Increased prevalence of MDR non fermenters group of bacteria recovered from nosocomial infections in tertiary care hospital, East Midnapur, West Bengal

 

 

Abstract               Aim of study: To evaluate the incidence rate of Non-fermenters group of bacteria along with their multidrug resistant pattern. Materials and methods: A retrospective cross-sectional study was undertaken to assess the frequency of NFGB group from different clinical specimens and their respective sensitivity pattern from available microbiology Laboratory data of ICare Medical College and Hospital, Haldia, East Midnapur, West Bengal, during the period of one year. Results: Total of 4012 clinical samples were collected from both IPD and OPD of different departments of the college. Clinical specimens of Urine 1104, Pus 1020, Blood 820, Sputum 900, CSF 10, Body fluid 158 were collected. Out of the total 4012 samples, 720 (17.90%) were culture positive. Of which 58(8%) isolates were identified as Non- fermenters. The predominant organisms isolated within Non fermenters were-Pseudomonaspp-38(58.4%) followed by Acinetobacter spp-14 (24.1%), Stenotrophomona spp-4 (6.8%) and Burkholderia spp -2(3.4%). Pseudomona spp were mostly sensitive to Colistin-73.6%, followed by ciprofloxacin-59.8% and piperacillin- tazobactum- and cefepime - 52%. Sensitivity pattern of penems(34-39%) were not encouraging. For Acinetobacter spp, colistin and minocycline were observed to be predominantly sensitive. As Stenotrophomona and Burkholdera spp. are Intrinsically resistant to different group of antibiotics, ceftazidime, penems, minocycline, levofloxacin, co-trimoxazole were selected for AST. Minocycline(65%), Co-trimoxazole (70%),and ceftazidime(55%) were observed predominantly sensitive. Conclusion; Non fermenters group of bacteria are multi drug resistant hence Nosocomial infections are difficult to treat. Selection of antibiotics for AST should exclude the intrinsically resistant group of antibiotics and include specific target group to facilitate therapeutic goal.

Key Word: NFGNB, acinetobacterspp, pseudomonaspp, multidrug resistant.

 

 

INTRODUCTION

NFGNB are aerobic, nonsporing, gram negative organisms and are taxonomically placed in a diverse group. They are saprophytic in nature and do not use carbohydrate as a source of energy or degrade them through metabolic pathway other than fermentation^{1 .}Some of them are commensals in human gut. The major organisms of such heterogenous group of NFGNB are pseudomona spp, acinetobacterspp, stenotrophomonaspp and burkhodoria spp. NFGNB accounts for about 15% of bacterial isolates from different clinical samples^2,3. They are responsible for life-threating infection like-septicemia, pneumonia, mening it is, UTI, SSIandVAP. The epidemiological prevalence profile of NFGNB and their susceptibility profile was never been studied in this region of west Bengal. The present study was conducted with the objective of identifying NFGNB isolates from all clinical samples by following a simple identification scheme through conventional method in our microbiology laboratory. The intention remains clear that this simple technique will be regularly followed by the technologists. This will ultimately help us to formulate an antibiotic protocol to counter those emerging multi drug resistant organisms. “Niche organisms” or “niche pathogens” that primarily cause opportunistic health care associated infections in patients who are critically ill or immunocompromised^4,5. They do not fit conveniently into a single family of well characterized genera and taxonomic placement of many are still unresolved. This includes diverse organisms such as Pseudomonas, Acinetobacter, Alcaligenes, Stentrophomonas, Flavobacter, Oligella, Flavimonas, Agrobacter, Sphingomonas etc. Many studies had been done to determine the prevalence of these organisms in urine sample. Isolation rates for NFGNB in urine samples was 10.8% -11%, with the distribution of isolates as 72%-87% Pseudomonas aeruginosa, followed by 10.4%-18% Acinetobacterbaumanii, and 0.77% Acinetobacterlwoffii Butour present study includes all the clinical samples covering all types of hospital admitted patients from SSI to VAP. In our study, drug resistance pattern shows the multi drug resistance with some promising results in few groups of antibiotics.⁶ NFGB initially colonize in the site followed by invasion due to selection pressure or trauma^{. (7 and8)}.Meticulous use, maintaining proper drug dose, barrier nursing, bundle care approach can restrict infections by these emerging strains.

 

MATERIALS AND METHODS

A total of 4012 clinical samples were collected from both IPD and OPD of different departments of the college, during April 2017 to March study 2018, in a cross sectional epidemiological study of twelve months duration. In the preceding year, before this study period, total 3870 clinical samples were collected from IPD and OPD ,with that assumption, total 4012 cases were selected, in the whole year ,for this study. Ethical clearance was obtained from Institutional ethics committee before conducting the study. The patients who were recently on oral or injectable antibiotics and where culture results showed more than two organisms were excluded from the study. Clinical specimens of urine 1104, pus 1020, blood 820, sputum 900, csf 10, body fluid 158 from surgery, orthopedics, ENT, OBG and eye and medicine unit were collected. Samples were processed and analysis were done in our microbiology department maintaining adequate sterility in Biosafety cabinet. The samples were processed as per guideline of Mackie andMcCartney,14^th edition and for antibiogram CLSI,2019 guidelines were followed. Samples were inoculated on blood agar, Chocholateagar, MacConkey agar and for AST test Mueller-Hinton agar was used. Disc diffusion method of Kirby –Bauer was followed for sensitivity pattern analysis. NFGNB were identified using motility test, oxidase test, OF tests, nitrate reduction test, TSI and by other standard biochemical test as per protocol. The scheme of identification of NFGNB is described here -

A. Motility

1. Motile organisms Pseudomona, Burkholderia, Stenotrophomona.
2. Non–motile organisms Acinetobacter, kingella, Moraxella.

B.OXIDASE Test

1. Positive Pseudomonas, Burkholderia.
2. Negative- Acinetobacter, stenotrophomonas.

Group characters: For Pseudomons spp- motile, nitrate-+ve, Oxidase-+ve, OF-oxidative, Arginine-+ve. For Acinetobacter spp-non motile, oxidase-negative. For stenotrophomona- motile, OFGlucose-ve, OF Maltose-ACID, lysine+ve, Oxidase- negative. For Burkholderia- motile, oxidase -+,lysine -+ve, gram positive diplococci, safety pin shaped in methylene blue stain. For AST the following antibiotics were selected-Amikacin, cefepime, ceftazidime, ciprofloxacin, cefoperazone+sulbactam, colistin, gentamycin, imipenem, levofloxacin, meropenem, piperacillin+tazobactam, minocyclin, trimethoprim+sulfamethoxazole. Non fermenters are intrinsically resistant to some of the commonly used antibiotics.⁹ So, those antibiotics which were intrinsically resistant to a group of bacteria should be avoided during AST study. Antibiotic susceptibility test was performed as per CLSI guideline, 2019 following Kirby Bauer disc diffusion technique on M-H agar media. As control strain E. Coli ATCC 25922 and P. Aeruginosa ATCC 27853 were used. The clinical significance of the isolated NFGNB was assessed by analyzing the clinical, pathological and radiological reports. The risk factors like pneumonia, malignancy, immune-suppressive therapy, brochiectasis, diabetes etc were also searched for.

RESULTS

Of the total 4012 samples collected, 720(17.90%) were culture positive as per the inclusion criteria mentioned above. Of this, 58(8%) isolates were identified as Non fermenters(chart-1) Most of the Pseudomona and Acinetobacter species were identified from Pus sample. Stenotrophomona were mostly identified from Bal fluid and sputum specimens. Burkholderia spp were identified in Blood. Out of 58 cases of Non-fermenters, 38(65%) was Pseudomona, 14(24.3%) were Acinetobacter, 4 (6.8%) were stenotrophomona and 2(3.4%) cases of Burkholdoria spp(chart 2 and 3).

Table 1: Sample isolation and distribution of non fermenters

 

Figure 1: % distribution of non-fermenters.

 

Table 2: Total case and frequency distribution

Antibiotic sensitivity pattern was done as per CLSI guideline 2019.Disc diffusion method of Kirby-Bauer was adopted. Antibiotics were selected excluding intrinsically resistant one for each group of Non fermenter organism. In our study, Pseudomona was maximum sensitive to colistin(73.6%), followed by ciprofloxacin (59.8%),piperacillin- tazobactum (52%) and penems(34-39%) (chart-4and5).

Table 3: Frequency of antibiotic sensitive/resistance

 

Table 4: % Distribution of sensitivity/Resistance of Pseudomona spp

For 14 isolated Acinetobacter spp maximum sensitivity was observed for colistin 09 (64.2%), followed by minocyclin 07(50%), penems(35.7-42.8%),Piperacillin + tazobactam 05(35.7%), aminoglycosides (28.5-35.7%)(chart-6).

 

 

 

 

 

Table 4: % distribution of sensitivity/Resistance of Acinetobacter spp.

For 4 isolated Stenotrophomonas spp. the following antibiotics were applied for AST. Ceftazidime, cefepime, Tigeycycline, Minocycline, Trimethoprime+sulfamethoxazole, colistin and Chloramphenicol. Amongst the isolated 4 stenotrophomona spp, AST showed predominantly sensitive to trimethoprime+ sulfamethoxazole 3(75%) and Colistin 3 (75%), followed by Minocycline 2(50%), Chloramphenicol 2(50%) and Tigeycycline 2(50%) (chart-7).

 

Table 5: % distribution of sensitivity/Resistance of Stenotrophomona spp.