Enterococcus faecalis and Candida albicans in the dental root canal and periapical infections.

OBJECTIVE: The aim of the present study was to examine the prevalence of Enterococcus faecalis and Candida albicans in endodontic infections. METHODS: Samples for microbiological examination were collected from 32 patients with deep dental caries, infected dental root canal, or periapical infection. RESULTS: Cultivation of the dental samples yielded four strains of Enterococcus faecalis (12.5 %), and three strains of Candida albicans (9.4 %). All Enterococcus faecalis isolates were susceptible to ampicillin, one isolate was resistant to tetracycline, two to erythromycin and azithromycin (additional 2 had intermediate susceptibility), and one strain had intermediate susceptibility to ciprofloxacin and moxifloxacin. CONCLUSION: We conclude that Enterococcus faecalis and Candida albicans can participate in the dental root canal and periapical infections, and the use of effective irrigant solutions and intracanal medicaments active against these microbes is important in order to prevent endodontic therapy failures. Unexpected was the isolation of C. albicans from a nine-year-old child with periodontitis apicalis. This finding must draw attention to the possibility that even at such a young age, this microorganism could be a potential etiological agent in endodontic infections (Tab. 2, Ref. 34). Text in PDF www.elis.sk.

[Susceptibility of Staphylococcus aureus biofilms to vancomycin, gemtamicin and rifampin]. / Citlivost' kmenov staphylococcus aureus rastúcich v biofilme na vankomycín, gentamicín a rifampicin.

STUDY OBJECTIVES: To detect biofilm formation in Staphylococcus aureus strains and to determine the minimal biofilm inhibition concentrations (MBIC) and the minimal biofilm eradicating concentrations (MBEC) of vancomycin, gentamicin and rifampin. To compare the MBIC and MBEC with the minimal inhibition concentration (MIC) and minimal bactericidal concentration (MBC) data for planktonic Staphylococcus aureus forms that are commonly used in antimicrobial susceptibility testing for the purposes of individualized therapy. PATIENTS AND METHODS: Fifteen S. aureus strains isolated from central venous catheters, intratracheal tubes and wound drainage tubes from the patients of the University Hospital, Bratislava-Staré Mesto were included in the study. Selected virulence factors were characterized. The biofilm formation potential was measured by a modified crystal violet micro-assay. The presence of viable cells biofilm in was tested using 3-(4,5-dimethylthiazol--2-yl)-2,5-diphenyl tetrazolium bromide (MTT). The MIC and MBC of vancomycin, gentamicin and rifampin was tested in planktonic S. aureus forms by the broth microdilution method. The MBIC and MBEC of these antimicrobial drugs for biofilm S. aureus forms were determined by a modified microdilution method. Student's t-test was used for statistical analysis of the results. RESULTS: All of the study strains formed biofilm, with only two of them having a low biofilm formation potential. MTT revealed moderate to high metabolic activity of bacteria biofilm in Vancomycin MICs and MBICs were identical in 80 % of the study strains. Vancomycin MBECs are higher than MBCs in all the study strains, are interpreted as resistance according to the criteria of the Clinical and Laboratory Standards Institute (CLSI) and make the drug unsuitable for use in the treatment. In vitro gentamicin MBICs indicated susceptibility according to the CLSI criteria but gentamicin MBECs were interpreted as gentamicin resistance. Rifampin MICs and MBICs of the study strains revealed susceptibility. Rifampin MBCs were interpreted as susceptibility, but based on MBECs, 13% of the study strains were considered as resistant and 13% of the study strains showed intermediate susceptibility. The differences between gentamicin and rifampin MICs and MBICs and those between MBCs and MBECs of all antimicrobials tested were statistically significant. CONCLUSION: The tested biofilm S. aureus forms showed high MBECs of vancomycin, gentamicin and rifampin, with rifampin only being suitable for therapeutic use. To provide reliable results for individualized antibiotic therapy, it will be needed to test in vitro biofilm formation, to determine MBIC and MBEC of antimicrobial drugs using a standardized method, to interpret the test results in relation to biofilm S. aureus forms and to establish the interpretation criteria for MBIC and MBEC similarly to MIC and MBC.

Clinical pseudomonas aeruginosa: potential factors of pathogenicity and resistance to antimicrobials.

Resistance to 17 antimicrobials, surface hydrophobicity, motility, biofilm, production of N-acylhomoserine lactone signal molecules (N-butyrylhomoserine lactone and N-3-oxolauroylhomoserine lactone) and response to oxidative stress were analyzed in 47 clinical Pseudomonas aeruginosa strains. In addition to natural resistance, the strains demonstrated the greatest level of resistance to cefotaxime (91.5%). Isolates in the range of 44.7-57.4% were resistant to aminoglycosides and ciprofloxacin, of 25.5-36.2% to cephalosporins. On the other hand, 97.9% remained susceptible to meropenem, 93.6% to piperacillin + tazobactam and 87.2% to piperacillin. The majority of the strains (72.3%) manifested their hydrophilic character. Higher zones of motility showed 12 isolates (in average 54.8 mm) as compared to the others (30.2 mm). Approximately 1/3 of the strains (29.8%) produced a higher amount of biofilm quantified by measuring the absorbance of solubilized crystal violet (0.20-0.46) than the rest of isolates (0-0.19). All but two strains produced N-3-oxolauroylhomoserine lactone and in 48.9% of samples N-butyrylhomoserine lactone were detected. Only four isolates with higher biofilm production showed both types of homoserine lactone. Majority of the strains (70.2%) manifested higher resistance to H2O2 than the rest of the strains. The group of strains resistant to aminoglycosides and ciprofloxacin revealed a significantly higher number of hydrophobic strains (compared with the sensitive ones). In contrast, higher number of strains sensitive to aminoglycosides and ciprofloxacin or only to ciprofloxacin produced N-butyrylhomoserine lactone and biofilm (compared to the resistant ones). Such association was not found among the rest of the tested parameters. The results indicate that the resistance to antimicrobials in P. aeruginosa isolates was not generally associated with changes in the production of the pathogenicity factors.

Hemolytic uremic syndrome caused by verotoxin-producing Escherichia coli O26. Case report.

Verotoxin-producing Escherichia coli (VTEC) are nowadays among the most important emerging group of food-borne pathogens (VTEC strains cause gastroenteritis that can be complicated by the hemorrhagic colitis or hemolytic uremic syndrome, HUS). Escherichia coli 026 producing verotoxin 2 was isolated and its identity confirmed by examination of phenotype and genotype; the strain was first described in Slovakia in association with the development of HUS in a 4-year-old girl.

A family outbreak of haemolytic uraemic syndrome and haemorrhagic colitis caused by verocytotoxigenic Escherichia coli O157 from unpasteurised cow's milk in Slovakia.

This report describes a family outbreak of verocytotoxigenic Escherichia coli O157 (VTEC) infection, involving nine persons from one extended family, which occurred in eastern Slovakia. Three children suffered from haemolytic uraemic syndrome, two children had bloody diarrhoea, and four adults were asymptomatic carriers. Fourteen sorbitol-non-fermenting E. coli O157 isolates harbouring the vtx2, eae and ehxA genes were obtained. Verocytotoxin 2 activity was demonstrated in all 14 isolates. After epidemiological surveillance, the source of infection was identified as unpasteurised cow's milk.

Detection of Shiga toxins, intimin and enterohemolysin in Escherichia coli strains isolated from children in eastern Slovakia.

Fifty Escherichia coli strains isolated from stool samples of 51 healthy children, 143 strains isolated from stool samples of 327 children with diarrhea and 24 strains isolated from stool samples of 21 children with suspected hemolytic uremic syndrome were examined for the presence of Shiga toxin-producing E. coli virulence factors (shiga toxin 1 and 2, intimin and enterohemolysin) and their genes. Vero-cell assay and latex agglutination were used for detection of Shiga toxin 1 and 2, TSB agar with washed erythrocytes was used for detection of enterohemolysin; genes encoding shiga toxin 1 and 2, intimin and enterohemolysin were detected using multiplex PCR. The presence of E. coli strains harboring genes encoding shiga toxin 1 and 2 (12 strains), intimin (34 strains) and enterohemolysin (12 strains) was demonstrated.

Susceptibility of Streptococcus pneumoniae isolated from the respiratory tract of hospitalized children with respiratory tract infections.

The most frequent nasopharyngeal carriers of Streptococcus pneumoniae are young children. Frequent use of antimicrobial therapy in children facilitates the selection of penicillin-resistant strains in this population. These strains, especially if highly resistant, may cause serious therapeutic problems. Aim of the study was to monitor penicillin- and multidrug-resistant S. pneumoniae strains in hospitalized children with respiratory tract infections. Hospitalized children up to five years were examined for S. pneumoniae presence in their upper respiratory tract. Susceptibility to penicillin, erythromycin, trimethoprim/sulfamethoxazole, tetracycline, and chloramphenicol was determined by the disk-diffusion method. The minimal inhibitory concentrations (MIC) of penicillin, erythromycin and trimethoprim/sulfamethoxazole were measured by the E-test. S. pneumoniae strain was isolated from 60 (34.7%) out of 173 microbiologically examined children; 2 different strains were isolated in 9 cases. Nine strains (13.0%) were penicillin resistant with MICs ranging from 1.5 to 8 mg/L, and 17 strains (24.6%) had intermediate susceptibility. Seventeen (24.6%) strains were erythromycin resistant (MIC > or = 1 mg/L). Eighteen strains (26.1%) were resistant and 7 strains (10.1%) were intermediately susceptible to trimethoprim/sulfamethoxazole. Ten strains (14.5%) were not susceptible to tetracycline, and 11 (15.9%) to chloramphenicol. Non-susceptibility (resistance or intermediate susceptibility) to the tested antimicrobials was more prevalent in penicillin-nonsusceptible strains. The current level of S. pneumoniae resistant to antimicrobial drugs in children with respiratory tract infections in the hospital department monitored in our study do not cause problems in the choice of antibacterial therapy. Penicillins still can remain the drug of choice in cases when typical bacterial causing agents of respiratory tract infections are suspected. (Tab. 3, Fig. 2, Ref. 31.)

Carriage of antibiotic-resistant Streptococcus pneumoniae by children in eastern and central Europe--a multicenter study with use of standardized methods.

With use of standardized techniques, a study of nasopharyngeal pneumococcal carriage in children in six Central and Eastern European cities was undertaken during the winter of 1993-1994. Nasopharyngeal swab specimens were collected from 954 children (predominantly under the age of 5 years) who were hospitalized or attending outpatient clinics or day-care centers. Susceptibility of isolates was determined by disk diffusion (on Mueller-Hinton agar with 5% sheep blood). Disks containing 1 micrograms of oxacillin were used to screen for susceptibility to penicillin G. Pneumococci were recovered from 258 (27.0%) of the 954 children. A variety of strains were recovered, and most penicillin-resistant strains were resistant to multiple agents. Minimum inhibitory concentrations of penicillin for selected resistant strains were 0.125-8 micrograms/mL. Resistance to penicillin was common in strains from Bulgaria, Romania, and Slovakia. Resistance to erythromycin and chloramphenicol occurred in Bulgarian and Romanian strains. Strains from Poland were all susceptible to penicillin, but many were resistant to tetracycline. Resistance to trimethoprim-sulfamethoxazole was common in Bulgarian, Romanian, and Slovak strains. Czech and Russian strains were predominantly susceptible to antibiotics. Most resistant strains were of serotypes 6, 14, 19, and 23.

[Modern views on pneumococcal infections in infants and toddlers]. / Súcasné názory na pneumokokové infekcie u dojciat a batoliat.

Pneumococci colonize the upper respiratory tract predominantly in sucklings and toddlers. By means of their factors of virulence (capsule, ahesines, peptidoglycan, and polysaccharides of the capsule, cytoplasmic membrane enzymes) they can either avoid or impair the immunity mechanisms causing thus severe infections especially in children younger than three years of age and in patients with immunity defects. Regarding the possibility of occurrence of pneumococci with altered susceptibility to penicillin and some other drugs (erythromycin, cotrimaxazol, ceftriaxon, chloramphenicol, tetracycline) it is necessary to treat severe pneumococcal infections on the basis of in vitro detected susceptibility.

[Bacterial virulence factors and their role in the pathogenesis of pyogenic infections of the abdominal cavity and mediastinum]. / Faktory virulencie baktérií a ich úcast' v patogenéze pyogénnych infekcií brusnej dutiny a mediastína.

Purulent peritonitis are caused predominantly by anaerobic bacteria which come from physiological intestinal flora. Mediastinitis is caused amidst other etiologic factors also by bacteria inhabiting the oropharyngeal region, as well as microorganisms causing diseases localized in the proximity of mediastinum. Anaerobic sporulating bacteria both Gram positive and negative cause often miscellaneous infections due to Staphylococcus aureus, Enterobacteriacae, Streptococcus, Enterococcus. It involves a group of bacteria which are able to produce a fibrin network in their proximity, to resist phagocytosis by their structures, to distruct the components of the complement system and immunoglobulins, to impair membranes of cells which leads by means of their factors of virulence to formation of defectuous immunity. Microbiological examination requires the material to be sent for anaerobic cultivation and the antimicrobial therapy must take into account its polymicrobic etiology. (Ref. 23.)

Staphylococcus aureus in chronic and recurrent infections.

Ninety-four Staphylococcus aureus strains isolated from chronic and recurrent skin and respiratory tract infections were investigated for several virulence factor expressions. Production of protein A was noticed in all of the tested strains in amounts from less than 0.1 to more than 2.5 ng per 10(6) bacterial cells. The percentage of the extracellularly produced protein A was found to lie between 4.5 and 27.8%. Two strains (both from the respiratory tract) produced more than 50% of protein A in the extracellular form and one strain did not produce any detectable amount of the extracellular protein A; 99% of the tested strains produced the clumping factor, 96% staphylocoagulase, 79% staphylokinase and 90% gelatinolytic activity; 79% produced alpha-toxin exclusively or in combination with delta- or beta-toxin; 8% of strains produced beta-toxin. There were differences in beta-toxin production between strains from the respiratory tract (5%) and skin infections (25%). delta-Toxin was produced by 53% of the strains. In each of the tested strains a complex of virulence factors was detected. The importance of inactivated extracellular products (especially alpha- and delta-toxin and in the case of skin infections also beta-toxin) as components of staphylococcal whole-cell vaccine was suggested.

[The effect of Staphylococcus aureus vaccine on professional phagocytes in vitro and in vivo]. / Vplyv vakcíny Staphylococcus aureus na profesionálne fagocyty in vitro a in vivo.

Effect of Staphylococcus aureus vaccine on metabolic and functional activities of polymorphonuclear leucocytes and guinea pig macrophages was observed. The tested vaccine following a short contact with human polymorphonuclear leucocytes isolated from peripheral blood inhibited candidacidal and phagocytic activities, whereas the phagocytic index stayed unchanged. The tested vaccine stimulated the INT-reductase activity and superoxide production, as well as extracellular liberation of lysosome enzymes from polymorphonuclear leucocytes. Application of the Staphylococcus aureus vaccine to guinea pigs 35, 30, 28, and 23 days prior to the acquirement of peritoneal macrophages, augmented, as compared to the control group, the amount of peritoneal macrophages and their phagocytic activity. Candidacidal and metabolic activities stayed unchanged. The results imply that the contact of phagocytic cells with the antigen, affects their biochemical and functional activities. Activities are dependent of the length of the period during which the antigen stimulation takes place, and of its quantity. Examination of phagocytes can be recommended for adjustment of both, vaccine doses and intervals between their individual applications. (Tab. 5, Ref. 19.).

Functional and metabolic changes of guinea pig peritoneal macrophages induced by bacterial vaccines.

Phagocytic activity of peritoneal macrophages of guinea pigs injected subcutaneously with bacterial vaccines was found to be increased. The phagocytic index remained unchanged or was decreased. In addition, a decreased candidacidal activity was observed. Metabolic activation of macrophages, measured by the INT test, was inhibited in unstimulated cells while cells stimulated with zymosan or opsonized zymosan exhibited higher values of the INT test as compared with control animals. After injection of vaccines the number of peritoneal macrophages was increased, but the spleen mass decreased.

Effect of cyclophosphamide on the candidacidal activity of rabbit peritoneal macrophages.

Single and repeated intravenous administration of cyclophosphamide significantly decreased the candidacidal activity of rabbit peritoneal macrophages. Using higher doses of the drug, a more pronounced decrease, persisting up to 10 d, was observed. The phagocytic index has not changed significantly 10 d after cyclophosphamide injection as compared with controls. No changes in the phagocytic activity were recorded. The decreased candidacidal activity may be one of the causes of serious microbial infections in cyclophosphamide-treated patients.

Modulatory effect of glucans on the functional and biochemical activities of guinea-pig macrophages.

The particulate and soluble glucan preparations isolated from Saccharomyces cerevisiae and Candida albicans affected various activities of guinea-pig macrophages. The stimulation of INT reduction and superoxide production were observed in the presence of all insoluble and some soluble glucans in vitro, but most of the preparations under study had an inhibitory effect on phagocytic activity. On the other hand, the stimulation of both metabolic and functional activities was obtained in vivo. Macrophages from guinea-pigs treated with glucans exerted an increased ability to reduce INT and to produce superoxide. Their candidacidal capacity was rapidly elevated, and peritoneal macrophages had raised phagocytic activity as well. A more pronounced stimulatory effect was observed in the presence of insoluble rather than soluble glucans, and this was more expressive in vitro than in vivo.