**1. Introduction**

#### **1.1 A brief introduction**

The most common cause of sexually transmitted genital infections is *Chlamydia trachomatis* [1]. Almost all the affected individuals are asymptomatic, thus providing an ongoing reservoir of infection. Conjunctivitis and pneumonia can occur in infants born through an infected birth canal. The rectum and conjunctivae are common epithelial sites where males and females can develop clinical syndromes due to infection. There is an incubation period of 5–15 days following infection before symptomatic disease develops. The infection may remain active in asymptomatic individuals for an indefinite period before they become symptomatic.

Among 10 studies of untreated, uncomplicated genital chlamydial infections, 56–89% detected the presence of chlamydia over the short term (weeks to months after diagnosis), and 46–57% detected the presence of chlamydia over the long term [2]. There is, however, a lack of documentation of the date of infection or evaluation of whether the infection was persistent or recurrent. This limits our understanding of the duration of untreated chlamydial infections. According to subsequent modeling

studies, chlamydial infections are less likely to establish. In contrast, once established, the disease progresses slowly and more slowly in males than in females (mean undetected durations of 2.84 and 1.35 years, respectively, in males and females [3, 4]. The treatment of all patients with Chlamydia is recommended, despite the possibility of spontaneous resolution.

#### **1.2 A clinical analysis of female syndromes**

The majority of females who are infected with *C. trachomatis* are asymptomatic, but the pathogen is a significant contributor to several clinical syndromes that are common among women.

#### *1.2.1 Genitourinary tract infection*

Females are at high risk of cervix infections [5], and a significant proportion may also have urethral infections. When left untreated, cervical cavity infections may progress into the upper genital tract, resulting in pelvic inflammatory disease, infertility, and chronic pain. Pregnant women with genital chlamydial infections are also at risk for complications.

An increased risk of chlamydial infection has been associated with cervical ectropion (columnar epithelium on the outer surface of the cervix in addition to the endocervical canal). Furthermore, some studies have linked cervical neoplasia to the infection [6, 7], but the extent of this effect remains unknown.

### *1.2.2 Cervicitis*

In most cases (at least 85%) of females with cervicitis, no symptoms are observed, which is why young, sexually active females should undergo routine annual screenings. There was only 6–14% of females who developed a new infection within a year of testing who had symptoms of genital chlamydial infection in four out of five sites in a multinational study that looked at women at high risk for genital chlamydial infection using polymerase chain reaction testing of vaginal swabs [8]. Some of the symptoms that can be confused with vaginitis or genital tract pathology are a change in vaginal discharge, intermenstrual vaginal bleeding, and post-coital bleeding. These symptoms can present in many ways, such as an increase in release, a change in color or odor, an increase in itching or burning, or an increase in pain or discomfort during intercourse. The discharge may also have an abnormally high pH, indicative of an infection. Abnormal exam findings are found in approximately 10–20% of females with genital chlamydial infection. When signs of cervicitis are present, they include mucopurulent discharge from the endocervical cavity, easily induced bleeding from the endocervical cavity, and edematous ectopy.

It has been observed that some of these females report symptoms of urinary tract infections, such as frequency and dysuria, but they do not report symptoms specific to the urethra. If not subjected to specific tests for C trachomatis, these females may be mistaken for cystitis [9, 10]. Despite pyuria in the urine analysis, no organisms are detected in the Gram stain or bacterial culture. Therefore, it is reasonable to suspect that sexually active females with pyuria and no bacteriuria may have a chlamydial infection of the urethra based on the combination of symptoms described above.

As a result of these conditions, several possible diagnoses are available, including low-colony urinary tract infections (such as *Staphylococcus saprophyticus*), which cannot be confirmed by culture or detected by urinalysis, or urethritis caused by another STI, such as *Neisseria gonorrhoeae*, Trichomonas vaginalis, or herpes simplex.

#### *1.2.3 Pelvic inflammatory disease*

As a result of C trachomatis ascending to the upper reproductive tract (uterus, fallopian tubes, and ovaries), pelvic inflammatory disease (PID) can develop [16–20]. The prevalence of clinical PID in females presenting to STI clinics ranged from 2 to 4.5% between the diagnosis of chlamydia infection and the follow-up visit [2]. Following the administration of ineffective antibiotics against Chlamydia, a small study of 20 females with *N. gonorrhoea* and *C. trachomatis* coinfection reported a 30% incidence of PID [11]. As a result, no cases of clinical PID have been reported in studies of females at low risk of exposure to chlamydia after a year without treatment. As many cases of PID do not cause symptoms and are only detected later in cases of tubal infertility, these studies may underestimate the incidence of PID in chlamydial infection.

Most commonly, abdominal and pelvic pain is present with symptoms of PID. Infection with chlamydia in conjunction with cervicitis should raise a significant suspicion that the upper genital tract is involved. PID is characterized by cervical motion and tenderness in the uterus or adnexa. PID caused by C trachomatis is associated with a higher rate of subsequent tubal infertility, ectopic pregnancy, and chronic pelvic pain as compared with PID caused by gonorrhea, which typically presents in an acute manner [12].
