were more common in 41-60 yrs age group. A total of 9 (39.1%) Acinetobacter spp were isolated in 14-20 yrs age group. NFGNB isolates were higher in males 74 (74%) as compared to females 26 (26%) (Table/Fig 1), (Table/Fig 2).

The most common isolate was P. aeruginosa (49%), followed by A. baumannii and P. fluorescens (19%, 17%) (Table/Fig 3). Majority of NFGNB were isolated from pus (71%) and urine (11%) samples. Out of 71 (71%) isolates from pus, majority were P. aeruginosa (35), only two isolates are B. cepacia and S. maltophilia. Out of 11 (11%) isolates from urine, majority were P. aeruginosa (3), and only one isolate is A. lwoffii.

Out of 10 (10%) isolates from sputum, majority were P. aeruginosa (6) and one isolate is B. cepacia. Out of three (3%) isolates from pleural fluid, A. baumannii (2), and P. aeruginosa (1) were isolated.

Out of 49 isolates of P. aeruginosa, all 49 (100%) were resistant to cefipime, 33 (67.34%) isolates were resistant to ceftazidime and only 1 (2.04%) isolate was resistant to imipenem. Out of 17 isolates of P. fluorescens, all 17 (100%) were resistant to both ceftazidime, cefipime (Table/Fig 4). Overall, out of 100 NFGNB, 92 (92%) isolates are resistant to cefipime, 75 (75%) to ceftazidime, 73 (73%) to ticarcillin, respectively. Out of 100, 75% of NFGNB resistance to ceftazidime, indicated positive for ESBL production. And, only 3% of NFGNB resistance to imipenem indicated MBL producers.
 
DISCUSSION
A total of 100 NFGNB were isolated from 204 clinical samples with an isolation rate of 49%. Out of 204 different clinical samples 156 (76.5%) gram negative bacilli were isolated. In remaining 48 (23.5%) samples, 11 (22.9%) samples showed no growth, and 37 (77.1%) samples showed polymicrobial infection. Out of 156 (76.5%) gram negative bacilli, 126 (80.8%) were non lactose fermenters and 30 (19.2%) were lactose fermenters. Out of 100, 40 isolates were found from surgical wards. Higher number of NFGNB were isolated in age group of 41-60 years 41 (41%). 32 (47.1%) Pseudomonas spp and 2 (75%) A. faecalis were more common in 41-60 yrs age group. A total of 9 (39.1%) Acinetobacter spp were isolated in 14-20 yrs age group. NFGNB isolates were higher in males 74 (74%) as compared to females 26 (26%) (Table/Fig 1), (Table/Fig 2).

The most common isolate was P. aeruginosa (49%), followed by A. baumannii and P. fluorescens (19%, 17%) (Table/Fig 3). Majority of NFGNB were isolated from pus (71%) and urine (11%) samples. Out of 71 (71%) isolates from pus, majority were P. aeruginosa (35), only two isolates are B. cepacia and S. maltophilia. Out of 11 (11%) isolates from urine, majority were P. aeruginosa (3), and only one isolate is A. lwoffii.

Out of 10 (10%) isolates from sputum, majority were P. aeruginosa (6) and one isolate is B. cepacia. Out of three (3%) isolates from pleural fluid, A. baumannii (2), and P. aeruginosa (1) were isolated.

Out of 49 isolates of P. aeruginosa, all 49 (100%) were resistant to cefipime, 33 (67.34%) isolates were resistant to ceftazidime and only 1 (2.04%) isolate was resistant to imipenem. Out of 17 isolates of P. fluorescens, all 17 (100%) were resistant to both ceftazidime, cefipime (Table/Fig 4). Overall, out of 100 NFGNB, 92 (92%) isolates are resistant to cefipime, 75 (75%) to ceftazidime, 73 (73%) to ticarcillin, respectively. Out of 100, 75% of NFGNB resistance to ceftazidime, indicated positive for ESBL production. And, only 3% of NFGNB resistance to imipenem indicated MBL producers.
 
CONCLUSION
The P.aeruginosa and A. baumannii were the most common NFGNB isolated in the present study and showed good sensitivity to imipenem, amikacin and piperacillin. NFGNB have shown a varied sensitivity pattern and they showed higher rate of resistance to cefipime and ceftazidime. So, the present study highlights that there is a need to identification and monitoring sensitivity patterns of NFGNB for proper management of infections cause by nonfermenters and also to avoid unnecessary usage of antibiotics and emergence of drug resistance.
 
ACKNOWLEDGEMENT
Acknowledgement

Authors are thankful to Department of Microbiology, Government General Hospital, Kakinada, for providing financial and necessary facilities to complete this study.
 
REFERENCES
1.
Malini A, EK Deepa, BN Gokul, SR Prasad. Non-fermenting gram negative bacilli infections in a tertiary care hospital in Kolar, Karnataka. J Lab Physician. 2009;1(2):62-66.
2.
Argenta AR, Fuentefria DB, Sobottka AM. Prevalence and antimicrobial susceptibility of NFGNB isolated from clinical samples at a tertiary care hospital. RSBMT. 2017;50(2):243-47.
3.
Anuradhak, VV Sailaja, P Umabala, T Satheesh, Lakshmi V. Sensitivity pattern of gram negative bacilli to three β-lactam/β-lactamase inhibitor combinations using the automated API system. IJMM. 2007;25(3):203-08.
4.
Peerzada BY, Bhatawadekar SM, Chakraborthy A, Lahiri KK. Non fermenting gram negative bacilli as emerging pathogens – report from tertiary care hospital in Western India. Indian Journal of Research. 2017:6(40).
5.
Juyal D, Prakash R, Shankarnarayan SA, Sharma MK, Negi V, Sharma N. Prevalence of NFGNB and their in vitro susceptibility pattern in a tertiary care hospital of Uttarkhand, A study from foothills of Himalaya. SJHS. 2013;2(2):108-12.
6.
Bhargava D, Kar S, Saha M, Prevalence of NFGNB infection in tertiary care hospital in Birgunj , Nepal. I.J.C.M.A.S, 2015;4(7):301-07.
7.
Pappu RK, Singh MN, Sagar S. Trends of NFGNB isolated from clinical samples and Antimicrobial Sensitivity Pattern from patients Attending in Tertiary care Hospital at Sahasra, North Bihar. JMSCR. 2019;07, (9):662-65.
8.
Sharma M, Pant ND. Prevalence and in vitro antimicrobial susceptibility patteren of NFGNB isolated in a tertiary care hospital in Katmandu, Nepal. Asian Journal of Biomedical and Pharmaceutical sciences. 2017;7:13-15.
9.
Bansal R, Soni R, Tiwari YK. Prevalence of nonfermenters among various clinical samples and their antibiotic resistance at tertiary care centre, Jhalawar, India, IJCMAS,2019,8(7):1851-58.
10.
Bhatnagar R, Kumar S, Bansal, G, Mehra SK. Identification and antimicrobial susceptibility pattern of clinical isolates of NFGNB. Int J Pharma Research and Health Sciences. 2014;2(4):347-51.
11.
Singamsetty S, Yarlagadda P, Myneni RB, Penmetcha U. Identification and antimicrobial susceptibility pattern of NFGNB in a tertiary care hospital : our experience. IJHSR. 2016, 6(8): 105-11.
12.
Sarwat T, Yousuf M, Khan AS, Kakru DK, Dutta R. Prevalence and Antibiogram of Non-fermenting Gram – negative bacilli in blood stream infections : study in a tertiary care centre, western Uttar Pradesh , India. Topical Doctor. 2021;51(3):322-25.
13.
Grewal US, Bakshi R, Walia G, Shah PR. Antibiotic susceptibility profiles of NFGNB at a tertiary care hospital in patiala, India. Niger Postgrad Med J. 2017;24(2):121-25.
14.
Washington W Jr, Stephen Alen, William Janda, Elmer Koneman, Gary Procop, Paul Schreckenberger et al. In Koneman’s colour atlas and textbook of diagnostic Microbiology, 6th edition.Lippincott Williams and Wilkins company, 2006, Nonfermenting Gram negative bacilli , pp . 305 – 91.
15.
Clinical and Laboratory standards Institute. Performance standards for antimicrobial susceptibility testing ,15th informational supplement, CLSI document M 100- S15,Way ne.PA: Clinical and Laboratory standards Institute, 2005.
16.
Mackie and McCartney, Practical Medical Microbiology, 14th edition, page – 152.
17.
Shrihari N, Ishwarya M, Characterization and Antibiotic sensitivity pattern of NFGNB from various clinical samples at a tertiary care hospital, IJCMAS, 2019;809:172.