Bacillus anthracis

Bacillus anthracis
	Photomicrograph of Bacillus anthracis (fuchsin-methylene blue spore stain).; Photomicrograph of Bacillus anthracis (fuchsin-methylene blue spore stain).
Scientific classification
Kingdom:	Bacteria;
Phylum:	Firmicutes;
Class:	Bacilli;
Order:	Bacillales;
Family:	Bacillaceae;
Genus:	Bacillus;
Species:	B. anthracis;
Binomial name
	Bacillus anthracis; Cohn 1872

File:B anthracis diagram en.png

Structure of Bacillus anthracis.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Jesus Rosario Hernandez, M.D. [2]

Overview

Bacillus anthracis is a Gram-positive, facultatively anaerobic, rod-shaped bacterium of the genus Bacillus. An endospore forming bacterium, B. anthracis is a natural soil-dwelling organism, as well as the causative agent of anthrax.^[1]

Each cell is about 1 by 6 μm in size.

Historical background

B. anthracis was the first bacterium conclusively demonstrated to cause disease, by Robert Koch in 1877.^[2] The species name anthracis is from the Greek anthrakis (ἄνθραξ), meaning coal and referring to the most common form of the disease, cutaneous anthrax, in which large black skin lesions are formed.

Pathogenicity

Under conditions of environmental stress, B. anthracis bacteria naturally produce endospores which rest in the soil and can survive for decades in this state. When ingested by a cattle, sheep, or other herbivores, the bacteria begin to reproduce inside the animal and eventually kill it, then continue to reproduce in its carcass. Once the nutrients are exhausted, new endospores are produced and the cycle repeats.^[3]

B. anthracis has at least 89 known strains, ranging from highly virulent strains with biological warfare and bioterrorism applications (Ames and Vollum) to benign strains used for inoculations (Sterne). The strains differ in presence and activity of various genes, determining their virulence and production of antigens and toxins. The form associated with the 2001 anthrax attacks produced both toxin (consisting of three proteins: the protective antigen, the edema factor and the lethal factor) and a capsule (consisting of a polymer of glutamic acid). Infection with anthrax requires the presence of all three of these exotoxins.^[4]

The bacterium can be cultivated in ordinary nutrient medium under aerobic or anaerobic conditions.

Treatment

Infections with B. anthracis can be treated with β-lactam antibiotics such as penicillin, and others which are active against Gram-positive bacteria.^[5]

Treatment

Antimicrobial therapy

Bacillus anthracis treatment

1. Treatment for cutaneous anthrax, without systemic involvement^[6]

Preferred regimen (regardless of penicillin susceptibility or if susceptibility is unknown) (1): Ciprofloxacin 500 mg PO bid for 7-10 days

Preferred regimen (regardless of penicillin susceptibility or if susceptibility is unknown) (2): Doxycycline 100 mg PO bid for 7-10 days

Preferred regimen (regardless of penicillin susceptibility or if susceptibility is unknown) (3): Levofloxacin 750 mg PO qd for 7-10 days

Preferred regimen (regardless of penicillin susceptibility or if susceptibility is unknown) (4): Moxifloxacin 400 mg PO qd for 7-10 days

Alternative regimen (1): Clindamycin 600 mg PO tid for 7-10 days

Alternative regimen (2): Amoxicillin 1 g PO tid (for penicillin-susceptible strains) for 7-10 days

Alternative regimen (3): Penicillin VK 500 mg PO qid (for penicillin-susceptible strains) for 7-10 days

Note: Duration of treatment is 60 days for bioterrorism-related cases and 7-10 days for naturally acquired cases.

2. Treatment for systemic anthrax including anthrax meningitis, inhalational anthrax, injectional anthrax, and gastrointestinal anthrax; and cutaneous anthrax with systemic involvement, extensive edema, or lesions of the head or neck^[6]

2.1 Systemic anthrax with possible/confirmed meningitis

2.1.1 Bactericidal agent (fluoroquinolone)

Preferred regimen (1): Ciprofloxacin 400 mg IV q8h for 2-3 weeks

Preferred regimen (2): Levofloxacin 750 mg IV q24h for 2-3 weeks

Preferred regimen (3): Moxifloxacin 400 mg IV q24h for 2-3 weeks AND

2.1.2 Bactericidal agent (ß-lactam) for all strains, regardless of penicillin susceptibility or if susceptibility is unknown

Preferred regimen (1): Meropenem 2 g IV q8h for 2-3 weeks

Preferred regimen (2): Imipenem 1 g IV q6h for 2-3 weeks

Preferred regimen (3): Doripenem 500 mg IV q8h for 2-3 weeks

Preferred regimen (4): Penicillin G 4 MU IV q4h (for penicillin-susceptible strains) for 2-3 weeks

Preferred regimen (5): Ampicillin 3 g IV q6h (for penicillin-susceptible strains) for 2-3 weeks AND

2.1.3 Protein synthesis inhibitor

Preferred regimen (1): Linezolid 600 mg IV q12h for 2-3 weeks

Preferred regimen (2): Clindamycin 900 mg IV q8h for 2-3 weeks

Preferred regimen (3): Rifampin 600 mg IV q12h for 2-3 weeks

Preferred regimen (4): Chloramphenicol 1 g IV q6-8h for 2-3 weeks

Note (1): Patients exposed to aerosolized spores will require prophylaxis to complete an antimicrobial drug course of 60 days from onset of illness.

Note (2): Increased risk for seizures associated with Imipenem/Cilastatin treatment.

Note (3): Linezolid should be used with caution in patients with thrombocytopenia because it might exacerbate it. Linezolid use for > 14 days has additional hematopoietic toxicity.

Note (4): Rifampin is not a protein synthesis inhibitor. However, it may be used in combination with other antimicrobial drugs on the basis of its in vitro synergy.

2.2 Systemic anthrax when meningitis has been excluded

2.2.1 Bactericidal agent

Preferred regimen (1): Ciprofloxacin 400 mg IV q8hfor 2 weeks

Preferred regimen (2): Levofloxacin 750 mg IV q24h for 2 weeks

Preferred regimen (3): Moxifloxacin 400 mg q24h for 2 weeks

Preferred regimen (4): Meropenem 2 g IV q8h for 2 weeks

Preferred regimen (5): Imipenem 1 g IV q6h for 2 weeks

Preferred regimen (6): Doripenem 500 mg IV q8h for 2 weeks

Preferred regimen (7): Vancomycin 20 mg/kg IV q8h (maintain serum trough concentrations of 15-20 µg/mL) for 2 weeks

Preferred regimen (8): Penicillin G 4 MU IV q4h (penicillin-susceptible strains) for 2 weeks

Preferred regimen (9): Ampicillin 3 g IV q6h (penicillin-susceptible strains) for 2 weeks AND

2.2.2 Protein synthesis inhibitor

Preferred regimen (1): Clindamycin 900 mg IV q8h for 2 weeks

Preferred regimen (2): Linezolid 600 mg IV q12h for 2 weeks

Preferred regimen (3): Doxycycline 200 mg IV initially, then 100 mg IV q12h for 2 weeks

Preferred regimen (4): Rifampin 600 mg IV q12h for 2 weeks

Note: Patients exposed to aerosolized spores will require prophylaxis to complete an antimicrobial drug course of 60 days from onset of illness.

3. Specific considerations

3.1 Treatment of anthrax for pregnant Women

3.1.1 Intravenous antimicrobial treatment for systemic anthrax with possible/confirmed meningitis ^[7]

3.1.1.1 A bactericidal agent (fluoroquinolone)

Preferred regimen (1): Ciprofloxacin 400 mg IV q8h for 2–3 weeks

Preferred regimen (2): Levofloxacin 750 mg IV q24h for 2–3 weeksOR

3.1.1.2 A bactericidal agent (ß-lactam)

3.1.1.2.1 For all strains, regardless of penicillin susceptibility or if susceptibility is unknown

Preferred regimen: Meropenem 2 g q8h for 2–3 weeks

3.1.1.2.2 Alternatives for penicillin-susceptible strains

Alternative regimen (1): Ampicillin 3 g IV q6h for 2–3 weeks

Alternative regimen (2): Penicillin G 4 MU IV q4h for 2–3 weeks OR

3.1.1.3 A protein synthesis Inhibitor

Preferred regimen (1): Clindamycin 900 IV mg q8h for 2–3 weeks

Preferred regimen (2): Rifampin 600 IV mg q12h for 2–3 weeks

Note: At least one antibiotic with transplacental passage is recommended.

3.1.2 Intravenous antimicrobial treatment for systemic anthrax when meningitis has been excluded

3.1.2.1 A bactericidal Antimicrobial

Preferred regimen (1): Ciprofloxacin 400 mg IV q8h for 2 weeks

Preferred regimen (2): Levofloxacin 750 mg IV q24h for 2 weeks OR

3.1.2.2 A bactericidal Agent (ß-lactam)

3.1.2.2.1 For all strains, regardless of penicillin susceptibility or if susceptibility is unknown

Preferred regimen: Meropenem 2 g q8h for 2 weeks OR

3.1.2.2.2 Alternatives for penicillin-susceptible strains

Alternative regimen (1): Ampicillin 3 g IV q6h for 2 weeks

Alternative regimen (2): Penicillin G 4 MU IV q4h for 2 weeks OR

3.1.2.3 A protein synthesis inhibitor

Preferred regimen (1): Clindamycin 900 IV mg q8h for 2 weeks

Preferred regimen (2): Rifampin 600 IV mg q12h for 2 weeks

3.1.3 Oral antimicrobial treatment for cutaneous anthrax without systemic involvement

3.1.3.1 For all strains, regardless of penicillin susceptibility or if susceptibility is unknown

Preferred regimen: Ciprofloxacin 400 mg IV q8h

Note: Duration of treatment is 60 days

3.2 Treatment for anthrax in childern ^[8]

3.2.1 Treatment of cutaneous anthrax without systemic involvement (for children 1 month of age and older)

3.2.1.1 For all strains, regardless of penicillin susceptibility or if susceptibility is unknown

Preferred regimen (1): Ciprofloxacin 30 mg/kg/day PO bid (not to exceed 500 mg/dose) for 7-10 days

Preferred regimen (2):

If patients body weight is < 45 kg: Doxycycline 4.4 mg/kg/day PO bid (not to exceed 100 mg/dose) for 7-10 days

If patients body weight is = 45 kg: Doxycycline 100 mg/dose PO bid for 7-10 days

Preferred regimen (3): Clindamycin 30 mg/kg/day PO tid (not to exceed 600 mg/dose) for 7-10 days

Preferred regimen (4):

If patients body weight is < 50 kg: Levofloxacin 16 mg/kg/day PO bid (not to exceed 250 mg/dose) for 7-10 days

If patients body weight is > 50 kg: Levofloxacin 500 mg PO qd for 7-10 days

3.2.1.2 Alternatives for penicillin-susceptible strains

Alternative regimen (1):Amoxicillin 75 mg/kg/day PO tid (not to exceed 1 g/dose) for 7-10 days

Alternative regimen (2): Penicillin VK 50-75 mg/kg/day PO tid or qid for 7-10 days

3.2.2 Combination therapy for systemic anthrax when meningitis can be ruled out (for children 1 month of age and older)

3.2.2.1 A bactericidal antimicrobial

3.2.2.1.1 For all strains, regardless of penicillin susceptibility or if susceptibility is unknown

Preferred regimen (1): Ciprofloxacin 30 mg/kg/day IV divided q8h (not to exceed 400 mg/dose) for 14 days

Preferred regimen (2): Meropenem 60 mg/kg/day IV divided q8h (not to exceed 2 g/dose) for 14 days

Preferred regimen (3):

If patients body weight is < 50 kg: Levofloxacin 20 mg/kg/day IV divided q12h (not to exceed 250 mg/dose) for 14 days

If patients body weight is > 50 kg: Levofloxacin 500 mg IV q24h for 14 days

Preferred regimen (4): Imipenem/Cilastatin 100 mg/kg/day IV divided q6h (not to exceed 1 g/dose) for 14 days

Preferred regimen (5): Vancomycin 60 mg/kg/day IV divided q8h (follow serum concentrations) for 14 days

3.2.2.1.2 Alternatives for penicillin-susceptible strains

Alternative regimen (1): Penicillin G 400 000 U/kg/day IV divided q4h (not to exceed 4 MU/dose) for 14 days

Alternative regimen (2): Ampicillin 200 mg/kg/day IV divided q6h (not to exceed 3 g/dose) for 14 days AND

3.2.2.2 A protein synthesis inhibitor

Preferred regimen (1): Clindamycin, 40 mg/kg/day IV divided q8h (not to exceed 900 mg/dose) for 14 days

Preferred regimen (2): (non-CNS infection dose)

If patient is < 12 y old: Linezolid 30 mg/kg/day IV divided q8h for 14 days

If patient is = 12 y old: Linezolid 30 mg/kg/day IV divided q12h (not to exceed 600 mg/dose) for 14 days

Preferred regimen (3):

If patients body weight is < 45 kg: Doxycycline 4.4 mg/kg/day IV loading dose (not to exceed 200 mg) THEN Doxycycline 4.4 mg/kg/day IV divided q12h (not to exceed 100 mg/dose) for 14 days

If patients body weight is =45 kg: Doxycycline 200 mg IV loading dose THEN Doxycycline 100 mg IV given q12h for 14 days

Preferred regimen (4): Rifampin 20 mg/kg/day IV divided q12h (not to exceed 300 mg/dose) for 14 days

Note: Duration of therapy for 14 days or longer until clinical criteria for stability are met.Will require prophylaxis to complete an antimicrobial course of up to 60 days from onset of illness.

3.2.3 Triple therapy for systemic anthrax (anthrax meningitis or disseminated infection and meningitis cannot be ruled out) for Children 1 Month of Age and Older

3.2.3.1 A bactericidal antimicrobial (fluoroquinolone)

Preferred regimen (1): Ciprofloxacin 30 mg/kg/day IV divided q8h (not to exceed 400 mg/dose) for 2–3 wks

Preferred regimen (2):

If patients body weight is < 50 kg: Levofloxacin 16 mg/kg/day IV divided q12h (not to exceed 250 mg/dose) for 2–3 wks

If patients body weight is > 50 kg: Levofloxacin 500 mg IV q24h for 2–3 wks

Preferred regimen (3):

If patients age is 3 months to < 2 years: Moxifloxacin 12 mg/kg/day IV, divided q12h (not to exceed 200 mg/dose) for 2–3 wks

If patients age is 2-5 years: Moxifloxacin 10 mg/kg/day IV divided q1h (not to exceed 200 mg/dose) for 2–3 wks

If patients age is 6–11 years: Moxifloxacin 8 mg/kg/day IV divided q12h (not to exceed 200 mg/dose) for 2–3 wks

If patients age is 12–17 years, = 45 kg body weight: Moxifloxacin 400 mg IV q24h for 2–3 wks

If patients age is 12–17 years, < 45 kg body weight: Moxifloxacin 8 mg/kg/day IV divided q12h (not to exceed 200 mg/dose) for 2–3 wks AND

3.2.3.2 A bactericidal antimicrobial (ß-lactam or glycopeptide)

3.2.3.2.1 For all strains, regardless of penicillin susceptibility testing or if susceptibility is unknown:

Preferred regimen (1): Meropenem 120 mg/kg/day IV divided q8h (not to exceed 2 g/dose) for 2–3 wks

Preferred regimen (2): Imipenem/Cilastatin 100 mg/kg/day IV divided q6h (not to exceed 1 g/dose) for 2–3 wks

Preferred regimen (3): Doripenem 120 mg/kg/day IV divided q8h (not to exceed 1 g/dose) for 2–3 wks

Preferred regimen (4): Vancomycin 60 mg/kg/day IV divided q8h for 2–3 wks

3.2.3.2.2 Alternatives for penicillin-susceptible strains

Alternative regimen (1): Penicillin G 400 000 U/kg/day IV divided q4h (not to exceed 4 MU/dose) for 2–3 wks

Alternative regimen (2): Ampicillin 400 mg/kg/day IV divided q6h (not to exceed 3 g/dose) for 2–3 wks AND

3.2.3.3 A protein synthesis inhibitor

Preferred regimen (1):

If patients age is < 12 y old: Linezolid 30 mg/kg/day IV divided q8h for 2–3 wk

If patients age is = 12 y old: Linezolid 30 mg/kg/day,IV divided q12h (not to exceed 600 mg/dose) for 2–3 wk

Preferred regimen (2): Clindamycin 40 mg/kg/day IV divided q8h (not to exceed 900 mg/dose) for 2–3 wk

Preferred regimen (3): Rifampin 20 mg/kg/day IV divided q12h (not to exceed 300 mg/dose) for 2–3 wk

Preferred regimen (4): Chloramphenicol 100 mg/kg/day IV divided q6h for 2–3 wk

Note (1): Duration of therapy for 2–3 wk or greater, until clinical criteria for stability are met.Will require prophylaxis to complete an antimicrobial course of up to 60 days from onset of illness.

Note (2): A 400-mg dose of Ciprofloxacin IV, provides an equivalent exposure to that of a 500-mg ciprofloxacin oral tablet.

3.2.4 Oral follow-up combination therapy for severe anthrax (for Children 1 Month of Age and Older)

3.2.4.1 A bactericidal antimicrobial

3.2.4.1.1 For all strains, regardless of penicillin susceptibility or if susceptibility is unknown

Preferred regimen (1): Ciprofloxacin 30 mg/kg/day PO bid (not to exceed 500 mg/dose)

Preferred regimen (2):

If patients body weight is < 50 kg: Levofloxacin 16 mg/kg/day PO bid (not to exceed 250 mg/dose)

If patients body weight is = 50 kg: Levofloxacin 500 mg PO qd

3.2.4.1.2 Alternatives for penicillin-susceptible strains

Alternative regimen (1): Amoxicillin 75 mg/kg/day PO tid (not to exceed 1 g/dose)

Alternative regimen (2): Penicillin VK 50–75 mg/kg/day PO tid or qds AND

3.2.4.2 A protein synthesis inhibitor:

Preferred regimen (1):Clindamycin 30 mg/kg/day PO tid (not to exceed 600 mg/dose)

Preferred regimen (2):

If the patients body weight is < 45 kg: Doxycycline 4.4 mg/kg/day PO bid (not exceed 100 mg/dose)

If the patients body weight is = 45 kg: Doxycycline 100 mg PO bid

Preferred regimen (3): (non-CNS infection dose):

If the patients age is < 12 yrs old: Linezolid 30 mg/kg/day PO tid

If the patients age is = 12 yrs old: Linezolid 30 mg/kg/day PO bid (not to exceed 600 mg/dose)

Note: Duration of therapy to complete a treatment course of 14 days or greater. May require prophylaxis to complete an antimicrobial course of up to 60 days from onset of illness.

3.2.5 Dosing in preterm and term neonates 32 to 44 Weeks postmenstrual Age (Gestational Age Plus Chronologic Age)

3.2.5.1 Triple therapy for severe anthrax(anthrax meningitis or disseminated infection and meningitis cannot be ruled out)

3.2.5.1.1 Bactericidal antimicrobial (fluoroquinolone) therapy

3.2.5.1.1.1 For 32–34 weeks gestational age

For 0–1 week of age

Preferred regimen (1): Ciprofloxacin 20 mg/kg/day IV divided q12h for 2–3 weeks

Preferred regimen (2): Moxifloxacin 5 mg/kg/day IV q24h for 2–3 weeks

For 1–4 weeks of age

Preferred regimen (1): Ciprofloxacin 20 mg/kg/day IV divided q12h for 2–3 weeks

Preferred regimen (2): Moxifloxacin 5 mg/kg/day IV q24h for 2–3 weeks

3.2.5.1.1.2 For 34–37 week gestational age

For 0–1 wk of age

Preferred regimen (1): Ciprofloxacin 20 mg/kg/day IV divided q12h for 2–3 weeks

Preferred regimen (2):Moxifloxacin 5 mg/kg/day IV q24h for 2–3 weeks

For 1–4 wk of age

Preferred regimen (1): Ciprofloxacin 20 mg/kg/day IV divided q12h for 2–3 weeks

Preferred regimen (2): Moxifloxacin 5 mg/kg/day IV q24h for 2–3 weeks

3.2.5.1.1.3 Term newborn infant

For 0–1 week of age

Preferred regimen (1): Ciprofloxacin 30 mg/kg/day IV divided q12h for 2–3 weeks

Preferred regimen (2): Moxifloxacin 10 mg/kg/day IV q24h for 2–3 weeks

For 1–4 weeks of age

Preferred regimen (1): Ciprofloxacin 30 mg/kg/day IV divided q12h for 2–3 weeks

Preferred regimen (2): Moxifloxacin 10 mg/kg/day IV q24h for 2–3 weeks AND

3.2.5.1.2 A bactericidal antimicrobial (ß-lactam)

3.2.5.1.2.1 For all strains, regardless of penicillin susceptibility or if susceptibility is unknown:

3.2.5.1.2.1.1 For 32–34 weeks gestational age

For 0–1 week of Age :

Preferred regimen (1): Meropenem 60 mg/kg/day IV divided q8h for 2–3 weeks

Preferred regimen (2): Imipenem 50 mg/kg/day IV divided q12h for 2–3 weeks

Preferred regimen (3): Doripenem 20 mg/kg/day IV divided q12h for 2–3 weeks

For 1–4 wk of Age :

Preferred regimen (1): Meropenem 90 mg/kg/day IV divided q8h for 2–3 weeks

Preferred regimen (2): Imipenem 75 mg/kg/day IV divided q8h for 2–3 weeks

Preferred regimen (3): Doripenem 30 mg/kg/day IV divided q8h for 2–3 weeks

3.2.5.1.2.1.2 For 34–37 week gestational age

For 0–1 week of Age :

Preferred regimen (1): Meropenem 60 mg/kg/day IV divided q8h for 2–3 weeks

Preferred regimen (2): Imipenem 50 mg/kg/day IV divided q12h for 2–3 weeks

Preferred regimen (3): Doripenem 20 mg/kg/day IV divided q12h for 2–3 weeks

For 1–4 week of Age :

Preferred regimen (1): Meropenem 90 mg/kg/day IV divided q8h for 2–3 weeks

Preferred regimen (2): Imipenem 75 mg/kg/day IV divided q8h for 2–3 weeks

Preferred regimen (3): Doripenem 30 mg/kg/day IV divided q8h for 2–3 weeks

3.2.5.1.2.1.3 Term newborn infant

For < 1 week of age

Preferred regimen (1):Meropenem 60 mg/kg/day IV divided q8h for 2–3 weeks

Preferred regimen (2): Imipenem 50 mg/kg/day IV divided q12h for 2–3 weeks

Preferred regimen (3): Doripenem 20 mg/kg/day IV divided q12h for 2–3 weeks

For 1–4 week of age

Preferred regimen (1):Meropenem 90 mg/kg/day IV divided q8h for 2–3 weeks

Preferred regimen (2): Imipenem 75 mg/kg/day IV divided q8h for 2–3 weeks

Preferred regimen (3): Doripenem 30 mg/kg/day IV divided q8h for 2–3 weeks

3.2.5.1.2.2 Alternatives for penicillin-susceptible strains

3.2.5.1.2.2.1 For 32–34 weeks gestational age

For 0–1 week of age

Alternative regimen (1):Penicillin G 200000 Units/kg/day IV divided q12h for 2–3 weeks

Alternative regimen (2): Ampicillin 100 mg/kg/day IV divided q12h for 2–3 weeks

For 1–4 week of age :

Alternative regimen (1): Penicillin G 300000 Units/kg/day IV divided q12h for 2–3 weeks

Alternative regimen (2): Ampicillin 150 mg/kg/day divided IV q12h for 2–3 weeks

3.2.5.1.2.2.2 For 34–37 week gestational age

For < 1 week of age

Alternative regimen (1): Penicillin G 300000 Units/kg/day IV divided q12h for 2–3 weeks

Alternative regimen (2): Ampicillin 150 mg/kg/day IV divided q12h for 2–3 weeks

For 1–4 week of age

Alternative regimen (1): Penicillin G 400000 Units/kg/day IV divided q12h for 2–3 weeks

Alternative regimen (2): Ampicillin 200 mg/kg/day IV divided q12h for 2–3 weeks

3.2.5.1.2.2.3 Term newborn infant

For 0–1 week of age

Alternative regimen (1): Penicillin G 300000 Units/kg/day IV divided q12h for 2–3 weeks

Alternative regimen (2): Ampicillin 150 mg/kg/day IV divided q12h for 2–3 weeks

For 1–4 week of age

Alternative regimen (1): Penicillin G 400000 Units/kg/day IV divided q12h for 2–3 weeks

Alternative regimen (2): Ampicillin 200 mg/kg/day IV divided q12h for 2–3 weeks AND

3.2.5.1.3 A protein synthesis inhibitor

3.2.5.1.3.1 For 32–34 weeks gestational age

For < 1 week of age

Preferred regimen (1): Linezolid 20 mg/kg/day IV divided q12h for 2–3 weeks

Preferred regimen (2): Clindamycin 10 mg/kg/day IV divided q12h for 2–3 weeks

Preferred regimen (3): Rifampin 10 mg/kg/day IV divided q12h for 2–3 weeks

Preferred regimen (4): Chloramphenicol 25 mg/kg/day IV q24h for 2–3 weeks

For 1–4 week of age

Preferred regimen (1): Linezolid 30 mg/kg/day IV divided q8h for 2–3 weeks

Preferred regimen (2): Clindamycin 15 mg/kg/day IV divided q8h for 2–3 weeks

Preferred regimen (3): Rifampin 10 mg/kg/day IV divided q12h for 2–3 weeks

Preferred regimen (4): Chloramphenicol 50 mg/kg/day IV q12h for 2–3 weeks

3.2.5.1.3.2 For 34–37 week gestational age

For < 1 week of age

Preferred regimen (1): Linezolid 30 mg/kg/day IV divided q8h for 2–3 weeks

Preferred regimen (2): Clindamycin 15 mg/kg/day IV divided q8h for 2–3 weeks

Preferred regimen (3): Rifampin 10 mg/kg/day IV divided q12h for 2–3 weeks

Preferred regimen (4): Chloramphenicol 25 mg/kg/day IV q24h for 2–3 weeks

For 1–4 week of age

Preferred regimen (1):Linezolid 30 mg/kg/day IV divided q8h for 2–3 weeks

Preferred regimen (2): Clindamycin 20 mg/kg/day IV divided q6h for 2–3 weeks

Preferred regimen (3): Rifampin 10 mg/kg/day IV divided q12h for 2–3 weeks

Preferred regimen (4): Chloramphenicol 50 mg/kg/day IV q12h for 2–3 weeks

3.2.5.1.3.3 Term newborn infant

For < 1 week of age

Preferred regimen (1):Linezolid 30 mg/kg/day IV divided q8h for 2–3 weeks

Preferred regimen (2): Clindamycin 15 mg/kg/day IV divided q8h for 2–3 weeks

Preferred regimen (3): Rifampin 10 mg/kg/day IV divided q12h for 2–3 weeks

Preferred regimen (4): Chloramphenicol 25 mg/kg/day IV q24h for 2–3 weeks

For 1–4 week of age

Preferred regimen (1): Linezolid 30 mg/kg/day IV divided q8h for 2–3 weeks

Preferred regimen (2): Clindamycin 20 mg/kg/day IV divided q6h for 2–3 weeks

Preferred regimen (3): Rifampin 20 mg/kg/day IV divided q12h for 2–3 weeks

Preferred regimen (4): Chloramphenicol 50 mg/kg/day IV q12h for 2–3 weeks

Note :Duration of therapy for 2–3 weeks, until clinical criteria for stability are met. Will require prophylaxis to complete an antibiotic course of upto 60 days from onset of illness.

3.2.5.2 Therapy for severe anthrax when meningitis can be ruled out

3.2.5.2.1 A bactericidal antimicrobial

3.2.5.2.1.1 For all strains, regardless of penicillin susceptibility or if susceptibility is unknown

3.2.5.2.1.1.1 For 32–34 weeks gestational age

For < 1 week of age

Preferred regimen (1): Ciprofloxacin 20 mg/kg/day IV divided q12h for 2-3 weeks

Preferred regimen (2): Meropenem 40 mg/kg/day IV divided q8h for 2-3 weeks

Preferred regimen (3): Imipenem 40 mg/kg/day IV divided q12h for 2-3 weeks

For 1–4 week of age

Preferred regimen (1): Ciprofloxacin 20 mg/kg/day IV divided q12h for 2-3 weeks

Preferred regimen (2): Meropenem 60 mg/kg/day IV divided q8h for 2-3 weeks

Preferred regimen (3): Imipenem 50 mg/kg/day IV divided q12h for 2-3 weeks

3.2.5.2.1.1.2 For 34–37 week gestational age

For < 1 week of age

Preferred regimen (1): Ciprofloxacin 20 mg/kg/day IV divided q12h for 2-3 weeks

Preferred regimen (2): Meropenem 60 mg/kg/day IV divided q8h for 2-3 weeks

Preferred regimen (3): Imipenem 50 mg/kg/day IV divided q12h for 2-3 weeks

For 1–4 week of age

Preferred regimen (1): Ciprofloxacin 20 mg/kg/day IV divided q12h for 2-3 weeks

Preferred regimen (2): Meropenem 60 mg/kg/day IV divided q8h for 2-3 weeks

Preferred regimen (3): Imipenem 75 mg/kg/day IV divided q8h for 2-3 weeks

3.2.5.2.1.1.3 Term newborn infant

For < 1 week of age

Preferred regimen (1): Ciprofloxacin 30 mg/kg/day IV divided q12h for 2-3 weeks

Preferred regimen (2): Meropenem 60 mg/kg/day IV divided q8h for 2-3 weeks

Preferred regimen (3): Imipenem 50 mg/kg/day IV divided q12h for 2-3 weeks

For 1–4 week of age

Preferred regimen (1):Ciprofloxacin 30 mg/kg/day IV divided q12h for 2-3 weeks

Preferred regimen (2): Meropenem 60 mg/kg/day IV divided q8h for 2-3 weeks

Preferred regimen (3): Imipenem 75 mg/kg/day IV divided q8h for 2-3 weeks

Vancomycin IV (dosing based on serum creatinine for infants of 32 wk gestational age). Follow vancomycin serum concentrations to modify dose.

If Serum creatinine < 0.7 then Vancomycin 15 mg/kg/dose IV q12h for 2-3 weeks

If Serum creatinine 0.7 -0.9 then Vancomycin 20 mg/kg/dose IV q24h for 2-3 weeks

If Serum creatinine 1–1.2 then Vancomycin 15 mg/kg/dose IV q24h for 2-3 weeks

If Serum creatinine 1.3–1.6 then Vancomycin 10 mg/kg/dose IV q24h for 2-3 weeks

If Serum creatinine > 1.6 then Vancomycin mg/kg/dose IV q48h for 2-3 weeks

Note: Begin treatment with a 20 mg/kg loading dose OR

3.2.5.2.1.2 Alternatives for penicillin-susceptible strains

3.2.5.2.1.2.1 For 32–34 weeks gestational age

For < 1 week of age

Alternative regimen (1): Penicillin G 200000 U/kg/day IV divided q12h for 2-3 weeks

Alternative regimen (2): Ampicillin 100 mg/kg/day IV divided q12h for 2-3 weeks

For 1–4 week of age

Alternative regimen (1): Penicillin G 300000 U/kg/day IV divided q8h for 2-3 weeks

Alternative regimen (2): Ampicillin 150 mg/kg/day IV divided q8h for 2-3 weeks

3.2.5.2.1.2.2 For 34–37 week gestational age

For < 1 week of age

Alternative regimen (1): Penicillin G 300000 U/kg/day IV divided q8h for 2-3 weeks

Alternative regimen (2): Ampicillin 150 mg/kg/day IV divided q8h for 2-3 weeks

For 1–4 week of age

Alternative regimen (1): Penicillin G 400000 U/kg/day IV divided q6h for 2-3 weeks
Alternative regimen (2): Ampicillin 200 mg/kg/day IV divided q6h for 2-3 weeks

3.2.5.2.1.2.3 Term newborn infant

For < 1 week of age

Alternative regimen (1): Penicillin G 300000 U/kg/day IV divided q8h for 2-3 weeks

Alternative regimen (2): Ampicillin 150 mg/kg/day IV divided q8h for 2-3 weeks

For 1–4 week of age

Alternative regimen (1): Penicillin G 400000 U/kg/day IV divided q6h for 2-3 weeks

Alternative regimen (2):Ampicillin 200 mg/kg/day IV divided q6h for 2-3 weeks

3.2.5.2.2 A protein synthesis inhibitor

3.2.5.2.2.1 For 32–34 weeks gestational age

For < 1 week of age

Preferred regimen (1): Clindamycin 10 mg/kg/day IV divided q12h for 2–3 wks

Preferred regimen (2): Linezolid 20 mg/kg/day IV divided q12h for 2–3 wks

Preferred regimen (3): Rifampin 10 mg/kg/day IV q24h for 2–3 wks

For 1–4 week of age

Preferred regimen (1): Clindamycin 15 mg/kg/day IV divided q8h for 2–3 wks

Preferred regimen (2): Linezolid 30 mg/kg/day IV divided q8h for 2–3 wks

Preferred regimen (3): Rifampin 10 mg/kg/day IV q24h for 2–3 wks

3.2.5.2.2.2 For 34–37 week gestational age

For < 1 week of age

Preferred regimen (1): Clindamycin 15 mg/kg/day IV divided q8h for 2–3 wks

Preferred regimen (2): Linezolid 30 mg/kg/day IV divided q8h for 2–3 wks

Preferred regimen (3): Rifampin 10 mg/kg/day IV q24h for 2–3 wks

For 1–4 week of age

Preferred regimen (1): Clindamycin 20 mg/kg/day IV divided q6h for 2–3 wks

Preferred regimen (2): Linezolid 30 mg/kg/day IV divided q8h for 2–3 wks

Preferred regimen (3): Rifampin 10 mg/kg/day IV q24h for 2–3 wks

3.2.5.2.2.3 Term newborn infant

For 0–1 week of age :

Preferred regimen (1): Clindamycin 15 mg/kg/day IV divided q8h for 2–3 wks

Preferred regimen (2): Linezolid 30 mg/kg/day IV divided q8h for 2–3 wks

Preferred regimen (3): Doxycycline 4.4 mg/kg/day IV divided q12h, (loading dose 4.4 mg/kg) for 2–3 wks

Preferred regimen (4): Rifampin 10 mg/kg/day IV q24h for 2–3 wks

For 1–4 week of age :

Preferred regimen (1): Clindamycin 20 mg/kg/day IV divided q6h for 2–3 wks

Preferred regimen (2): Linezolid 30 mg/kg/day IV divided q8h for 2–3 wks

Preferred regimen (3): Doxycycline 4.4 mg/kg/day IV divided q12h, (loading dose 4.4 mg/kg) for 2–3 wks

Preferred regimen (4): Rifampin 10 mg/kg/day IV q24h for 2–3 wks

Note: Duration of therapy for 2–3 wks, until clinical criteria for stability are met (see text). Will require prophylaxis to complete an antimicrobial course of upto 60 days from onset of illness

3.2.5.3 Oral follow-up combination therapy for severe anthrax

3.2.5.3.1 A bactericidal antimicrobial

3.2.5.3.1.1 For all strains, regardless of penicillin susceptibility or if susceptibility is unknown

3.2.5.3.1.1.1 For 32–34 weeks gestational age

For < 1 week of age

Preferred regimen: Ciprofloxacin 20 mg/kg/day PO bid

For 1–4 week of age

Preferred regimen: Ciprofloxacin 20 mg/kg/day PO bid

3.2.5.3.1.1.2 For 34–37 week gestational age

For < 1 week of age

Preferred regimen: Ciprofloxacin 20 mg/kg/day PO bid

For 1–4 week of age

Preferred regimen: Ciprofloxacin 20 mg/kg/day PO bid

3.2.5.3.1.1.3 Term newborn infant

For < 1 week of age

Preferred regimen: Ciprofloxacin 30 mg/kg/day PO bid

For 1–4 week of age

Preferred regimen: Ciprofloxacin 30 mg/kg/day PO bid OR

3.2.5.3.1.2 Alternatives for penicillin-susceptible strains

3.2.5.3.1.2.1 For 32–34 weeks gestational age

For < 1 week of age

Alternative regimen (1): Amoxicillin 50 mg/kg/day PO bid

Alternative regimen (2): Penicillin VK 50 mg/kg/day PO bid

For 1–4 week of age

Alternative regimen (1): Amoxicillin 75 mg/kg/day PO bid

Alternative regimen (2): Penicillin VK 75 mg/kg/day PO bid

3.2.5.3.1.2.2 For 34–37 week gestational age

For < 1 week of age

Alternative regimen (1): Amoxicillin 50 mg/kg/day PO bid

Alternative regimen (2): Penicillin VK 50 mg/kg/day PO bid

For 1–4 week of age

Alternative regimen (1): Amoxicillin 75 mg/kg/day PO bid

Alternative regimen (2): Penicillin VK 75 mg/kg/day PO tid

3.2.5.3.1.2.3 Term newborn infant

For < 1 week of age

Alternative regimen (1): Amoxicillin 75 mg/kg/day PO tid

Alternative regimen (2): Penicillin VK 75 mg/kg/day PO tid

For 1–4 week of age

Alternative regimen (1): Amoxicillin 75 mg/kg/day PO tid
Alternative regimen (2): Penicillin VK 75 mg/kg/day PO tid or qid

3.2.5.3.2 A protein synthesis inhibitor

3.2.5.3.2.1 For 32–34 weeks gestational age

For < 1 week of age

Preferred regimen (1): Clindamycin 10 mg/kg/day PO bid

Preferred regimen (2): Linezolid 20 mg/kg/day PO bid

For 1–4 week of age

Preferred regimen (1): Clindamycin 15 mg/kg/day PO bid

Preferred regimen (2): Linezolid 30 mg/kg/day PO bid

3.2.5.3.2.2 For 34–37 week gestational age

For < 1 week of age

Preferred regimen (1): Clindamycin 15 mg/kg/day PO tid

Preferred regimen (2): Linezolid 30 mg/kg/day PO tid

For 1–4 week of age

Preferred regimen (1): Clindamycin 20 mg/kg/day PO qid

Preferred regimen (2): Linezolid 30 mg/kg/day PO tid

3.2.5.3.2.3 Term newborn infant

For < 1 week of age

Preferred regimen (1): Clindamycin 15 mg/kg/day PO tid

Preferred regimen (2): Doxycycline 4.4 mg/kg/day PO bid (loading dose 4.4 mg/kg)
Preferred regimen (3): Linezolid 30 mg/kg/day PO tid

For 1–4 week of age

Preferred regimen (1): Clindamycin 20 mg/kg/day PO qid
Preferred regimen (2): Doxycycline 4.4 mg/kg/day PO bid (loading dose 4.4 mg/kg)
Preferred regimen (3): Linezolid 30 mg/kg/day PO tid

Note: Duration of therapy to complete a treatment course of 10–14 days or greater. May require prophylaxis to complete an antimicrobial course of upto 60 days from onset of illness.

3.2.5.4 Treatment of cutaneous anthrax without systemic involvement

3.2.5.4.1 For all strains, regardless of penicillin susceptibility or if susceptibility is unknown

3.2.5.4.1.1 For 32–34 weeks gestational age

For < 1 week of age

Preferred regimen (1): Ciprofloxacin 20 mg/kg/day PO bid

Preferred regimen (2): Clindamycin 10 mg/kg/day PO bid

For 1–4 week of age

Preferred regimen (1): Ciprofloxacin 20 mg/kg/day PO bid
Preferred regimen (2): Clindamycin 15 mg/kg/day PO tid

3.2.5.4.1.2 For 34–37 week gestational age

For < 1 week of age

Preferred regimen (1): Ciprofloxacin 20 mg/kg/day PO bid

Preferred regimen (2): Clindamycin 15 mg/kg/day PO tid

For 1–4 week of age

Preferred regimen (1): Ciprofloxacin 20 mg/kg/day PO bid

Preferred regimen (2): Clindamycin 20 mg/kg/day PO qid

3.2.5.4.1.3 Term newborn infant

For < 1 week of age

Preferred regimen (1): Ciprofloxacin 30 mg/kg/day PO bid

Preferred regimen (2): Doxycycline 4.4 mg/kg/day PO bid (Loading dose 4.4 mg/kg)

Preferred regimen (3): Clindamycin 15 mg/kg/day PO tid

For 1–4 week of age

Preferred regimen (1): Ciprofloxacin 30 mg/kg/day PO bid

Preferred regimen (2): Doxycycline 4.4 mg/kg/day PO bid (Loading dose 4.4 mg/kg)

Preferred regimen (3): Clindamycin 20 mg/kg/day PO qid

3.2.5.4.2 Alternatives for penicillin-susceptible strains

3.2.5.4.2.1 For 32–34 weeks gestational age

For < 1 week of age

Alternative regimen (1): Amoxicillin 50 mg/kg/day PO bid
Alternative regimen (2): Penicillin Vk 50 mg/kg/day PO bid

For 1–4 week of age

Alternative regimen (1): Amoxicillin 75 mg/kg/day PO tid

Alternative regimen (2): Penicillin Vk 75 mg/kg/day PO tid

3.2.5.4.2.2 For 34–37 week gestational age

For < 1 week of age

Alternative regimen (1): Amoxicillin 50 mg/kg/day PO bid
Alternative regimen (2): Penicillin Vk 50 mg/kg/day PO bid

For 1–4 week of age

Alternative regimen (1): Amoxicillin 75 mg/kg/day PO bid

Alternative regimen (2): Penicillin Vk 75 mg/kg/day PO bid

3.2.5.4.2.3 Term newborn infant

For < 1 week of age

Alternative regimen (1): Amoxicillin 75 mg/kg/day PO tid
Alternative regimen (2): Penicillin Vk 75 mg/kg/day PO tid

For 1–4 week of age

Alternative regimen (1): Amoxicillin 75 mg/kg/day PO tid

Alternative regimen (2): Penicillin Vk 75 mg/kg/day PO tid or qid
Note : Duration of therapy for naturally acquired infection is 7–10 days and for a biological weapon–related event,may require additional prophylaxis for inhaled spores to complete an antimicrobial course of up to 60 days from onset of illness.