Susceptibility of Staphylococcus aureus strains to commercial therapeutic phage preparations.

OBJECTIVES: The aim of this study was to determine the susceptibility of Staphylococcus aureus strains to commercial phage preparations. The strains were isolated from clinical patients as well as from nasal mucosa of healthy carriers. BACKGROUND: The elevating number of antibiotic-resistant S. aureus strains present a therapeutic challenge, especially in high-risk patients. One of the promising ways to solve this problem is phage therapy. METHODS: Susceptibility of 111 carrier strains of S. aureus (4 strains were methicillin-resistant; MRSA) and 81 clinical isolates from bloodstream or skin and soft tissue infections (28 were MRSA) to four commercial phage preparations was assessed in vitro by spot assay. The clonality of S. aureus strains was determined by spa typing. RESULTS: Spa typing revealed 97 distinct spa types. A proportion of 73-80 % of the tested S. aureus strains were revealed to have in vitro phage susceptibility, depending on the clonal affiliation of the strains and phage preparation tested. The susceptibility to phage preparations was significantly higher in MRSA strains (p < 0.001). CONCLUSIONS: In vitro results indicate a promising therapeutic potential of the tested commercial anti-staphylococcal phage preparations. They could be applied to a broad spectrum of bacterial clones, and have an excellent activity especially against MRSA strains (Tab. 2, Fig. 2, Ref. 43).

Characterisation of Cronobacter strains isolated from hospitalised adult patients.

Bacteria belonging to the genus Cronobacter are opportunistic pathogens known for causing rare but serious infections in neonates, including meningitis, necrotising enterocolitis and sepsis. Cronobacter infections occur also in adult populations, however, they generally have milder manifestations and their prevalence is uncertain. In this study, the presence of Cronobacter strains from adult patients in the University Hospital in Bratislava was investigated and overall 18 confirmed isolates from 321 patients (5.3%) were recovered. No Cronobacter positive sample was detected in 215 sputum samples from outpatients. The highest occurrence of Cronobacter strains was observed from stroke patients and this may be associated with an abnormal swallowing ability. The isolated strains belonged to the species Cronobacter sakazakii and Cronobacter malonaticus. In silico genotyping (MLST, CRISPR-cas array profiling) of whole genome sequences assigned the strains to three different MLST clones. The majority (12/18) of the isolated strains were sequence type ST513 or single locus variants ST514 and ST515, thereby being members of C. sakazakii pathovar clonal complex CC4. However, according to core genome MLST analysis the ST513-ST515 strains created a unique cluster substantially different from other CC4 strains. The isolated strains were susceptible to 18 tested antibiotics. All strains possess a genomic island encoding for increased thermal tolerance. As Cronobacter strains are frequently present in dried foods of plant origin, spread of a specific clone within a hospital may be caused by food transmission and may be facilitated by its tolerance to environmental stresses such as desiccation and temperature.