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Biomedical subjects

F O'Grady

Publications and source records attributed to F O'Grady.

At least 73 records · Page 4Linked to original sources
PubMed1975

Response of ampicillin resistant Escherichia coli to cephalosporins in an in vitro model simulating conditions of bacterial growth in the urinary bladder.

Five ampicillin resistant strains of Escherichia coli were exposed to cephalosporins in an in vitro model which simulates the hydrokinetic features of the urinary bladder. Although the strains showed substantial zones of inhibition when tested against cephalosporins by the disc diffusion method, the results in the bladder model suggest that, in conditions where the antibiotic concentration is being reduced by dilution and micturition as well as enzymic hydrolysis by the organism, activity of this group of agents may be insufficient to eradicate infection. It is suggested that the results warrant a closer investigation into the efficacy of cephalosporins against ampicillin resistant Gram negative bacilli in vivo.

Ampicillin↗
PubMed1975

Theory of hydrokinetic clearance of bacteria from the urinary bladder. I. Effect of variations in bacterial growth rate.

If the bladder is regularly emptied in appropriate circumstances the concentration of bacteria in successively voided samples progressively falls. By making a number of assumptions about conditions of bacterial growth in the bladder the way in which this washout of bacteria will occur can be predicted. Such predictions give a form of washout curve which differs significantly from that commonly encountered in patients. The shape of the predicted washout curve is affected by the form of the bacterial growth curve but this influence is not sufficient to account for the observed difference between patients and predictions.

Bacteriuria↗
PubMed1975

Theory of hydrokinetic clearance of bacteria from the urinary bladder. II. Effects of "bound" organisms and diuresis.

When patients with urinary infection drink large volumes of water and empty the bladder at frequent regular intervals, the concentration of bacteria in the voided samples commonly falls rapidly at first and then remains almost constant. The present theoretical analysis leads to the conclusion that the rapid initial fall in concentration is a function of diuresis and that the subsequent constant output originates from bacteria bound to multiplication sites on the uroepithelium from which their progeny are shed into the urine.

Bacteriuria↗
PubMed1974

Periurethral enterobacterial carriage in pathogenesis of recurrent urinary infection.

Periurethral carriage rates of enterobacteria have been studied in 20 normal women, 34 patients between episodes of bacteriuria, 34 patients with the "urethral syndrome," and 15 asymptomatic abacteriuric patients with a previous history of frequency and dysuria.Over a six-week period no difference in the Escherichia coli carriage rate was shown between these four groups. The carriage of all enterobacteria was slightly but significantly (P <0.05) lower in normal women compared with the patient groups but no difference was observed between the latter. There was no difference in the recovery rate and carriage of individual E. coli serotypes between the four groups.It is concluded that the presence of enterobacteria or E. coli on the periurethral area is not the principal determinant factor in the pathogenesis of recurrent urinary tract infection or the urethral syndrome and that definition of carriage status is of little practical value in management.

Adult↗
PubMed1974

Activity of FL 1060, a new beta-lactam antibiotic, against urinary tract pathogens.

The effect of the new beta-lactam antibiotic FL 1060 on urinary tract pathogens, of which 71 were sensitive to and 100 resistant to ampicillin, is presented here. When tested by conventional methods FL 1060 was found to be highly active against ampicillin-sensitive strains of E. coli but phenotypically resistant variants readily emerged, particularly when a large inoculum was used. Thirty-one per cent of ampicillin-resistant strains were found to be sensitive to less than 500 mug FL 1060 per ml, and in general this antibiotic was more active than ampicillin against resistant strains. In a system simulating the mechanical features of the urinary bladder the activity of FL 1060 against three sensitive strains of E. coli was found to be greater than ampicillin in conditions of low, but not high, osmolality.

Ampicillin↗
PubMed1973

Ammonia production by intestinal bacteria.

Bacterial growth and the production of ammonia from urea and by deamination of peptone has been examined at various pHs in both conventional static bacterial cultures and in a continuous cultivation system. Growth occurred on primary testing of 93 out of 100 strains of aerobic Gram-negative bacteria at pH 5, and 48 out of 50 strains of Esch. coli at pH 4.6. Hydrolysis of urea by Proteus mirabilis decreased steadily from pH 7.2 to pH 5.3; below pH 5.3 little hydrolysis occurred. Ammonia production from peptones by Esch. coli decreased from pH 7.2 to pH 4.6. Considerable variation was noted in the ability of different strains to produce ammonia. Experiments with cultures containing both Esch. coli and Pr. mirabilis showed that more ammonia was produced at low pH than was produced by cultures of single organisms. At low pH reduction in the count of organisms was not found to be an essential prerequisite for reduction of ammonia formation.

Ammonia↗
PubMed1973

The effect of perfusion on the flora of the excluded colon.

The bacterial flora of excluded colonic segments of three patients has been examined in the normal resting state and following perfusion.The flora of the excluded colon was substantial and qualitatively similar to that of faeces. Perfusion for two hours at 10 ml per minute usually reduced counts of organisms present in the issuing effluent by 1 to 1(1/2) logs in two patients, but rises in the counts of some organisms were recorded from the third patient. Prolonged rapid perfusion or the inclusion of antibiotics in the perfusing solution was necessary to obtain a substantial reduction in counts. Rapid perfusion resulted in the appearance of organisms that had not been recovered during slower perfusions.

Bacteroides↗