Background:The emergence of drug resistance among diarrheagenic Escherichia coli (E. coli) in the pediatric population is an important cause of morbidity and mortality in developing countries.Material and Methods:Isolation and identification of E. coli strains from stool specimens are carried out according to standard techniques. Antibiotic susceptibility testing was performed using disc-diffusion method. Plasmid profiling and conjugation experiments were done to analyze the antibiotic resistance transfer from one bacterium cell to another through plasmid.Results:Out of 170 pediatric diarrheal samples, 105 (61.76%) E. coli strains were isolated. About 90% of E. coli strains were resistant to most of the antimicrobial agents tested. All the isolates were resistant to ampicillin, imipenem and cotrimoxazole and were sensitive to amikacin. The resistance to antibiotics shows 29 different antibiotic resistance patterns. About 67 (64%) strains of E. coli isolates harbored plasmids, and 51 (76.1%) of them were able to transfer their plasmids. The plasmid sizes ranged from 1.0 to 25 kb, the most common plasmid of size 4.8 kb being detected in all the plasmid-harbored E. coli strains. The results of transconjugation show that all the transconjugant colonies were carrying 4.8-kb plasmid and were resistant to ampicillin, imipenem and cotrimoxazole.Conclusion:There is an increase in the prevalence of drug resistance among E. coli isolates, and conjugal transfer of plasmids has greatly contributed to the rapid spread of antibiotic resistance among E. coli isolates.

Backgrounds: Pseudomonas aeruginosa is a classic opportunistic pathogen with innate resistance to many antibiotics and disinfectants. The lung is a main target for colonization and infection by the bacteria either in the context of a chronic, progressively deteriorating infectious and inflammatory pulmonary disease such as cystic fibrosis (CF) or in a more acute setting such as severe pneumonia in immunocompromised patients [1]. Aim and Objectives: To study the prevalence, virulence and the resistance pattern, phenotypic and genotypic characterization of P. aeruginosa from sputum samples. Materials and Methods: The present study was carried out with a total of 500 clinical sputum samples, which were received from patients, admitted to the various departments of Rajah Muthiah Medical College & Hospital, Annamalai University, Chidambaram. Result: Of the 500 samples subjected for isolation and identification of P. aeruginosa, 116 (23.20%) were positive. The isolated strains were tested for antibiotic sensitivity patterns. 93.10% of P. aeruginosa showed a maximum sensitivity to Ofloxacin, Norfloxacin and 86.20% of strains were highly resistant to Cefotaxime. The same isolates were also tested for phenotypic characterization of Extended Spectrum of Beta Lactamases by double disc synergy method against Cefotaxime and Clavulanic acid, according to the criteria of Hi-Media [2]. Of the resistant strains of P. aeruginosa iso-P. A. Shiny et al. 81 lated from sputum, 59% were positive for ESBL. The genotype characterization of ESBL P. aeruginosa showed 40% of CTX-M and 46.66% SHV gene. Conclusion: The present study strongly recommends for further checking of the antibiotic resistant strains of P. aeruginosa for phenotypic characterization of ESBL for effective treatment.