Application: Antimicrobial Agents

Application: Antimicrobial Agents
Antimicrobial agents are essential components in the treatment of various bacterial
infections as they help to kill or prevent the growth of microbes such as bacteria, fungi, and
protozoans. Prior to the discovery of antimicrobial agents, treatment options for patients
with bacterial infections were limited. For many patients, treatment often resulted in the
amputation of limbs or even death. Today, treatment options for bacterial infections
typically have a more positive prognosis. Due to the various types of infections presented in
patients, it is essential to be able to identify the underlying cause of the infection “whether
bacterial or viral” before recommending drug treatments. This will help you identify
whether or not an antimicrobial agent would be appropriate and which specific agent
would target the infection. In this Assignment, you consider the appropriate use of
antimicrobial agents for infections.
To prepare:
Describe the categories of antimicrobial agents.
Think about differences between viral and bacterial infections.
Reflect on why proper identification of the infection is key to selecting the proper
antimicrobial agent.
To complete:
Write a 3-4 page paper that addresses the following:
�Describe the categories of antimicrobial agents.
�Describe differences between viral and bacterial infections.
�Explain why proper identification of viral and bacterial infections is key to selecting the
proper antimicrobial agent.
�You must have introduction and conclusion in your paper

Applications of Antimicrobial Agents

Antimicrobials are agents are used to inhibit the growth of microbes or kill them. The discovery
of antimicrobial agents led to the revolution of clinical medicine, marking a transition from the
indigenous to modern antimicrobial treatment options (Scholar & Pratt, 2000). Nowadays there

are numerous antimicrobial agents, but penicillin was the first antimicrobial agent to be
discovered in 1928 (Kingston, 2008). However, antimicrobial agents are either microbicidal
meaning that they kill their target microbes or microbiostatic meaning that they inhibit the
growth of their target microbes. Despite the high number of antimicrobial agents, they are
broadly categorized according to their target microorganisms. For example, there are four main
categories of antimicrobial agents such as: antibacterials, antivirals, antiprotozoals and
antifungals (Levy, 1994).
The aforementioned categories impart their antimicrobial activity through selective toxicity, but
there are also some non-selective antimicrobial agents including disinfectants such as bleach
(Scholar & Pratt, 2000). Moreover, irrespective of many antimicrobial agents currently present,
only a few of them have been useful clinically since their clinical use is purely dependent on
selective toxicity whereby they inhibit or kill the microbes without harming or with a few side
effects to the patient. Furthermore, it is important to properly identify the infection and the
microbe underlying cause of the infection prior to selecting the appropriate antimicrobial agent
to be prescribed to a patient (Kingston, 2008).
Categories of Antimicrobial Agents
Antimicrobial agents are categorized according to their target microbes including: antibacterials
(targeting bacteria), antivirals (targeting viruses), antiprotozoals (targeting protozoans) and
antifungals (targeting fungi). In this term paper the above mentioned four main categories of
antimicrobial agents will be discussed as follows:

Antibacterials: Antibacterials also referred to as antibiotics are used to treat bacterial infections.
It is generally considered that antibacterials are lowly toxic to humans, but their prolonged use

can result to decreased population of gut flora, which can negatively impact on health (Levy,
1994). The original description of the term antibiotic considered only those formulations that had
been obtained from living organisms, but currently its application also extent to synthetic
antimicrobials, such as the sulphonamides (Kingston, 2008). Antibacterials usually target both
Gram-positive and Gram-negative bacteria. Nowadays, antibiotics are among the drugs that are
most commonly used where 30% or more of hospital admitted patients’ treatments are using one
or more courses of antibiotics (Scholar & Pratt, 2000). However, despite the technological
advancements in clinical pharmacology, the main challenge facing the use of antibacterials has
been the alarming increase in resistance to existing antibacterial agents. Moreover, antibacterial
agents are classified according to their mode of action including: beta-lactams, semisynthetic
beta-lactams, clavulanic acid, monobactams, carboxypenems, aminoglycosides, glycopeptides,
lincomycins, macrolides, polypeptides, rifamycins, tetracyclines, semisynthetic tetracycline,
chloramphenicol, quinolones, fluoroquinolones as well as growth factor analogs (Wainwright,
1989; Scholar & Pratt, 2000).

Antivirals: Antiviral drugs are used to treat viral infections and specific antivirals are used for
the treatment of specific viruses. Antivirals are relatively harmless to the patient, and mostly they
do not destroy their target virus; but instead they cause inhibition of their development
(Kingston, 2008). The antivirals are classified according to their targeted stage of viral infection
and they include: entry inhibitors, uncoating inhibitors, reverse transcription, integrase,
transcription, translation/antisense, translation/ribozymes, protein processing and targeting as
well as protease inhibitors (Scholar & Pratt, 2000).
Antiprotozoals: Antiprotozoals are used to treat protozoan and parasitic infections, such as
those caused by nematodes, infectious protozoa, cestodes, trematodes, and amoebae (Kingston,

2008). The antiprotozoals are aimed at killing the infecting protozoans or parasites without
serious harm to the host. Antiprotozoals are classified according to their mode of action
including: quinines, anti-folates and nucleic acid analogs (Levy, 1994).
Antifungals: Antifungals are used to treat fungal infections by killing or inhibiting further
growth of fungi. In clinical practice antifungals are used to treat infections such as ringworm,
athlete’s foot, and thrush by exploiting differences between fungal and mammalian cells
(Wainwright, 1989). Antifungals are classified according to their mode of action including:
polyenes, azoles, allylamines, and echinocandins (Levy, 1994).
Differences between Viral and Bacterial Infections
In order for effective use of antimicrobial agents in treatment of viral and bacterial infections, it
is important to be aware of the differences between these two types of infections. For instance,
viral infections are caused by viruses whereas bacterial infections are caused by bacteria (Mason,
2012). Often viral infections are characterized by changes in temperature, hot and cold sweats,
sore throat and runny nose as well as all-pervasive aching in the joints and muscles. Moreover,
bacterial infections tend to often infect the sinuses, the urinary and gut tracts, the chest or the
throat often indicated by mucous or sputum which is green, yellow or grayish (Steckelberg,
2011). Furthermore, viral infections often weaken the immune system allowing the onset of
opportunistic infections, but bacterial infections alone rarely weaken the immune system
(Mason, 2012). Examples of viral infections include: include chickenpox, common cold and
AIDS whereas some examples of bacterial infections include: strep throat, urinary tract
infections and tuberculosis (Steckelberg, 2011).

The significance of proper identification of the infection to selecting the appropriate
antimicrobial agent

Proper identification of a patient’s infection is very crucial prior to selection of the appropriate
antimicrobial agent for use. This is attributable to the fact that upon proper identification of the
infection, the right antimicrobial agent will be selected for treatment which eventually results to
decreased local symptoms while at the same time preventing serious sequelae or complications
from the infection (Mason, 2012). Moreover, proper identification of the infection prevents
misuse of antimicrobial agents in treating various infections using the wrong antimicrobial
agents which may lead to the emergence of pathogens that are resistant to antimicrobial agents,
resulting in a serious threat to global public health (Steckelberg, 2011).
In conclusion, it is clearly evident that antimicrobial agents have been playing a very crucial role
in clinical use to treat various microbial infections, thus improving the quality of health care
delivery as well as saving lives. Moreover, it has also been found that the antimicrobial agents
work effectively through selective toxicity to the microbes meaning bacterial and viral infections
are treated by different antimicrobial agents. This creates the necessity for proper identification
of the infection prior to selection of the antimicrobial agent for use.


Kingston, W. (2008). Irish contributions to the origins of antibiotics. Irish journal of medical
science, 177(2), 87–92.
Levy, S.B. (ed) (1994). Drug Resistance: The New Apocalypse (special issue) Trends
Microbiology, 2(3), 341–425.