PubMed Health⌕ Search

Biomedical subjects

S D Allen

Publications and source records attributed to S D Allen.

8 recordsLinked to original sources
PubMed1979

Ureolytic Escherichia coli of human origin: serological, epidemiological, and genetic analysis.

Forty-five strains of ureolytic Escherichia coli of human origin, isolated in the United States between 1956 and 1977, were characterized by geographical distribution, site of infection, serotype, resistance to antibiotics, and biochemical reactions. All strains were studied for the ability to generate clones of nonureolytic E. coli (segregants), and a subset of these were selected for plasmid analysis and a variety of bacterial matings. There did not appear to be a common geographical distribution, serotype, antibiogram, or other aberrant biochemical reactions other than the hydrolysis of urea among these strains. The predominance of urinary tract isolates (46.7% total) may reflect a relationship between urea hydrolysis and pathogenesis at this site. Ten of the strains (22.2%) did segregate nonureolytic E. coli colonies, and all possessed at least one common plasmid species with a molecular weight of about 65 X 10(6). Only strain 1138-77 serotype O16:H6 conjugally transfered the ability to hydrolyze urea, ferment sucrose, and resist inhibition by sulfadiazide simultaneously. The resulting, recombination-deficient E. coli K-12 tranconjugant was found to possess a plasmid with a molecular weight of about 80 X 10(6) to 90 X 10(6).

Anti-Bacterial Agents↗
PubMed1979

Comparison of capillary ear blood and arterial blood to validate capillary sampling as an accurate assay of blood gas in swine.

Capillary sampling in swine can be performed as an accurate assay of arterial blood gases. Studies with swine provided results similar to, or slightly more favorable than, those reported for human beings, depending upon which cutaneous technique was used on human beings. On the basis of free flow or arterilization of the cutaneous sample and of the correlation between capillary and arterial pH, CO2 partial pressure (PCO2), and O2 partial pressure (PO2) values, the capillary sampling technique of complete incisement of a 2-mm section from the tip of the warmed porcine ear could be a substitution technique for arterial blood sampling. Free flow with this technique was maximized and high correlation coefficients (r) for pH (r = 0.96), PCO2 (r = 0.82), and PO2 (r = 0.90) capillary-arterial values (n = 37) were obtained.

Animals↗
PubMed1978

Anaerobic flora of the normal human conjunctival sac.

Specimens from the conjunctival sacs of 92 healthy eyes were cultured on two separate occasions to determine the presence or absence of a persistent anaerobic flora. Aerobic bacteria and fungi were also studied for comparison. Of the 184 eye cultures, 112 (60.9%) contained at least one microorganism. Obligate anaerobes were recovered from 51.6% (95/184) of the cultures. Propionibacterium acnes, the predominant anaerobe encountered, was present in 49.5% (91/184) of the eyes. Aerobic and facultatively anaerobic bacteria, present in 32.6% of the total eye cultures, were less common than obligate anaerobes. Staphylococcus epidermidis was the most common of these. Fungi were rarely found. Our findings suggest that the conjunctival sac is either sterile or normally contains small numbers of anaerobic, aerobic, or facultatively anaerobic bacteria. As other workers have suggested, the origin of the bacteria in the eyes may be the skin of the eyelids.

Adult↗
PubMed1978

Diagnosis and etiology of nongonococcal urethritis.

The observation of more than four polymorphonuclear cells (PMN) per high-power field (hpf) in gram-stained smears of urethral secretions was found to differentiate patients with urethritis from patients without urethritis. A urethral discharge was present in 78% of patients with nongonococcal urethritis (NGU). Dysuria without demonstrable urethral discharge and with fewer than four PMN/hpf did not appear to fit into the NGU spectrum. NGU is now defined to include men who have negative urethral cultures for Neisseria gonorrhoeae with a urethral discharge and/or more than four PMN/hpf in their urethral smears. The findings of more than four PMN/hpf in the urethral smears of 22%of asymptomatic sexually active men with more than one sexual partner (polygamous controls) suggests that asymptomatic NGU is not uncommon. Chlamydia trachomatis was isolated significantly more frequently from the NGU study group than from the control group (P less than 0.001). This study adds Corynebacterium vaginale (Haemophilus vaginalis), group B streptococci, and yeasts to the list of sexually transmitted microorganisms that are not etiologic determinants of NGU.

Chlamydia trachomatis↗
PubMed1978

Use of ethanol for selective isolation of sporeforming microorganisms.

When mixed cultures containing sporeforming bacteria were treated with heat or with ethanol, the latter consistently resulted in better recovery of Clostridium and Bacillus species. Both techniques were effective in eliminating vegetative cells. An ethanol concentration greater than 25% and exposure for 45 min or longer were necessary to kill all vegetative cells in mixed-culture samples. Ethanol treatment (50% ethanol for 1 h) was effective for isolating sporeforming bacteria from intestinal specimens. Seven different species of Clostridium were the only bacteria isolated from the ethanol-treated specimen of intestinal contents from the large bowel of a patient. It was concluded that treatment with ethanol for 1 h is an effective technique for selective isolation of sporeforming bacteria from mixed cultures and certain types of clinical specimens.

Bacillus↗
PubMed1977

Bacteriological studies in a patient with antibiotic-associated pseudomembranous colitis.

Detailed aerobic and anaerobic bacteriological studies on the operative specimen from a patient with antibiotic-associated pseudomembranous colitis revealed approximately 10(11) facultatively anaerobic bacteria, but less than 10(5) obligate anaerobes per g of involved colonic tissue. Fourteen isolates of Escherichia coli, three isolates of Pseudomonas aeruginosa, and two isolates of Streptococcus fecalis were identified. The majority of the organisms were resistant to most of the antibiotics that the patient had received. Examinations of E. coli for heat-labile and heat-stable enterotoxins and tissue invasiveness were negative, and enterotoxin tests on the P. aeruginosa isolates were negative. Inoculation of mice with the bacterial isolates revealed no unusual pathogenicity. These findings suggest that antibiotic-associated colitis is associated with a marked loss in anaerobic colonic flora, but the colitis could not be explained by the presence of enterotoxins, tissue invasiveness, and pathogenicity of remaining microorganisms.

Aged↗
PubMed1975

Bacteremia with upper gastrointestinal endoscopy.

Fifty patients undergoing upper gastrointestinal fiberoptic endoscopy were studied prospectively for the development of bacteremia by aerobic and anerobic blood cultures obtained before, during, and at 5 and 30 minutes after the procedure. Forty-six patients were culture negative; four had positive cultures at 5 or 30 minutes after the procedure, or at both times. The level of bacteremia as estimated by pour plates was very low. Bacteremia did not correlate with the performance of biopsy or the type of mucosal abnormality found. It is concluded that only very high-risk patients should receive antimicrobial prophylaxis before this procedure. The minor risk of this low-level bacteremia should not be considered a contraindication to the performance of upper gastrointestinal endoscopy.

Duodenal Diseases↗