Infectious Conjunctivitis: Causes, Symptoms, and Transmission

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1. Background of the case study (Total: 5 marks)
1.1 What is infectious conjunctivitis?
Infectious conjunctivitis is the inflammation of the conjunctiva of eye which is the
thin transparent layer of the tissue that covers the white part of the eye. The main cause of
infection is due to bacteria and virus. They are mostly spread due to transfer of bacteria
from the skin or respiratory system. Other cause could be physical contact with infected
person, insect and poor hygiene (Liang et al., 2016). The viral conjunctivitis is caused due
to the virus of common cold which can get into the eye by transfer through sneezing and
coughing. The most common symptoms of the infectious conjunctiva are redness, swollen,
discharge of excess sticky fluids, tear, irritation, pain and etching of eyes. The eyes
become pink due to dilated blood vessels. Due to excess discharge of fluids the vision
become blurred. Infectious conjunctiva can be of two types which includes chronic
conjunctivitis and acute conjunctivitis that is related with level and time period of infection
(Deiner et al., 2018). The conjunctivitis which last for above 3 weeks are regarded as
chronic conjunctivitis and those that last for less than 3 weeks are known as acute
conjunctivitis.
1.2 Of the four micro-organisms listed below, justify which one is more likely to be the cause
of John’s eye infection. Indicate why the other micro-organisms from the list are least likely
to cause the infection.
Legionella pneumophila
Yes or no, with reason:
No, Legionella pneumophila is not the cause of eye infection of John because
this organism is one of the human pathogenic bacteria which is known to be the causative
agent for the legionnaires disease also called as legionellosis. The infection is spread due
to showers, hot water system and nebuliser. The infection by the Legionella
pneumophila gives rise of symptom of fever, cough, chest pain and breathlessness.
Hence, such symptoms are not observed it the case study of Mr john hence, Legionella

pneumophila cannot be the reason for the conjunctivitis (Rolando et al., 2016).
Plasmodium ovale
Yes or no, with reason:
No, Plasmodium ovale is the protozoa which is responsible to cause tertian
malaria and is not reported to be the cause of conjunctivitis. Parasitic protozoa does not
cause eye infection hence Mr John cannot have Legionella pneumophila infection
(Soulard et al., 2015).
Adenovirus
Yes or no, with reason:
Yes. Adenovirus can be the reason for the eye infection in Mr John as being a
virus it is known to cause redness and discharge of sticky fluids. It is reported in the case
study that Mr John was having red eye with sticky discharge hence it could be the reason
conjunctivitis in Mr john (Lee et al., 2018).
Staphylococcus aureus
Yes or no, with reason:
Yes, it could also be the reason for the conjunctivitis in Mr john, as he was
showing the symptom of the sticky discharge, redness in eyes and inflammation which are
the sign for the acute bacterial conjunctivitis. Staphylococcus aureus is the gram positive
bacteria which is the known to infect the outer layer of the eye and is most prevalent in the
adult. They are mostly transferred through polluted air (Matsuura et al., 2017).
2. Mechanism of action and adverse reactions (Total: 5 marks)
2.1 Describe the mechanism of action of gentamicin?
Gentamicin is the type of antibiotic which is used to treat bacterial infection. It is
effective against various type of bacterial infection mostly the gram negative bacteria. It is
an aminoglycoside antibiotics which works by interacting with the 30S ribosomal subunit of
the bacteria which interrupt the mechanism of translation. The chemical aminoglycoside is
effective in lowering the infection caused by the Staphylococcus aureus as being a gram
positive bacteria is susceptible to gentamycin (Cushnie, O’Driscoll, & Lamb, 2016).
The drug works by binding to the 30S and 16S rRNA and interrupt the nucleotides and
amino acid of S12 protein. Such action is known to interfere with the decoding site and

disrupts tRNA from translating protein. Hence, bacterial ribosome become non-functional
infection gets lowered.
2.2 Name two adverse reactions of this drug?
One of the most important adverse reaction that is caused by gentamycin is
kidney damage. As the drug contain aminoglycoside it is regarded as the most potent
nephrotoxic which can damage the function of kidney and level of creatinine gets
increased. The side of gentamycin is mostly caused when taken in high dose, concurrent
use and long duration of the intake of drug Chashmi, Emadi & Khastar, 2017.
Other adverse reaction can happen is damage to inner ears. Due to long use of the
medicine, the drug damages the nerves connecting the ear which can lead to hearing loss.
The drug mostly affect the inner hair cells and vestibular apparatus of the ear due to which
person cannot balance their body. Therefore, the doctor recommend to stay hydrated
when they are under the medication of the gentamycin (Rauch, 2016).
3. Physiological basis of signs (Total: 10 marks)
3.1 sign 1:
Sticky discharge from the eye
Explanation of this phenomenon:
One of the most common sign of conjunctivitis is discharge of sticky fluid from
the eye. The lacrimal gland function to secrete aqueous layer of the tear. It contain
lysosomal enzyme which protect the eye from infection (Smith, 2018). However, in
conjunctivitis infection, there is inflammation of sclera layer which result discharge of thick
and sticky fluid. Hence, John was reported with such kind of discharge which confirms the
bacterial infection.
3.2 sign 2:
Swollen eye
Explanation of this phenomenon:
Second sign noted in Mr John was swollen eye. It is evident from the study of
Hsu et al. (2019) that eye can gets swollen when there is some sort of allergic reaction
due to bacteria or virus. In such allergic reaction, the eye release histamine which is a
chemical mediators and causes dilation of the eye’s blood vessel (Hsu et al., 2019). This
make the eye to swell and become itchy. Thus, such sigh also points towards