The impact of rufloxacin given as prophylaxis to patients with cancer on their oral and faecal microflora

The effect of antibiotics on the composition of the intestinal microbiota - a systematic review

OBJECTIVE

Antibiotics change the composition of the intestinal microbiota. The magnitude of the effect of antibiotics on the microbiota and whether the effects are short-term or persist long-term remain uncertain. In this review, we summarise studies that have investigated the effect of antibiotics on the composition of the human intestinal microbiota.

METHODS

A systematic search was done to identify original studies that have investigated the effect of systemic antibiotics on the intestinal microbiota in humans.

RESULTS

We identified 129 studies investigating 2076 participants and 301 controls. Many studies reported a decrease in bacterial diversity with antibiotic treatment. Penicillin only had minor effects on the intestinal microbiota. Amoxicillin, amoxcillin/clavulanate, cephalosporins, lipopolyglycopeptides, macrolides, ketolides, clindamycin, tigecycline, quinolones and fosfomycin all increased abundance of Enterobacteriaea other than E. coli (mainly Citrobacter spp., Enterobacter spp. and Klebsiella spp.). Amoxcillin, cephalosporins, macrolides, clindamycin, quinolones and sulphonamides decreased abundance of E. coli, while amoxcillin/clavulante, in contrast to other penicillins, increased abundance of E. coli. Amoxicllin, piperacillin and ticarcillin, cephalosporins (except fifth generation cephalosporins), carbapenems and lipoglycopeptides were associated with increased abundance of Enterococcus spp., while macrolides and doxycycline decreased its abundance. Piperacillin and ticarcillin, carbapenems, macrolides, clindamycin and quinolones strongly decreased the abundance of anaerobic bacteria. In the studies that investigated persistence, the longest duration of changes was reported after treatment with ciprofloxacin (one year), clindamycin (two years) and clarithromycin plus metronidazole (four years). Many antibiotics were associated with a decrease in butyrate or butryrate-producing bacteria.

CONCLUSION

Antibiotics have profound and sometimes persisting effects on the intestinal microbiota, characterised by diminished abundance of beneficial commensals and increased abundance of potentially detrimental microorganisms. Understanding these effects will help tailor antibiotic treatment and the use of probiotics to minimise this 'collateral damage'.

Effects of treatment with antimicrobial agents on the human colonic microflora

Antimicrobial agents are the most valuable means available for treating bacterial infections. However, the administration of therapeutic doses of antimicrobial agents to patients is a leading cause of disturbance of the normal gastrointestinal microflora. This disturbance results in diminishing the natural defense mechanisms provided by the colonic microbial ecosystem, making the host vulnerable to infection by commensal microorganisms or nosocomial pathogens. In this minireview, the impacts of antimicrobials, individually and in combinations, on the human colonic microflora are discussed.

Microflora in oral ecosystems in subjects with radiation-induced hyposalivation

AIM

To analyse the microbial flora in specific oral sites in 13 dentate subjects, 6-8 months after completed radiation therapy (RT group) and in 13 matched controls.

MATERIAL AND METHODS

The microflora on the tongue, buccal mucosa, vestibulum, supragingival plaque and subgingival region was analysed using duplicate sampling and cultivation technique. A clinical examination was also performed.

RESULTS

Candida albicans was found in one or more sites in 54% of the RT subjects and in 15% of the controls. In three RT subjects, C. albicans was found at all four sites analysed. An unexpected finding was that enterococci were found in all RT subjects and in high number in 38%. None of the controls harboured enterococci. In supragingival plaque, Lactobacillus spp. were detected in 92% of the RT subjects and the number and proportion of Lactobacillus spp. were extremely high compared with the controls. Mutans streptococci were detected in high numbers in 31% of the RT subjects, while they were not detected in 23%.

CONCLUSION

The microbial results explain why some RT subjects have an increased susceptibility to oral diseases and stress that site-specific microbial analysis is an important diagnostic tool when planning oral health preventive care for RT subjects.

Comparison of Etest, agar dilution, broth microdilution and disk diffusion methods for testing in vitro activity of levofloxacin against Staphylococcus spp. isolated from neutropenic cancer patients

The susceptibility to levofloxacin of 194 consecutive staphylococcal (45 Staphylococcus aureus and 149 coagulase-negative staphylococci) isolates from neutropenic patients was determined by Etest and the results compared with those obtained using NCCLS-methods (broth microdilution, agar dilution and disk diffusion). Overall agreement at +/- 1log(2) dilution for Etest compared with broth microdilution and agar dilution was 99.0 and 83.5%, respectively. The Etest category agreement with broth microdilution and disk diffusion was 95.9 and 89.7%, respectively. Comparison of categories with Etest and agar dilution method gave only 67.0% absolute categorical agreement, with 29.9% minor errors and 10.7% major errors. No very major errors occurred by the four methods tested. Our results show that Etest is a valid alternative to the reference NCCLS-methods for monitoring the clinical usefulness of levofloxacin against staphylococci isolates from neutropenic patients.

Effect of antimicrobial agents on the ecological balance of human microflora

The normal microflora acts as a barrier against colonisation of potentially pathogenic microorganisms and against overgrowth of already present opportunistic microorganisms. Control of growth of opportunistic microorganisms is termed colonisation resistance. Administration of antimicrobial agents, therapeutically or as prophylaxis, causes disturbances in the ecological balance between the host and the normal microflora. Most studies on the impact of antimicrobial agents on normal microflora have been carried out on the intestinal flora. Less is known on the effects on oropharyngeal, skin, and vaginal microflora. Disturbances in the microflora depend on the properties of the agents as well as of the absorption, route of elimination, and possible enzymatic inactivation and/or binding to faecal material of the agents. The clinically most common disturbances in the intestinal microflora are diarrhoea and fungal infections that usually cease after the end of treatment. A well-balanced microflora prevents establishment of resistant microbial strains. By using antimicrobial agents that do not disturb colonisation resistance, the risk of emergence and spread of resistant strains between patients and dissemination of resistant determinants between microorganisms is reduced. In this article, the potential ecological effects of administration of antimicrobial agents on the intestinal, oropharyngeal, and vaginal microflora are summarised. The review is based on clinical studies published during the past 10 years.

Effect of quinolones on intestinal ecology

Quinolones have a selective effect on the normal human intestinal microflora. Published data on 13 different quinolone agents [ciprofloxacin, enoxacin, norfloxacin, ofloxacin, pefloxacin, lomefloxacin, levofloxacin, sparfloxacin, rufloxacin, sitafloxacin (DU-6859a), gatifloxacin, trovafloxacin and moxifloxacin] show that gram-negative aerobic bacteria, especially Enterobacteriaceae, are strongly suppressed or eliminated during therapy. Gram-positive aerobic cocci are affected strongly by administration of sitafloxacin and moxifloxacin and to minor degrees by the other quinolones. Three new quinolones--gatifloxacin, trovafloxacin and moxifloxacin--are very active against anaerobic bacteria in vitro but have minor effects on the anaerobic intestinal human microflora. Similar findings have been reported for the other 10 quinolones. Thus, the quinolone antibacterials have an ecological impact on the human intestinal microflora, mainly on the enterobacteria, that should be taken into account when these agents are used for prophylaxis or treatment of gastrointestinal bacterial infections.