Miroslav Votava

Use of GBS Media for Rapid Detection of Group B Streptococci in Vaginal and Rectal Swabs from Women in Labor

Abstract In order to evaluate the differences in efficacy, three methods were used to detect group B streptococci (GBS) in women in labor. The recommended method for detecting GBS carriage in pregnant women is to culture vaginal and anorectal swabs in a selective broth medium and to subculture them onto blood agar. This method was compared with the use of GBS agar and GBS broth, both of which produce an orange pigment in response to GBS strains. A total of 319 women in labor were screened. Among the 638 specimens tested, 134 (21%) were positive in the selective Todd-Hewitt broth subcultured onto sheep blood agar, 133 (20.8%) were positive on the GBS agar and 126 (19.7%) were positive in the GBS broth. Altogether, 89 (27.9%) women in labor were found to be colonized with GBS; 87 (97.8%) of them were identified as carriers using the Todd-Hewitt broth, 87 (97.8%) with the GBS agar and 86 (96.6%) with the GBS broth. These results indicate that both GBS agar and GBS broth are reliable methods that can be used to screen for maternal and neonatal GBS colonization.

Biofilm detection and the clinical significance ofStaphylococcus epidermidis isolates

The ability ofStaphylococcus epidermidis to produce biofilm was compared in 147 clinically significant strains repeatedly isolated from blood cultures of patients with bloodstream infection and in 147 strains isolated from skin. The strains were examined for the presence ofica operone, for the ability to form biofilm by Christensen’s test-tube method and for the production of slime by Congo Red agar method. Theica operone was found in 92 (62.6 %) blood isolates and in 44 (29.9) isolates from skin. Christensen’s test-tube method was positive in 79 (53.7) and 33 (22.4), Congo Red agar method in 64 (43.5) and 31 (21.1) of blood and skin isolates, respectively. All three methods were more frequently positive in clinically significant isolates from blood than in strains isolated from skin. The detection ofica operone and the Christensen’s test-tube method showed better correlation with the clinical significance than the Congo Red agar method.

Importance of biofilm in Candida parapsilosis and evaluation of its susceptibility to antifungal agents by colorimetric method.

The ability ofC. parapsilosis (an important cause of nosocomial infections) to produce biofilm was evaluated in 32 bloodstream isolates and 85 strains isolated from skin. The biofilm formation was found in 19 (59%) blood isolates and only in 33 (39%) isolates from skin. The antifungal susceptibility was assessed for amphotericin B, itraconazole and voriconazole in planktonic and biofilm form of the 19 biofilm-positive bloodstream strains by broth microdilution method according toNCCLS standards. The method was modified by the use of resazurin as a colorimetric indicator of the metabolically active cells which makes the determination of the effect of antifungal agents easier. Biofilm forms of all strains were more resistant than their planktonic form.

Antibiotic synergy against biofilm-forming Pseudomonas aeruginosa

Eight antibiotics (aztreonam, ceftazidim, cefoperazon, cefepim, netilmicin, amikacin, ofloxacin and ciprofloxacin) exhibited antimicrobial activity individually and/or in combinations against 20 wild-type biofilm-forming strains of Pseudomonas aeruginosa. The strains were less susceptible in biofilm; in 10 strains antibiotic synergy was observed for the combination of aztreonam and ciprofloxacin. Synergy was also demonstrated in the case of β-lactams and aminoglycosides, β-lactams and fluoroquinolones, aminoglycosides and fluoroquinolones, and for monobactams and β-lactams although the strains were resistant to the individual antibiotics. Synergism or partial synergism was found with one or more antibiotic combinations against 32.4% of isolates.

Inhibition of bacterial pathogens by lactobacilli

Lactobacilli produce many antimicrobial substances including organic acids, hydrogen peroxide and bacteriocins. Antagonistic activity of lactobacilli is an important factor in the protection of the vagina of fertile women against infection by certain pathogens. In the present study, we investigated 17 strains of lactobacilli, including 11 strains of vaginal origin. The aim was to investigate in more detail the antibacterial activity of lactobacilli and to attempt to assess substances responsible for inhibition. The investigated lactobacilli inhibited some strains of Escherichia coli, Serratia marcescens, Shigella boydii, Listeria monocytogenes, Listeria ivanovii, Listeria innocua and Staphylococcus aureus. We have provided evidence that inhibition is due mainly to organic acids and to a lesser extent, to bacteriocins.

Determination of minimal regrowth concentration (MRC) in clinical isolates of various biofilm-forming bacteria

Based on the ability to attach to polymeric surfaces, the formation of biofilms was determined in 5 wild-type strains (Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumanii, Escherichia coli, Staphylococcus warneri). Using modified Christensen method, minimum regrowth concentration (MRC) of piperacillin, piperacillin-tazobactam, cefoperazon, ceftazidim, cefepim, meronem, ciprofloxacin, netilmicin and amikacin for Gram-negative and of ampicillin-sulbactam, chloramphenicol, tetracycline, clindamycin, vancomycin and teicoplanin for Gram-positive bacteria was estimated in trypticase-soy broth medium after a 1-d growth on polystyrene microtiter plates. Adherent bacterial populations exhibited reduced antimicrobial susceptibility, which was not shown in submerged cultures. Our results indicate that MRC can predict therapeutic outcome of antibiotic treatment better than the minimum inhibitory concentration tests commonly used.

The differences in the isoelectric points of biofilm-positive and biofilm-negative Candida parapsilosis strains

The isoelectric points of 39 Candida parapsilosis strains were determined by means of capillary isoelectric focusing. The value of the isoelectric point corresponded well with cell surface hydrophobicity, as well as with the ability to form biofilm in these yeasts.

Phospholipase D-neutralization in serodiagnosis of Arcanobacterium haemolyticum and Corynebacterium pseudotuberculosis Infections

Phospholipase D (PLD) neutralization was used to examine sera of humans (n = 40) with a spontaneous infection by Arcanobacterium haemolyticum, sheep and goats (n = 76 and 79 respectively) with a spontaneous infection by Corynebacterium pseudotuberculosis, mice (n = 26) experimentally immunized with PLD from A. haemolyticum (PLD-A) and mice (n = 28) experimentally immunized with PLD from C. pseudotuberculosis (PLD-C). PLD-A and PLD-C were also used as neutralizing antigens. A positive result of neutralization was due to an inhibition of the haemolytic synergism with the equi factor from Rhodococcus equi. The titres of sera neutralizing the homologous PLD were always significantly higher than those neutralizing the heterologous PLD. The proportion of sera that were able to neutralize the homologous PLD in sheep, goats and mice immunized with PLD-A significantly exceeded the proportion of sera that neutralized the heterologous PLD. The antigenic properties of PLD-A and PLD-C were similar but not identical.

Rhodococcus equi Infections of Persons with and without a Contact with Animals

Ivanova I. Ye., T. A. Derendiayeva, G. I. Meleshko, Yeo Ya. Shepelev: Higher Plants in a Biological Life SupportSystemfor Man. Acta vet. Bmo 1996,65: 27-32. A model of human biological life support system (BLSS) was created with a photoautotrophic link including unicellular algae and higher plants having an equal oxygen production. This system model supported the vital activities of two people at the biomass regeneration of 92% from that consumed by them. The plant cultures studied were wheat grown on 11.25 m2 (of a total 15 m2) and several vegetable species. The total photosynthetic productivity of the plants was high, stable over the studied time span, and independent on the composition of the system. However, the grain productivity of wheat decreased periodically, and during certain harvests it decreased to almost zero. A detailed analysis revealed that this decrease was not caused by any of the systems adjacent links as a similar decrease in yield was also found in the control period with an autonomous growth of the plants in a closed volume of a chamber. Inclusion of bigher plants into BLSS led to a considerable improvement od food supply regeneration for man as compared to the previous model with only 26% regeneration effect. This inclusion did not exert any marked effect upon the general closure of the cycle. However, the biological value of the food for man was increased dramatically. This improvement is the main goal of designing and operating such BLSS systems. Regeneration. ecosystem. photosynthesis, photoautotroph link, unicellular algae. higher p.lants The prospect of long-teon existence of man outside the Earths biosphere (interplanetary flights, lunar and planetary bases) is connected with creating an artificial environment with the help of regenerating it from the products of vital activity. This environment must correspond to the evolutionarily conditioned biological needs of the humans and to provide their lives for generations. The fact of adaptive biology shows that the full-value environment for humans and other terrestrial organisms is the natural environment of the Earth. In order to recreate that environment artificially it is necessary to reproduce the mechanisms existing on Earth, i. e. to foon closed ecological systems including man. The lack of our knowledge about the natural environment of the humans prevents us from reproducing it by non-biological means, even if it were possible. The investigation of the problem of creating biological life-support systems (BLSS) of man began as early as in the 60ies. By the present time, experimental BLSS models have been created with different structures and different degrees of the cycle closure. , The creation of the systems was based on the ecological concept according to which strategy and tactics were worked out providing the organisms and populations were studied and then united into biocenoses, including also humans. The main method of solving the problem was the method of experimental modelling from the simple to the complex (Rashevski 1966).

Organ cultures of human Fallopian tubes for the propagation of viruses

Attempts were made to grow certain viruses in organ cultures of Fallopian tube. Influenza A2 and B, parainfluenza type 2, rhinovirus type 2, ECHO virus type 11 and adenovirus type 7 were observed to multiply, but poliovirus type 1, a human “coronavirus” and rhinovirus type 3 did not.