Identification, characterization and purification of the lantibiotic staphylococcin T, a natural gallidermin variant.

Staphylococcin T (StT), an antibacterial agent produced by a Staphylococcus cohnii T strain, was purified to homogeneity by ammonium sulphate precipitation, gel filtration, cation exchange and fast performance liquid chromatography (FPLC). The final yield was about 20%, and over a 1000-fold increase in the specific activity was obtained. Mass determination (2166 Da), amino acid sequencing (Ile-Ala-Xaa-Lys-Phe-Leu-Xaa-Xaa-Pro-Gly-Xaa-Ala-Lys-block) and DNA sequencing demonstrated that StT is identical to gallidermin, a lanthionine-containing antimicrobial peptide. StT has a broad spectrum of bactericidal activity against Gram-positive and some Gram-negative bacteria. StT appears to damage cell membrane, and as a result causes an efflux of ions and an immediate block in macromolecular synthesis. Moreover, electron microscopic observations reveal morphological changes, with a loss of ribosomes and condensation of the nucleoid DNA. These changes are followed by a dissolution of the cell contents resulting in a bacterial ghost composed of seemingly intact cell walls with remnants of the cytoplasmic membrane and internal structure. Since StT exhibits antimicrobial activity especially against the Staphylococcus species, this compound may be of use in the treatment of staphylococcal infections.

[Susceptibility to antibiotics of Staphylococcus aureus strains]. / Wrazliwosc na antybiotyki szczepów Staphylococcus aureus.

Staphylococcus aureus is a very important pathogen in humans about 20% of all bacterial infections are caused by S. aureus. Because the staphylococcal sensitivity patterns have changed, the aim of this study was to investigate the current susceptibility of the S. aureus strains to 9 antibiotics: penicillin (P), amoxacillin/clavulanic acid (AMC), erythromycin (E), cortimoxazole (SXT), tetracycline (T), chloramphenicol (C), mupirocin (MUP), gentamicin (Ge) and vancomycin (Va). Susceptibility testing was performed by disc diffusion technique, by the procedure outlined by the National Committe for Clinical Laboratory Standards (NCCLS). Susceptibility to methicillin was determined using 5 micrograms methicillin disks. beta-lactamase production in the penicillin-resistant strains was detected with nitrocefin impregnated disk (Cefinase, BBL Microbiology system). The microbiological characteristics of the samples: 338 of the isolates were derived, from noses and the throats 382--from surgical wound secretions. The analysis of the results showed that most S. aureus strains (82.8%) are penicillin resistant and beta-lactamase producing 13.5% of all strains were methicillin-resistant. 16.5%--were erythromycin resistant; 3.2%--were cotrimoxazole resistant; 51.4%--were mupirocin resistant; 20.6%--were gentamicin resistant. All of the strains were vancomycin sensitive.

[Presence of various Acinetobacter species in urinary tract infections]. / Wystepowanie róznych gatunków z rodzaju Acinetobacter w zakazeniach ukladu moczowego.

Species classification of 39 strains of Acinetobacter isolated from urinary tract infections (UTI) was performed by API 20NE tests. On the whole 24 biotypes were differentiated which formed 4 species and one biotype had no defined species classification. Acinetobacter baumani was most numerously represented. Seventy seven percent of strains were isolated from urine samples from women. About 90% of Acinetobacter strains were isolated as single pathogens. Sensitivity of these strains to 23 antibiotics and chemotherapeutics using ATB-UR and disc diffusion technique was evaluated. Of all cephalosporins tested ceftazidime was the most active. All strains tested were sensitive to imepenem. The high percentage of strains was sensitive to quinolones of IIIrd generation. The high percentage of strains was resistant to nitrofurantoin.

Haemolytic activity of Morganella morganii strains.

Haemolytic activity on solid and liquid media of 103 Morganella morganii strains isolated from clinical sources was investigated. The ability to produce haemolysin was found in 42.7% of strains. All strains capable to produce haemolysin on blood agar media also revealed haemolytic activity in some liquid media. Haemolysins were found in the supernatants and filtrates of the cultures in peptone water but not in Brain Heart Infusion and Trypticase Soy Broth. The maximal titer of haemolysin was observed in the logarithmic phase of growth. Heating and incubation with trypsin led to complete loss of haemolytic activity.