In vitro activity of flomoxef compared to moxalactam, cefoxitin, cefotaxime, and clindamycin against anaerobes

To assess the in vitro activity of flomoxef (6315-S), moxalactam, cefoxitin, cefotaxime, and clindamycin against anaerobes 197 clinical isolates (27 Bacteroides fragilis, 42 B. thetaiotaomicron, 10 B. vulgatus, 7 B. ovatus, 6 B. uniformis, 6 B. distasonis, 7 Bacteroides melaninogenicus group, 11 Bacteroides oralis group, 21 Clostridium difficile, 7 C. perfringens, 3 C. sporogenes, 3 Clostridium spp., 33 Propionibacterium acnes, 14 Peptococcaceae) were studied by means of agar dilution tests. The MIC90 of B. fragilis was less than 2 micrograms/ml for flomoxef, less than 4 micrograms/ml for moxalactam, less than 16 micrograms/ml for cefoxitin, less than 128 micrograms/ml for cefotaxime and less than 2 micrograms/ml for clindamycin. The respective MIC90's of B. thetaiotaomicron were less than 64, less than 128, less than 32, less than 256 and 8 micrograms/ml. Strains of the other Bacteroides species and groups were more susceptible to flomoxef and the other antibiotics than B. thetaiotaomicron. Against Clostridium difficile flomoxef (MIC90 less than 4 micrograms/ml) proved to be superior to the other agents tested. Most of the Clostridium strains other than C. difficile were also susceptible to flomoxef; anaerobic grampositive cocci and Propionibacterium acnes were very sensitive (MIC90's less than 1 and less than or equal to 0.125 micrograms/ml, respectively). Its anti-anaerobic activity, together with its efficacy against aerobes, should make flomoxef a useful adjunct to the arsenal of modern antibiotic therapy.

[The effect of a combination of ampicillin and sulbactam against clinical anaerobic isolates]

Effect of a Combination of Ampicillin and Sulbactam on Clinical Isolates of Anaerobic Bacteria. The antimicrobial susceptibility of 182 recent clinical isolates of anaerobic bacteria to ampicillin alone, ampicillin plus 1 mg/l sulbactam, ampicillin plus 5 mg/l sulbactam, and cefoxitin was studied by means of agar dilution tests. The ampicillin-sulbactam combination (Unacid) was most effective against species of the Bacteroides fragilis group, the MIC90 of ampicillin plus 5 mg/l sulbactam for B. fragilis being less than or equal to 1 mg/l, compared to 256 mg/l of ampicillin, 4 mg/l of ampicillin plus 1 mg/l sulbactam, and 8 mg/l of cefoxitin. No significant difference between ampicillin alone and in combination with sulbactam was observed against gram-positive anaerobic rods or cocci.

Steroid regulation of somatostatin mRNA in the rat hypothalamus

The participation of gonadal steroid hormones in the regulation of the expression of the somatostatin gene in the hypothalamus and cerebral cortex was studied by using a quantitative densitometric hybridization assay which allows the direct measurement of specific somatostatin mRNA levels. The levels of somatostatin mRNA in hypothalamus were found to be significantly decreased following gonadectomy in both male and female rats (67% in males and 75% in females). Moreover, with in situ hybridization histochemistry somatostatin mRNA was similarly reduced following gonadectomy in the dorsal portion of the periventricular region and in the ventromedial nucleus. Estradiol dibenzoate treatment reversed the decrease in somatostatin mRNA in females within 24 h and testosterone treatment reversed the decrease in castrated males. In contrast, there was no significant change in cerebral cortex somatostatin mRNA levels after gonadectomy. These results suggest that sex steroids are involved in the regulation of the somatostatin gene in the hypothalamus, possibly at the transcriptional level.

Growth hormone releasing factor and somatostatin concentrations in the milk of lactating women

The concentrations of growth hormone releasing factor (GRF) and somatostatin, two hypothalamic neuropeptides involved in the regulation of growth hormone secretion, were measured in human milk samples. The study was performed in healthy women within 48 h of delivery or during established lactation (between 1 and 64 weeks post delivery). No statistically significant correlation was found between the levels in milk of either of the neuropeptides and the gestational age at birth. However, lower values of GRF (23 +/- 4.7 pg/ml vs. 40.5 +/- 4.9 pg/ml) were found in milk obtained during established lactation than in milk obtained close to delivery. A positive correlation was observed between somatostatin and GRF concentrations in milk. The possible involvement of milk neuropeptides in the control of growth hormone secretion in the neonate, as well as in the regulation of other physiological processes, are evaluated.

Suitability of in-vitro xenodiagnosis: development of Trypanosoma cruzi in Triatoma infestans depending on larval stage of bugs and number of trypomastigotes taken during in-vitro blood meal

A study on artificial xenodiagnosis was carried out for the identification of T. cruzi, the causative organism of the American Trypanosomiasis (Chagas Disease) using the natural vector T. infestans. It was investigated whether one single T. cruzi (strain B) is sufficient for successful infection of T. infestans. Since the infection took place by artificial feeding, the average amount of blood taken by larval stages I-V in one meal was determined. On the basis of these results the feeding solution (defibrinated cattle blood) containing the corresponding T. cruzi-concentration/ml was prepared and twenty-one days after the infection feces were investigated for the presence of T. cruzi. It could be shown that one T. cruzi is sufficient for infection of larval stages I-V, although the rate of infection in larval stages IV and V was much lower than in larval stages I-III. These experiments demonstrate that xenodiagnosis can also be performed in-vitro. The possible negative effects due to biting of bugs for in-vivo xenodiagnosis of patients can be avoided. Using this method, far more bugs can be used than in conventional xenodiagnosis increasing the likelyhood of detecting at least one infected T. infestans. Additional experiments simulating postal dispatch during three days at 4 degrees C and 27 degrees C proved that blood samples from far distant places may be sent to be examined at laboratory.

[The determination of clonidine by charge-transfer-complex formation with iodine]

The donor clonidine (1) forms a charge-transfer-complex of stoichiometric composition 1:1 with the sigma-acceptor iodine. The association constant was determined by means of the Hildebrand-Beneshi equation being 38,000 l/mol. At first it forms an outer complex, characterized by charge-transfer band at 285 nm and the blue-shifted iodine band at 393 nm. From this complex the inner ionic complex results depending on time in which iodine iones arise reacting with unconnected iodine to triiodiones. These show absorptions at 291 and 364 nm. Resulting from it an assay of 1 worked out. The regression line is y = (4.370 +/- 0.256) x + (0.411 +/- 0.053), Srel = 1.3% (n = 10) and the linear range is placed between 0.01-0.25 mg/10 ml solution.

Evaluation of the Cobas Bact automated system for susceptibility testing of Enterobacteriaceae, Pseudomonas aeruginosa, and Enterococcus faecalis to azlocillin, mezlocillin, and ciprofloxacin compared to NCCLS and DIN standards

The aim of automated susceptibility testing systems like the Cobas Bact is to provide the clinicians with rapid and reliable results for the care of patients and to decrease the work load in microbiological laboratories. Because data about accuracy on mezlocillin, azlocillin and ciprofloxacin were lacking, we investigated 184 bacterial strains and compared the results of the Cobas Bact susceptibility testing to standardized agar dilution and agar diffusion methods. Essential correlations for all methods compared exceeded 90% for the three chemotherapeutics and all species investigated, with the exception of Pseudomonas aeruginosa. On an average only 1.5% very major errors were observed with the several species of Enterobacteriaceae, whereas P. aeruginosa and Enterococcus faecalis were characterized by the complete absence of very major errors when Cobas Bact was correlated to NCCLS agar diffusion.

New developments in medical microbiology: computer-assisted diagnosis and automated instruments

Time and accuracy required for diagnosis are two of the most important factors in medical microbiology. Computer-assisted diagnosis is one tool to overcome these problems. The software of such systems, much more than the hardware, is of utmost importance and both have to fulfill several items. 1) High flexibility and integration within the already existing working schemes of the laboratory. 2) Terminals in every laboratory. 3) High speed of calculation. 4) Online data transfer from automated instruments. 5) External terminals on intensive care units. 6) Epidemiological and etiopathological investigations have to be possible at any time. In the laboratory the burden of simple, repeating tasks is diminished, inquiries can be made in a minute and precise information about the epidemiological situation can be gained within a few hours. Thus, calculated antimicrobial therapy depending on the incidence of certain pathogens in given specimens in different departments is possible. In the case of fast-growing bacteria, preliminary reports, including susceptibility testing available within the first 24 h, are possible and will be of great help to the clinician in monitoring the calculated antimicrobial regimen. External terminals will allow continuous flow of data from the laboratory to wards and vice versa.

In vitro activity of ampicillin plus sulbactam against anaerobes compared to ampicillin and cefoxitin

The antimicrobial susceptibility of 195 recent clinical isolates of anaerobic bacteria was studied to ampicillin alone, ampicillin + 1 mg/l sulbactam, ampicillin + 5 mg/l sulbactam, and cefoxitin by means of agar dilution tests. The ampicillin-sulbactam combinations were the most effective drugs against species of the Bacteroides fragilis group, the MIC90 of ampicillin + 5 mg/l sulbactam for B. fragilis being less than 1 mg/l, compared to 256 mg/l of ampicillin, 4 mg/l of ampicillin + 1 mg/l sulbactam, and 8 mg/l of cefoxitin. No significant difference between ampicillin alone and in combination with sulbactam was observed against gram-positive anaerobic rods, Peptococcus spp. and Peptostreptococcus spp. with MIC's less than 2 mg/l.

Quantitative studies on the vaginal flora of asymptomatic women and patients with vaginitis and vaginosis

Vaginal washings of 22 patients with vaginitis, 11 with vaginosis, and 12 healthy subjects were investigated quantitatively and qualitatively for aerobic and anaerobic bacteria and yeasts. Gardnerella vaginalis was recovered from 9 of the vaginitis patients, 7 of the vaginosis patients, and 4 of the asymptomatic subjects. Obligate anaerobes were found in 11 of the vaginitis patients, 4 of the vaginosis patients, and none of the control subjects. Bacteroides bivius was the anaerobe most frequently isolated from symptomatic subjects. Anaerobic vibrios were recovered twice from symptomatic subjects. The counts for Gardnerella vaginalis and anaerobes when present were generally very high. The most frequent aerobes were beta-hemolytic streptococci (group B) and staphylococci.

The formation of a neo-intima in textile prostheses implanted in the aorta of rats and dogs

The formation of a neo-intima in textile prostheses implanted in the rat and dog aorta was studied by means of light- and scanning electron microscopy. Two independent cellular layers (the superficial and deep ingrowth layers) developed on the free surface and under the fibrin layer initially deposited on the inner surface of the prostheses. The superficial ingrowth layer invades the prosthesis from both the proximal and distal aortic stumps and extends over the primary fibrin layer, or replaces it. This layer consists mainly of smooth muscle cells of the triangular aortic type covered by endothelial-like cells. The deep ingrowth layer originates from cellular elements of the prosthetic bed. Fibroblasts, myofibroblasts and spindle-shaped smooth muscle cells invade the fibrin layer through the interstices of the fabric structure of the prosthesis. Precursors of endothelial cells, however, are absent from this population. The superficial and the deep ingrowth layers may become joined by progressive replacement of the fibrin layer, but remain distinguishable because of their different cellular components. When a continuous cellular layer is established on the inner surface of the prosthesis, and this is then covered by endothelial-like cells, the neo-intima formed remains stable during long-term studies.