A Study on Isolation and Antibiotic Sensitivity Testing of Pseudomonas aeruginosa Isolated from Patients with Respiratory Tract Infection with Special Reference to Phenotypic and Genotypic Characterization of Extended Spectrum Beta Lactamases (ESBL)

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 isolated 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.