Changes in periurethral microflora after antimicrobial drugs.

Abstract

The periurethral flora was examined in 18 girls by use of a quantitative sampling method before, during, and three weeks after treatment with antibiotics for upper respiratory tract infections. Eight girls received amoxicillin. In five of them the anaerobic flora showed a reduction in total counts and in numbers of different species, and ali eight girls got a heavy colonisation with enterobacteria during treatment. Three weeks after treatment the anaerobic and aerobic flora had reversed to the pretreatment composition. In 10 girls treated with trimethoprim-sulphamethoxazole the anaerobic flora remained unaffected and no enterobacterial overgrowth was registered during the study period. We propose that antibiotics could be one among several factors involved in the pathogenesis of urinary tract infection, by suppression of the anaerobic microflora and promotion of the colonisation with enterobacteria. The periurethral microflora in healthy females is dominated by anaerobic bacteria with only scanty growth of aerobic Gram negative rods. ' 2 In females prone to recurrent urinary tract infections, the periurethral region is often colonised with uropathogens, even during infection free intervals.2' A disturbed anaerobic microflora is also found.5 The normal flora on various body surfaces provides a natural defence against colonisations with new potentially pathogenic bacteria, that is, 'colonisation resistance '.68 Antibiotics may disturb the colonisation resistance and thereby facilitate the development of infections.The present study is part of a project investigating factors involved in the pathogenesis of urinary tract infection, and examines the effects of antibiotics on the periurethral microflora in girls treated for upper respiratory tract infections and with no history of urinary tract infection. The aims were to investigate the effects on the predominant anaerobic flora and the concomitant effects on colonisation with Gram negative aerobic bacteria. Subjects and methods SUBJECTSEighteen prepubertal girls (aged 3-13 years, median 4 years) were included in the study. They all attended the emergency ward for otitis media and upper respiratory tract infections, requiring antibiotic treatment. None had a history of urinary tract infection or had been treated with antibiotics during the three month period before entering the study. Informed parental consent were given in all cases. STUDY DESIGNTen girls were treated with trimethoprimsulphamethoxazole (6 mg trimethoprim and 40 mg sulphamethoxazole/kg/day) and eight girls with amoxicillin (50 mg/kg/day) orally for five to seven days. Sampling of periurethral bacteria was performed immediately before treatment, on the last day of medication, and three weeks after termination of the antibiotic course. METHODSThe aerobic and anaerobic periurethral flora were examined by a quantitative sampling method.' A 5 ml plastic syringe filled with sterile 12% gelatin (Difco), was cut at the needle end of the syringe and the gelatin part was pressed against the urethr...

Genetic basis of resistance in Propionibacterium acnes strains isolated from diverse types of infection in different European countries

“…A 5-mL plastic syringe filled with 12% sterile gelatine (Difco Laboratories, USA) was cut at the needle end of the syringe and gelatine was pressed against the skin surface for 10 seconds without rotation. A 2-mm slice of gelatine with the bacterial bearing surface (approximately area 1 cm 2 ) was cut-off, put in a sterile glass tube with 2 mL prereduced peptone-yeast-glucose (PYG) medium (Difco Laboratories, Detroit, MI, USA) and immediately transported to the laboratory, as previously described for the collection of the skin microflora (Borglund et al, 1984;Lidefelt et al, 1991;Sullivan et al, 2001b). It was shown previously that the follicular casts from patients colonized with high numbers of resistant bacteria on the skin surface not always contain antibiotic resistant P. acnes.…”

Urethral cultures in female patients with a spinal cord injury

“…Since the gram negative bacilli cultured from the urethra were most likely from the fecal¯ora, it is also possible that this observation re¯ects an indirect e ect of antibiotics on the bowel¯ora that has been described previously. 12,13 …”

Bacterial resistance in urinary tract infections: how to stem the tide

“…A study by Lidefelt et al showed that girls treated with amoxicillin for upper respiratory tract infections showed a significant drop in anaerobic periurethral flora and a heavy colonisation with enterobacteria during treatment. However, this effect was not observed when the upper respiratory tract infections were treated with trimethoprimsulfamethoxazole [18]. Another study identified prior penicillin V treatment as a risk factor for the development of pyelonephritis in infants and pre-school children and, although not demonstrated, destruction of the commensal microflora can be inferred [19].…”