Sophia, B (2006) Study of Acinetobacter Species as a Nosocomial Pathogen by Plasmid Profile Typing. Masters thesis, Madurai Medical College, Madurai.
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Abstract
INTRODUCTION : The genus Acinetobacter originally proposed by Brisou and Prevot (1954) comprised of a heterogeneous collection of non-motile Gram-negative organisms, which could be distinguished from other similar organisms by their lack of pigmentation (Ingram and Shewan, 1960). The history of the oxidase-negative, nonmotile. Gram-negative diplobacilli now constituting the genus Acinetobacter has been confused for many years (Henriksen, 1973, 1976). These bacteria were originally classified in to various genera including “Bacterium”, “Neisseria”, “Alcaligenes”, ”Mima”, “Herellea”, “Achromobacter” and “Moraxella”. For some time this group of bacteria was referred to as the oxidase negative Moraxella. The application of modern methods of taxonomy including carbon source utilisation tests, genetic transformation. DNA hybridisation, and RNA sequence comparison (by hybridisation or direct sequencing) has now resolved the earlier confusion. Progress in Acinetobacter taxonomy has now provided a new insight into Acinetobacter ecology and epidemiology. Acinetobacter species are Gram Negative, strongly aerobic, oxidase negative, catalase positive, non-motile, encapsulated non-fermenting coccobacilli with DNA G+C content of 39-47%. Members of genus Acinetobacter are widely distributed in nature and commonly found as a part of normal flora of humans. They are commonly found on skin and occasionally in the respiratory tract, genitourinary tract, gastrointestinal tract and conjunctiva. They are also found in soil, water and in hospital environment where they can cause serious infections in immunocompromised people and observed to be highly resistant to commonly used antibiotics and drugs.68 Members of the genus Acinetobacter are short plump, gram-negative rods that often become more coccoid in the stationary phase. Cells commonly occur in pairs or chains of variable length that are occasionally difficult to destain. No spores are formed. AIM AND OBJECTIVES : To isolate and identify Acinetobacter to species level from various clinical and environmental samples. To identify the multidrug resistant Acinetobacter species from various clinical and environmental samples and to isolate plasmids from these resistant isolates. To compare the plasmid profile of clinical isolates with the environmental isolates to find the identity between the two and to confirm that Acinetobacter species occur as an important nosocomial pathogen. To show that plasmid profile typing is a useful tool for epidemiological investigation of Acinetobacter species. CONCLUSION Gram-negative Non-Fermenters were commonly isolated from the medical wards, surgery wards, orthopedic wards and burns ward. Among the Non-Fermenters, Acinetobacter was shown to be the commonest organism isolated in these wards. The Acinetobacter was speciated by the biochemical reactions and it was found that Acinetobacter baumannii was commonly isolated from orthopaedic wards and Acinetobacter calcoaceticus and Acinetobacter hemolyticus were commonly isolated from burns wards. The antimicrobial susceptibility pattern of the three species of Acinetobacter showed that 63.6% Acinetobacter calcoaceticus were resistant to common antibiotics like ampicillin, piperacillin, gentamicin and ciprofloxacin. One of the antibiotic resistant isolate of Acinetobacter calcoaceticus showed 9 bands in plasmid profile typing showing that Acinetobacter calcoaceticus was showed higher resistance to antibiotics and this sample was isolated from the pus sample from a burns patient. Similar study on the environmental samples also showed that 75% antibiotic resistance for Acinetobacter calcoaceticus in burns ward. One isolate from the mattress of burns ward showed 9 bands, similar to the one in the pus sample of burns patient confirming that the infection in the burns patient may be from the environment. This is further supported by the same molecular weight of bands identified from both clinical and environmental samples in the burns ward. Thus Acinetobacter calcoaceticus occurs as a nosocomial pathogen in burns wards. Simple Agarose Gel Electrophoretic Method was employed for the detection and preliminary characterization of plasmid DNA present in clinical and environmental isolates and proved to be useful tool for survey work and the epidemoiolgical investigation of nosocomical infection.
| Item Type: | Thesis (Masters) |
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| Uncontrolled Keywords: | Acinetobacter Species ; Nosocomial Pathogen ; Plasmid Profile Typing. |
| Subjects: | MEDICAL > Microbiology |
| Depositing User: | Subramani R |
| Date Deposited: | 24 Jul 2017 04:44 |
| Last Modified: | 24 Jul 2017 04:44 |
| URI: | http://repository-tnmgrmu.ac.in/id/eprint/1672 |
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