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SUMMARYThis study was undertaken to determine the distribution of phage types of Staphylococcus aureus isolates from hospital outbreaks or sporadic cases received in our laboratory during the past 14 years. The records for 15803 isolates from 55 Spanish hospitals have been analysed.In relation to sporadic isolates we have been able to detect the predominance of phage group I and non-typable staphylococcal strains. Since 1989, we have observed a considerable increase in hospital infection caused by methicillinresistant S. aureus strains which we could differentiate in to two groups; one belonging to phage group III (6/47/54/75/77/84/85) and other groups of nontypable strains which could be classified as phage group I-III after heat treatment (29/77/84) and with similar patterns by reverse typing (6/47/53/54/75/83A/ 84/85/W57/1030/18042).During 1990 and 1991, these strains have extended widely to at least six different autonomous regions creating an epidemic situation in Spain.

The capacity of Candida spp. to form biofilms allows them to attach either to living or inert surfaces, promoting their persistence in hospital environments. In a previous study, we reported strain-to-strain variations in Candida spp. biofilm development, suggesting that some genotypes may be greater biofilm formers than others. In this study, we hypothesize that isolates pertaining to clusters may be found more frequently in the environment due to their ability to form biofilms compared to singleton genotypes. Two hundred and thirty-nine Candida spp. isolates (78 clusters) from candidemia patients admitted to 16 hospitals located in different cities and countries—and the same number of singleton genotypes used as controls—were tested in terms of biofilm formation using the crystal violet and the XTT reduction assays. Candida albicans clusters showed higher biofilm formation in comparison to singleton genotypes (P < .01). The biofilms formed by intra-hospital C. albicans clusters showed higher metabolic activity (P < .05). Furthermore, marked variability was found among species and type of cluster. We observed that the higher the number of isolates, the higher the variability of biofilm production by isolates within the cluster, suggesting that the production of biofilm by isolates of the same genotype is quite diverse and does not depend on the type of cluster studied. In conclusion, candidemia Candida spp. clusters—particularly in the case of C. albicans—show significantly more biomass production and metabolic activity than singleton genotypes.