Conjugating bovine trypsin with oligosaccharides maltotriose, raffinose and stachyose increased its thermostability and suppressed autolysis, without affecting its cleavage specificity. These conjugates accelerated the digestion of protein substrates both in solution and in gel, compared to commonly used unmodified and methylated trypsins.
A rather fast and complicated progression of an infection caused by some strains of Staphylococcus aureus could be associated with the expression and co-action of virulence factor complexes in these strains. This study screened the antibiotic susceptibility and prevalence of virulence markers in isolates of meticillin-resistant S. aureus (MRSA) obtained from patients hospitalized at the University Hospital in Olomouc, Czech Republic. A total of 100 isolates was screened for 13 genes encoding extracellular virulence determinants (tst, pvl, eta, etb, sea, seb, sec, sed, see, seg, seh, sei and sej) and for their distribution in sample types. Eighty-nine isolates were positive for at least one of the genes. Genes for etb, pvl, see and seh were not detected in any of the MRSA isolates. No statistically significant differences in the occurrence of the determinants studied among sample types were found. INTRODUCTIONStaphylococcus aureus is one of the major nosocomial pathogens. Particular attention should be paid to meticillin-resistant S. aureus (MRSA). Resistance to meticillin is determined by the presence of the mecA gene encoding penicillin-binding protein with very low affinity to blactam antibiotics (Chambers, 1997). S. aureus produces a broad spectrum of extracellular and cell wall-associated virulence determinants (Foster, 2002). Among them, a wide variety of surface adhesins known as microbial surface components recognizing adhesive matrix molecules (MSCRAMMs) has been described (Patti et al., 1994).The most common staphylococcal proteins anchored in the cell wall are proteins with affinity to fibrinogen (i.e. clumping factors A and B, encoded by the clfA and clfB genes, respectively), fibronectin (fnbA), collagen (cna), sialoprotein (bbp), elastin (ebpS) and adhesins with unknown function (sdrC and sdrE) (Jonsson et al., 1991;Josefsson et al., 1998; McDevitt et al., 1997;Ní Eidhin et al., 1998; Park et al., 1996;Speziale et al., 1986;Tung et al., 2000). The second group of virulence factors is represented by a family of bacterial proteins with superantigen activity: enterotoxins A-E, G-R and U (encoded by the genes seasee, seg-ser and seu), toxic shock syndrome toxin-1 (TSST-1, encoded by tst), exfoliative toxins A and B (eta and etb) and other toxins such as a-, b-, c-and d-toxin and the Panton-Valentine leukocidin (pvl) (Arbuthnott et al., 1982;Bhakdi & Tranum-Jensen, 1991;Bohach et al., 1990;Prevost et al., 1995).Apart from syndromes caused by toxin production, S. aureus pathogenesis results from synergistic interactions of a variety of the above-mentioned factors. Exfoliative toxin and pyrogenic toxin superantigen production enables S. aureus to cause staphylococcal scalded skin syndrome (SSSS), staphylococcal toxic shock syndrome and staphylococcal food poisoning. Experimental models indicate that the expression of receptors for fibrinogen and fibronectin is associated with endocarditis, whereas the presence of adhesins for sialoprotein, collagen and fibronectin is associated with arthritis and osteomyel...
Background: The prosthetic arteriovenous grafts (AVG) being used increasingly to create hemodialysis access are prone to infections that pose potentially life-threatening infectious and bleeding complications, as well as loss of dialysis access. In this study, we identified the bacteriologic agents of infected AVGs by site swab, blood culture, and prosthesis cultures, and to evaluate the role of microbiological findings in the management of the infection. Methods: We focused on 51 patients with 53 AVGs operated on in our clinic from January 2006 to December 2009. An infected AVG was identified by clinical, ultrasound, and microbiological findings. Sensitivity to antibiotics was determined for all bacterial strains. Isolates were identified by pulsed-field gel electrophoresis (PFGE) of bacterial DNA. In a few cases, positron emission tomography-computed tomography (PET-CT) examination was performed. Results: Strains of Staphylococcus spp., especially S. aureus, were the most frequent cause of infected AVG. All S. aureus strains were sensitive to methicillin. With the exception of a single case, isolates obtained simultaneously from the skin site and the vascular prosthesis were identical genetically. Conclusions: Our results suggest that bacterial infectious agents detected in site swab, blood, or graft culture confirm a suspicion of AVG infection. A PET-CT examination can provide confirmation. The combination of microbiologic and radionuclide findings can improve the management of the AVG infection, but surgery remains essential.
ABSTRACT:A major reason for resistance of Enterobacteriaceae to beta-lactam antibiotics is production of ESBLs and AmpC beta-lactamases. As their more detailed description in poultry is unavailable in the Czech Republic, the presented study aimed at assessing their occurrence and molecular characteristics. A total of 154 composite samples from broilers and 150 cloacal swabs from turkeys were examined. Production of ESBLs was detected in seven Escherichia coli isolates and AmpC enzymes in two E. coli isolates. The most frequent ESBL types were CTX-M-1 and SHV-12 and the most common AmpC enzymes were the CMY-2 types.
The aim of this study was to determine both the occurrence and the genetic basis of resistance to erythromycin among 1 235 <I>Staphylococcus</I> spp. isolates obtained between 2000 and 2006 from (a) raw milk and meat (1 704 samples), (b) foodstuffs produced from these (451 samples), and (c) contact surfaces at processing plants and dairy farms (363 samples) in the Czech Republic. Isolates were screened by broth microdilution method for resistance to erythromycin and further 11 antimicrobial agents. In addition, isolates were screened by agar dilution (erythromycin range 1–128 mg/l) and D-zone test for inducible resistance to macrolides, lincosamides and streptogramin B (iMLS<sub>B</sub>). Forty isolates were found to be either resistant, or intermediate, to erythromycin (3.2% of isolates); of these, more than 50% were identified as <I>S. epidermidis</I>. A total of 15 (1.2%) resistant isolates of staphylococci originated from foodstuffs. Resistance mediated by methylation – i.e. iMLS<sub>B</sub>-resistance (10 isolates with the <I>erm</I>(A) or <I>erm</I> (C) gene) and constitutive MLS<sub>B</sub>-resistance (one isolate with the <I>erm</I> (B) and <I>erm</I> (C) genes) – exhibited a significantly high level of resistance to erythromycin with minimum inhibitory concentrations (MIC) of 64 – >128 mg/l (MIC<sub>mode</sub> = >128 mg/l). In contrast, the efflux mechanism encoded by the <I>msr</I>(A) gene (13 isolates; MIC<sub>range</sub> = 4–128, MIC<sub>mode</sub> = 128 mg/l), the inactivation mechanisms of resistance encoded by the <I>mph</I>(C) gene (three isolates; MIC<sub>range</sub> = 8–32 mg/l), and/or their combination (13 isolates; MIC<sub>range</sub> = 4–128, MIC<sub>mode</sub> = 64 mg/l) led to lower MIC values. The efflux gene <iomsr</I>(A) dominated among the erythromycin-resistant isolates (65% of resistant isolates). This first report on the resistance of <I>Staphylococcus</I> spp. to erythromycin in the Czech Republic illustrates that, while occurrence was low, isolates from food were nevertheless carriers of <I>erm</I> (A), <I>erm</I> (B), <I>erm</I> (C),<I> msr</I>(A) and <I>mph</I>(C) genes for resistance to erythromycin and, therefore, represent a potential thread to humans.
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