[Staphylococcus aureus prevalence among hospitalized patients]

OBJECTIVE. To determine the prevalence of Staphylococcus aureus strains among hospitalized patients at the beginning of their hospitalization and during their treatment and the resistance of strains to antibiotics, and to evaluate epidemiologic characteristics of these strains. PATIENTS AND METHODS. Sixty-one patients treated at the Department of Cardiac, Thoracic and Vascular Surgery were examined. Identification of Staphylococcus aureus strains was performed using plasmacoagulase and DNase tests. The resistance of Staphylococcus aureus to antibiotics, beta-lactamase production, phagotypes, and phagogroups were determined. The isolated Staphylococcus aureus strains were tested for resistance to methicillin by performing disc diffusion method using commercial discs (Oxoid) (methicillin 5 microg per disk and oxacillin 1 microg per disk). RESULTS. A total of 297 Staphylococcus aureus strains were isolated. On the first day of hospitalization, the prevalence rate of Staphylococcus aureus strains among patients was 67.3%, and it statistically significantly increased to 91.8% on days 7-10 of hospitalization (P<0.05). During hospitalization, patients were colonized with Staphylococcus aureus strains resistant to cephalothin (17.6% of patients, P<0.05), cefazolin (14.6%, P<0.05), tetracycline (15.0%, P<0.05), gentamicin (37.7%, P<0.001), doxycycline (30.7%, P<0.001), and tobramycin (10.6%, P>0.05). Three patients (4.9%) were colonized with methicillin-resistant Staphylococcus aureus strains, belonging to phage group II phage type 3A and phage group III phage types 83A and 77; 22.6-25.5% of Staphylococcus aureus strains were nontypable. During hospitalization, the prevalence rate of phage group II Staphylococcus aureus strains decreased from 39.6% to 5.7% (P<0.05) and the prevalence rate of phage group III Staphylococcus aureus strains increased to 29.5% (P<0.001). CONCLUSIONS. Although our understanding of Staphylococcus aureus is increasing, well-designed community-based studies with adequate risk factor analysis are required to elucidate further the epidemiology of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus. Surveillance of methicillin-resistant Staphylococcus aureus provides relevant information on the extent of the methicillin-resistant Staphylococcus aureus epidemic, identifies priorities for infection control and the need for adjustments in antimicrobial drug policy, and guides intervention programs.

Evaluation of bacteriophage ϕ11 host recognition protein and its host-binding peptides for diagnosing/targeting Staphylococcus aureus infections

BACKGROUND

Evaluating the potential of using both synthetic and biological products as targeting agents for the diagnosis, imaging, and treatment of infections due to particularly antibiotic-resistant pathogens is important for controlling infections. This study examined the interaction between Gp45, a receptor-binding protein of the ϕ11 lysogenic phage, and its host Staphylococcus aureus (S. aureus), a common cause of nosocomial infections.

METHODS

Using molecular dynamics and docking simulations, this study identified the peptides that bind to S. aureus wall teichoic acids via Gp45. It compared the binding affinity of Gp45 and the two highest-scoring peptide sequences (P1 and P3) and their scrambled forms using microscopy, spectroscopy, and ELISA.

RESULTS

It was found that rGp45 (recombinant Gp45) and chemically synthesised P1 had a higher binding affinity for S. aureus compared with all other peptides, except for Escherichia coli. Furthermore, rGp45 had a capture efficiency of > 86%; P1 had a capture efficiency of > 64%.

CONCLUSION

These findings suggest that receptor-binding proteins such as rGp45, which provide a critical initiation of the phage life cycle for host adsorption, might play an important role in the diagnosis, imaging, and targeting of bacterial infections. Studying such proteins could accordingly enable the development of effective strategies for controlling infections.

[Place of Staphylococcus aureus in the bacterial isolations of the University Hospital Center of Dakar. Preliminary results of serotyping and phage typing]

Out of 18 837 strains isolated between 1972 and 1980, by the laboratory of bacteriology of the Dakar Teaching Hospital, 2 925 strains of Staphylococcus aureus have been identified. This germ was the cause of 14,4 p. 100 of all diagnosed septicemia, ranging second in frequency after Salmonella. It was the most frequent germ in pura (54,8 p. 100 of strains) and rated 29,2 p. 100 of the strains isolated from pleural fluids. It was less frequent in bacterial meningitidis (2,5 p. 100) and in infections of the urinary tract (3,6 p. 100). About one hundred coagulase + strains were studied further. A clumping factor was found in 98 p. 100 of the strains (Staphyslide test). In addition, serotyping and lysotyping were carried out: --80,8 p. 100 of strains were lysotyped --25,6 p. 100 of them belonging to type I --7,7 p. 100 to type II --10,3 p. 100 to type III --33,3 p. 100 belonging to two or three types --11,5 p. 100 to I and II --16,7 p. 100 to I and III --5,1 p. 100 to I and II and III Some strains gave positive responses with 94-96 and 187 phages.