Biomedical subjects
Publications and source records attributed to M C Roberts.
Of 15 Peptostreptococcus sp. strains isolated between 1975 and 1984, 13 hybridized with the Tet K, Tet M, or Tet O determinant. A donor Peptostreptococcus anaerobius strain carrying the three determinants could transfer Tet M to P. anaerobius and Fusobacterium nucleatum recipients but not to an Enterococcus faecalis recipient, while neither Tet K nor Tet O was transferred.
Classifications of 48 atypical clinical isolates of Mobiluncus spp. were determined on the basis of biochemical reactions, morphology, antigenic profiles, and DNA hybridization studies. Two new subgroups with unique antigenic profiles are described. Like typical Mobiluncus species, the antigenic variant of M. mulieris is associated with bacterial vaginosis. The atypical isolates of M. curtisii were frequently recovered from women with normal vaginal flora and were also recovered from sterile body sites. These isolates may be incorrectly identified if current biochemical and morphological criteria are used for identification. Gram stain morphology, however, correctly identifies these isolates to the species level. The characterization of these atypical isolates has important implications for future investigations in which serological methods are used for diagnosis, epidemiology, and determination of pathogenicity of Mobiluncus spp.
The microbiological and epidemiological correlates of vaginal colonisation by Mobiluncus species were examined among randomly selected women attending a sexually transmitted disease (STD) clinic. Women positive for Trichomonas vaginalis were excluded. Mobiluncus spp. were detected by Gram stained vaginal smear in 21% of 633 STD clinic patients, including 53% of those with and 4% of those without bacterial vaginosis (BV), as diagnosed by clinical criteria. Gardnerella vaginalis and Mycoplasma hominis detected by vaginal culture and Mobiluncus detected by vaginal Gram stain were each independently associated with BV after adjusting by logistic regression for the presence of sexually transmitted disease pathogens, gravidity, parity and number of lifetime sexual partners (p less than 0.001 for each organism). Bacterial vaginosis was negatively correlated with isolation of lactobacilli, yeast and herpes simplex virus. After adjusting for presence or absence of BV, women with Mobiluncus were more likely to harbour G vaginalis (odds ratio 5.6, 95% confidence interval 1.6-19.5), M hominis (OR 3.7, 95% CI 2.0-7.0) and Neisseria gonorrhoeae (OR 2.9, 95% CI 1.4-6.0) and less likely to harbour vaginal yeast (OR 0.4, 95% CI 0.2-1.0); were more likely to be black (OR 2.7, 95% CI 1.5-4.6), and to have been pregnant (OR 1.8, 95% CI 1.1-3.1); but after the adjustment for BV, vaginal colonisation by Mobiluncus was not associated with symptoms of odour, abdominal pain, menstrual irregularities, or with adnexal tenderness. In summary, Mobiluncus, Gardnerella vaginalis and Mycoplasma hominis were independently associated with a clinical diagnosis of bacterial vaginosis, and Mobiluncus was further associated with the presence of BV-associated microorganisms (M hominis and G vaginalis), N gonorrhoeae, black race, and gravidity.
The association of feeding practices with the development of digestive disorders in horses has long been recognized, although the underlying mechanisms had been barely considered. The physiologic consequences of meal frequency may help to explain the relationship and prove to be of major significance in the induction of many conditions. Many Equidae kept for performance and leisure activities are fed high-energy, low-forage rations twice daily, with limited access to hay or grazing. Rapid ingestion of such meals stimulates a copious outpouring of upper alimentary secretions and results in transient hypovolemia (15% plasma volume loss). Subsequent activation of the renin-angiotensin-aldosterone system (RAAS) contributes to the preservation of circulatory status. Large meals may accelerate digesta passage to the cecum and, thereby, increase soluble carbohydrate availability for large intestinal fermentation. Intense periods of fermentation develop that require significant shifts of fluid into the colonic lumen. This is followed by net fluid absorption, which, in part, is dependent on postprandial increases of aldosterone. Potential consequences of these events include (1) imbalances in the RAAS response, which may promote conditions favorable to gastrointestinal disturbance, notably large intestinal impaction, and (2) changes in the gastrointestinal microflora, which may affect the intraluminal endotoxin pool and the population of enterotoxin-producing bacteria. In contrast to episodic feedings, similar changes are absent or greatly attenuated under simulated grazing conditions (for example, small, frequent meals). Thus, modification of management practices to facilitate a more continuous feeding pattern may significantly reduce the incidence of digestive problems in the stabled horse.
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The distributions of the nucleotide sequences related to the tetracycline resistance determinants Tet K, Tet L, Tet M, and Tet O were studied by dot blot hybridization with randomly chosen clinical urogenital tract isolates of viridans group streptococci, Streptococcus agalactiae, Enterococcus faecalis, Gardnerella vaginalis, Lactobacillus spp., Fusobacterium nucleatum, Peptostreptococcus spp., and Veillonella parvula. Among the Peptostreptococcus spp., 79% of the isolates hybridized with one (64%) or more (36%) of the probes for Tet K (27%), Tet L (30%), Tet M (75%) and Tet O (13%). Of the viridans group streptococci, 82% of the strains hybridized with one (34%) or more (66%) of the four probes. The distribution of the four determinants in this group was as follows: Tet K, 36%; Tet L, 31%; Tet M, 43%; Tet O, 61%. Twenty-nine percent of the enterococci and forty-six percent of the group B streptococci hybridized with the probes; however, the Tet K, Tet L, and Tet O determinants were found in only a few strains, while the Tet M determinant predominated. A total of 29% of the F. nucleatum isolates, 55% of the G. vaginalis isolates, and 26% of the V. parvula isolates hybridized with the Tet M determinant. In contrast, 43% of the Lactobacillus spp. hybridized with the Tet O determinant. The data indicate that tetracycline resistance determinants are common to many of the microorganisms isolated from the urogenital tract.
Tetracycline-resistant Fusobacterium nucleatum, Haemophilus ducreyi, Mycoplasma hominis, Peptostreptococcus spp., Ureaplasma urealyticum, and Veillonella parvula had DNA sequences which showed homology throughout the length of the Tet M transposon, Tn916. In contrast, Gardnerella vaginalis, commensal Neisseria spp., and the 25.2-megadalton plasmid family lacked the complete transposon.
Two-high-level-tetracycline-resistance Moraxella (Branhamella) catarrhalis strains were shown to carry DNA sequences which hybridized with the Tet B probe. The determinant appeared to be located in the chromosome and was nontransferable.
Two tetracycline-resistant Fusobacterium nucleatum strains were able to transfer, by conjugation, tetracycline resistance and the Tet M determinant to recipient F. nucleatum, Peptostreptococcus anaerobius, and Enterococcus faecalis strains at a frequency of 10(-1) to 10(-8).
A panel of experts, participating in a Delphi poll, identified significant issues facing psychosocial aspects of health care for children in the future. In three rounds of feedback and evaluation, ten top future issues were composited in rank order: chronic illness and complex health care needs; sociogenic problems; unequal access to health care; lack of financial resources for psychosocial services; increased focus on prevention; children without primary caregivers; complex ethical questions; family-centered care; training of health care professionals; and interdisciplinary integration. Implications of these issues are discussed.
The effect of meal size and frequency on plasma volume, plasma aldosterone concentration and urinary Na and K clearances was determined in ponies. A daily maintenance ration of hay-grain pellets was provided either as a multiple feeding regimen, ie, 12 equal portions fed at 2-hour intervals, or as single large feedings, ie, half the ration fed every 12 hours at 0800 and 2000 hours. Only the effect of the single morning feeding was studied, using the latter regimen. Serial measurements of plasma volume were made by use of an indicator-dilution technique and indocyanine green (0.15 mg/kg of body weight, IV) that allowed repeated determinations at 2-hour intervals. Ingestion of the single large meal caused a 15% decrease in plasma volume by the end of a 1-hour feeding period. Feeding hypovolemia was confirmed by a coincident increase in plasma protein concentration (12%) and, in separate experiments, by analysis of postfeeding changes in the elimination of Evans blue dye. Plasma aldosterone concentration was significantly (P less than 0.05) increased from 2 to 5 hours after feeding. Urinary Na clearance decreased in response to feeding and remained lower than the prefeeding value until 9 hours after feeding. Urinary K clearance increased from prefeeding and reached a peak value between 5 and 7 hours after feeding. Creatinine clearance was unaffected. In contrast, the aforementioned variables were unchanged during the multiple regimen. Results indicate that ingestion of a large concentrate meal by ponies causes periprandial hypovolemia, activation of the renin-angiotensin-aldosterone system, and a subsequent antinatriuresis-kaliuresis that lasts for several hours.
Using radial immunodiffusion as a standard, 4 screening techniques for detection of failure of passive transfer in equine neonates were compared for sensitivity, specificity, positive and negative predictive values, efficiency, and cost. The techniques compared were latex agglutination test, membrane filter ELISA, dipstick ELISA, and glutaraldehyde coagulation (GC) test. Test results of 50 serum samples from foals 24 to 60 hours old revealed consistently highest accuracy in the GC test at IgG concentrations of 400 and 800 mg/dl, and lowest cost per test, using the GC test. Two hundred fifty-three serum samples from foals 24 to 60 hours old were evaluated for comparison of results of GC and radial immunodiffusion tests. Overall efficiency was 92 and 91% at serum IgG concentrations of 400 and 800 mg/dl, respectively. Under most field circumstances, the GC test would be the preferred screening test for detection of failure of passive transfer in equine neonates.
An ovarian adenocarcinoma with teratomatous elements was removed from a 9-year-old mare. Although no other lesions were detected at ovariectomy, multifocal metastatic masses led to cachexia and euthanasia 2 months later. This case reaffirms the need to exercise caution when removing ovarian masses to prevent seeding of the abdomen. This report includes discussion of the WHO system of classification of ovarian tumors.
In King County, Washington, penicillinase-producing Neisseria gonorrhoeae infections increased from 0.8% of reported cases of gonorrhea in 1986 to 6.8% of cases in the third quarter of 1987, then stabilized at 2.7% to 3.6% of cases. Of 268 penicillinase-producing N gonorrhoeae isolates tested, 159 (59%) belonged to a single clone, as evidenced by auxotyping, protein-I serotyping, plasmid analysis, and antimicrobial susceptibility testing. As this strain spread, the predominance of cases shifted from whites to blacks and from men to equal numbers of men and women. The proportion of cases associated with illicit drug use rose steadily from 19% in the first quarter of 1987 to 82% in the fourth quarter. Sixty percent of cases occurred in prostitutes or recent sexual contacts of prostitutes. These results suggest that core gonorrhea transmitters in King County are predominantly black illicit drug users, prostitutes, and their sexual partners. These are priority target populations for behavioral intervention and other measures to control the spread of all sexually transmitted diseases, including human immunodeficiency virus infection.
Strongly catalase-positive Gram-negative anaerobic rods were isolated from approximately half of all intra-abdominal specimens received from patients with gangrenous and perforated appendicitis, and subsequently also from normal faecal specimens. The organism was originally detected on Bacteroides-bile-aesculin (BBE) agar, and grew slowly on non-selective anaerobic media containing blood. It was stimulated by bile and differed from other known genera by being urease- and catalase-positive, and by reducing nitrate. It did not reduce sulphate. Other anaerobic Gram-negative rods showed no homology by DNA dot-blot hybridization. The thermal melting profile of chromosomal DNA showed 39-40 mol% G + C. The whole-cell fatty acid methyl ester profile included cyclic and branched long-chain acids, and differed from those of all other anaerobes that have been tested. beta-Lactamase was not detected. The name Bilophila wadsworthia gen. nov., sp. nov. is proposed for this organism.
A reproducible, reversible model of colitis induced in ponies by administering castor oil (2.5 ml/kg bodyweight [bwt] per os) was characterised by abdominal pain, fever, watery diarrhoea, dehydration, hypovolaemia, toxaemia, leucopenia, decreased serum Cl, Na and K levels and metabolic acidosis. The signs were most severe between 24 and 48 h post induction, stabilisation was frequently observed after 72 h, although diarrhoea could persist beyond 96 h. Morphological and in vitro transport studies (right ventral colon) were conducted on tissues from animals destroyed at 24, 48 and 72 h. In the caecum and colon, surface epithelial disruption and exfoliation from the basement membrane occurred between 24 and 48 h. Early signs of recovery were evident by replenishment of denuded areas with columnar epithelium at 72 h. The crypt epithelium was unaffected throughout the intestinal tract. In vitro transport studies were consistent with the morphological findings. Decreased Na-Cl absorption and normal Cl secretion indicated an impaired surface epithelium coincident with an undamaged cryptal epithelium. Increased mucosal permeability was demonstrated by high ionic conductance and large unidirectional isotopic fluxes. Tissue conductance improved during in vitro incubation suggesting epithelial repair after removal of castor oil. Changes in the population and proportion of bacteria in the faeces as diarrhoea ensued were confirmed at necropsy with a predominance of E. coli and Enterobacter/Klebsiella sp in the large bowel. The experimental induction of castor oil colitis showed many similarities to intestinal endotoxaemia and the secretory type diarrhoea encountered in naturally occurring acute colitis syndromes in horses. The model could prove applicable in studying the pathophysiological mechanisms precipitating such life-threatening disorders.
The increasing resistance of genital mycoplasmas to tetracycline poses a problem because tetracycline is one of the few antimicrobial agents active against Mycoplasma hominis, Ureaplasma urealyticum, chlamydiae, gonococci, and other agents of genitourinary-tract disease. Since the quinolones are a promising group of antimicrobial agents, the susceptibilities of M. hominis and U. urealyticum to the newer 6-fluoroquinolones were determined by the agar dilution method. Ciprofloxacin, difloxacin, and ofloxacin had good activity against M. hominis, with the MIC for 50% of isolates tested (MIC50) being 1 microgram/ml. Fleroxacin, lomefloxacin, pefloxacin, and rosoxacin had MIC50s of 2 micrograms/ml. Enoxacin, norfloxacin, and amifloxacin had MIC50s of 8 to 16 micrograms/ml, and cinoxacin and nalidixic acid were inactive (MIC50, greater than or equal to 256 micrograms/ml). Overall, the activities of 6-fluoroquinolones for ureaplasmas were similar to those for M. hominis, with MICs being the same or twofold greater. The most active 6-fluoroquinolones against ureaplasmas were difloxacin, ofloxacin, and pefloxacin, with MIC50s of 1 to 2 micrograms/ml. Ciprofloxacin was unusual in that the MIC50 for M. hominis was 1 microgram/ml, whereas the MIC50 for ureaplasmas was 8 micrograms/ml. Since the MIC50s for the most active quinolones approximate achievable concentrations in blood and urine, quinolones have promise in treating mycoplasmal infections.
Tetracycline resistance determinants are widespread and distinguishable genetically and biochemically. The nomenclature for this increasing number of determinants has been varied and inconsistent. This communication suggests ways of naming these determinants and their genes and gene products consistent with current genetic terminology.