Antibiotic Treatment Guidelines

Introduction to Antibiotic Treatment

The American Academy of Family Physicians, Centers for Disease Control and Prevention (CDC), and other medical societies provide guidelines for antibiotic treatment, emphasizing the importance of proper treatment and follow-up for various infections 1, 2, 3, 4, 5

The CDC recommends benzathine penicillin G 2.4 million units IM in a single dose for primary, secondary, and early latent syphilis, and 7.2 million units total, administered as 3 doses of 2.4 million units IM at 1-week intervals for late latent syphilis or latent syphilis of unknown duration, with a strength of evidence level of high 3, 4, 5, 6, 7, 2
Alternative treatments for syphilis include Doxycycline 100 mg orally twice daily for 14 days, Ceftriaxone 1 g IV/IM daily for 10 days, and Tetracycline 500 mg orally four times daily for 14 days (early) or 28 days (late), with a strength of evidence level of moderate 8, 3, 4
The CDC recommends the following treatments for syphilis:

Stage of Syphilis	Recommended Treatment
Primary Syphilis	Benzathine penicillin G 2.4 million units IM in a single dose [5, 3]
Secondary Syphilis	Benzathine penicillin G 2.4 million units IM in a single dose [5, 3]
Early Latent Syphilis	Benzathine penicillin G 2.4 million units IM in a single dose [5, 3]
Late Latent Syphilis or Latent Syphilis of Unknown Duration	Benzathine penicillin G 7.2 million units total, administered as 3 doses of 2.4 million units IM at 1-week intervals [6, 7, 5, 2, 3]
Neurosyphilis	Penicillin G aqueous 18-24 million units IV daily, administered as 3-4 million units every 4 hours for 10-14 days [5, 3]

Pregnant women should be treated with penicillin, as it is the only proven effective treatment, and desensitization is required if allergic, with a strength of evidence level of high, as recommended by the CDC 3, 9, 5, 4
For HIV-infected patients, the CDC recommends the same regimens as HIV-negative patients, but with closer follow-up, with a strength of evidence level of moderate 3, 8, 6
If a patient misses a dose in the weekly therapy schedule, an interval of 10-14 days between doses might be acceptable before restarting the sequence, according to pharmacologic considerations, but missed doses are never acceptable for pregnant women, and the full course of therapy must be repeated if any dose is missed 5

Quantitative nontreponemal serologic tests (RPR or VDRL) should be repeated at 6, 12, and 24 months to monitor treatment success, with a strength of evidence level of high, as recommended by the CDC 3
Treatment success is indicated by a fourfold decline in titers within 12-24 months, and patients should be evaluated for retreatment if titers increase fourfold, an initially high titer fails to decline, or signs or symptoms attributable to syphilis develop, with a strength of evidence level of high 3
Approximately 15% of patients may not meet standard criteria for serological cure 12 months after adequate treatment, with a moderate strength of evidence supporting the need for ongoing monitoring 9, 6

All sexual partners should be evaluated clinically and serologically for syphilis, and partners exposed within 90 days of diagnosis should be treated presumptively even if seronegative, while partners exposed >90 days before diagnosis should be treated based on clinical and serological evaluation, with a strength of evidence level of high, as recommended by the CDC 3
Partner notification and treatment is essential, with sexual contacts within 90 days of diagnosis being treated presumptively, even if seronegative, and contacts from >90 days being treated presumptively if follow-up is uncertain, with a strength of evidence level of high, as recommended by the CDC 3, 9, 5

The Infectious Diseases Society of America recommends Clindamycin for penicillin-allergic patients with cellulitis/erysipelas, and Doxycycline plus Clindamycin for animal/human bites 10
The American Academy of Family Physicians recommends Clindamycin 7 mg/kg per dose three times daily (maximum 300 mg per dose) for 10 days for patients who require alternative treatments 1
The European Society of Cardiology recommends Vancomycin 30 mg/kg/24 h IV divided into two doses for 4 weeks for streptococcal endocarditis 11

Treatment failure is considered when signs or symptoms persist or recur, there is a sustained fourfold increase in non-treponemal tests, or the expected fourfold decrease in titers is not observed within the established period, with a high strength of evidence supporting the importance of monitoring for treatment failure 9, 2
For patients with a history of severe reactions (anaphylaxis, angioedema, bronchospasm), all β-lactams should be avoided, and skin testing with major determinant (benzylpenicilloyl poly-L-lysine) and penicillin G can identify ~90-97% of allergic patients, with a strength of evidence level of moderate 5, 2