Brucellosis Treatment Guidelines

First-Line Treatment Options

• The optimal treatment of uncomplicated brucellosis should be based on a six-week regimen of doxycycline (100 mg twice daily) combined either with streptomycin (1 g daily) for 2-3 weeks, or rifampicin (600-900 mg daily) for six weeks 1, 2, 3
• Doxycycline: 100 mg twice daily orally for 6 weeks, is a preferred regimen when combined with streptomycin or rifampicin 3, 4
• Streptomycin: 15 mg/kg daily intramuscularly for 2-3 weeks, has the lowest relapse rate when combined with doxycycline 3, 4
• Rifampicin: 600-900 mg daily as a single morning dose for 6 weeks, is an alternative first-line option when combined with doxycycline 3, 4
• Gentamicin: 5 mg/kg daily parenterally in 1 dose for 7 days, offers comparable efficacy to streptomycin when combined with doxycycline 4

Second-Line Treatment Options

• Trimethoprim-Sulfamethoxazole (TMP-SMX): 800+160 mg twice daily for 6 weeks, is a cost-effective alternative in certain resource-limited settings 4
• Quinolone-Containing Regimens, such as ofloxacin or ciprofloxacin, should be reserved as second or third agents in combination regimens 4

Treatment Duration and Monitoring

• Standard treatment duration is 6 weeks for most regimens 3, 4
• Relapse rates range from 5% to 15% of uncomplicated cases even with appropriate treatment 1
• Relapses are usually mild and can be treated successfully with the same regimens 1

Public Health Considerations

• In regions where brucellosis and tuberculosis coexist, consider the public health implications of using rifampicin, as this may contribute to mycobacterial resistance 5

Brucellosis Treatment Recommendations

First-Line and Second-Line Treatment Options

• The World Health Organization recommends Doxycycline-Gentamicin as a first-line treatment option for uncomplicated brucellosis, with comparable efficacy to Doxycycline-Streptomycin, and the advantage of wider availability of gentamicin and shorter duration of parenteral therapy 6
• The Centers for Disease Control and Prevention suggest that Trimethoprim-Sulfamethoxazole containing regimens may be used as a cost-effective alternative in resource-limited settings or as a third agent in combination therapy for complicated cases, with reported response rates above 90% 7
• The European Centre for Disease Prevention and Control advises that Quinolone-containing regimens should be reserved as second or third agents in combination regimens due to higher cost and risk of promoting antimicrobial resistance 8

Gentamicin Dosing for Brucellosis Treatment

Recommended Treatment Regimens for Brucellosis

• The American College of Physicians recommends doxycycline 100 mg twice daily orally for 6 weeks plus streptomycin 15 mg/kg daily intramuscularly for 2-3 weeks (AI recommendation) 9, 10
• The American College of Physicians recommends doxycycline 100 mg twice daily orally for 6 weeks plus rifampicin 600-900 mg daily as a single morning dose for 6 weeks (AI recommendation) 9, 10
• The World Health Organization recommends doxycycline 100 mg twice daily orally for 6 weeks plus gentamicin 5 mg/kg daily parenterally in a single dose for 7 days (BI recommendation) 9, 11

Gentamicin Dosing Considerations

• The standard gentamicin dosing is 5 mg/kg daily, and the fixed dose of 500 mg is not recommended 9
• The duration of gentamicin treatment should be 7 days when combined with doxycycline 9, 11

Treatment Efficacy Data

• Non-comparative studies using gentamicin for 5-7 days showed failure/relapse rates of 10-20%, which is approximately 5% higher than WHO-recommended regimens 9, 10

First‑Line Treatment Recommendations for Uncomplicated Brucellosis

Recommended Regimens (AI – highest evidence)

Advantages of Doxycycline‑Rifampicin

Regimens with Lower Recommendation Strength (CII)

Alternative Regimens (BI strength)

Special Clinical Situations

First‑Line Treatment Recommendations for Uncomplicated Brucellosis

Primary Regimen (Lowest Relapse Rate)

• The American Infectious Diseases Society recommends doxycycline 100 mg orally twice daily for 6 weeks combined with streptomycin 15 mg/kg intramuscularly daily for 2–3 weeks as the drug of choice for uncomplicated adult brucellosis, achieving a relapse rate of ≈5 % (AI recommendation, good evidence) 14.

Alternative First‑Line Regimen (Oral‑Only Preference)

• Doxycycline 100 mg orally twice daily for 6 weeks plus rifampicin 600–900 mg once daily for 6 weeks is also AI‑recommended, but relapse rates are higher (≈16 % versus 5 % with doxycycline‑streptomycin) and should be reserved for situations where intramuscular injections are impractical or streptomycin is unavailable 14.
• In regions with endemic tuberculosis, the use of rifampicin may promote mycobacterial resistance and should be avoided when possible 14.

Alternative Aminoglycoside Regimen (When Streptomycin Unavailable)

• Doxycycline 100 mg orally twice daily for 6 weeks combined with gentamicin 5 mg/kg parenterally once daily for 7 days carries a BI recommendation (moderate evidence) and offers comparable efficacy with a slightly higher relapse rate (≈10–20 %) compared with the primary regimen 14.

Second‑Line Options (Lower‑Quality Evidence)

Trimethoprim‑Sulfamethoxazole (TMP‑SMX)

• TMP‑SMX 800 mg/160 mg twice daily for 6 weeks receives a CII recommendation (poor evidence, optional). When used as monotherapy for 45 days, relapse rates approach 46 % 14.

Quinolone‑Containing Regimens

• Ofloxacin or ciprofloxacin should be reserved for second‑ or third‑line use in combination regimens; they have a CII recommendation due to higher cost and potential to foster antimicrobial resistance, with efficacy comparable to doxycycline‑rifampicin but higher relapse rates 14.

Critical Treatment Principles

Treatment Duration

• A standard 6‑week course is required for uncomplicated brucellosis; courses shorter than 4 weeks are linked to unacceptably high relapse rates (~22 %) 14.
• Even with optimal therapy, overall relapse rates range from 5 % to 15 % 14.

Necessity of Combination Therapy

• Monotherapy historically yields relapse rates of 2–39 %; a well‑designed trial reported a 13 % relapse rate with monotherapy versus 4.8 % with combination therapy, underscoring that combination regimens are essential to prevent relapse and resistance 14.

Common Pitfalls to Avoid

• Do not select rifampicin‑based regimens as first choice when streptomycin is available, because they have significantly higher relapse rates (16 % vs 5 % with doxycycline‑streptomycin) 14.
• Do not shorten aminoglycoside courses: gentamicin requires 7 days and streptomycin requires 14–21 days to achieve optimal outcomes 14.
• Do not use TMP‑SMX as monotherapy, as relapse rates can reach 46 % 14.
• Do not discontinue therapy early based on symptom resolution; microbiological cure lags behind clinical improvement 14.