NTA Level 5 • Semester 1 • PST05103

Chlamydial Infections

Pharmaceutical Microbiology • Source Session/Topic 22

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Session 22: Chlamydial Infections

Total Session Time: 120 minutes

Pre-requisites

• Human anatomy and physiology

Students Learning Tasks

By the end of this session students are expected to be able to:

• Describe chlamydial infection (causative agents, transmission, signs

and symptoms)

• Describe treatment, prevention and control chlamydial infection

Resources Needed:

• Flip charts, marker pens, and masking tape

• Black/white board and chalk/whiteboard markers

SESSION OVERVIEW

SESSION CONTENTS

STEP 1: Presentation of Session Title and Learning Tasks (5 minutes)

READ or ASK students to read the learning tasks and clarify

ASK students if they have any questions before continuing

STEP 2: Characteristics of Chlamydia (15 minutes)

• The genus chlamydia consists of obligate intracellular bacteria

• The bacteria have cell wall resembling Gram negative bacteria but do

not have peptidoglycan. They have DNA, RNA and ribosomes.

• All chlamydiae exhibit similar morphologic features, share a common

group antigen, and multiply in the cytoplasm of their host cells by a

distinctive developmental cycle

• The chlamydiae lack mechanisms for the production of metabolic energy

and cannot synthesize adenosine triphosphate (ATP)

• This restricts them to an intracellular existence, where the host cell

furnishes energy-rich intermediates

• Three species of Chlamydiae infect humans namely Chlamydia

trachomatis, Chlamydia pneumoniae, and Chlamydia psittaci

• C. trachomatis causes Trachoma, urogenital infections, lymphogranuloma

venerium and pneumonia

• C. pneumoniae causes bronchitis, sinusitis and pneumonia

• C. psittaci causes psittacosis

STEP 3: Cause and Transmission of Trachoma (10 minutes)

• Trachoma is a chronic conjunctivitis caused by infection with

Chlamydia trachomatis

• It is one of the commonest causes of blindness worldwide.

• It is a chronic keratoconjunctivitis that begins with acute

inflammatory changes in the conjunctiva and cornea and progresses to

scarring and blindness

• The disease is associated with poverty and crowded living conditions

• It is endemic in Africa, middle east, India and South East Asia,

mostly affecting children

• Trachoma is transmitted through inoculation of eye by contaminated

hands, flies, clothing and droplets.

STEP 4: Signs and Symptoms of Trachoma (30 minutes)

• The incubation period for chlamydial conjunctival infection is 3–10

days

• In endemic areas, initial infection occurs in early childhood, and the

onset of the long-term consequence, trachoma, is insidious

• Chlamydial infection is often mixed with bacterial conjunctivitis in

endemic areas, and the two together produce the clinical picture

• The earliest features of trachoma are lacrimation, mucopurulent

discharge, conjunctival hyperemia, and follicular hypertrophy

• Microscopic examination of the cornea reveals epithelial keratitis,

subepithelial infiltrates, and extension of limbal vessels into the

cornea (pannus)

• As the pannus extends downward across the cornea, there are scarring

of the conjunctiva, eyelid deformities (entropion, trichiasis), and an

added insult caused by eyelashes sweeping across the cornea

(trichiasis)

• With secondary bacterial infection, loss of vision progresses over a

period of years.

• Generally, the signs and symptoms include;

o Photophobia in early stages or re- infection

o Follicles in the upper tarsal plate seen as round and white

nodules in active diagnostic

o In late stages, in-turned eyelashes rub on the cornea leading to

corneal ulcers

o Loss of vision due to corneal Scarring

• Clinical Stages according to World Health Organization

o Trachomatous Inflammation Follicular (TF) – Presence of at least 5

follicles on the upper tarsal plate

o Trachomatous Inflammation Intense (TI) – There is intense

inflammation, the conjunctival blood vessels cannot be seen

o Trachomatous Scarring (TS) – Presence of white scars in the upper

tarsal plate

o Trachomatous Trichiasis (TT) – Presence of some eye lashes rubbing

against the cornea

o Corneal Opacity (CO) – Presence of corneal opacity (scar)

affecting the central cornea

STEP 5: Treatment, Prevention and Control of Trachoma (20 minutes)

Treatment

• Non pharmacological management

o Face washing and total body hygiene to prevent transmission of

disease from one person to the other

o Environmental improvement/hygiene

• Pharmacological management

o Use of antibiotics

▪ Tetracyclines e.g. oxytetracycline ointment 3%

▪ Macrolides e.g. azithromycin

• Surgery

o To correct entropion in Trachomatous Trichiasis (TT) patients

o This procedure can be done at a Dispensary or Health Centre and

community level by a trained health worker

Prevention and Control

• The World Health Organization has initiated the S-A-F-E program to

eliminate blinding trachoma and at least markedly reduce clinically

active disease

o Surgery for deformed eyelids

o Antibiotic use involving periodic azithromycin therapy

o Face washing and hygiene

o Environmental improvement such as building latrines and decreasing

the number of flies that feed on conjunctival exudates.

STEP 6: Nongonococcal Urethritis and Lymphogranuloma Venereum (30 minutes)

Urogenital infections

• C. trachomatis also causes urogenital infections in both male and

female

• In female the infection is almost asymptomatic

o May cause cervicitis, urethritis, salpingitis and postpartum fever

• In male the infection is symptomatic

o It causes nongonococcal urethritis (which must be ruled out in

treatment of gonorrhea or co-treated)

o Urethritis, dysuria and pyuria

o It is a common cause of post-gonococcal urethritis

• Treatment options include use of Tetracycline e.g. doxycycline,

macrolides e.g. erythromycin and sulphonamides

• Preventive measures include sanitation, safe sex practices, treatment

of patients and their sexual partners.

Lymphogranuloma venereum (LGV)

• Is a sexually transmitted infection caused by C. trachomatis

• The disease presents initially (first stage) with small painless

vesicular lesion at infection site, fever, headache and myalgia.

• Later (second stage)

o Inflammation of draining lymph nodes

o Fever, headache and myalgia

o Buboes (inguinal swellings) which rupture and drain

o Proctitis

o Ulcers

STEP 7: Key Points (5 minutes)

• The genus chlamydia consists of obligate intracellular bacteria

because they lack mechanisms to produce metabolic energy

• Three species of Chlamydiae infect humans namely Chlamydia

trachomatis, Chlamydia pneumoniae, and Chlamydia psittaci

• C. trachomatis is the most important species that causes Trachoma,

urogenital infections, lymphogranuloma venerium and pneumonia

• Trachoma is a chronic conjunctivitis which is one of the commonest

causes of blindness worldwide. The disease is associated with poor

living conditions

• Trachoma can be prevented by maintenance of hygiene especially face

hygiene while blindness can be avoided by early diagnosis and

treatment with antibiotics and simple surgical procedures.

• Nongonococcal urethris caused by C. trachomatis must be ruled out when

treating patients with gonorrhoea. Otherwise the two infections must

be treated together. Medicines that act against gonococci are not

active against chlamydia.

STEP 8: Evaluation (5 minutes)

• How is trachoma transmitted?

• What are the stages of trachoma according to the World Health

Organization?

• How is nongonococcal urethritis treated?

References

Hugo and Russell (2011), Pharmaceutical Microbiology 8th Edition, Willey-

Blackwel publications

Karen C. Carroll et al (2013); Jawetz, Melnick and Adelberg’s Medical

Microbiology 27th Ed. McGraw Hill Co. Inc.

Greenwood et al (2012); Medical Microbiology, 18th edition Churchill

Livingstone

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