ABSTRACT
To analyze the mechanisms of resistance to carbapenems among imipenem resistant A. baumannii recovered from different wards at Charles Nicolle Hospital. From January to December 2007, 50 carbapenem-resistant A. baumannii isolates were recovered from hospitalized patients. MICs were performed by agar dilution method and interpreted according to CLSI guidelines. Metallo-beta-lactamase production was evaluated using imipenem-EDTA disk synergy test. PCR and DNA sequencing targeting blaOXA genes were performed and pulsed field gel electrophoresis was used for epidemiologic study. Most of the isolates were obtained from patients hospitalized in surgery [62%] and Intensive Care Units [22%]. All strains showed high level of resistance to ticarcillin [MIC50 > 2048micro g/ml], ticarcillin-clavulanic acid [MIC50 >1024micro g/ml], aztreonam [MIC50 = 512micro g/ml], ceftazidim [MIC50 = 512micro g/ml], imipenem [MIC50 = 512micro g/ml], meropenem [MIC50 =128micro g/ml] and cefepime [MIC50 = 256micro g/ml]. Metallo-beta-lactamase production was negative for all isolates. The co-existence of blaOXA-51-like/ blaOXA-23-like was detected in 82% [n= 41]. The genes blaOXA- 24-like and blaOXA-58-like were not found in any isolate. All isolates harboured a blaOXA-51-like gene. Sequencing confirmed the presence of blaOXA-23 and blaOXA-69 genes. Eight distinct patterns were observed [A: 41 isolates, B: 1 isolate, C: 1 isolate, D: 1 isolate, E: 1 isolate, F: 2 isolates, G: 1 isolate, H: 2 isolates]. Production of OXA-23 was the important mechanism of resistance to carbapenem among A. baumannii. Strengthening of prevention measures are required to control further spread of carbapenemases in Tunisia
ABSTRACT
A. baumannii is an important opportunistic pathogen widely distributed in the hospital environment and responsible for a variety of nosocomial infections especially in patients from intensive care units. We describe an outbreak of Acinetobacter baumannii [16 stains] in 3 intensive care units [I, II, III] at Charles Nicolle hospital of Tunis over a 5 month period [March to July 2005]. The antimicrobial susceptibility was determined by disc diffusion test and the genetic relatedness of isolates was done by Random Amplified Polymorphic DNA [RAPD] analysis. Two strains not related to the outbreak were used for the discrimination of the technique. Samples were collected from blood [44%], materials [31%], pus [6.5%], urines [6.5%] and respiratory tract [12.5%]. Antibiotic resistance pattern showed 2 different profiles. However, molecular typing of isolates revealed 3 distinct profiles [A, B, C] represented respectively by 8, 7 and one isolates. The major profile was the profile A found in 5 patients and in materials. It was appeared firstly in intensive care unit I. then in the 2 other units [II and Ill]. The profile B was observed also in the 3 units. However, the profile C was found in one patient in unit I. These data emphasize the need for active surveillance for multidrug-resistant Acinetobacter baumannii, and the value of molecular typing of strains in hospital settings to investigate spread of infection
Subject(s)
Acinetobacter Infections , Hospitals, Teaching , Disease Outbreaks , Drug Resistance, Multiple, Bacterial , Intensive Care Units , Microbial Sensitivity Tests , Cross InfectionABSTRACT
A retrospective multicentric study was carried out over a period of 2 years [1999-2000]. 2659 strains of pseudomonas aeruginosa were collected from 4 university hospitals [charles Nicolle Hospital, pediatric Hospital and national center of Bone Marrow Transplantation in Tunis, Habib Bourguiba Hospital in Sfax]. Epidemiological profile and antibiotic susceptibility were analyesd. All bacteria were identified by conventional methods and antibiotic susceptibility tests were performed according to CA-SFM guidelines. The strains were recovered essrntially from surgical wards [33%] and intensive care units [22%]. Pseudomonas aeruginosa was isolated mainly from pus [36%] urine [32%]and respiratory samples [18%]. 25% of strains were resistant to ticarcilline, 18% to cefsulodine, 9% to ceftazidime, 14% to imipenem and amikacin and 25% to ciprofloxacin. Moreover, the resistance rates varied from hospital to hospital and from unit to another. The resistant strains were isolated particularly from urology and intensive care units: respectively 62% and 39% for ticarcilline; 26% and 13% for ceftazidime. The acquired resistance to b-lactams seems largely due to penicillinase production. The frequency of resistance to ceftazidime was the lowest and seem associated to chromosomal cephalosporinase over production
Subject(s)
Drug Resistance, Microbial , Microbial Sensitivity Tests , Retrospective Studies , Multicenter Studies as TopicABSTRACT
Enterococci are an important cause of infective endocarditis. Their resistance to most of the antibiotics involve real therapeutic problems. We report the first clinical isolate of glycopeptide resistant enterococus from blood culture of patient with a prostetic valve endocarditis. The strain is an E.faecium with a high level of resistance to vancomycin and teicoplanin [MlC>256mg/I],a low level of resistance to gentomycin [MIC=6mg/l] and susceptibile to ampicillin [MIC=1.5mg/I]. Therapeutic failure was observed leading to a surgical treatment. Therapy of such infection caused by multiresistant Enterococcus must be based on the study of bactericidal activity of antibiotic associations. In order to control the spread of this emerging resistance, the implementation of control measures is necessary