Journal of Antimicrobial Chemotherapy (2002) 49, 135-139
© 2002 The British Society for Antimicrobial Chemotherapy
Impact of quinupristin/dalfopristin (RP59500) on the faecal microflora in healthy volunteers
a INSERM EMI 9933, Groupe Hospitalier Bichat-Claude Bernard, AP-HP Paris; b Service de Microbiologie Médicale, Institut Gustave-Roussy, Villejuif; c Aventis, Antony, France
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and methodsResultsDiscussionAcknowledgementsReferences |
|---|
The effect of 5 days' administration of quinupristin/dalfopristin (RP59500) on the faecal microflora was evaluated in healthy volunteers. Twenty healthy volunteers received 7.5 mg/kg of quinupristin/dalfopristin infused over 1 h twice daily for 5 days and four received a matched placebo. Faecal samples were collected before, during and after treatment (days –1/–2, 6, 8, 14/15, 35 ± 2, 60 ± 4, 90 ± 4). In the treated volunteers, anaerobes, including sporulating and Gram-negative bacteria, decreased slightly during treatment, whereas numbers of enterococci and Enterobacteriaceae increased significantly (P < 0.01). Counts of anaerobes and enterococci resistant to erythromycin or to quinupristin/dalfopristin increased significantly (P < 0.01) during treatment and returned slowly to their baseline levels after the end of treatment. Mean faecal antibiotic concentrations reached 291 ± 184 and 42 ± 22 Ìg/g of faeces for quinupristin and dalfopristin, respectively, by the fifth day of treatment. Counts of yeasts were not influenced significantly by the treatment. No emergence of glycopeptide-resistant enterococci, Staphylococcus aureus, Pseudomonas aeruginosa or Clostridium difficile was observed. No episode of diarrhoea was reported. In conclusion, quinupristin/dalfopristin administration was associated with a temporary shift towards resistance of the endogenous flora and a temporary increase in counts of enterobacteria and enteroccocci. However, no decrease in colonization resistance towards exogenous potentially pathogenic bacteria was observed and the observed modifications disappeared within 12 weeks after the end of quinupristin/dalfopristin administration.
|
Introduction |
|---|
|
TopAbstractIntroductionMaterials and methodsResultsDiscussionAcknowledgementsReferences |
|---|
The overgrowth of drug-resistant intestinal bacteria or of potential pathogens is often associated with antibiotic treatments1,2 and is a matter of concern since it may lead to the spread of potentially pathogenic bacteria and the diffusion of genes encoding resistance to antibiotics. Quinupristin/dalfopristin is the first injectable streptogramin antibiotic. It is a combination of two semisynthetic pristamycin derivatives, quinupristin and dalfopristin, in a fixed 30:70 ratio and is active against Gram-positive bacteria such as staphylococci, streptococci, Enterococcus faecium and Clostridium difficile, and some Gram-negative bacteria such as Neisseria.3 Previous studies showed that other antibiotics from the chemically related macrolide family such as erythromycin,4 roxithromycin5 and spiramycin6 had a limited impact on the human faecal flora, although they could promote transient increases in the faecal counts of resistant bacteria. Quinupristin/dalfopristin is eliminated mainly through the faeces,7 but no data are available concerning the effect of treatment on intestinal bacteria. The impact of quinupristin/dalfopristin on the faecal flora of healthy human volunteers was thus investigated.
|
Materials and methods |
|---|
|
TopAbstractIntroductionMaterials and methodsResultsDiscussionAcknowledgementsReferences |
|---|
Twenty-four healthy non-hospitalized male adults aged 20–42 years (median 26 years), were included in the study. Informed consent was obtained from all the volunteers, and the study protocol was approved by the local ethics committee. Twenty volunteers were assigned to receive quinupristin/dalfopristin 7.5 mg/kg iv for 5 days in 500 mL infusions over 1 h every 12 h. Four received placebo infusions. The volunteers were hospitalized during the treatment period only, and they were asked to adhere to their usual lifestyle and food preferences afterwards. The volunteers were interviewed by a physician about intestinal symptoms and stool consistency daily during their hospital stay, and then at days 8, 14, 36, 60 and 90 when they visited the clinic for further sampling. They were asked to report all intakes of anti-infective medication. No subject had to be withdrawn for intercurrent infection or intercurrent intake of an anti-infective drug.
Faecal samples were obtained before treatment (day 0), at the end of treatment (day 6) and after treatment, at days 8, 14 ± 1, 35 ± 2 for all the 24 volunteers and also at days 60 ± 4 and 90 ± 4 for 12 of them.
Total anaerobes and sporulating anaerobes were counted on Wilkins–Chalgren agar (Sanofi Diagnostic Pasteur, Marnes-La-Coquette, France). Counts of sporulating anaerobes were performed after inactivation of vegetative bacteria by alcoholic shock, as described previously.8 Gram-negative anaerobes were counted on Wilkins–Chalgren supplemented with kanamycin (100 mg/L) and vancomycin (7.5 mg/L). Enterococci were counted on bile aesculin agar (BAA) (Korano Médical, La Balme-Les Grottes, France). Resistant bacteria from all these species were counted on the same media, which were supplemented with either erythromycin (10 mg/L) or quinupristin/dalfopristin (10 mg/L). Vancomycin-resistant enterococci were counted on BAA supplemented with vancomycin (8 mg/L). Enterobacteriaceae were counted on Drigalski agar (Korano Médical) alone or supplemented with erythromycin (400 mg/L) for detection of clones with high levels of resistance to erythromycin.4 Pseudomonas aeruginosa was counted on cetrimide agar (Sanofi Diagnostic Pasteur) and yeast on Sabouraud agar with chloramphenicol (bioMérieux, Marcy l'Étoile, France). Staphylococci were detected using Chapman agar (Korano Médical) alone or supplemented with erythromycin (10 mg/L) or quinupristin/dalfopristin (10 mg/L). Presumptive isolates of enterococci and of staphylococci growing on media containing antibiotics were further identified using API systems (bioMérieux). Clostridium difficile was detected using cefoxitin cycloserine fructose agar (bioMérieux). All faecal samples were assayed for C. difficile toxins using a commercially available enzyme immunoassay (Premier cytoclone A+B; Meridian Diagnostics, Inc., Cincinnati, OH, USA) according to the recommendations of the manufacturer.
Faecal concentrations of quinupristin and dalfopristin were determined in 12 of the volunteers receiving quinupristin/dalfopristin using a microbiological bioassay9 with Staphylococcus aureus HBD511 and Staphylococcus epidermidis HBD523, respectively. They were chosen for their resistance to either dalfopristin or quinupristin and their simultaneous susceptibility to the synergic combination of dalfopristin/quinupristin. The dalfopristin-resistant strain S. aureus HBD511 and Antibiotic Medium 1 (Difco Laboratories, Detroit, MI, USA) containing dalfopristin (20 mg/L) were used to assay quinupristin and related products. Conversely, the quinupristin-resistant strain S. epidermidis HBD523 and Mueller–Hinton agar (bioMérieux) containing quinupristin (20 mg/L) were used to assay dalfopristin and related products. The amount of quinupristin and dalfopristin added to the medium was chosen to permit the expression of synergy but was low enough to be deprived of inhibitory activity on the indicative strain. Therefore, the inhibition zone diameters obtained were proportional, respectively, to either quinupristin or dalfopristin concentration. Levels of detection were 0.16 and 0.18 mg/L for quinupristin and dalfopristin, respectively.
Statistical analysis of the changes in faecal flora was performed by computing the P value from a paired comparisons t-test for the difference between counts obtained before, and at day 6 or 8, whichever value showed the largest difference from baseline.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and methodsResultsDiscussionAcknowledgementsReferences |
|---|
No significant changes were observed in the faecal flora of the placebo-treated volunteers (data not shown). In the volunteers receiving quinupristin/dalfopristin, the anaerobic flora was quantitatively slightly modified during treatment (Figure 1
). The number of total, sporulating and Gram-negative anaerobes decreased significantly (P < 0.01) at day 6, returned to baseline level at day 8 and remained constant up to the last evaluation (Figure 1). Erythromycin-resistant (not shown) and quinupristin/dalfopristin-resistant (Figure 1) anaerobes, either total, sporulating or Gram-negative, increased significantly (P < 0.01) during treatment and slowly returned to baseline levels. The total number of enterococci (Figure 1), erythromycin-resistant (not shown) and quinupristin/dalfopristin-resistant (Fig-ure 1) enterococci all increased significantly (P < 0.01) up to day 8 and returned to their baseline level by day 35 (Figure 1). Three of 12 (25%), 15 of 18 (83.3%) and 22 of 24 (91.7%) resistant enterococci isolated before treatment, and at days 8 and 35, respectively, were identified as Enterococcus faecalis. Glycopeptide-resistant enterococci were detected in three volunteers (Enterococcus faecium in two subjects and E. faecalis in one) in only one sample from each volunteer at days 6, 8 and 35, respectively. Counts of total Enterobacteriaceae increased significantly (P < 0.01) at day 8 and returned to their baseline level by day 15 (Figure 1). P. aeruginosa (data not shown) and yeasts (Figure 1) were either absent or present in low numbers before administration of the drug, and these counts remained similar during treatment. Members of the family Enterobacteriaceae with high-level resistance to erythromycin were detected in two subjects, at day 8 in one (Enterobacter agglomerans) and at day 33 in the other (Escherichia coli). S. aureus strains were isolated in only six faecal samples from six volunteers. None of the strains was resistant to quinupristin/dalfopristin. C. difficile was identified in only one subject at day 34, but no production of toxin A or B was detected in any subject during the study. No episode of loose stools or diarrhoea was reported.
|
The mean faecal antibiotic concentration reached 291 ± 184 and 42 ± 22 µg/g of faeces for quinupristin and dalfopristin, respectively, at the fifth day of treatment (Figure 2
). Large inter-subject variations were observed. The ratio of concentrations of quinupristin over those of dalfopristin remained in the range that allows a synergic activity on days 5 and 6, but not on day 8 (Figure 2). Quinupristin or dalfopristin was undetectable in faeces on day 14 or 15.
|
) and of quinupristin (•) in healthy volunteers. |
Discussion |
|---|
|
TopAbstractIntroductionMaterials and methodsResultsDiscussionAcknowledgementsReferences |
|---|
Our results showed that 5 days of iv quinupristin/dalfopristin was associated with transient changes in the faecal bacterial counts in human volunteers. The duration of the treatment was limited to 5 days in our volunteers because of the risk of venous reactions associated with repeated iv peripheral administration of quinupristin/dalfopristin. The most striking effect noted was an increase in the faecal counts of anaerobes and of enterococcal populations resistant to erythromycin or to quinupristin/dalfopristin. Although the methods used did not allow differentiation between species, particularly among anaerobes, we chose them because our objective was to judge the impact of the treatment on bacterial groups as a whole, not on individual species, focusing on microorganisms potentially pathogenic for humans such as members of the family Enterobacteriaceae, of the genus Enterococcus and yeasts. Due to the technique used (direct plating on selective agar containing antibiotic at critical concentrations), it can be assumed that the MICs for the bacteria reported as resistant were over the critical concentrations.
The range of bacterial counts found among volunteers before the experiment started was sometimes broad, particularly for resistant bacteria. Similar observations have been reported by others.10 It was noteworthy that levels of resistant bacteria returned to baseline levels after administration of quinupristin/dalfopristin ceased. These modifications were probably related to the transient presence of significant amounts of quinupristin/dalfopristin in the faeces of the volunteers during treatment. A similar shift towards resistance in the faecal microflora has been reported previously in volunteers given other anti-Gram-positive agents from a chemically related macrolide family such as erythromycin,4 spiramycin6 and roxythromycin.5 It also seems possible that resistance of E. faecium to linezolid, a new and promising anti-Gram-positive agent, occurs during treatment.11 Numbers of Enterobacteriaceae increased during quinupristin/dalfopristin administration, in contrast with what has been observed previously with erythromycin.4 The disappearance of enterobacteria during erythromycin administration was explained by the very high antibiotic faecal concentrations achieved, and this was not observed with other macrolides such as spiramycin6 or roxythromycin.5 Numbers of enterococci also increased during quinupristin/dalfopristin administration; they returned to baseline numbers, as did numbers of Enterobacteriaceae, after the end of treatment. This transient increase in the counts of these two groups probably reflects the activity of quinupristin/dalfopristin on dominant anaerobic bacterial populations, which cause the so-called ‘barrier effects’12 and colonization resistance13,14 that prevent the overgrowth of enterobacteria and enterococci within the normal intestinal bacterial ecosystem.15 Decrease of resistance to colonization during quinupristin/ dalfopristin administration was, however, limited, since we did not observe any significant colonization by naturally resistant microorganisms such as P. aeruginosa or yeasts. No colonization by S. aureus or C. difficile was observed, probably because quinupristin/dalfopristin is highly active against these two species. Altogether, administration of quinupristin/dalfopristin for 5 days had a limited impact over time on the faecal flora of humans.
|
Acknowledgements |
|---|
|
TopAbstractIntroductionMaterials and methodsResultsDiscussionAcknowledgementsReferences |
|---|
This study was supported in part by a grant from Aventis Laboratories (France).
|
Notes |
|---|
* Correspondence address. Laboratoire de Bactériologie, Hôpital Bichat-Claude Bernard, 75018 Paris, France. Tel: +33-1-40-25-85-00; Fax: +33-1-40-25-85-81; E-mail: antoine.andremont{at}bch.ap-hop-paris.fr
|
References |
|---|
|
TopAbstractIntroductionMaterials and methodsResultsDiscussionAcknowledgementsReferences |
|---|
1 . Chachaty, E., Rosembaum, M., Tancrède, C. & Andremont, A. (1991). Effect of oral cefotiam hexetil (SCE 2174) on faecal bacteria in human volunteers. Microbial Ecology in Health and Disease 4, 89–94.
2
.
Andremont, A., Sancho-Garnier, H. & Tancrede, C. (1986). Epidemiology of intestinal colonization by members of the family Enterobacteriaceae highly resistant to erythromycin in a hematology-oncology unit. Antimicrobial Agents and Chemotherapy 29, 1104–7.
3 . Johnson, A. P. & Livermore, D. M. (1999). Quinupristin/dalfopristin, a new addition to the antimicrobial arsenal. Lancet 354, 2012–3. [Web of Science][Medline]
4 . Andremont, A., Raibaud, P. & Tancrède, C. (1983). Effect of erythromycin on microbial antagonisms: a study in gnotobiotic mice associated with a human fecal flora. Journal of Infectious Diseases 148, 579–87. [Web of Science][Medline]
5
.
Pecquet, S., Chachaty, E., Tancrede, C. & Andremont, A. (1991). Effects of roxithromycin on fecal bacteria in human volunteers and resistance to colonization in gnotobiotic mice. Antimicrobial Agents and Chemotherapy 35, 548–52.
6
.
Andremont, A., Tancrede, C. & Desnottes, J. F. (1991). Effect of oral spiramycin on the faecal and oral bacteria in human volunteers. Journal of Antimicrobial Chemotherapy 27, 355–60.
7
.
Bergeron, M. & Montay, G. (1997). The pharmacokinetics of quinupristin/dalfopristin in laboratory animals and in humans. Journal of Antimicrobial Chemotherapy 39, 129–38.
8
.
Borriello, S. & Honour, P. (1981). Simplified procedure for the routine isolation of Clostridium difficile from faeces. Journal of Clinical Pathology 34, 1124–7.
9 . Chabbert, Y. & Boulingre, H. (1957). Modifications pratiques concernant le dosage des antibiotiques en clinique. Revue Française des Etudes Cliniques et Biologiques 2, 636–40.
10 . Edlund, C., Sjostedt, S. & Nord, C. E. (1997). Comparative effects of levofloxacin and ofloxacin on the normal oral and intestinal microflora. Scandinavian Journal of Infectious Diseases 29, 383–6. [Web of Science][Medline]
11 . Gonzales, R., Schreckenberger, P. C., Graham, M. B., Kelkar, S., Den Besten, K. & Quinn, J. P. (2001). Infection due to vancomycin-resistant Enterococcus faecium resistant to linezolid. Lancet 357, 1179. [Web of Science][Medline]
12
.
Ducluzeau, R., Ladire, M., Callut, C., Raibaud, P. & Abrams, G. (1977). Antagonistic effect of extremely oxygen-sensitive clostridia from the microflora of conventional mice and of Escherichia coli against Shigella flexneri in the digestive tract of gnotobiotic mice. Infection and Immunity 17, 415–24.
13 . Van der Waaij, D., Berghuis, J. M. & Lekkerkerk-van der Wees, J. E. C. (1971). Colonization resistance of the digestive tract in conventional and antibiotic treated mice. Journal of Hygiene 69, 405–11.
14
.
Vollaard, E. J. & Clasenen, H. A. L. (1994). Colonization resistance. Antimicrobial Agents and Chemotherapy 38, 409–14.
15 . Finegold, S., Sutter, V. & Mathisen, G. (1983). Normal indigenous intestinal flora. In Human Intestinal Microflora in Health and Disease, (Hentges, D. J., Ed.), pp. 3–31. Academic Press, London.
Received 9 April 2001; returned 13 June 2001; revised 19 September 2001; accepted 25 September 2001
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  A.-C. Cremieux, C. Muller-Serieys, X. Panhard, F. Delatour, M. Tchimichkian, F. Mentre, and A. Andremont Emergence of Resistance in Normal Human Aerobic Commensal Flora during Telithromycin and Amoxicillin-Clavulanic Acid Treatments Antimicrob. Agents Chemother., June 1, 2003; 47(6): 2030 - 2035. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||