Screening of ESBL-producing Enterobacteriacae concomitant with low degree of transmission in intensive care and bone marrow transplant units.

BACKGROUND: Extended-spectrum ß-lactamase-producing Enterobacteriaceae (ESBL-E) are spreading worldwide in both hospital and community settings. In this study, the molecular epidemiology and the transmission modalities of ESBL-E in intensive care- and bone marrow transplant were investigated. METHODS: All patients included in this study were screened for presence of ESBL-E on admission and weekly. Relevant ß-lactamase genes were identified by PCR and sequencing. RESULTS: A total of 669 patients were included in this study. On admission, ESBL-producing Escherichia coli were detected in 49 (7.3%) patients and ESBL-producing Klebsiella pneumoniae in one patient. The most common ESBL types among E. coli isolates were CTX-M-15 (38.8%) and CTX-M-1 (38.8%). Furthermore, 12 of 49 (24.5%) ESBL-producing E. coli could be assigned to the epidemic clone ST131. A single patient acquired ESBL-producing E. coli during the hospital stay but cross-transmission could not be demonstrated. Among 1095 environmental samples none revealed ESBL. CONCLUSIONS: Our results suggest that early detection of ESBL-producing Enterobacteriaceae and consequent implementation of basic hygiene measures and contact isolation may reduce the transmission rate during the hospital stay.

Resistance to tobramycin and colistin in isolates of Pseudomonas aeruginosa from chronically colonized patients with cystic fibrosis under antimicrobial treatment.

Tobramycin and colistin represent 2 standard antimicrobial agents in the treatment of cystic fibrosis (CF) patients who are chronically colonized with Pseudomonas aeruginosa. In this study, we determined the rate of resistance to tobramycin and colistin in 1844 isolates of P. aeruginosa obtained from 22 CF patients under alternate therapy with inhaled tobramycin and colistin. Resistance to tobramycin was observed in 27.5% of isolates. In contrast, all isolates were susceptible to colistin. Molecular typing of selected isolates suggested that only 1 clone occurred over time in each patient. To conclude, resistance to tobramycin in P. aeruginosa isolates from CF patients under antimicrobial therapy may occur while colistin resistance remains uncommon.

Prevalence and antimicrobial susceptibility of microorganisms isolated from sputa of patients with cystic fibrosis.

BACKGROUND: New emerging pathogens and associated antimicrobial resistance mechanisms have been observed in the respiratory tract of patients suffering from cystic fibrosis (CF) in the last years. Amongst others, the rate of metallo-beta-lactamase (MBL)-producing Pseudomonas aeruginosa strains is growing. However, there are no published data on the prevalence of MBL-producing P. aeruginosa in CF patients to our knowledge. METHODS: In this study, 271 sputum samples of 60 CF patients were collected during a 12-months period. Microbiological cultures and antimicrobial susceptibility tests of the most frequently isolated bacteria were performed. RESULTS: 464 bacterial and 414 fungal strains were isolated and characterized. 63.3% of the patients harbored Staphylococcus aureus, 50% P. aeruginosa, 16.6% Haemophilus influenzae, 15% Stenotrophomonas maltophilia and 13.3% non tuberculous Mycobacteria (NTM). Methicillin resistant S. aureus (MRSA) and MBL-producing P. aeruginosa were detected in 3 (5%) and 5 (8.3%) patients respectively. Among the fungi, Aspergillus fumigatus and Candida albicans showed the highest prevalence. CONCLUSIONS: The detection of MBL-producing P. aeruginosa and MRSA in CF patients confirms that antimicrobial resistance patterns should be always kept under surveillance. Moreover hygiene regulations in CF clinics should prevent a further spread of resistant bacterial strains.