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Biomedical subjects

A R Ronald

Publications and source records attributed to A R Ronald.

At least 163 records · Page 9Linked to original sources
PubMed1978

Antimicrobial susceptibility of Haemophilus ducreyi.

The susceptibility of 19 isolates of Haemophilus ducreyi from a recent chancroid outbreak and four reference strains was determined in vitro to 13 antimicrobial agents. The rabbit intradermal test for virulence was positive for all of the local isolates, but not for the reference strains. The "nonvirulent" reference strains were inhibited by lower minimum inhibitory concentrations (MICs) of most agents tested. For the virulent isolates, the range of MICs (in micrograms per milliliter) of the following were: of vancomycin, 8 to 128; of polymyxin, 32 to 128; of cloxacillin, 32 to 64; of tetracycline, 0.5 to 32; of cephalothin, 4 to 8; of doxycycline, 0.25 to 8; and of kanamycin, 1 to 8. Three strains were resistant to penicillin and ampicillin (MIC >/= 128 mug/ml), and these three strains produced beta-lactamase. The remainder were susceptible to 4 mug/ml. All strains were susceptible to rifampin (MIC </= 1 mug/ml), chloramphenicol (MIC </= 4 mug/ml), sulfisoxazole (MIC </= 8 mug/ml), and nalidixic acid (MIC </= 8 mug/ml). These susceptibilities of H. ducreyi indicate several antimicrobial agents that may be effective for chancroid treatment and support the use of vancomycin in a selective medium for the culture of chancroid genital ulcers.

Animals↗
PubMed1978

Comparison of specimen collection and laboratory techniques for isolation of Haemophilus ducreyi.

Sixteen patients with clinical chancroid were studied prospectively; different culture media and sampling techniques from genital lesions were evaluated. Technique A was aspiration of a saline wash from the ulcer which was pooled and inoculated into rabbit blood, rabbit blood + vancomycin (5 microgram/ml), and semisolid chocolate agar + vancomycin (3 microgram/ml). Each primary culture medium was subcultured to chocolate agar with 1% IsoVitaleX (CA), CA with vancomycin (3 microgram/ml) plus polymyxin (7.5 microgram/ml; CA + vp). Technique B was the use of a cotton swab, plated directly on CA, CA + v, and CA + vp. Nine strains of Haemophilus ducreyi were obtained. Technique A yielded seven strains, whereas technique B yielded eight strains; with each technique, five strains were isolated only after use of selective antibiotic media. CA + v medium yielded the largest number of isolates. Direct inoculation by swab to CA + v from chancroidal ulcers is effective as an isolation technique for growth of H. ducreyi.

Bacteriological Techniques↗
PubMed1978

Determination of the hemin requirement of Haemophilus ducreyi: evaluation of the porphyrin test and media used in the satellite growth test.

Gonococcal (GC) agar supplemented with glucose and glutamine was found to be superior to Eugonagar and Trypticase soy agar in demonstrating the hemin requirement of 23 strains of Haemophilus ducreyi by the satellite growth test. The porphyrin test confirmed the requirement for exogenous hematin. With the agar dilution technique, using supplemented GC agar, the hemin concentration required to initiate growth was 10 microgram/ml, and the optimal hemin concentration to produce growth equivalent to that on chocolate agar was between 200 and 500 microgram/ml. On GC agar with added glucose and glutamine, the lowest hemin concentration impregnated in paper disks able to initiate satellite growth was 50 microgram/ml. The hemin requirements of these H. ducreyi were much higher than that reported for other Haemophilus species.

Bacteriological Techniques↗
PubMed1978

Anaerobic and aerobic urethral flora in healthy females.

We characterized the aerobic and anaerobic urethral flora of five healthy females by performing urethral and midstream urine cultures once weekly for 8 weeks. Aerobic cultures were performed monthly for an additional 3 months. Lactobacillus spp. were isolated from 52 of 57 samples, Staphylococcus epidermidis from 42 of 57, Corynebacterium spp. from 26 of 57, and alpha-hemolytic streptococci from 14 of 57. Two subjects had E. coli serogroup O6 and group B streptococci isolated on five occasions, respectively. Anaerobes were isolated from 32 of 35 urethral urines (91%). Bacteroides melaninogenicus accounted for 46% of these isolates. The anaerobic urethral flora varied slightly from week to week, and a similar anaerobic flora was isolated from the introitus, fourchette, and cutaneous perineum. In addition, anaerobes were isolated from 16 of 18 healthy females who had a urethral urine sample cultured once only, and B. melaninogenicus was the most frequent isolate. Of the 21 B. melaninogenicus isolates identified to subspecies, 14 were subsp. intermedius.

Adolescent↗
PubMed1978

Bacteremic Haemophilus influenzae genitourinary tract infections in adults.

Six cases of bacteremia associated with genitourinary (GU) tract infections in adults due to Haemophilus influenzae occurred during a 42-month period at the Health Sciences Centre in Winnipeg, Canada. Four cases were associated with pregnancy or abortion, one with acute salpingitis, and one with urinary tract manipulation. Four of the five strains available for serotyping were nontypable. Clinical conjunctivitis was present in one patient, and infants born to two other patients developed purulent conjunctivitis from which H influenzae was grown. These six cases, and others from the literature, include a wide spectrum of GU tract infections due to this organism. With the rising incidence of severe infections in adults due to this organism, and the widespread emergence of ampicillin-resistant strains, H influenzae must be considered a GU tract pathogen.

Adolescent↗
PubMed1977

Clinical and laboratory study of tobramycin in the treatment of infections due to gram-negative organisms.

Tobramycin, an aminoglycoside antibiotic, was used to treat 52 infections due to gram-negative organisms in 51 patients. Complicated urinary tract infections, bacteremia and pyelonephritis accounted for 80% of the infections. The rate of immediate satisfactory response was 79%. During therapy with tobramycin, resistant organisms emerged in four patients--two Pseudomonas aeruginosa and two Escherichia coli strains. There were four superinfections with tobramycin-resistant Providencia sp. In four seriously ill patients the serum creatinine concentration increased 1 mg/dL or more; in three the increase was transient. No auditory toxicity was noted in the 19 patients in whom serial audiograms were made. In vitro testing of isolates from these patients showed that tobramycin and gentamicin had equal activity against Enterobacteriaceae. Tobramycin was two to four times more active against susceptible P. aeruginosa.

Adolescent↗
PubMed1977

Bacteremia due to Bacteroidacceae: a review of 92 cases.

The clinical courses of 92 patients who had bacteremia due to Bacteroidaceae were reviewed. The overall mortality rate was 21% (19 patients). There was no significant difference between mortality rates when patients were grouped by anticipated clinical course of underlying disease (nonfatal, ultimately fatal, and rapidly fatal) and when they were grouped by type of antibacterial therapy (appropriate, including clindamycin, chloramphenicol, lincomycin, and carbenicillin; or inappropriate, signifying no antibiotic treatment or treatment with antibiotics other than the four listed above). However, there was a correlation between recovery of the patient and portal of entry of the infectious agent; patients whose source of infection was the gastrointestinal tract had a mortality rate of 29% (17 of 58 patients), whereas there were no deaths among the 26 women whose presumed source of bacteremia was the genital tract. Increasing age appeared to be an important factor as well; 17 of 19 deaths occurred in patients who were older than 40 years. There was no significant difference between the mortality rate of patients who were treated with clindamycin (15%, eight of 52 patients) and that of patients who were treated with chloramphenicol (44%, four of nine).

Adult↗
PubMed1977

Amoxicillin therapy of acute urinary infections in adults.

Fifty-two patients, 48 females and 4 males, with suspected urinary infection were treated with amoxicillin. Twenty-two females with presumed bladder infection were treated with amoxicillin, 250 mg three times a day for 7 days; 26 females and 4 males with presumed renal infection were treated with amoxicillin, 500 mg three times a day for 14 days. Five patients were immediate treatment failures, with positive urine cultures during therapy. All five patients had been infected with amoxicillin-resistant urinary pathogens. Three patients, treated as for bladder infections, reinfected during 6 weeks of follow-up, and only one relapsed. Two patients, treated as for renal infections, reinfected, whereas four relapsed. During therapy, amoxicillin-susceptible gram-negative rods were eradicated from the periurethral area in all but one patient. Of 28 patients studied, 19 acquired a predominant growth of either resistant aerobic gram-negative rods or Candida albicans from periurethral cultures. Our findings suggest that these two regimens of amoxicillin achieve satisfactory cure rates in urinary infection, but both regimens significantly alter the normal periurethral flora.

Acute Disease↗
PubMed1976

Bacteriuria localization and response to single-dose therapy in women.

One hundred women with bacteriuria had the infection localized by the "bladder-washout" technique. Thirty-six of the 39 with infection confined to the bladder were cured with a single intramuscular injection of 500 mg of kanamycin sulfate, whereas 47 of the 65 patients with infection originating from their upper tract relapsed almost immediately. None of the seven patients with abnormal pyelograms and associated upper tract infection was cured with kanamycin. These results suport the hypothesis that bladder infections in women can be readily cured with a very short course of therapy. Women who relapse after a single injection of kanamycin almost always have renal infection.

Adolescent↗
PubMed1976

Clinical evaluation of amikacin in treatment of infections due to gram-negative aerobic bacilli.

The efficacy and safety of amikacin were evaluated in 42 patients with infections presumed to be due to gram-negative rods. The dosage of 7.5 mg of amikacin/kg every 12 hr was administered intramuscularly to 32 patients and intravenously to seven patients; three patients with renal impairment were given a modified regimen. The duration of treatment was three to 51 days (mean, 9.6 days). Of 19 patients with acute pyelonephritis, five had positive blood culture results. Ten patients had chronic urinary infection, and isolates of Pseudomonas aeruginosa from four of these patients acquired resistance to amikacin during therapy. Of seven patients with gram-negative bacteremia from sources other than the urinary tract, four showed satisfactory and three had less than optimal responses to therapy with amikacin. Two patients with chronic osteomyelitis or soft tissue infection improved but subsequently relapsed. Two patients with acute febrile illness, in whom the etiologic agent was unidentified, recovered. Serial audiograms revealed no change in 26 of 27 patients; one had a significant deterioration in hearing. A transient rise in the level of serum creatinine was noted in three patients. Serial tests of liver function revealed no abnormalities.

Adolescent↗
PubMed1976

Emergence of gentamicin- and carbenicillin-resistant Pseudomonas aeruginosa in a hospital environment.

Strains of Pseudomonas aeruginosa resistant to either gentamicin or carbenicillin have been noted since their introduction into clinical use. During a 6-month period, twice-weekly cultures were obtained from all patients treated with either gentamicin or carbenicillin and from all patients with a positive culture for P. aeruginosa. Susceptibility testing to gentamicin and carbenicillin and pyocine typing were performed on all isolates. Organisms with a minimal inhibitory concentration greater than 12.5 mug of gentamicin per ml or greater than 100 mug of carbenicillin per ml were defined as resistant. P. aeruginosa was cultured from 238 patients. One patient was initially infected with a gentamicin-resistant isolate. In 11 other patients, serial cultures revealed the emergence of resistance to gentamicin. All but one of these resistant isolates occurred in patients treated with gentamicin. In eight instances the pyocine and/or serological types before and after the change in sensitivity pattern were the same. Gentamicin-resistant P. aeruginosa emerged significantly more often in patients treated with gentamicin than in those who did not receive gentamicin. Carbenicillin-resistant P. aeruginosa emerged in four of 14 patients treated with carbenicillin. Seventeen of the 238 patients were infected de novo with carbenicillin-resistant P. aeruginosa. Carbenicillin-resistant P. aeruginosa emerged significantly more often in patients treated with carbenicillin than in those who did not receive carbenicillin. No evidence was found for in-hospital spread of resistant P. aeruginosa.

Adult↗
PubMed1976

Immune response to a purified cytoplasmic protein of Neisseria gonorrhoeae.

This paper describes studies based on the hypothesis that the immunogenicity of the gonococcus is impaired by a component toxic to immunocytes. Cytoplasm of colony type 1 gonococci was found to contain a protein fraction beta+t not present in colony type 4 gonococci. From the results of further analysis it is tentatively deduced that beta+t consists of a toxic component Tbeta-t and an immunogen.

Amino Acids↗
PubMed1975

Trimethoprim-resistant Enterobacteriaceae in urinary tract infection.

The incidence of trimethoprim-resistant Enterobacteriaceae has not increased since the introduction of the combination trimethoprim-sulfamethoxazole (TMP-SMX) into the clinical use at our centre in 1973. Using the minimum inhibitory concentration (MIC) as the index of trimethoprim resistance, this ranged from 1.6 to 800 mug/ml; for the majority of isolates it lay between 1.6 and 12.5 mug/ml. About half of these trimethoprim-resistant organisms were sensitive to sulfonamide. In vitro data suggest that organisms resistant to sulfonamide as well as to trimethoprim, where the MIC for the former drug is 3.1 mug/ml or less, will be susceptible to the combination. More resistant organisms, i.e., those for which the MIC of trimethoprim is 6.2 mug/ml or more, often appear quite resistent to the combination. There is no evidence that previous therapy with TMP-SMX is a significant predisposing factor to infection with these organisms, although there is a significant correlation between previous TMP-SMX therapy and infection with organisms with a high level of trimethoprim resistance. Organisms harbouring R-factor resistance or thymine-dependent mutants were not encountered during the course of this study.

Drug Combinations↗
PubMed1975

A comparison of trimethorprim-sulfamethoxazole with sulfamethoxazole alone in infections localized to the kidneys.

Ninety patients with urinary tract infections were treated in a randomized double-blind study with either a combination of trimethoprim and sulfamethoxazole (TMP-SMX) or sulfamethoxazole alone (SMX). Thirty of 42 patients treated with TMP-SMX were cured by the time of follow-up compared with 26 of 48 treated with SMX alone. Of the 29 patients infected with SMX-resistent organisms, the combination TMP-SMX cured 12 of 17, whereas SMX alone cured 2 of 12. Of the 61 patients infected with SMX-sensitive organisms, TMP-SMX cured 18 of 25; SMX alone cured 24 of 36. In 50 women the infection was found localized to The upper urinary tract by the use of the Fairley bladder washout technique. TMPsmx cured 16 or 24 of these patients with proved upper tract infections and SMX alone cured 11 of 26. Although none of these differences were significant, TMP-SMX appears to be an effective drug combination for the therapy of proved upper tract infection and is also effective in eradicating sulfonamide-resistant organisms.

Administration, Oral↗
PubMed1975

Prophylaxis of recurring urinary tract infection in females: a comparison of nitrofurantoin with trimethoprim-sulfamethoxazole.

Twenty-eight females with recurrent urinary tract infection were treated to eradicate their existing infections and then observed for recurrences while receiving one of the three following prophylactic regimens for 6 to 12 months: nitrofurantoin, 50 mg daily; one half tablet of trimethoprim-sulfamethoxazole (TMP-SMX) twice weekly; or one tablet of TMP-SMX once weekly. Preadolescent girls received half the adult doses. After completion of the course of prophylactic agent the patients were followed up at bimonthly intervals until infection recurred. After eradication of this new infection they were started on another prophylactic regimen. Six infections (1.0/patient-year) recurred in patients on nitrofurantoin, four infections (0.4/patients-year) reucrred in those receiving twice weekly TMP-SMX, and 12 infections (1.3/patient-year) in those receiving once weekly TMP-SMX. The mean interval between discontinuation of prophylaxis and recurrence of infection was 2.6 months. TMP-SMX in the doses used eliminated aerobic gram-negative rods from swabs from the anal canal in many patients. Gram-negative organisms resistant to trimethoprim did not cause infection either during or after therapy.

Administration, Oral↗