Anti-infective agents are drugs that are designed to act selectively on foreign organisms that have invaded and infected the body of a human host. Ideally, these drugs would be toxic to the infecting organisms only and would have no effect on the host (or human) cells.
•Antimicrobial therapy (often termed “antibiotic therapy”) is the use of medications to treat infections caused by bacteria, viruses, and fungi. •Antimicrobial must use selective toxicity to kill or otherwise control microbes without destroying host cells. As a result, individual groups of Antiinfectives tend to have unique characteristics (to be discussed on next page). In addition, their respective methods of actions may include (to be discussed thoroughly on page 3): oDestroying the cell wall, which are present in bacteria but not found in mammals. oPreventing viral replication through reduction of enzymes needed by the virus to reproduce. •New antimicrobials must be continually created due to changes in DNA of microorganisms, called conjugation, which produces resistance to multiple existing drugs. •Super-infection is a type of resistance caused when normal flora are killed by use of an antibiotic, thus favoring the emergence of a new infection that is difficult to eliminate. •Selection of antimicrobial medications is based on FOUR MAJOR multiple factors (to be discussed later).
Several major examples of Anti-infectives includes,
anti-bacterials (or antibiotics)- able to slow down growth or harm bacteria anti-fungals (or anti-MYCOTICS)- able to slow down or harm fungi, anti-virals- able to slow down or harm viruses,
BEFORE I CONTINUE, allow me to make one quick clarification: Parasites are organisms that prey on humans. They tend to be large in size so we refer to such as Protozoa and Helminths (or parasitic worms). Others are small in size and sometimes could be bacteria or viruses.
anti-protozoals- able to slow down or harm protozoan,
anti-helmintics- able to slow down or harm parasitic worms anti-neoplastics- able to destroy cancer cells within human living tissues.
CHARACTERISTICS OF ANTI-INFECTIVES in General
Anti-infectives that are able to slow down the growth AND also able to destroy (or Kill) an infective pathogen are described as BACTERICIDAL. Anti-infectives that are able to slow down the growth BUT UNABLE to destroy (or Kill) an infective pathogen are described as BACTERIOSTATIC.
Another way to look at anti-infectives is as follow-
Anti-infectives can have a small group of pathogens against which they are only effective as such they are described as having a NARROW SPECTRUM activity. Anti-infectives which are effective against a many pathogens are described as having a BROAD (or EXTENDED) SPECTRUM activity.
FOUR MAJOR FACTORS WHICH GOVERNS THE SELECTION OF ANTIMICROBIALS MEDICATIONS 1.Identification of the causative agent:
oGram stain – Examine an aspirate of body fluid under the microscope, where micro-organisms may be identified directly. oCulture of the fluid – Apply the aspirate to culture medium and allow colonies of the micro- organisms to grow over several days. A culture may be preferable to gram stain in cases where positive identification cannot be made by the first method.
2.Sensitivity of the micro – organism to the anti microbial oDisk diffusion test (also called Kirby-Bauer test) is most common. oBroth dilution method is a quantitative method that helps determine the necessary amount of antibiotics for a specific infection.
oImmune Systems of Clients
In clients with an intact immune system, the antibiotic works with host defense systems to suppress organisms. Antibiotics that are not bactericidal may be used. Clients who are immunocompromised need strong bactericidal antibiotics. oSite of the Infection
Certain sites are difficult for antimicrobials to reach. •Infections in cerebral spinal fluid,...