Chitosan-protein scaffolds loaded with lysostaphin as potential antistaphylococcal wound dressing materials.

AIMS: The development of technology for preparing chitosan-protein scaffolds loaded with lysostaphin, which potentially could be used as dressing for wound treatment and soft tissue infections caused by Staphylococcus aureus. METHODS AND RESULTS: The unique technology of chitosan solubilization using gaseous CO(2) instead of organic or inorganic acids was used for the incorporation of lysostaphin, the enzyme that exhibits bactericidal activity against staphylococci, within the structure of chitosan-protein sponges. The developed chitosan-protein scaffolds loaded with lysostaphin revealed high antistaphylococcal activity, which has been confirmed with a large (n = 143) collection of clinical (skin and wound infections) and animal (bovine mastitis) isolates of these bacteria, including MRSA. No change of bactericidal activity of the lyophilized materials has been observed during half-year storage at 4°C. CONCLUSIONS: The developed materials are potential candidates for preparing biologically active, antistaphylococcal wound dressing materials. SIGNIFICANCE AND IMPACT OF THE STUDY: Staphylococci belong to the most popular and most burdensome aetiological factors of wound and soft tissues infections. The developed chitosan-protein scaffolds loaded with lysostaphin could be a possible solution to problems associated with treatment of these infections.

Identification and antimicrobial resistance of Enterococcus spp. isolated from surface water.

In the study species distributions and antimicrobial resistance profiles were determined among riverine Enterococcus spp. Susceptibility of the isolates was tested against: ampicillin, imipenem, teicoplanin, vancomycin, erythromycin, linezolid, fosfomycin, ciprofloxacin, levofloxacin, moxifloxacin, tetracycline, high levels of gentamicin and streptomycin. The enterococci were detected in all of the analyzed water samples, periodically exceeding the mandatory standards of the EU Bathing Water Directive. Isolates were predominantly E. faecium (68.6%) and E. faecalis (21.6%) strains. The remaining isolates belonged to E. casseliflavus/gallinarum (5.2%), E. hirae (3.9%), and E. durans (0.7%). Of enterococci strains, 27% were susceptible to all tested antimicrobial agents and as much as 9% were classified as multiple-antibiotic-resistant (MAR). Resistance to erythromycin was common in all investigated areas (55%), followed by resistance to ciprofloxacin (22%) and tetracycline (14%). The resistance phenotypes related to glycopeptides and high-level aminoglycosides were also observed. Relatively low frequency of ampicillin resistance was found among studied strains, in contrast to the frequent use of this antimicrobial agent in Poland. According to the obtained results the Enterococcus should be regarded as an important genus, according to its potential contribution to dissemination of antimicrobial resistance in the water environment.

Epidemiological investigation of nosocomial outbreak of staphylococcal skin diseases in neonatal ward.

During a 1-month period, eight neonates developed staphylococcal skin disease diagnosed as a bullous impetigo in the maternity unit of the Provincial Hospital in Gdansk. An epidemiological investigation based on phenotyping and genotyping methods was performed. All neonates involved in the outbreak, their mothers and 15 staff members were screened for carriage of Staphylococcus aureus by nasal swabs. Isolated strains were compared with strains cultured from affected skin and purulent conjunctiva of infected newborns. Isolates were analyzed for the presence of the etA and etB genes using polymerase chain reaction and genotyped by pulsed-field gel electrophoresis (PFGE) and coa gene polymorphism. The analyzed S. aureus strains were methicillin-sensitive and could be divided into two groups according to antibiotyping, phage typing, coa polymorphism and PFGE pattern. The first group consisted of etA and etB negative strains, and the second one involved only the etB positive ones. Our results have shown that there were two different clusters of infection caused by two populations of S. aureus strains. Among the 15 medical staff members screened we have found seven carriers. However, phage typing revealed that distinct strains unrelated to the outbreak isolates were carried. Although we have not been able to establish the source of bacteria involved in the outbreak, our results suggest that for both groups, mothers could be the source of the infecting strains.

[Hemolytic activity of Klebsiella pneumoniae and Klebsiella oxytoca]. / Hemolityczna aktywnosc paleczek Klebsiella pneumoniae i Klebsiella oxytoca.

We demonstrated that Klebsiella pneumoniae and Klebsiella oxytoca possess a selective haemolytic activity on rabbit erythrocytes. Thirty one Klebsiella strains (18 strains of K. pneumoniae and 13 strains of K. oxytoca) were isolated from hospitalized patients. The liquid (Trypcase-soy broth--TSB) and solid (Trypcase-soy agar--TSA) medium, containing the red cells were used for the tests. All the screened strains showed a haemolytic effect on rabbit erythrocytes, provided that the supernatants of the cultures were preincubated with beta-mercaptoethanol or calcium chloride. There was no human and sheep erythrocyte lysis.

[Usefulness of plasmids as epidemiologic markers for typing of Klebsiella]. / Przydatnosc plazmidów jako epidemiologicznych markerów do typowania paleczek Klebsiella.

The study was aimed at evaluation of utility of plasmids as epidemiological markers for interspecific differentiation of 200 strains of Klebsiella isolated from patients with generalized infections and hospitalized at intensive care ward of the Gdansk Medical Academy. Strains isolated from the ward environment were also investigated. In the first phase of this study classical methods of typing were used, such as determination of the biochemical, bacteriocin (susceptibility to 8 bacteriocins) and phage types, and MIC for 9 antibiotics. Basing on these methods it was found that 41 types of Klebsiella pneumoniae, 13 types of Klebsiella oxytoca and 1 type of Klebsiella ozenae occur. Six groups of bacteria were differentiated in the group which had the same type. These strains were investigated for plasmid and restrictive patterns. Identity of types occurring in individual groups was detected. For one of them, a restrictive pattern was determined by cleavage of plasmid DNA by a restrictive Eco RV enzyme. In remaining groups such pattern was not found, both after treatment with Eco RV and Hha I enzyme and this may be associated with modification of the plasmid DNA. Strains belonging to one of these groups did not contain plasmids in their cells.

[Mycoplasma pneumonia]. / Mykoplazmowe zapalenia pluc.

Two cases of mycoplasma pneumonias are presented. Initially this etiology was not suspected. Prior to hospitalization they were treated with cefamandole and carbenicillin and cephradine with gentamycin without any improvement in the clinical state of the patients. After serological tests finding a high titer of serum antibodies (1: 2560) the therapy was altered in the first patient to minocycline (in a dose of 200 mg per day for 16 days) and in the second to doxycycline (in a dose of 200 mg per day for 10 days). The first patient improved clinically after two days of altered therapy, the second after 10 days. Both patients were discharged fully recovered after 32 and 36 days of hospitalization.

Phage typing of Klebsiella strains in epidemiological studies.

A set of 14 routinely applied bacteriophages was used for the typing of Klebsiella pneumoniae and Klebsiella oxytoca strains isolated from patients in 1983-1986. The phage-sensitive strains (65%) differed in respect to the place and time of isolation which manifested itself by an occurrence of specific lysotypes in Wroclaw, Gdansk, Wernigerode and Wloclawek, as well as various repeatibility on the lysotypes within 10 years.