Prevalence of ESBL Producing Gram Negative Bacilli in Post Operative Wound Infections.

Vasudevan, J (2006) Prevalence of ESBL Producing Gram Negative Bacilli in Post Operative Wound Infections. Masters thesis, Coimbatore Medical College, Coimbatore.


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INTRODUCTION : Resistant bacteria are emerging world wide as a threat to the favorable out come of common infections in community and hospital settings. Even before the development of penicillin the first beta lactam anti biotic there was an emergence of resistance to betalactam antibiotics. The most important single mechanism of resistance to these antibiotics is due to the production of beta lactamases by gram positive and gram-negative organisms. The enzymes are thought to have evolved from penicillin binding proteins with which they show some sequence homology. This development was likely due to the selective pressure by beta lactam producing soil organisms found in the environment. Because of their increased spectrum of activity against the oxyiminocephalosporins, these enzymes are called extended spectrum beta lactamases which are capable of hydrolyzing and inactivating a wide variety of beta lactam antibiotics like third generation cephalosporin’s and penicillin’s. ESBL producing gram negative bacteria are of increasing importance on a worldwide basis and these pathogens are beginning to pose a serious threat. There is some evidence to suggest that over use of b lactams has imposed a selective pressure on pathogens to acquire resistance genes and mutate these to confers a broader range of activities. ESBLs have been reported from all parts of the world. However there is wide variation of the prevalence even in closely related regions. ESBLs have been found in a wide range of gram-negative bacteria and the majority of the strains belong to the family Enterobacteriacae. Enterobacteriacae producing ESBLs enzymes are a clinical threat and have been associated with increased mortality in severe infection. AIMS AND OBJECTIVES : 1. Collection of specimens from post operative wound infections. 2. Inoculation of specimens onto suitable culture media for isolation of organisms. 3. Selection of gram negative bacilli that are resistant to third generation cephalosporins. 4. Detection of ESBL from these strains using screening (Double Disk Synergy Test - DDST) and confirmatory test (Phenotypic Confirmatory Disk Diffusion Test) 5. Analysis and comparison of different methods for ESBL detection. 6. To study the prevalence of ESBL producing Gram negative bacilli in post operative wound infections. MATERIALS AND METHODS : The study was conducted in the Department Microbiology, Coimbatore Medical College Hospital, Coimbatore from October 2004 to September 2005. The subjects considered for our study were 120 patients admitted in the post operative surgical wards with surgical wound infections and those who had inclusive criteria of Grade IV (pus) of south ampton wound grading system. The study material consist of wound swabs from post operative surgical wound site. Samples were collected from them using the following protocol – sample collection technique - The wound area was wiped with sterile saline (or 70% alcohol) swabbed along the leading edge of the wound. Wound swabs were collected from 120 patients with clinical infected wounds and 15 from out patients attending the Review OPD (After discharge surveillance). RESULTS : The susceptibility Results for ESBL Positive isolates by Agar Dilution method (MIC determination) were studied and analysed. It was found that there was a decrease of >3 doubling dilutions in MICs of cefotaxime, ceftazidine with clavulanic acid compared to the MIC of cefotaxime, ceftazidine alone. CONCLUSION : The prevalence of ESBL producing gram negative bacilli in operative wound infection identified in this study was 37.50% which was with in the range of 28 to 84% reported in India. ESBL production was found to be coexsisted with resistance to several other antibiotics. ESBLs are encoded by plasmids which also carry co- resistant genes for other antibiotics. We found such associated co-resistance with cotrimaxazole, 44.66% gentamicin, 38.73% ciprofloxacin, 41.09% oflaxacin 39.18%. Since co-resistance to non b lactum antibiotics, cotrimaxazole, gentamicin and quinolones was observed, combination of Imipenem+amikacin were found to be alternatives for the treatment of life threatening infections, like septicemia, hospital acquired pneumonia, intravisceral abscess due to faster killing rates of Amikacin. Our study highlights the emergence of ESBL producing Klebsiella pneumoniae (48.01%) isolates endowed with extremely wide spectrum of antibiotic resistance including resistance to cotrimaxazole, gentamicin and quinolones suggest that ESBL producing Klebsiella pneumoniae isolates have emerged as one of the major multidrug resistance organisms. In this study, prevalence of ESBL was found in 37.5% of the strains isolated from the surgical wounds with a high degree of associated co-resistance to non b lactum antibiotics. Therefore Formulation of an appropriate hospital antibiotic policy is necessary to control these infections. Knowing the prevalence of ESBL positive strains in a hospital environment will become necessary to formulate a policy of empirical therapy in high risk units.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Prevalence ; ESBL Producing ; Gram Negative Bacilli ; Post Operative Wound Infections.
Subjects: MEDICAL > Microbiology
Depositing User: Subramani R
Date Deposited: 14 Aug 2017 06:29
Last Modified: 14 Aug 2017 06:29

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