[Antimicrobial susceptibility and molecular typing of Enterococcus faecium isolated from humans, chickens and environment in Canary Islands (Spain)]. / Susceptibilidad a antimicrobianos y tipificación molecular de Enterococcus faecium aislados de muestras de origen humano, animal y ambiental en Gran Canaria.

Comparative studies on antimicrobial susceptibility patterns and molecular typing of Enterococcus isolates of different origins provides valuable information concerning the epidemiology of enterococcal infections. We analyzed clinical isolates and we surveyed faecal samples of humans (hospitalised patients and healthy volunteers), faecal samples of poultry and environmental samples. A total of 68 E. faecium isolates were obtained: 43 from humans, 5 from poultry and 20 from water. We compared the antibiotic resistance patterns and pulsed field gel electrophoresis (PFGE) profiles of these strains.We used polymerase chain reaction (PCR) to examine them for the presence of 8 aminoglycoside resistance genes. Differences among percentages of antimicrobial resistance between clinical and non clinical isolates were found. All enterococci were susceptible to vancomycin and teicoplanin. Four aminoglycoside resistance genes were detected, most frequently ant(6)-Ia and aph(3')-IIIa. Presence of isolates resistant to gentamicin but negative for all genes tested suggest that additional resistance genes may exist. VRE are still rare inside and outside hospitals in Gran Canaria (Spain). The high frequency of ampicillin resistance among clinical enterococci and the fact that several isolates share the same PFGE type were isolated from different wards of our hospital suggest that ampicillin-resistant E. faecium are endemic in our Hospital.

Epidemiological evidence of the spread of a Mycobacterium tuberculosis strain of the Beijing genotype on Gran Canaria Island.

Molecular epidemiological studies suggest that particular Mycobacterium tuberculosis strains have an enhanced capacity to spread within a community. One strain, the Beijing genotype, has been associated with outbreaks in a number of communities throughout the world. IS6110 restriction fragment length polymorphism (RFLP) analysis was performed on M. tuberculosis isolates from 566 of the 721 patients (78.5%) diagnosed with tuberculosis (TB) on Gran Canaria Island from 1993 to 1996, as well as 35% of isolates from 1991-1992 (85 strains). RFLP identification of the family of strains of the Beijing genotype was confirmed by spoligotyping. Medical records of all patients were reviewed and epidemiological links were identified. Of 566 M. tuberculosis isolates from 1993 to 1996 with RFLP available, 72% belonged to clusters. The largest contained 75 cases and was caused by a strain of the Beijing genotype that was introduced to the island in 1993. It was found in 10 patients in 1993 (5.5%), 12 in 1994 (8.1%), 18 in 1995 (16.4%), and 35 in 1996 (27.1%). Epidemiological linkage was confirmed for 68% of cases. This study has demonstrated rapid dissemination of this strain of the Beijing genotype. This genotype might play an important role in the future of the worldwide tuberculosis epidemic.

Exogenous reinfection with tuberculosis on a European island with a moderate incidence of disease.

The frequency and determinants of exogenous reinfection and of endogenous reactivation of tuberculosis in patients previously treated are poorly understood. In Gran Canaria Island, Spain, between 1991 and 1996, 962 tuberculosis cases were confirmed by culture. Drug susceptibility testing was performed on available bacterial isolates and IS6110-based RFLP genotyping was carried out. Twenty-three patients (2.4%) had two positive cultures separated by at least 12 mo, 18 of whom had bacterial DNA available for genotypic analysis. The initial and final isolates from eight (44%) were different genotypes, indicating exogenous reinfection. Six of them were retreated after cure and two retreated after default. Six were HIV seronegative and two were HIV seropositive. Endogenous reactivation was seen in the remaining 10 patients of whom eight were retreated after default and two after cure. Three of the eight (38%) being retreated after default developed multidrug resistance. One genotype was responsible for a second episode of tuberculosis in five cases, three exogenous reinfections and two endogenous reactivations. In the context of a moderate incidence of tuberculosis, exogenous reinfection is an important cause of TB recurrence, even in HIV-seronegative patients.