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Biomedical subjects

J E Brorson

Publications and source records attributed to J E Brorson.

At least 19 recordsLinked to original sources

Efficacy of long-term antimicrobial prophylaxis after acute pyelonephritis in pregnancy.

The efficacy of antimicrobial prophylaxis for recurrent urinary infection after an episode of acute febrile pyelonephritis was assessed in 27 pregnant women. Immediately following a 2-week treatment course for acute pyelonephritis, low-dose prophylaxis with a proper antimicrobial agent taken at bedtime daily was continued until 1 month after delivery. 23 women received 50 mg of nitrofurantoin, and 2 each were given 250 mg of amoxycillin and 250 mg of cephalexin, respectively. The treatment regimens were well tolerated and there were no breakthrough infections during a total of 7.8 patient-years of treatment. These results show that long-term low-dose antimicrobial prophylaxis is highly effective in this population at high risk of recurrent acute pyelonephritis.

Acute Disease↗

Concentration of phenoxymethylpenicillin in tonsillar tissue.

Seventeen patients underwent tonsillectomy 55-120 min after receiving oral phenoxymethylpenicillin 12.5 mg/kg bodyweight. The penicillin concentration in serum and tonsillar tissue in each patient was determined by a microbial assay. In 9 patients with tonsillar hyperplasia, but with no prior history of tonsillitis, the mean penicillin concentration in serum and in tonsillar tissue was 5.0 mg.l-1 and 1.32 mg.g-1, respectively, and in 8 patients with manifest tonsillitis the corresponding values were 3.01 mg.l-1 and 0.67 mg.g-1. It appears that the penicillin concentration in tonsillar tissue is about 1/5 to 1/4 of that in serum, regardless of whether the tonsils are inflamed or hypertrophied.

Adolescent↗

The bacteriology of operated renal stones.

In a group of patients consecutively operated on for renal stones, more than half of the patients had urinary tract infection. In a significant number of the patients with infection stones containing magnesium ammonium phosphate, no urease-producing microorganism could be cultured. Escherichia coli was on the other hand rather frequently cultured from the stone in these patients. This suggests the possibility that E. coli might be involved in stone formation. The correlation between stone and voided urine cultures was incomplete. It is thus important to perform stone cultures. This could be done without loss of accuracy by culturing crushed stones.

Adolescent↗

Morphological lesions of the rat urinary tract induced by inoculation of mycoplasmas and other urinary tract pathogens.

The effects on the urinary tract after inoculation of Ureaplasma urealyticum into the rat bladder were evaluated and compared to that seen after Mycoplasma hominis, Escherichia coli and Proteus mirabilis inoculation. The inoculation of the urease-producing organisms P. mirabilis and U. urealyticum were associated with the formation of struvite bladder stones and predominantly hyperplastic lesions of the bladder. The P. mirabilis inoculated rats also displayed marked pyelonephritis. A similar but much less pronounced reaction also occurred in the kidneys of some of the U. urealyticum inoculated rats. P. mirabilis could frequently be recultured. In contrast, this was not possible with U. urealyticum, but the organism was detected by scanning electron microscopy 2 weeks after the inoculation. Inoculation of M. hominis was associated with a few mild lesions of the bladder, but inflammatory lesions were not present in the kidneys. The study confirms the potential of Ureaplasma to form struvite stones in rat urinary tract. It also demonstrates that it can induce inflammatory changes in both bladder and kidney of rats without concomitant stone formation.

Animals↗

Comparison of serum concentrations of ceftazidime and tobramycin in newborn infants.

Peak and trough serum concentrations of ceftazidime and tobramycin were determined in neonates with suspected septicaemia in an open randomized study. Mean peak serum levels were 85 (+/- 4.4 SE) mg/l for ceftazidime and 5.8 (+/- 0.3 SE) mg/l for tobramycin. The peak serum levels of ceftazidime were well above the reported minimal inhibitory concentration (MIC)90 values of pathogenic bacteria encountered in neonates, while peak serum levels of tobramycin were lower than reported MIC90 values for Klebsiella, Pseudomonas, Enterobacter and Serratia species. Nine of 33 tobramycin-treated patients had potentially toxic trough serum levels (greater than 2 mg/l) and nine had subtherapeutic peak serum levels (less than 4 mg/l). The dosage of this antibiotic had to be changed frequently. In comparison only 2 of 29 ceftazidime-treated patients had subtherapeutic peak levels (less than 40 mg/l) and none had potentially toxic trough levels (greater than 40 mg/l). Ceftazidime, in comparison with tobramycin, has a more favourable antibacterial spectrum and routine determinations of peak and trough serum levels should not be necessary.

Ampicillin↗

Susceptibility to beta-lactam antibiotics and gentamicin of gram-negative bacilli isolated from hospitalized patients: a Swedish multicenter study.

A total of 952 blood and 1543 urine isolates of gram-negative bacilli from hospitalized patients in 1986-1987 were consecutively collected by 10 Swedish laboratories and tested for susceptibility to 8 beta-lactam antibiotics and to gentamicin. The isolates were mostly Escherichia coli (58% and 44%, respectively) and Klebsiella sp. (17% and 18%). Resistance to ampicillin in blood and urine isolates was found in 35% and 45%, respectively, to piperacillin in 5% and 6%, to cephalothin in 26% and 34%, to cefuroxime in 12% and 22%, to cefotaxime in 3% and 5%, to ceftazidime in 1% and 1%, to imipenem in 0.5% and 0.1%, to aztreonam in 3% and 2%, and to gentamicin in 0.8% and 0%. Resistance of clinically important gram-negative bacilli to new beta-lactam antibiotics and to gentamicin is infrequent in Sweden.

Ampicillin↗

Culture from epipharynx of little value in bacterial pneumonia.

In 75 patients with acute pneumonia of moderate severity a comparative study between transtracheal aspiration (TTA), sputum culture and epipharynx culture was carried out. Organisms considered as the probable etiological agent were found in 53% with TTA. The same organisms were found in only 27% in sputum samples and in 21% in epipharynx samples. No serious complications with TTA was noted.

Adult↗

The regression line for erythromycin is not valid for beta-hemolytic streptococci group A.

The antibacterial activity of erythromycin to 50 beta-hemolytic streptococci group A was assessed using disc diffusion and MIC techniques on solid media at pHs 6, 7 and 8 in CO2, aerobic and anaerobic atmospheres. The majority of the strains were only intermediately sensitive to erythromycin according to the disc diffusion method, whereas they were sensitive as judged by the MIC determination. This demonstrates that the regression line is invalid for the drug-bug combination of erythromycin and beta-hemolytic streptococci group A. It was also shown that the activity of erythromycin is reduced at a lower pH and in CO2 incubation.

Aerobiosis↗

In vitro aminoglycoside resistance of gram-negative bacilli and staphylococci isolated from blood in Sweden 1980-1984.

The in vitro susceptibility to gentamicin, tobramycin, amikacin and netilmicin in septicaemia isolates was followed during 1980-1984 in 6-8 Swedish laboratories. The bacterial distribution was similar over the years and was dominated by Escherichia coli and staphylococci. Resistance to gentamicin was found in 2.3-3.6%, to tobramycin in 1.4-3.4%, to amikacin and netilmicin in 0.5-0.9%. Production of aminoglycoside modifying enzymes was observed among resistant strains.

Amikacin↗

Concrement formation in the urinary bladder in rats inoculated with Ureaplasma urealyticum.

To study the concrement-forming ability of Ureaplasma urealyticum in the urinary tract, viable and heat-killed ureaplasmas as well as urease and non-urease-producing bacteria were inoculated into the bladder in rats. Viable ureaplasmas, in contrast to heat-killed, caused the formation of bladder stones with a frequency corresponding to urease-producing bacteria (Proteus mirabilis). It was not possible to reculture the inoculated ureaplasmas from the urinary tract. Non-urease producing microorganisms (Escherichia coli and Mycoplasma hominis) only occasionally induced stone formation. The results indicate that U. urealyticum can initiate stone formation, a property that appears to be associated with the urease activity of the organism.

Animals↗

Elimination of mycoplasmas from cell cultures utilizing hyperimmune sera.

Eighteen cell lines contaminated with various mycoplasmas have been treated with hyperimmune sera and mycoplasmas have been eradicated from all. After treatment the cell lines have been observed for a least one year and they are still free from mycoplasma contamination as ascertained by four independent mycoplasma detection assays. The hyperimmune sera used were of high titer, type-specific and growth-inhibiting. These sera were produced by immunization of rabbits with purified membranes from Mycoplasma orale, M. arginini, M. hominis, M. fermentans, M. hyorhinis and Acholeplasma laidlawii. In addition to elimination of mycoplasmas from cell cultures we have successfully used these sera for detection and typing of mycoplasma contamination in cell cultures.

Animals↗

Studies in vivo on the killing rate and refractory period of penicillin V in an experimental streptococcal infection.

The refractory period and the killing rate of beta-haemolytic streptococci after exposure to phenoxymethylpenicillin were tested in an in-vivo model. beta-Haemolytic streptococci were injected into steel net chambers implanted subcutaneously on the backs of rabbits. The rabbits were treated with infusions of phenoxymethylpenicillin, either as a single dose to measure the refractory period or as repeated doses in order to measure the killing rate of streptococci. The peak concentration of phenoxymethylpenicillin in tissue chamber fluid occurred about 16-120 min post infusion, and reached 0.4 mg/l in infected and 0.6 mg/l in uninfected tissue cage fluid. In the tissue cage fluid the phenoxymethylpenicillin concentration exceeded 0.03 mg/l, the MIC-value for the streptococcal strain used, for at least 6 h. After a single infusion there was a decline in viable count. The bacteria did not reach their original numbers until 60-70 h later. After the sixth infusion streptococci were no longer detectable in tissue cage fluid. There was a close correlation between viable counts before treatment and the time required for eradication of bacteria. L-phase variants of beta-haemolytic streptococci were not found when tissue cage fluid was plated on special media.

Animals↗

Susceptibility of Bordetella pertussis to doxycycline, cinoxacin, nalidixic acid, norfloxacin, imipenem, mecillinam and rifampicin.

The susceptibility of Bordetella pertussis to doxycycline, cinoxacin, nalidixic acid, norfloxacin, imipenem (N-formimidoyl-thienamycin), mecillinam and rifampicin was studied by agar and broth dilution. There were discrepancies between MICs registered on solid medium and in fluid medium. There seems to be a need for methodological studies on the antibiotic susceptibility of Bord. pertussis using different techniques. None of the compounds tested seemed to be realistic alternatives to the well documented erythromycin.

Amdinocillin↗