agents or toxins against civilians, with the objective of causing fear, illness, or death” (2,3). The
CDC has classified the most likely agents according to their cumulative properties and threat
(Table 1) (1,4–8). This definition has been expanded to include attacks against animals and
plants (2). In fact, animals may likely act as early warning “sentinels” (9).
Between 1900 and 1999, there were 415 incidents (278 cases between 1960 and 1999) of the
use or attempted use of chemical, biological, or radiological materials by criminals or terrorists.
In recent years, investigations into these threats, especially biological threats, have dramat-
ically increased (10). Awareness of the history of the use of biological weapons will help the
clinician better appreciate future epidemiologic threats. We present this abbreviated history in
Table 2 (1,2,5,11).
Maintain an Index of Suspicion
Specific epidemiologic characteristics should raise the clinician’s index of suspicion that he is
dealing with a bioterrorism event. These are listed in Table 3 (1,2,5,12).
Protect Yourself (and Your Patients)
Intensive care units render care to a relatively small proportion of hospitalized patients, but
nationally account for<20% of health care–associated infections (13). “Hand hygiene...”
overall, is the most important element in preventing nosocomial infections (13). A review of
infection control is essential in order to effectively apply isolation principles in the event of a
bioterrorist attack.
The two-tier system for preventing nosocomial infections consists of (i) standard
precautions, and (ii) transmission-based precautions (TBP). Standard precautions (the
combination of universal precautions and body substance isolation precautions) apply to all
patients, and presumes that “ALL blood, body fluids, secretions, excretions except sweat, non-
intact skin, and mucous membranes” may transmit infectious agents. Standard precautions
include hand hygiene, safe injection practices and handling of sharps, personal barrier
precautions and supplies, and addressing the risk of contamination of the patient environment.
Newer elements such as respiratory hygiene/cough etiquette, safe injection practices, and the
use of masks for inserting catheters or procedures involving a lumbar puncture have been
added (13).
TBP are employed when contagion cannot be contained by standard precautions. For the
agents most likely to be encountered in a bioterrorist attack, TBP are needed to safely render
care. The three categories of TBP are contact precautions, droplet precautions, and airborne
precautions. These precautions are always applied together with standard precautions, and
may be used in combination with one another. (See Ref. 13 for details.)
In brief,contact precautionsrequire personnel to don personal protective equipment prior
to entering the patient’s room, and remove it before leaving (preferably in the anteroom of the
patient’s isolation room). Single rooms are always preferred, but where cohorting is the only
option, there must be greater than 3 ft distance between beds (13).Droplet precautionsdo not
require rooms with special air handling or ventilation. In addition to other protective
garments, all those entering the room must wear a mask. A respiratory mask is not necessary.
Patients must also wear a mask when they are transported from the room (13).
Airborne precautionsare required for infectious agents that are a threat over long distances
(i.e., rubeola virus, varicella virus,Mycobacteria tuberulosis,SARS-CoV, smallpox). Patients
suspected of infection with these agents should be placed in a single room designated as an
airborne infection isolation room (AIIR) (14,15). Guidelines for these rooms include monitored
negative pressure, 12 air exchanges per hour for new construction or renovation, 6 air
exchanges for existing facilities, and air exhausted directly outside or through high efficiency
particulate air (HEPA) filtration before return. It is mandatory to implement a respiratory
protection program that includes the use of respirators, fit testing, and user seal checks. Where
this cannot be accomplished, an N95 or higher-level respirator must be worn (13).
TBP should be instituted as soon as the patient arrives at the hospital. As identification of
the pathogen may take one or more days, decisions must be made based upon clinical
presentation (syndromic application—see Table 4) (13,16). Table 5 lists the recommended
isolation precautions for each of the organisms by class (13,16–22).
Bioterrorism Infections in Critical Care 433