TABLE 8. Empiric* treatment regimens for nonpregnant adults aged ≥18 years with systemic† anthrax with or without meningitis,§ by descending order of preference — CDC recommendations, 2023.
| Regimen |
Example |
||
|---|---|---|---|
| Regimen 1. Two bactericidal drugs from different antimicrobial drug classes plus a PSI or an RNAI |
Ciprofloxacin plus meropenem plus minocycline¶ |
||
| Regimen 2. One bactericidal drug plus a PSI |
Meropenem plus doxycycline |
||
| Regimen 3. One bactericidal drug plus a second bactericidal drug from a different antimicrobial drug class |
Meropenem plus ciprofloxacin |
||
| Regimen 4. One bactericidal drug plus an RNAI (rifampin should not be used as monotherapy) |
Meropenem plus rifampin |
||
| Regimen 5. A PSI plus an RNAI (rifampin should not be used as monotherapy) |
Minocycline or doxycycline plus rifampin |
||
| Regimen 6. Two PSIs from different antimicrobial drug classes |
Minocycline plus clindamycin |
||
| Regimen 7. A single bactericidal drug |
Meropenem |
||
| Regimen 8. A single PSI |
Minocycline or doxycycline or clindamycin |
||
|
First-line antimicrobial drug**
| |||
|
Bactericidal drug
|
PSI
|
||
|
Treatment (listed drugs joined by “or” are considered equivalent)
|
Dosage
|
Treatment
|
Dosage
|
| Meropenem†† |
2 g every 8 hours IV |
Minocycline§§ |
200 mg x 1 dose IV, then 100 mg every 12 hours IV |
| or | |||
| Ciprofloxacin§§ |
400 mg every 8 hours IV |
Doxycycline§§ |
200 mg x 1 dose IV, then 100 mg every 12 hours IV |
| or | |||
| Levofloxacin§§ |
500 mg every 12 hours IV |
||
| PCN-S only: | |||
| Penicillin G§§ |
4 million units every 4 hours IV |
||
| or | |||
| Ampicillin†† |
2 g every 4 hours IV |
||
| Imipenem/cilastatin†† |
1 g every 6 hours IV |
||
| or | |||
| Ampicillin/sulbactam†† |
3 g every 6 hours IV |
||
|
Alternative antimicrobial drug¶¶
| |||
|
Bactericidal drug
|
PSI/RNAI
|
||
|
Treatment
|
Dosage
|
Treatment
|
Dosage
|
| Piperacillin/tazobactam†† |
3.375 g every 4 hours IV |
Omadacycline††,*** |
200 mg x 1 dose IV on day 1, then 100 mg every 24 hours IV |
| Moxifloxacin†† |
400 mg every 24 hours IV |
Eravacycline††,*** |
1 mg/kg every 12 hours IV |
| Vancomycin††,*** |
15 mg/kg every 12 hours IV over a period of 1–2 hours (target AUC24 of 400 µg x h/mL [preferred]; if AUC24 is not available, maintain serum trough concentrations of 15–20 µg/mL). Consider a loading dose of 20–35 mg/kg for critically ill patients. |
Clindamycin†† |
900 mg every 8 hours IV |
| Linezolid†† |
600 mg every 12 hours IV |
||
| Rifampin††,††† |
600 mg every 12 hours IV |
||
| Chloramphenicol††,§§§ |
1 g every 6–8 hours IV |
||
| plus | |||
|
Antitoxin (single dose as an adjunct to antimicrobial drug; listed antitoxins joined by “or” are considered equivalent)
| |||
|
Treatment
|
Dosage
|
||
| Raxibacumab¶¶¶ |
40 mg/kg IV |
||
| or | |||
| Obiltoxaximab¶¶¶ |
16 mg/kg IV |
||
| AIGIV**** |
420 units IV |
||
Abbreviations: AIGIV = anthrax immunoglobulin intravenous; AUC24 = area under the concentration-time curve from 0 to 24 hours; FDA = Food and Drug Administration; IV = intravenous; PCN-S = penicillin-susceptible strains; PEPAbx = antimicrobial postexposure prophylaxis for anthrax; PSI = protein synthesis inhibitor; RNAI = RNA synthesis inhibitor.
* Definitive therapy should be directed by antibiotic susceptibility test results, when available.
† “Systemic” was defined as one or more of the following using cutoffs for adults aged ≥18 years: hyperthermia or hypothermia, tachycardia, tachypnea, hypotension, or neutrophilia or neutropenia (Source: Katharios-Lanwermeyer S, Holty JE, Person M, et al. Identifying meningitis during an anthrax mass casualty incident: systematic review of systemic anthrax since 1880. Clin Infect Dis 2016;62:1537–45).
§ Refer to Figure for guidance on clinical signs and symptoms of anthrax meningitis. If meningitis is not suspected and susceptibilities are known, start at regimen 2.
¶ For anthrax meningitis, consider using antimicrobial drugs that have demonstrated potential neuroprotective benefits in vivo (e.g., minocycline, doxycycline, clindamycin, and ß-lactamase inhibitors).
** For highly bioavailable antimicrobial drugs (e.g., ciprofloxacin, doxycycline, and linezolid), if the IV formulation is not available, oral formulations can be considered for patients with an intact gastrointestinal tract where absorption is expected to be complete after oral administration.
†† Not approved by FDA for anthrax PEPAbx, treatment, or both.
§§ Approved by FDA for anthrax PEPAbx, treatment, or both, but specific uses (e.g., doses, dosing schedules, and patient populations) recommended in this report might differ from the FDA-approved labeling.
¶¶ Alternative selections are for patients who have contraindications to or cannot tolerate first-line antimicrobial drugs or if first-line antimicrobial drugs are not available.
*** This antimicrobial drug does not cross an intact blood-brain barrier but might cross with meningitis because of breakdown of the barrier.
††† Rifampin is an RNAI and also bactericidal; however, it should not be used as monotherapy. Rifampicin is equivalent to rifampin and can be used if it is more readily available.
§§§ Chloramphenicol should not be used in combination with a bactericidal antimicrobial drug because the interaction might be antagonistic.
¶¶¶ Premedicate with IV or oral diphenhydramine within 1 hour before administration. Hypersensitivity and anaphylaxis have been reported after raxibacumab and obiltoxaximab administration.
**** An 840-unit dose of AIGIV can be considered for severe cases.