Clinical Management of Cases

Diagnosis and collection of samples

Despite its reputation, anthrax is not contagious, and humans are not highly susceptible to the disease. While theoretically it only takes one spore to initiate a cutaneous infection, B. anthracis is not invasive and usually requires a portal of entry through the skin, although in many cases this may be so small as to be unnoticed. Standard Universal Precautions (gloves, gowns, masks and hand washing) should be adopted to take the samples.

Precautions for sampling

The samples outlined below should be taken to confirm the diagnosis. These must be taken using Universal Precautions and with the utmost care to avoid inoculation injuries. The procedures for transporting samples to the laboratory are outlined elsewhere. The receiving laboratory should be telephoned to expect arrival. Chain of evidence documentation should also accompany all specimens; however in larger incidents this would only be required for several of the initial cases.

Samples to be taken from acutely ill patients

• Blood for culture (taken before antibiotic treatment).
• Nasal swabs (laboratory diagnosis is easier if these are sent dry since this prevents growth of other organisms and facilitates detection of anthrax spores).
• Respiratory samples including lung aspirates, pleural fluids, or sputum samples and swabs from cutaneous lesions.

Post mortem specimens

Samples may be taken from dead humans to assist diagnosis, including:

• Blood from a vein (the blood is non-clotting at death in anthrax).
• Respiratory tract samples.
• Swabs of haemorrhagic exudate from orifices.
• Swabs or sample of other body fluids if appropriate.

However full post-mortem examinations are discouraged if anthrax is suspected because of the risk of releasing anthrax spores present in body fluids, drips etc. If post-mortem is carried out, swabs or samples of lung, spleen or lymph node tissue should be sent (transport medium is not necessary, but it will not damage specimens).

Treatment

Ciprofloxacin is not licensed for use in children or pregnant women, but may be indicated in life-threatening illness. Although doxycycline is not recommended in childhood or pregnancy its use would be considered in a serious infection such as anthrax. There have been no formal studies of the use of ciprofloxacin during pregnancy, but it is unlikely to be associated with a high risk of abnormalities of foetal development. There is some evidence that the use of fluoroquinolones in children (including by breast feeding mothers) may be associated with tendinopathy and arthropathy.

Where the diagnosis is suspected but not confirmed, it may be necessary to start empirical treatment to cover the possibility of anthrax. Early treatment reduces fatality therefore ciprofloxacin should commence as soon as anthrax is suspected. Because the initial symptoms are difficult to distinguish from other flu-like disease a suggested strategy is to treat with a short three day course of ciprofloxacin until blood culture results are available. However, in these circumstances, it will also be necessary to treat concurrently for other causes of acute respiratory illness.

Inhalation and ingestion anthrax

Initially intravenous (IV) antibiotics should be administered. The recommended treatment for inhalation and ingestion anthrax is shown in the Table. Once the patient's condition improves and the susceptibility of the organism is available, therapy can be switched to a single oral antibiotic (ciprofloxacin or doxycycline).

It should be noted that benzylpenicillin or amoxicillin should NOT be used alone in initial treatment of anthrax and that cepahlosporins are ineffective for the treatment of anthrax.

The combination of rifampin and clindamycin demonstrated a synergistic effect in vitro against two strains of B. anthracis - Sterne and STi, both of which lack the pathogenicity plasmid (Athamna et al 2005). A number of other antibiotic combinations were either indifferent or antagonistic.

Sejvar et al (2005) suggest that for anthrax meningitis initial treatment should include an intravenous fluoroquinolone and not doxycycline, because doxycycline has poor central nervous system (CNS) penetration. In addition to an IV fluoroquinolone, one or two other agents that have good CNS penetration and activity against B. anthracis should be added (ie, penicillin, ampicillin, meropenem, vancomycin, rifampin). Case reports suggest that adding corticosteroids may be of benefit in the management of cerebral oedema/inflammation.

The early initiation of multi-drug antibiotic therapy is associated with decreased mortality in cases of inhalation anthrax (Holty et al 2006). It is suggested that the addition of vaccination to a short course of antibiotics would enhance protection afforded by antibiotics alone (Vietri et al 2006).

Table: Recommended treatment for inhalation and ingestion anthrax

	Antimicrobial agent	Duration
Adults (including pregnant women)	Ciprofloxacin 400mg IV every 12hr (or when appropriate 500mg oral twice daily) OR Doxycycline 100mg oral twice daily (when appropriate) PLUS One or two additional antibiotics (agents with in vitro activity include rifampicin, vancomycin, gentamicin, chloramphenicol, penicillin, amoxicillin, imipenem, meropenem and clindomycin)	60 days
Children	Ciprofloxacin 10mg/kg IV every 12hr, not to exceed adult dose of 1500mg per day (change to oral therapy, 15mg/kg PO not to exceed 1500mg per day, when appropriate) OR Doxycycline 100mg oral twice daily (NB: only for children > 8yrs and >45kg) PLUS One or two additional antibiotics (agents with in vitro activity include rifampicin, vancomycin, gentamicin, chloramphenicol, penicillin, amoxicillin, imipenem, meropenem and clindamycin)	60 days

Cutaneous anthrax

Ciprofloxacin or doxycycline should be considered first-line therapy. Treatment should be initiated with oral ciprofloxacin 500mg or doxycycline 100mg twice daily for 7 days. This can be changed to oral amoxicillin if the organism is found to be susceptible or if the patient cannot take a fluoroquinolone or tetracycline class drug. Adults are recommended to take 500mg amoxycillin 3 times a day. For children, 80mg/kg amoxicillin divided into 3 doses given 8 hourly is an option for completion of therapy after clinical improvement. The oral amoxicillin dose is based on the need to achieve appropriate minimum inhibitory concentration levels.

Cutaneous anthrax with signs of systemic involvement, extensive oedema, or lesions on the head or neck require intravenous therapy and a multi-drug approach is recommended.

Treatment may need to be continued for up to 60 days if there is suspicion of deliberate release in order to provide cover for inhalation anthrax, which may have been acquired concurrently.

Infection control practice

Decontamination of exposed persons

In the event of a known exposure to anthrax spores, the risk for re-aerosolisation is uncertain and is likely to depend on a number of variables, including the quantity of spores on the surface; the type of surface and host factors. However, even low numbers of spores could potentially lead to infection in any person having contact. An incident specific risk assessment will be required.

In situations where the threat of exposure to B. anthracis spores exists, cleansing of skin and potentially contaminated fomites such as clothing, personal possessions or environmental surfaces should take place. Decontamination of persons exposed to anthrax includes:

• Removal of contaminated clothing and possessions - it should be stored in labelled double plastic bags until exposure to anthrax has been ruled out.
• If anthrax is confirmed, all contaminated material must be incinerated or autoclaved.
• Minimal handling of clothing and fomites to avoid agitation.
• Instructing exposed persons to shower thoroughly with soap and water- appropriate facilities will be provided at the scene as necessary.
• Instructing attending personnel to wear full PPE when handling contaminated clothing and other fomites.

Isolation of patients

• Standard Universal Precautions should be used for the care of patients infected with B. anthracis - gloves, gowns, masks and hand washing.
• Single room placement for anthrax patients is not necessary.
• Airborne transmission does not occur.
• Skin lesions may be infectious, but this requires direct skin contact
• Standard Universal Precautions should be maintained when patients are moved.

Cleaning, disinfection & waste disposal

Contaminated environmental surfaces should be cleaned with hypochlorite solution (10,000ppm available chlorine).

Post-mortem procedures

Autopsy - The risk of acquiring anthrax following contact with the body of a person who has died from the disease is negligible, because person-to-person transmission is not documented for inhalational disease and there is no evidence of autopsy transmission.

Autopsy examinations are strongly discouraged if anthrax infection is suspected, as the body fluids in a patient who has died of anthrax are likely to have large numbers of the causative bacteria present and opening the body increases the risk that sporulation of the anthrax bacilli will occur. If an autopsy is necessary expert advice must be sought from the HPA. The Pathologist must be informed of the known or suspected diagnosis. Standard precautions for post-mortem examinations on patients infected with Containment Level 3 organisms are appropriate. Instruments should be autoclaved.

Similarly, body preparation should be carried out with normal control of infection procedures. Standard precautions for the disposal of bodies infected with Containment Level 3 pathogens should be observed, and the undertaker should be informed. Cremation is the preferred method for disposal of the deceased. Embalming of bodies should not be undertaken because the body fluids are likely to contain large numbers of the causative bacteria and therefore the process of embalming exposes the embalmer to an unacceptable risk.

Pacemaker removal is permitted. Pacemaker should be treated with hypochlorite solution (10,000 ppm available chlorine), bagged and disposed of appropriately (not by incineration).

Last reviewed: 23 December 2010