Randomized Open Trial of Gentamicin and Doxycycline for Eradication of Bartonella quintana from Blood in Patients with Chronic Bacteremia

Chronic Bartonella quintana bacteremia is known to occur inhomeless people exposed to lice. We present here the resultsof an open randomized trial performed to evaluate the efficacyof doxycycline in combination with gentamicin in the eradicationof B. quintana bacteremia. From 1 January 2001 to 1 April 2002,homeless people with blood cultures positive for B. quintanawere randomized to receive either no treatment (untreated controls)or a combination of gentamicin (3 mg/kg of body weight/day intravenouslyfor 14 days) and doxycycline (200 mg/day orally for 28 days).Patients were evaluated from the results of blood cultures performedbetween day 28 (the end of treatment) and day 90 postinclusion.Intention-to-treat analysis of 20 included patients showed eradicationof bacteremia in 7 out of 9 treated patients versus 2 out of11 untreated controls (P = 0.01). In the per-protocol analysis,eradication was obtained for 7 out of 7 treated patients versus2 out of 9 untreated controls (P = 0.003). This study demonstratesthe efficiency of the combination of doxycycline and gentamicinin eradicating B. quintana bacteremia.

INTRODUCTION

Top

Introduction

Bartonella quintana infection of humans was first describedduring World War I as being responsible for trench fever, afever occurring every five days and associated with headaches,shin pain, and dizziness (13, 18). Recent reports have indicateda reemergence of B. quintana infections among the homeless populationin cities in both Europe and the United States (2, 9, 24, 25).In 1994 the first cases of B. quintana endocarditis in homelesspeople were observed (5, 23), and in 1995 urban trench feverwas reported in France and in the United States (24, 25). Seroepidemiologicalstudies were then performed, and significant seroprevalenceagainst B. quintana was reported in France (1, 2) and in theUnited States (3, 10). In a study performed in 1997 in emergencydepartments of the university hospital in Marseilles, France(2), it was demonstrated that 14% of the homeless people testedhad blood cultures positive for B. quintana.

This bacterium is known to be responsible for endocarditis inhomeless people (5, 7, 15, 22, 23). Although the relationshipbetween bacteremia and endocarditis has not yet been demonstrated,it is likely that the treatment of bacteremia may be of importanceto prevent the occurrence of endocarditis. Recently we retrospectivelyreviewed data for bacteremic patients and found that only thosewho were treated with a combination of doxycycline and gentamicinwere cured, while those treated with ß-lactams ordoxycycline alone were not (6). In order to confirm those preliminaryretrospective results, we decided to conduct a randomized clinicaltrial to evaluate the efficacy of this antibiotic association.

MATERIALS AND METHODS

Top

Materials and Methods

The study was conducted in the Infectious Diseases Unit of theuniversity hospital (CHU-Nord) in Marseilles, France, from 1January 2001 to 1 April 2002. The trial was performed in accordancewith the Declaration of Helsinki and its Hong Kong Amendment.The trial protocol was reviewed and approval was given by aninstitutional review board (CCPPRB no. 00/62). Written informedconsent was obtained from all patients. It was hypothesizedthat 70% of bacteremic subjects are chronically infected (2).Considering an objective of reduction of chronic bacteremiafrom 70 to 2% after treatment and assuming a type I error of0.05 and a type II error of 0.20, it was determined necessaryto include 18 patients in the study (9 in each group).

Patients were enrolled if they were more than 18 years old andhad a blood culture positive for B. quintana. Exclusion criteriaincluded pregnancy, underlying cardiac diseases, such as thepresence of a valvulopathy or vegetation seen on the transesophagealechocardiography, previous vascular disease (aneurysm or vasculargraft), immunosuppression as defined by positive human immunodeficiencyvirus serology, cancer, diabetes, or dialyzed renal failure.Patients were randomized to receive either no treatment or acombination of 3 mg of gentamicin/kg of body weight as a singleintravenous daily dose for 14 days and 200 mg of doxycyclineas a single oral daily dose for 28 days. Group assignment wasperformed blindly by one of the authors (P. Brouqui or C. Foucault)by random sampling from previously prepared blocks of envelopscontaining four treatments and four untreated controls. Randomizationby block was performed in order to avoid recruitment bias. Untreatedcontrols were monitored after the end of the trial, and patientswith persistent positive blood cultures were treated with acombination of doxycycline and gentamicin, as proposed in thetrial.

Patients were recruited from emergency departments of the CHU-Nordin Marseilles, France, or from Marseilles city shelters duringan investigation performed to evaluate the health status ofhomeless people (P. Brouqui, unpublished data). Patients ofthe treatment group were hospitalized for the first 14 daysfor intravenous treatment with gentamicin and oral treatmentwith doxycycline. For the remaining 14 days oral treatment withdoxycycline was performed either in the hospital or in medicalfacilities of the city shelters of Marseilles. Serum creatininlevel and audiograms were monitored twice a week during treatmentwith gentamicin. Untreated controls were monitored either inthe hospital or in medical facilities of the city shelters.Blood cultures for B. quintana were performed once a week forpatients of both groups. Patients were evaluated on the basisof the results of blood cultures performed between day 28 (theend of treatment) and day 90 postinclusion.

Methods used to isolate B. quintana from blood have been describedelsewhere (11). Briefly, aerobic blood culture bottles (Bactecplus; Becton Dickinson Instrument Systems, Sparks, Md.) wereinoculated with whole blood and, even if no bacterial growthwas detected, after 7 days 1 ml of the broth was plated ontosheep blood agar plates and incubated at 37°C at 5% CO₂.Plates were examined weekly for 3 months. In addition, 1 mlof whole blood (collected in VACUTAINER tubes [Becton DickinsonVacutainer System, Rutherford, N.J.]) was plated directly ontosheep blood agar plates which were incubated and monitored asdescribed above. When Bartonella-like colonies were observed,confirmation was achieved by a PCR-based method (20, 21). Samplesof heparinized blood were also inoculated into the ECV 304 humanendothelial cell line by using the centrifugation-shell vialtechnique (11). Detection of B. quintana was carried out byimmunofluorescence with rabbit polyclonal antibodies raisedin our laboratory after 15, 30, and 45 days of incubation. Ifimmunofluorescence was positive, identification was performedby using the PCR-based method outlined above.

Statistical analysis was performed both for the intention-to-treatand for the per-protocol patient populations. For the intention-to-treatanalysis, loss of patients due to their dropping out of thestudy was considered treatment failure. Data were recorded byusing a standardized questionnaire, were captured by using Excelsoftware (Microsoft), and were analyzed by using Epi Info 6software (at http://www.cdc.gov/epiinfo/). Frequencies werecompared by the use of Fisher's exact test. Student's test wasused to compare quantitative data. A difference of P < 0.05was considered significant.

RESULTS

Top

Results

Between 1 January 2001 and 1 April 2002 a total of 35 homelesspeople had positive blood cultures for B. quintana and wereeligible for the study. Fifteen refused consent or were dischargedbefore the results of blood cultures were obtained and werenot subsequently reached; 20 were randomized. Nine were assignedto the treatment group and 11 were assigned to the untreatedgroup (Fig. 1). The subjects of both groups were not statisticallydifferent regarding age, sex, alcoholism, immune status, whiteblood cell count, mean corpuscular volume, and serologic status(Table 1). The delousing procedure was identical for the twogroups (including a complete change of clothes). Four patients(two in the treatment group and two untreated controls) weredropped out of the study. These patients were considered treatmentfailures in the intention-to-treat analysis, and data for thesepatients were not included in the per-protocol analysis. Ofthe two patients in the treatment group who left the study,one was discharged from the hospital on day 9 postinclusionand did not complete intravenous treatment with gentamicin andoral treatment with doxycycline and the other one refused bloodculture during follow up from day 21 postinclusion. Both ofthe two patients in the untreated group who left the study didnot come to follow-up consultations, and blood cultures werenot performed on them from day 21 postinclusion.

View larger version (28K):
[in this window]
[in a new window]
FIG. 1. Trial profile.

View this table:
[in this window]
[in a new window]
TABLE 1. Composition of the study population^a

Among the 20 patients whose data were used for the intention-to-treatanalysis, eradication of B. quintana bacteremia was obtainedfor 7 out of 9 in the treatment group and for 2 out of 11 inthe untreated control group (P = 0.01). Among the 16 patientswhose data were used in the per-protocol analysis, eradicationwas obtained for all 7 patients of the treatment group and for2 out of 9 in the untreated control group (P = 0.003) (Fig.1). Side effects were recorded for one patient in the treatmentgroup. He presented with two different side effects. The firstwas a transient increase of serum creatinin level during treatmentwhich did not necessitate renal dialysis and which was completelyregressive. He also presented with a photosensitization withfirst-degree skin burns of the face after sun exposure whichwas regressive without any aesthetic result. No statisticaldifference regarding clinical outcome was recorded for the twogroups during follow up. None of the patients of either groupdeveloped endocarditis. The mean time of resolution of bacteremiawas 26 ± 3.4 days following the initiation of doxycyclineplus gentamicin administration in the treatment group and 17.5± 4.9 days following enrollment in the trial in the untreatedcontrol group.

DISCUSSION

Top

Discussion

B. quintana is susceptible to many antibiotics (12), but aminoglycosidesare the only effective bactericidal agents and should constitutethe basis of the treatment of Bartonella chronic infections,except bacillary angiomatosis and peliosis (6, 16, 19). Preliminaryclinical data have suggested the efficiency of the combinationof gentamicin and doxycycline in treating B. quintana bacteremia,while ß-lactams and doxycycline alone were not effective(6). Many of the reported cases of Bartonella endocarditis havebeen cured by empirical therapies for blood-culture-negativeendocarditis that include ß-lactams and aminoglycosidesantibiotics. We retrospectively demonstrated that those receivingaminoglycosides were more likely to fully recover than thosewho did not, and when aminoglycosides were given for at least14 days they were more likely to survive than those with a shorterduration of therapy (16). Brucella spp. are phylogeneticallyclosely related to Bartonella spp. and share comparable microbiological,pathophysiological, and clinical findings (19). Among antimicrobialagents, only aminoglycosides (and to a lesser extent, doxycycline)are bactericidal on Brucella spp. (19), suggesting that thepresent knowledge of the treatment of the Brucella spp. infections(8) may help to define the optimum treatment of Bartonella-relatedinfections. Altogether these data lead us to propose the combinationof doxycycline and gentamicin for the treatment of chronic B.quintana bacteremia. The present trial demonstrates the efficiencyof this combination. The mean time of resolution of bacteremiawas different between the treatment group and the untreatedcontrols, and this could be due to the chronic aspect of B .quintana infection, as the duration of the bacteremia at thetime of recruitment of each patient was unknown and as someof the patients may be cured spontaneously.

To avoid confounding factors we have compared data that couldinfluence the spontaneous outcome of bacteremia. The two groupswere not different regarding age, sex, alcoholism, immune status,the presence of leukopenia, the mean corpuscular volume, andthe presence of significant levels of antibodies to B. quintana.The treatment of lice was also identical between the two groups.Patients of the treatment group were all hospitalized and receivedgood nutrition, while some of the untreated controls were monitoredin city shelters. One could hypothesize that nutrition may affectthe outcome of B. quintana bacteremia. Nevertheless, it hasbeen demonstrated that malnutrition in homeless people is morefrequently due to loss of appetite linked to chronic alcoholismthan to the lack of food (P. Brouqui, unpublished). No statisticaldifference was detected between treatment group and untreatedcontrol groups regarding alcoholism.

Only 20 of 35 eligible homeless people were randomized in thetrial. This is due to the particularity of the population studiedhere. The homeless, mainly young, are not seekers of medicalcare and often refuse hospitalization (4, 14). Primary isolationof B. quintana may require up to 45 days of incubation (13).Most homeless people involved in the trial were recruited duringan investigation performed in city shelters to evaluate thehealth status of homeless people. Considering the duration ofincubation of blood cultures, some homeless had left the sheltersby the time positive results were obtained and were not reacheddespite intensive searches in emergency rooms of the universityhospital and in city shelters (2).

The second major limit of this study is the high proportionof homeless who left the study. Up to 20% of randomized bacteremichomeless did not complete the study. Adherence to the follow-upportion of the study is difficult to obtain from homeless peopleand is often poor. In addition, access to health care may belimited by mental illness, transport problems, self neglect,and fear of institutionalization (4, 14).

Eradication of lice is difficult to achieve (17). The alternativefor control of B. quintana is the eradication of its human reservoir(6). Because many bacteremic patients exhibit antibodies toB. quintana, we speculate that they are immune and may not bereinfected. Consequently, systematic treatment would decreasethe prevalence of B. quintana infections, although the impactof such treatments remains to be evaluated.

B. quintana endocarditis is known to occur in homeless people(5, 7, 15, 22, 23). Death by unknown causes has been reportedfor one of our bacteremic homeless patients (6), and althoughthis could not be definitely attributed to endocarditis, thispossibility cannot be ruled out. Furthermore, the severity ofB. quintana endocarditis has been well established, with deathshaving been reported despite antibiotic therapy and valvularsurgery (7). The efficiency of the combination of gentamicinand doxycycline in eradicating B. quintana bacteremia may efficientlyprevent the occurrence of B. quintana endocarditis. Consideringthe poor adherence of the homeless population to medical careand treatment, a 1-month treatment including 14 days of intravenoustreatment is difficult to manage. Moreover, side effects havebeen observed during the trial, and therefore the treatmentshould be carefully managed. Better adherence to treatment shouldbe obtained with shorter duration, and this remains to be evaluatedin the future. Although further studies are needed, combinationof gentamicin and doxycycline should be recommended for treatmentof chronic B. quintana bacteremia.

ACKNOWLEDGMENTS

This work was supported by the "programme hospitalier de rechercheclinique 2000: Protocole SDF 2000-TA," Assistance Publique—Hôpitauxde Marseille.

FOOTNOTES

* Corresponding author. Mailing address: Unité des Rickettsies, CNRS UMR 6020, IFR48, Faculté de Médecine, Université de la Méditerranée, 27, Boulevard Jean Moulin, 13385 Marseille Cedex 05, France. Phone: 33 (0)4-91-38-55-17. Fax: 33 (0)4-91-38-77-72. E-mail: philippe.brouqui{at}medecine.univ-mrs.fr.

REFERENCES

Top