Staphylococcus aureus causes hospital-acquired (HA), community-acquired (CA) and companion animal and livestock-associated (LA) infections. Molecular epidemiology studies suggest that although host speciicity may be associated with speciic genetic lineages, recent human-to-animal and animal-to-human transmissions related to mobile genetic elements have been described. Gene transfers include virulence and antibiotic resistance genes, thus making it diicult to control multidrug resistance S. aureus infections. Bacteriophages (phages) and endolysins, the enzymes responsible for bacterial lysis by phages, are alternatives to the use of antibiotics for the control of S. aureus infections. In this work, we review current advances in the development of phage therapy and the study and design of recombinant endolysins to treat S. aureus infections. Preliminary results of bacteriophage isolation based on molecular epidemiology knowledge show that bacteriophages are speciic of genetic lineages and that this strategy may be used as an approach to isolate and evaluate new bacteriophages for therapy.

We describe a new method which uses cold absolute methanol-prefixed cells for adherence of enteropathogenic Escherichia coli to HEp-2 cells. We found that a method using bacteria grown in Penassay broth to 10 6 to 10 7 CFU/ml and incubated with prefixed cells for 3 h at 37؇C, showed 100% sensitivity and specificity against a method using live cells. The mechanisms by which enteropathogenic Escherichia coli (EPEC) causes diarrhea are uncertain; however, its ability to adhere to small intestine mucosa and efface epithelial microvilli is an important fact (6). Cravioto et al. (2) found that 80% of EPEC strains presented mannose-resistant adherence to HEp-2 cells. Three distinct patterns of adherence have been described: localized adherence (LA), in which bacteria attach to and form microcolonies in distinct regions of the surface; diffuse adherence (DA), in which bacteria adhere evenly to the whole cell surface, and aggregative adherence (AggA), in which aggregated bacteria attach to the cell in a stacked-brick arrangement (7, 8, 11). LA is a feature of attaching and effacing EPEC strains (5). The attaching and effacing lesion by EPEC is characterized by intimate attachment to brush border microvilli and actin concentration in this specific site which may be observed by fluorescence actin stain (FAS) (4). The adherence assay uses living cells. For this reason the utility of the method has been limited to some research centers. In addition, it has proven difficult to maintain tissue cultures in ordinary laboratories. We used strain E2348/69 serotype O127:H6 and strain B171 serotype O111:NM, kindly provided by M. S. Donnenberg and Jorge Giron, from the Center for Vaccine Development, University of Maryland. We used four LA ϩ strains (O111ab:H Ϫ , O119:H2, O114:H2, and O55:H7), one DA ϩ strain (O75), two AggA ϩ strains (O?: H10 and 0136:H33), and one strain without adherence (NA) (040), all of them kindly provided by Alejandro Cravioto, Departamento de Salud Publica, Facultad de Medicina, UNAM, Mexico. We also used 72 fresh isolates of EPEC strains from 72 children hospitalized in Hospital Infantil de Mexico for whom the clinical laboratory did not find another diarrhea causal agent. These were isolated during 6 months from March to August. The HEp-2 cell assay was done as previously described (2). Confluent 70 to 80% growth of HEp-2 cells was obtained on 13-mm diameter glass coverslips placed in the wells of a multiwell tissue culture plate (Nunc, Denmark). Bacteria were grown statically in Penassay broth overnight at 37ЊC. Twenty microliters of each bacterial culture was mixed with minimal essential medium (Gibco), 1% Dmannose was added to obtain a final concentration of between 10 6 and 10 8 CFU/ml, and the mixture was incubated for 3 h. The coverslips were washed three times with phosphate-* Corresponding author.