*2.1.1.2 Laboratory diagnosis*

Laboratory tests crucial for identifying *C. trachomatis* infections to confirm the diagnosis are [22]:

**Giemsa staining of smears:** The most common procedure worldwide for identificating *C. trachomatis* infection is microscopic evaluation of the cells with Giemsa stain. The easiest and earliest method of laboratory diagnosis was by direct indication of the Halberstaedter-Prowazek bodies with Giemsa staining of conjunctival smears. Although it may not be sensitive enough in patients with nonaggressive ocular disease, Giemsa stain detects the inclusions in most of the cases with follicular or papillar trachoma [12].

**Antigen detection assays:** The two tests available are Direct Fluorescent Antibody (DFA) and enzyme immunoassay (EIA). DFA with monoclonal antibodies is 90% sensitive and enzyme immunoassay (EIA) is believed to have a lower sensitivity. Both are used widely in routine.

**Tissue Culture Isolation:** Isolation of C. trachomatis in Hella cells or McCoy cells, etc., is the most specific method and is considered the "gold standard." However, sensitivity is low. C. trachomatis inclusions are detected either by Giemsa, Macchiavelli, or Gimenez staining or immunofluorescence assay after 48–72 h of incubation.

**Serology:** The most common tests are complement fixation and microimmunofluorescence tests. Infection by any serotype of C. trachomatis causes a crossreactive antibody reaction against all the serotypes. The antibodies persist for a long period; therefore, serology has a limited role in the diagnosis of acute chlamydial infections [23].

**Nucleic acid amplification tests:** The most commonly used tests are Polymerase Chain Reaction (PCR) assay and Ligase Chain Reaction (LCR) assay. Although they are the most sensitive and specific techniques for C. trachomatis detection, they are still not used for routine laboratory practices in poor countries due to the high cost and need for expertise [24].

### *2.1.1.3 Differential diagnosis*

For the diagnosis of trachoma, although follicles are not pathognomonic, their presence in endemic areas should be a strong reason for suspicion. Pannus, conjunctival scarring, and trichiasis seen in these areas are almost always attributable to trachoma. Herbert's pits are pathognomonic for previous trachomatous inflammation.

The most common differential diagnosis are as follows:


Toxic follicular conjunctivitis is secondary to topical medications or cosmetics. In areas where trachoma is endemic, pannus, conjunctival scarring, and trichiasis are almost attributable to trachoma. Corneal opacity, however, has many possible etiologies [25].

#### *2.1.1.4 Treatment*

#### *2.1.1.4.1 Personal (acute sporadic trachoma) treatment*

#### **Systemical**

Trachoma treatment consists of a 3–4 week use of oral antibiotics. The most commonly used medications are tetracycline (tetracycline 1 g/day or doxycycline 100 mg/ day) or oral erythromycin. Erythromycin is indicated for less side effects in children, breastfeeding women, and pregnant. The clinical response may take 9–18 weeks.

#### **Topical**

Topical tetracycline or erythromycin ointment is used at least twice a day for 5 days each for 6 months. Reusing topical medication is especially useful where the disease is endemic and reexposure is expected [26].

#### **Treatment aiming the eradication of the disease**

Through the provision of adequate water and hygiene facilities combined with education to promote facial cleanliness and the use of hygiene facilities, it was shown that only face-washing habits even reduced trachoma prevalence [27].

Reducing the fly population by 90%, causing less transmission with eye-seeking flies can reduce the active trachoma prevalence by 60% [28].

#### *Chlamydial Eye Infections DOI: http://dx.doi.org/10.5772/intechopen.111372*

To clear ocular *C. trachomatis* infection in endemic fields, antibiotic treatment may be helpful. Oral azithromycin (1 g/day for adults, 20 mg/kg/day for children) as a single dose is used [29]. It is claimed that in endemic areas, instead of topical treatment, a single dose of oral azithromycin is enough [30, 31].

Azithromycin is well tolerated and systemic antibiotic and is also effective for extraocular infection [32]. Topical tetracycline treatment 3–4 x 1 for 6 weeks is claimed to be equal to a single dose of azithromycin [33].

#### **Treatment of the complications**

Individuals with trachomatous trichiasis and entropion are at risk of corneal opacification and vision loss. To prevent these features from developing, the abrasive action of lashes on the cornea must be stopped by surgical correction of the eyelid margin, with epilation perhaps as an acceptable short-term option. For long-term solution, operation procedures for bilamellar tarsal rotation and posterior lamellar tarsal rotation (or Trabut) are recommended by WHO [34–36].

#### *2.1.2 Neonatal inclusion conjunctivitis*

The most common type of neonatal conjunctivitis worldwide is inclusion conjunctivitis. Inclusion conjunctivitis is caused by *C. trachomatis* serotypes D-K, which form chronic follicular conjunctivitis. Even though chlamydial infection typically affects the sexually active population, it can be transmitted to newborns by their infected mother during delivery. Infants exposed to the agent from the mother's genital tract during delivery, develop chlamydial ophthalmia neonatorum. Approximately 30–50% of infants exposed at birth develop the disease. Neonatal chlamydial conjunctivitis occurs in 2–6% of all newborns [37, 38].

Neonatal chlamydial conjunctivitis is an acute infection of the conjunctiva that is characterized by edema and erythema of the eyelids, palpebral conjunctivae, and purulent eye secretion. It typically occurs 5–14 days after the birth, although it can present earlier. Usually, the infection has a mild and self-limiting course. However, severe diseases can occur. Corneal scarring secondary to peripheral corneal pannus and conjunctival scarring may occur [39, 40]. Laboratory procedures to identify *C. trachomatis* are necessary for diagnosis. One of the two most commonly used methods is Giemsa staining of the conjunctival swab. However, it has only 50–90% sensitivity and requires a trained technician for section evaluation. The other method is McCoy cell culture. It is very expensive and reaching the result takes 2–3 days. Fortunately, new laboratory techniques are available for diagnosis. The enzyme-linked immune assay test has a sensitivity of approximately 90% and a specificity of over 95% and gives results within 2 hours. Direct immunofluorescent monoclonal antibody staining of the conjunctival swab is probably the most useful stereological test and has a specificity of 77–90% with a sensitivity of over 95% for chlamydia. It can be read immediately. It can show diseases that other tests miss. DNA detection tests can also be used. These tests have 90% sensitivity and almost 100% specificity [41].

The therapy objective for neonatal chlamydial conjunctivitis includes both the regression of conjunctivitis and the eradication of respiratory colonization. Therefore topical treatment is insufficient. An oral erythromycin treatment of 50 mg/kg/day in four divided doses for 2 weeks is recommended. If a total recovery is not observed, a second regime of the therapy may be given. The oral treatment should be given to the mother and her sexual partner, with 500 mg tetracycline or 500 mg erythromycin four times a day for 7 days. If pregnancy or breastfeeding exists erythromycin should be chosen [42].

Ocular prophylaxis for newborns has been found to be ineffective in protecting against chlamydial conjunctivitis. Several developed countries have stopped ocular prophylaxis of newborns and replaced it with routine treatment and prenatal screening of pregnant with a sexually transmitted infection [43].

#### *2.1.3 Adult inclusion conjunctivitis*

As neonatal inclusion conjunctivitis, adult inclusion conjunctivitis occurs with *C. trachomatis* D-K serotypes. The transmission of the agent is by sexual or hand-eye contact. Epidemiology revolves around sexual contact. The mode of transmission is through orogenital activities and transmission of genital secretions from hand to eye. The incubation period is 4–12 days. Inclusion conjunctivitis is predicted to develop in one in 300 patients with vernal chlamydial infection. In addition, *C. trachomatis* is the most common cause of chronic follicular conjunctivitis and is responsible for 20% of acute conjunctivitis cases. Because the disease is difficult to distinguish from the clinical findings of early trachoma, the term "paratrachoma" has been used to describe the entire spectrum of the disease with venerally transmitted chlamydial infection [44, 45].

The severity of symptoms in patients with inclusion conjunctivitis is very extensive. Some patients present as acute and mucopurulent conjunctivitis but, most patients have mild symptoms lasting for weeks or months Keratitis may develop in the second week of onset. Corneal involvement consists of superficial punctate keratitis, small marginal and central infiltrates, subepithelial infiltrates, limbal swelling, and superior limbal pannus. The disease imitates acute atopic conjunctivitis or other infectious conjunctivitis because, the signs and symptoms are insidious and most patients have similar nonspecific complaints such as unilateral mucous secretion, hyperemic eyes, crusting of eyelashes, glued eyelids, swollen eyelids, photophobia, itching, lacrimation, foreign body sensation, irritation, and blurred vision [46].

Diagnostic tests for chlamydial keratoconjunctivitis include conjunctival cytological examination, inoculation of susceptible cell lines followed by observation of cytopathic effect or visualization using various chemical or immunological staining agents, eye tears for various antibodies, and detection of chlamydial antigens in conjunctival and corneal specimens. Although the sensitivity of Giemsa staining is low, it is costly and time-consuming, this traditional cytological investigation is still the "gold standard," as isolating an infectious agent is definitive and allows further characterization. The detection of *C. trachomatis* DNA from ocular smears using commercial PCR assays was shown to be as valid as using urogenital samples and reached 95.71% in sensitivity and 90.00% in specificity. Therefore, PCR tests may be a quick and ideal tool for detecting ocular *C. trachomatis* infection [47].

As the infection is not limited to conjunctiva, systemic antibiotic use is recommended. Moreover, the sexual consorts must also receive a full course of therapy. Simultaneous treatment of all sexual partners is important to prevent reinfection. The recommended treatment, given for 3 weeks, includes either oral doxycycline 100 mg twice a day, oral tetracycline 500 mg four times a day, or oral erythromycin 500 mg four times a day. Tetracycline should not be used in pregnant or lactating women [42].

#### **2.2 Lymphogranuloma venereum conjunctivitis**

Lymphogranuloma venereum conjunctivitis is a very rare chlamydial conjunctivitis caused by *C. trachomatis* serotypes L1, L2, and L3. These agents classically cause a

#### *Chlamydial Eye Infections DOI: http://dx.doi.org/10.5772/intechopen.111372*

venereal disease characterized by suppurative inguinal or femoral lymphadenopathy. Occasionally, there are extragenital manifestations of the disease including aseptic meningitis, hepatitis, and conjunctivitis. The first ocular manifestations are the redness and edema of the eyelids. Other ocular manifestations are follicular hypertrophy, hyperemia, chemosis, and large granulomas. Pannus formation and peripheral superficial keratitis may occur. In some cases, phlyctenular conjunctivitis is present too. Episcleritis, uveitis and optic neuritis are among other rare clinical conditions reported. A large preauricular lymph node may be palpable.

The laboratory diagnosis is based on the microscopic detection of inclusion bodies, macrophages, and monocytes in Giemsa-stained conjunctival smears.

For treatment, oral tetracycline, 500 mg four times a day, for 4 weeks or oral doxycycline, 100 mg two times a day, for 4 weeks is used.
