Page 160 - Assurance of Sterility for Sensitive Combination Products and Materials

142 Assurance of sterility for sensitive combination products and materials

patients, from health-care personnel, from visitors, or from a patient’s own
body flora. In addition to people, transmission of infection can be from con-
taminated surfaces or objects, e.g., surgical instrumentation, contaminated
surfaces in patient rooms, and contaminated water sources (ice machines).

6.4.1.2 Susceptible host
Even if a source of infectious microorganisms is presented to a host, it does
not mean that an infection will result. The host must be susceptible to the
infection. There are several intrinsic factors that predispose a patient to in-
fection. The first hurdle is the host’s natural skin barrier. Breaching the in-
tegrity of the skin increases the chances of getting an infection. Medical and
surgical treatment can make a person more likely to get an infection. Next,
the infection must overcome the host immune system. Neonates and the el-
derly tend to have poorly developed or weakened immune systems and thus
are more prone to getting an infection. Similarly, hosts with an underlying
disease or who are immunocompromised are more likely to succumb to an
infection if exposed to microorganisms.
Host factors can impact how quickly or even if HAIs can be eradicated
by the host. The host’s genetic make-up influences the host’s susceptibility
to microorganisms. People with certain diseases, e.g., diabetes, will have a
more difficult time fighting an infection. Host defenses include:
1. Natural barriers, e.g., intact skin and mucous membranes;
2. Nonspecific immune response, e.g., phagocytic cells (neutrophils, mac-
rophages) and their products; and
3. Specific immune responses, e.g., antibodies, lymphocytes and
4. Natural flora
Intact skin prevents microorganisms from entering sterile body areas.
Mucous membranes also provide a barrier to the invasion of microorgan-
isms. In addition, mucous membranes have some antimicrobial properties.
The respiratory tract has upper airway filters and coughing can help propel
microorganisms away from the respiratory tract out of the body.
An inflammatory response directs the immune system to injury or infec-
tion sites. Microbial spread can be limited by inactivation of microorganisms by
ingestion by the phagocytes creating a foreign body occlusion. Once ingested,
oxidative products produced by the phagocytes will kill microorganisms.
A host can produce a variety of antibodies in response to a specific for-
eign body response. These antibodies can attract the host’s white blood cells
(WBCs) and activate the complement system. This can destroy the cell walls
of infecting microorganisms.