Tetracycline and Chloramphenicol Efficiency Against Selected Biofilm Forming Bacteria

Despite the constantly increasing need for new antimicrobial agents, antibiotic drug discovery and development seem to have greatly decelerated in recent years. Presented with the significant problem of advancing antimicrobial resistance, the global scientific community has attempted to find alternative solutions; one of the most promising ones is the evaluation and use of old antibiotic compounds. A number of old antibiotic compounds, such as aminoglycosides, chloramphenicol, and tetracycline, are re-emerging as valuable alternatives for the treatment of difficult-to-treat infections. This study examined the in vitro potency for biofilm formation of five isolates (Klebsiella sp., Pseudomonas aeruginosa, Achromobacter sp., Klebsiella pneumoniae, and Bacillus pumilis) and the effects of antibiotics on these biofilms. Furthermore the quantitative analysis of planktonic, loosely attached cells, and their susceptibility to antibiotics was also determined. Twitching motility was observed to determine any effect in the biofilm forming capability of the isolates. All the isolates tested were efficient biofilm-forming strains in the polypropylene and borosilicate test tubes. Standard bacterial enumeration technique and CV staining produced equivalent results both in biofilm and planktonic assays. The biofilm formation of all the strains was affected in the presence of tetracycline or chloramphenicol. Highly significant decrease (P < 0.01) in biofilm formation was observed by treatment with chloramphenicol compared to tetracycline. In addition, the two antibiotics also affected adversely the planktonic and loosely attached cells of all isolates. Thus, testing the effects of older antibiotics on biofilms may supply useful information in addition to standard in vitro testing, particularly in diseases where biofilm formation is involved in the pathogenesis.     

Stem alkaloids of Rauwolfia vomitoria

22 indole alkaloids were isolated from the stem bark of Nigerian Rauwolfia vomitoria and 20 characterized. The alkaloids comprised E-seco heteroyohimbine, sarpagan, dihydroindole, yohimbine and heteroyohimbine types. The biosynthetic relationship of the alkaloids is discussed.     

Genetic diversity in natural Cupressus sempervirens L. populations in Turkey

Nine polymorphic out of 13 isoenzymes (Gdh-A, Lap-A, Mdh-B, Mdh-C, Ndh-A, 6Pgd-B, Pgi-B, Pgm-A and Pgm-B) were used to assess genetic diversity in seven natural Cupressus sempervirens populations in South-western Anatolia. Except for Pgi-B, all loci were in Hardy–Weinberg equilibrium. A high level of genetic diversity was observed within populations. The mean number of alleles was 2.3±0.08, the effective number of alleles was 1.53±0.10, the percentage of polymorphic loci was 82.6±8.7%, expected heterozygosity was 0.350±0.039, observed heterozygosity was 0.326±0.039, and the fixation index was 0.049. Interpopulation differentiation was moderate, with differentiation indices of G_ST=0.073 and δ=0.104. A UPGMA tree and differentiation (D_j) showed that Kumluca, Kemer and Kas were the most differentiated populations. Pgm-B was one of the loci contributing most to interpopulation differentiation (G_ST=0.119; D_i=0.201), clearly distinguishing Eastern populations, as indicated by a highly significant correlation coefficient between D_j and longitude (R²=0.88^**). No other significant correlation was found between genetic measures and geographical traits for the Turkish cypress populations. A metanalysis of these and other cypress populations from Crete and the Aegean islands, that had been characterised previously using the same isoenzymes, showed no significant relationship between altitude and genetic measures (within-population differentiation or δ_T, observed heterozygosity, fixation index and D_j). Observed heterozygosity and latitude were negatively correlated. Longitude was found to be correlated with heterozygosity, fixation index and differentiation. Genetic and geographic distances were positively correlated over loci. Deviations from selective neutrality by Ewens–Watterson test were observed for Pgm-B, Ndh-A and 6Pgd-B.     

Subcellular distribution of 2′,3′-cyclic nucleotide-3′-phosphodiesterase in cat peripheral nerve

Subcellular distribution of 2′,3′-cyclic nucleotide-3′-phosphodiesterase (CNPase) in desheathed, saline perfused cat sciatic nerve is reported. CNPase specific activity was enriched in the total particulate (P₂) fraction and was low in the soluble (S₂) fraction. “Light-myelin” floating above the 0.60 M sucrose phase had the highest CNPase activity, 2.5-fold over the crude homogenate (CH). By contrast, enzyme activity in “heavy myelin” floating above the 0.85 M sucrose interface was equal to that of the CH and accounted for only 12% of total activity. CNPase activity in the membranes floating above the 0.25 and 0.60 and 0.85 M sucrose phases comprised nearly 70% of the total CNPase activity. The “light myelin” fraction floating above the 0.60 M sucrose accounted for approx. 51% of the total CNPase activity. SDS-PAGE of membranes individually harvested from above the 0.25 and 0.60 and 0.85 M sucrose phases revealed the presence of myelin-specific proteins (P₀, P₁; and P₂). Electron microscope examination demonstrated the presence of myelin in each membrane fraction. The results of this study show that the majority of CNPase activity is associated with “light myelin” in cat peripheral nerve.     

Cytomegalovirus and Herpes Simplex Virus Effect on the Prognosis of Mechanically Ventilated Patients Suspected to Have Ventilator-Associated Pneumonia

Objective

Cytomegalovirus (CMV) and herpes simplex virus (HSV) are common viruses that can affect critically ill patients who are not immunocompromised. The aim of this study was to determine whether the identification of CMV and/or HSV in mechanically ventilated critically ill patients suspected of having pneumonia was associated with an increased mortality.

Design

Prospective epidemiological study.

Setting

Medical intensive care unit of a tertiary medical center.

Patients

Ninety-three patients with suspected pneumonia.

Interventions

Patients with suspected pneumonia had bronchoalveolar lavage and blood samples taken to confirm the diagnosis. Antigenemia was used to detect CMV in the blood. Bronchoalveolar lavage samples were submitted to testing using quantitative real-time Polymerase Chain Reaction.

Measurements and Main Results

We identified 22 patients with a CMV infection, 26 patients with an HSV infection and 45 patients without CMV or HSV infection (control group). Mortality at day 60 was higher in patients with a CMV infection than in patients from the control group (55% vs. 20%, P<0.01). Mortality at day 60 was not significantly increased in the group with HSV infection. Duration of ICU stay and ICU mortality were significantly higher in patients with CMV infections when compared to patients from the control group, whereas ventilator free days were significantly lower in patients with CMV infections when compared to patients from the control group.

Conclusions

In critically ill patients, a CMV infection is associated with an increased mortality. Further interventional studies are needed to evaluate whether treatment could improve the prognosis.     

Effects of Externally Applied Pressure on the Haemodynamics of the Lower Limb

The effects of externally applied pressure of 5-150 mm Hg on the haemodynamics of the leg of dog and man were investigated. The criteria used for the assessments included femoral arterial and venous blood flow as well as vascular hydraulic conductance. The results indicated that external pressure of 5 mm Hg results in a very small non-significant increase in the femoral arterial and venous flow. Higher external pressure of 15 mm Hg or more significantly reduces the femoral arterial and venous flows as well as the vascular conductance. It therefore seems that compression produced by bandaging in horizontal supine subjects has little or no haemodynamic value and may prove to be harmful unless carefully controlled.     

Effect of Biocides on Biofilm Bacteria from Dental Unit Water Lines

Microbial biofilm formation in dental unit water lines (DUWL) is a phenomenon that has been recognized for nearly four decades. Water delivered by DUWL can harbor high numbers of bacteria, including opportunistic pathogens. Biofilms on tubing within DUWL may serve as a reservoir for these microorganisms and should therefore be controlled. In this study, the effects of eight biocides were monitored on DUWL biofilms individually and in combination by epifluorescence microscopy and total viable counts (TVC). The effects of sodium dodecyl sulphate (SDS), hydrogen peroxide (H₂O₂), sodium hypochlorite (NaOCl), phenol (Phe), Tween 20 (Tw 20), ethylenediaminetetraacetic acid (EDTA), chlorohexidine gluconate (CHX), and povidine iodine (PI) were tested on DUWL biofilms alone and in combination. PI was found to have negligible effects on biofilm removal either applied alone or in combined form with CHX. Applying all biocides simultaneously did not completely eliminate viable bacteria nor did they remove biofilm. Overall, when combined, the biocides performed better than singly applied products. The most effective biocides were NaOCl and Phe (both alone and in combination).     

Diversity analysis of dairy and nondairy Lactococcus lactis isolates, using a novel multilocus sequence analysis scheme and (GTG)5-PCR fingerprinting

The diversity of a collection of 102 lactococcus isolates including 91 Lactococcus lactis isolates of dairy and nondairy origin was explored using partial small subunit rRNA gene sequence analysis and limited phenotypic analyses. A subset of 89 strains of L. lactis subsp. cremoris and L. lactis subsp. lactis isolates was further analyzed by (GTG)(5)-PCR fingerprinting and a novel multilocus sequence analysis (MLSA) scheme. Two major genomic lineages within L. lactis were found. The L. lactis subsp. cremoris type-strain-like genotype lineage included both L. lactis subsp. cremoris and L. lactis subsp. lactis isolates. The other major lineage, with a L. lactis subsp. lactis type-strain-like genotype, comprised L. lactis subsp. lactis isolates only. A novel third genomic lineage represented two L. lactis subsp. lactis isolates of nondairy origin. The genomic lineages deviate from the subspecific classification of L. lactis that is based on a few phenotypic traits only. MLSA of six partial genes (atpA, encoding ATP synthase alpha subunit; pheS, encoding phenylalanine tRNA synthetase; rpoA, encoding RNA polymerase alpha chain; bcaT, encoding branched chain amino acid aminotransferase; pepN, encoding aminopeptidase N; and pepX, encoding X-prolyl dipeptidyl peptidase) revealed 363 polymorphic sites (total length, 1,970 bases) among 89 L. lactis subsp. cremoris and L. lactis subsp. lactis isolates with unique sequence types for most isolates. This allowed high-resolution cluster analysis in which dairy isolates form subclusters of limited diversity within the genomic lineages. The pheS DNA sequence analysis yielded two genetic groups dissimilar to the other genotyping analysis-based lineages, indicating a disparate acquisition route for this gene.