Antimicrobial resistance in Enterococcus faecalis at a tertiary care centre of northern India.

BACKGROUND & OBJECTIVES: Multiresistant enterococci are emerging as a leading nosocomial pathogen. Knowledge of the profile of antimicrobial resistance is essential to formulate treatment guidelines for infections caused by enterococci. This study reports the antimicrobial sensitivity of enterococci isolated during a one year period from clinical samples of patients admitted to a teriary care hospital of Delhi. METHODS: A total of 444 isolates of Enterococcus faecalis were screened for antimicrobial susceptibility by the disk diffusion technique as recommended by the National Committee for Clinical Laboratory Standards (NCCLS). Screening for vancomycin resistance was done by the vancomycin screen agar method recommended by NCCLS, which was confirmed by determination of minimum inhibitory concentration (MIC) using microbroth dilution and E-test methods. Vancomycin resistance phenotypes were determined by polymerase chain reaction. RESULTS: A total of 115 (26%) isolates had high level aminoglycoside resistance, 293 (66%) were resistant to ampicillin, 391 (88%) to ciprofloxacin and 377 (85%) to erythromycin. Vancomycin resistance was found in five (1%) isolates, of which four had van A phenotype and one had van B phenotype. INTERPRETATION & CONCLUSION: Emergence of vancomycin resistant enterococci is of concern due to the limited therapeutic options. Implementation of infection control measures can contain the spread of these resistant bacteria.

Phenotypic & genotypic variants of Pseudomonas aeruginosa isolated from children with cystic fibrosis in India.

BACKGROUND & OBJECTIVES: Pseudomonas aeruginosa is the leading cause of morbidity and mortality in patients with cystic fibrosis (CF). With increase in the chronicity of the disease, there is a diversification of the organism into different colony morphological types. The antimicrobial susceptibility of the organism varies with its colony morphology. The present work was carried out to study the different morphotypes of P. aeruginosa isolated from patients of cystic fibrosis. METHODS: We studied 38 children with CF attending the Paediatric Chest Clinic at the All India Institute of Medical Sciences, New Delhi, India during October 2000-January 2001 who were regularly followed up at the clinic. Patients were divided into 2 groups, Group 1 included all patients chronically infected with P. aeruginosa and Group 2 included patients who were infrequently colonized with this organism. Different colony morphological types of P. aeruginosa on culture media were identified. They were characterized by phenotypic methods using antibiograms and genotypic methods using enterobacterial repetitive intergenic consensus (ERIC) polymerase chain reaction and PCR-ribotyping. RESULTS: Fourteen of the 38 patients were colonized at least once with P. aeruginosa. Eight patients belonged to Group 1 and 42 isolates were obtained from these patients. Group 2 had 6 patients and 9 isolates were obtained from them. All patients in Group 1 harboured different colony morphotypes (Types 1-6) while all 6 patients in Group 2 showed a single type of colony morphology (Type 1). The isolates from Group 1 patients showed higher antimicrobial resistance as compared to Group 2 patients. Molecular typing of the isolates revealed 10 ERIC-PCR patterns and 2 PCR-ribotyping patterns among Group 1 and 2 ERIC-PCR and 1 PCR-ribotyping pattern among patients of Group 2. INTERPRETATION & CONCLUSION: The frequency of different morphotypes of P. aeruginosa and antibiotic resistance was higher among Group 1 patients. On molecular typing, more than one genotype was isolated from Group 1 patients while only one genotype was isolated from patients in Group 2. We conclude that at a given time, chronically infected patients can be colonized by phenotypically and genotypically distinct strains of P. aeruginosa which has an implication in the management of these patients.

Identification of Acinetobacter species isolated from clinical specimens by amplified ribosomal DNA restriction analysis.

BACKGROUND & OBJECTIVES: Taxonomy of Acinetobacter has been changing ever since it was recognized to be associated with human infections. Many biochemical schemes and molecular methods have been used for the species identification of this bacterium. Recently a simple molecular method called amplified ribosomal DNA restriction analysis (ARDRA) has been used to determine the genomospecies of ACINETOBACTER: An attempt is made in the present study to identify the Acinetobacter genomospecies isolated from clinical specimens using ARDRA and to see whether the environmental isolates are similar to those obtained from clinical specimens. METHODS: A total of 142 consecutive isolates of Acinetobacter sp. obtained from different clinical specimens (125) and environmental samples (17) of postoperative neurosurgery-intensive care unit were studied using ARDRA. Amplification was done using primers of 16S rRNA gene followed by restriction with Alu I, Cfo I and Mbo I enzymes separately to obtain a profile of patterns specific for a species. RESULTS: Of the 125 clinical isolates, 107 were Acinetobacter baumannii (genomospecies 2) and 18 were A. calcoaceticus (genomospecies 1); while 11 of the 17 environmental isolates were A. baumannii and 6 had unidentifiable patterns which were not found in the clinical isolates. INTERPRETATION & CONCLUSION: We found that ARDRA was a simple and reproducible method to be used in a clinical laboratory for identification of Acinetobacter species. A. baumannii was found to be the commonest species isolated from the patients and environment in our hospital. The presence of the same species of Acinetobacter in the environment suggests the role of environment as a source of infection to the patients in high risk units.