Brucellosis Relapse : A Retrospective Study of Risk Factors among Saudi Patients Elsayed

Background and study aim: Brucellosis is one of the most common zoonotic infections worldwide. Brucella organisms are able to survive and even multiply within mononuclear cells explaining the tendency of the disease to have a prolonged clinical course and relapse. The incidence of relapse in Brucellosis remains high; ranging from 5-30% of patients. The aim of this study is to evaluate possible risk factors of Brucellosis relapse. 
Patients and Methods: A retrospective study of 127 patients was conducted to evaluate risk factors of Brucellosis relapse. The diagnosis of relapse was based on recurrence of clinical picture within 3-6 months from treatment, increase agglutinating antibody titers and PCR. Different demographic, clinical, laboratory and serological parameters were studied based on the data gathered from the patients` electronic files. 
Results: Out of 127 patients, 21 (16.5%) patients were diagnosed as relapsers. No significant differences were found between relapsed and non-relapsed patients regarding age, sex, residence, clinical features, complications, lymphocytic count and serological titers. As regard treatment, regimens included Streptomycin and Doxycycline had a significant decrease in relapse occurrence. 
Conclusion: Anti-microbial regimen included Streptomycin and Doxycycline is the only preventive factor for Brucellosis relapse.


INTRODUCTION
Brucellosis is one of the most common zoonotic infections worldwide with more than 500.000new cases reported to World Health Organization (WHO) every year [1].It is still endemic in certain countries of Middle East, among these countries is Saudi Arabia, since it hosts a myriad of travellers and imports a high number of livestock [2].Occupational exposure is the most frequent route of infection, thorough inhalation of infectious aerosols, so it is common among shepherds, farmers and laboratories' staff.Non-occupational sources of infection include the consumption of un-pasteurized milk, goat cheese and raw meat [3].

Definite diagnosis of Brucellosis requires
isolation of the organism from the blood or other body fluids, but serological methods are rapid, easy to perform and may be the only tests available in certain settings [4].Identification of specific antibodies can be done by standard agglutination test (SAT) or 2 mercaptoethanol (2-ME).SAT is the most common serological test used in endemic countries with a titer ≥1/160 is considered significant in non-endemic areas and ≥1/320 in endemic areas [5].
Brucella organisms are able to survive and even multiply within mononuclear cells explaining the tendency of the disease to have a prolonged clinical course and relapse [6].Even with the correct treatment, the incidence of relapse in Brucellosis remains high, ranging from 5-30% of patients  These patients were treated according to the following regimens :  Regimen (1) included combination of streptomycin 1gm once daily and doxycycline 100 mg twice/day for 21 days, then doxycycline 100 mg twice/day and rifampicin 600 mg daily for another 21 days.

PATIENTS AND METHODS
 Regimen (2) included doxycycline 100mg twice/ day and streptomycin 1gm/day for 6 weeks.
The diagnosis of relapse was based on recurrence of clinical picture within 3-6 months from treatment; increase agglutinating antibody titers which was decreased previously and confirmed by PCR.
For each patient the following data were collected from electronic files: age, sex, residency (rural, urban), occupational exposure, clinical features (fever, body aches, myalgia, backache), laboratory results (CBC, Wright, 2ME) and antimicrobial regimens.

Statistical analysis:
All the data were registered in special forms designed for this study.The SPSS version 16 was used for statistical analysis.Chi-square test was used for comparing data of both groups.P value of < 0.05 indicates significant results.

RESULTS
Out of 127 studied patients, 104 (82%) were males and 23 (18%) were females.Regimen No. 1 and 2 showed statistically significant differences between relapsed and nonrelapsed patients while other regimens showed no differences (Figures 1 and 2).An important issue in studying the risk factors of Brucellosis relapse is the differentiation between relapse and reinfection.Relapse is reappearance of the compatible clinical features within 6 months after conclusion of treatment together with rising serological titers.In endemic areas, like Saudi Arabia, where the re-exposure risk is persistent, relapse is difficult to be differentiated from reinfection.In this study we used the PCR to confirm that the clinical features and rising antibody titer were due to relapse rather than reinfection.Morata et al. [8] reported that PCR is a sensitive method for early detection of relapse.
In this study, the only significant risk factor that might be responsible for relapse was the regimen of treatment.We evaluated 127 patients who were treated by 5 different regimens commonly used to treat Brucellosis in Saudi Arabia's community.The two regimens that were significantly found to prevent the relapse are those that included both streptomycin and doxycycline antibiotics (regimens 1 and 2).The duration of both regimens was 6 weeks.On the other hand, the other nonpreventive two regimens (regimens 3 and 4) did not include streptomycin but doxycycline and ofloxacin or rifampicin and co-trimoxazole.The duration was 4 weeks only.WHO has been approved the combination of doxycycline 100 mg twice/day for 6weeks and streptomycin (1 g/day intramuscularly) for 2-3 weeks, as the treatment regimen of choice in eradicating Brucella and prevent the relapse [1].Consistent with these results, Roushan et al.
[12] also reported that treatment regimen is the only preventive factor.
In their retrospective study the regimens that have been found to prevent relapse included streptomycin or gentamicin and doxycycline.
As regarding other risk factors that were postulated to be responsible for relapse including; lymphocytic count, depressed cell mediated immunity (CMI), complications, Brucella species and long duration between appearance of symptoms and initiation of treatment, there were non-significant differences between both groups regarding these factors.
Unfortunately, the duration of symptoms was not reported in some files of our patients, so we couldn't study this factor.

CONCLUSION
Anti-microbial regimen is the only preventive factor for Brucellosis relapse.This study recommends using combination of streptomycin and doxycycline for treatment of Brucellosis, since it has lower rate of relapse.On the other hand, none of the other studied factors were founded to prevent the relapse.

[7].
The aim of this study is to evaluate these factors and other demographic, clinical and serological factors, searching for possible factors of relapse of Brucellosis.

Table ( 1
): Demographic, clinical, serological data and treatment regimens among both populations [12][13][14][15]y (CMI), complications, Brucella species and long duration between appearance of symptoms and initiation of treatment[12][13][14][15]. We aimed in this study to evaluate these risk factors in addition to other demographic, serologic and laboratory factors, searching for possible factors responsible for relapse of Brucellosis.
From the above reported results, the14]ration of symptoms before treatment appears to be controversy.While Alavi et al., reported that longer duration of symptoms was associated with relapse,Ariza et al., and Solera et al. [13,14]reported that symptom duration of less than 10 days was associated with relapse.Unfortunately, we couldn't study this factor.Also, correlation of cytokines to the incidence of relapse was suggested by Aktug demir and Ural.We did not study the role of cytokines, since this study was retrospective.So, we recommend further prospective studies to be carried out and include other risk factors in order to predict relapse and hence prevention by rearranging treatment and monitoring of the patients.