**3. Management of human chlamydial infections**

Management of human Chlamydial infections will be discussed as separate sections and will include the most common etiological agents: *C. trochomatis, C. pneumoniae*, and *C. psittaci*, respectively.

#### **3.1 Management of** *C. trochomatis* **infections**

Infections due to *C. trochomatis* are caused by 19 serovars, which affect the ocular, genito-urinary tract, and pulmonary systems. Ocular infections mainly result from serovars A-C, which led to trachoma and to a lesser extent serovars D-K which led to inclusion conjunctivitis and sometimes infant pneumonia [28]. On the other hand, genito-urinary tract infections include chlamydia and lymphogranuloma venereum (LGV), which are caused by serovars D-K and serovars L1-L3, respectively [2, 18, 29].

In most men and women, chlamydia maintains an asymptomatic course and becomes a silent reservoir for infection [5, 30]. Spontaneous clearance of the pathogen may occur gradually over years but if chlamydia is not treated effectively, major medical conditions with both immediate and long-term complications could arise [3, 31, 32]. These health problems include clinical or subclinical pelvic inflammatory disease (PID) leading to chronic pelvic pain, infertility, ectopic pregnancy and Fitzhugh-Curtis syndrome in women; pre-term delivery, inclusion conjunctivitis, and pneumonia in the newborn; and reactive arthritis in both sexes [5, 33, 34]. It was also shown that untreated chlamydia may promote the spread of other STIs, such as human immunodeficiency virus (HIV) [35]. Therefore to prevent chlamydiaassociated diseases and to decrease the degree of transmission to susceptible populations, presumptive or guided therapy should be started in all suspected or confirmed chlamydia infections including asymptomatic diseases.

#### *3.1.1 Treatment of ocular infections due to* C. trachomatis

The most prevalent infectious etiology of blindness all over the world is *C. trachomatis*, which leads to ocular illnesses known as trachoma and adult/neonatal inclusion conjunctivitis*.* Trachoma is transmitted through direct or indirect contact with objects such as hands, fomites, bed sheets, eye-seeking insects, and polluted towels in unsanitary settings [28]. On the other hand, inclusion conjunctivitis is spread by perinatal transmission in neonates or by hand-to-eye inoculation of infected genital secretions in adults.

#### *3.1.1.1 Treatment of trachoma*

Trachoma specifically targets the world's poorest regions. According to data from June 2022 provided by the World Health Organization (WHO), 125 million people reside in areas where trachoma is an endemic disease [36]. Trachoma is initiated in early childhood and recurrent ocular infection leads to conjunctival scarring and eventually blindness. Trachoma incidents decreased as a result of general improvements in living conditions, but recent predictions show that 1.9 million individuals worldwide are blind or have significant vision problems as a result of trachoma. The WHO is implementing the SAFE strategy as part of a global initiative to eradicate blinding trachoma. The SAFE strategy includes early surgical intervention for trichiasis (contact between the eyelids and the eye that results in blindness), widespread use of antibiotics like azithromycin to manage infections, regular facial hygiene, and advancements in living conditions to minimize bacterial spread.

The World Health Organization divides trachoma into five stages, with Stages 1 and 2 characterized by trachomatous inflammation that is follicular (TF) or intense (TI), respectively; Stage 3 by trachomatous scarring (TS); Stage 4 by trachomatous trichiasis (TT); and Stage 5 by corneal opacity (CO), which results in visual impairment and blindness.

Antibacterial treatment is advised in the first two stages of trachoma's inflammatory phase (stages 1 and 2) and before scarring sets in, which is Stage 3 [37, 38]. The antibacterial drug of choice is oral azithromycin because it can be taken as a single dose, has a relatively long half-life, and is more concentrated in tissue than in plasma [39]. Adults and children are given a single oral dose of azithromycin at doses of 1 g and 20 mg/kg, respectively. In case of antibiotic failure, topical 1% tetracycline eye ointment, twice a day, for 6 weeks or erythromycin, 20 mg/kg (maximum 1 gr), orally, twice a day, for 14 days can be given. In stages 3 and 5, no treatment option exists but in Stage 4 surgical treatment is advocated for the protection of the cornea from abrasion.

Because trachoma is a major public health issue, the WHO recommends widespread administration of antibiotics in places with populations of 100,000–250,000 people and when the prevalence of the active trachoma, Stage 1 (TF), is greater than 5% in children aged 1–9 years. According to the most recent estimate of TF prevalence and until the percentage falls below 5%, it is advised that all inhabitants receive antibiotic therapy on an annual basis. It is also recommended that all inhabitants receive antibiotic medication annually up until the most current estimate of the prevalence of TF drops below 5% [40].

#### *3.1.1.2 Treatment of neonatal inclusion conjunctivitis*

Neonatal inclusion conjunctivitis is a preventable yet an undesired complication of active maternal chlamydial infection that affects newborns. Perinatal transmission of

#### *Treatment of Chlamydial Infections DOI: http://dx.doi.org/10.5772/intechopen.109648*

*C. trachomatis* to neonates during vaginal delivery occurs as high as 60% of the cases [41]. Though neonatal infection may retain an asymptomatic course, the infection is usually progressive and mostly affects the conjunctiva, nasopharynx, and lungs. Among infants presenting with conjunctivitis, the likelihood of neonatal-acquired inclusion conjunctivitis varies between 20 and 64% [41, 42]. Conjunctivitis that is left untreated can last for months and cause corneal and conjunctival scarring. Also, the disease may spread to the lungs and cause infantile pneumonia [41]. To prevent the systemic spread of the agent, all infants infected with *C. trachomatis* should receive treatment even if they are asymptomatic.

The neonatal inclusion conjunctivitis incubation period is generally 5–12 days after birth. Conjunctivitis in newborns younger than 30 days should be investigated for chlamydial infection, particularly if the mother has a past history of illness. Infection with ophthalmia neonatorum should also be considered and ocular samples should be examined for *Neisseria gonorrhoeae* [43].

Neonatal inclusion conjunctivitis is treated with oral erythromycin base or ethyl succinate, 50 mg/kg/day in four divided doses for 14 days. The alternative treatment is oral azithromycin 20 mg/kg/day for 3 days [44]. Both antimicrobials have been associated with infantile hypertrophic pyloric stenosis (IHPS) in infants less than 6 weeks of age; consequently, newborns medicated with any of these antimicrobials should be monitored for IHPS [45]. Compared to oral therapy, topical medication has been demonstrated to be ineffective in eliminating nasopharyngeal colonization and linked to persistent infection [46].

There is currently no effective prophylaxis for the prevention of newborn inclusion conjunctivitis, and neonatal gonococcal ophthalmia neonatorum prophylaxis does not offer protection against chlamydial conjunctivitis. Implementing health policies for routine antenatal testing and treatment of pregnant women at risk for chlamydia is advocated as a substitute, however, due to the financial burden of the strategy the screening programs cannot be utilized globally [47].
