Sexually Transmitted Diseases (STDs)

Haemophilus is a genus of Gram-negative coccobacilli, all of whose strains require at least 1 of 2 factors for growth (factor V [NAD] and factor X [heme]); therefore, it is most often isolated on chocolate agar, which can supply both factors. The most common pathogenic species is H. influenzae, which is transmitted through respiratory droplets and can cause epiglottitis, meningitis, otitis media, and pneumonia. H. ducreyi is transmitted through sexual contact and is the cause of chancroid, a type of genital ulcer.

Gonorrhea is a sexually transmitted infection (STI) caused by the gram-negative bacteria Neisseria gonorrhoeae (N. gonorrhoeae). Gonorrhea may be asymptomatic but commonly manifests as cervicitis or urethritis with less common presentations such as proctitis, conjunctivitis, or pharyngitis. Without antibiotic treatment, complications can occur. Complications for men may include epididymitis, prostatitis, balanitis, and periurethral abscess. Women may develop pelvic inflammatory disease, which can cause perihepatitis and fertility issues. Disseminated gonococcal infection is associated with fever, dermatitis, tenosynovitis, septic arthritis, and (rarely) endocarditis or meningitis. Gonorrhea diagnosis is made by microscopy, culture, or nucleic acid amplification tests. Management generally involves ceftriaxone, but treatment with doxycycline should be pursued if a coinfection with Chlamydia trachomatis (C. trachomatis) is not excluded.

Syphilis is a bacterial infection caused by the spirochete Treponema pallidum pallidum (T. p. pallidum), which is usually spread through sexual contact. Syphilis has 4 clinical stages: primary, secondary, latent, and tertiary. Primary syphilis begins with a chancre, a painless ulcer on the genitals. Progression to secondary syphilis manifests as a generalized maculopapular rash, which includes the palms and soles. The development of tertiary syphilis can cause severe neurologic (neurosyphilis), cardiovascular, and/or gummatous disease. The diagnosis is through both treponemal and nontreponemal testing. Penicillin G is the antibiotic of choice. The duration of management varies based on the stage of the disease.

Pelvic inflammatory disease (PID) is defined as a polymicrobial infection of the upper female reproductive system. The disease can affect the uterus, fallopian tubes, ovaries, and adjacent structures. Pelvic inflammatory disease is closely linked with sexually transmitted diseases, most commonly caused by Chlamydia trachomatis and Neisseria gonorrhoeae, as well as organisms associated with bacterial vaginosis, such as Gardnerella vaginalis. Common symptoms are lower abdominal pain, cervical discharge, and irregular vaginal bleeding. Complications of PID can include ectopic pregnancy, chronic pelvic pain, and infertility. Diagnosis is primarily clinical in addition to PCR testing of cervical specimens and sometimes imaging or laparoscopy. Due to its polymicrobial nature, PID treatment is with combination antibiotic regimens.

Treponema is a gram-negative, microaerophilic spirochete. Owing to its very thin structure, it is not easily seen on Gram stain, but can be visualized using dark-field microscopy. This spirochete contains endoflagella, which allow for a characteristic corkscrew movement. The bacteria are able to avoid immune recognition and phagocytosis by forming a protective coating with fibronectin. Humans are the only reservoir and transmission is through human-to-human contact. The most common species involved in human disease is Treponema pallidum subspecies pallidum, which is the causative agent of syphilis. Other clinically relevant species include T. pallidum pertenue, T. pallidum endemicum, and T. carateum. These are the causative organisms for yaws, bejel, and pinta, respectively.

Chlamydiae are obligate intracellular gram-negative bacteria. They lack a peptidoglycan layer and are best visualized using Giemsa stain. Chlamydiae species have a complex replication cycle consisting of 2 morphological forms: elementary bodies and reticulate bodies. The family of Chlamydiaceae comprises 3 pathogens that can infect humans: Chlamydia trachomatis, Chlamydia psittaci, and Chlamydia pneumoniae. Sometimes, C. psittaci and C. pneumoniae are classified as a separate genus, Chlamydophila. C. trachomatis is the most common bacterium responsible for causing sexually transmitted diseases in the United States and is associated with urogenital infections, lymphogranuloma venereum, neonatal conjunctivitis, and trachoma. C. psittaci causes psittacosis (parrot fever), whereas C. pneumoniae causes atypical pneumonia.

Herpes simplex virus infections are caused by either herpes simplex virus type 1 or 2. Type 1 viruses are more commonly associated with non-genital herpes, while type 2 viruses are more likely to be responsible for genital herpes diseases. The most common presenting sign is ulcers. While the healing process is usually excellent and subsequent scarring is very rare, topical and systemic antiviral therapy might be indicated to fasten the healing process, or prevent complications in the immunosuppressed.

Candidiasis is an opportunistic fungal infection that can affect the gastrointestinal tract, skin, or be systemic in immunocompromised patients. Clinical presentation is different from one patient to another and is dependent on the severity of immunosuppression and the anatomical site of the infection. Patients with candidiasis need topical antifungals for localized disease and systemic antifungals for esophagitis and systemic candidiasis. The important distinction between patients with neutropenia and without neutropenia can affect the choice of antifungals in systemic candidiasis.

In 1955, a cause of nonspecific vaginitis (bacterial vaginosis) was described by two scientists: Gardner and Dukes. The bug was named Haemophilus vaginalis, later the name was changed to Corynebacterium vaginale, and finally, the bacterium responsible for the condition obtained the name Gardnerella vaginalis (1980) after the scientist who discovered it. Gardnerella vaginosisis a non-specific infection of the vaginal tract caused by gram negative bacteria named as Gardnerella vaginalis. This condition is not regarded as sexually transmitted disease, but sexual activity enhances the development of the infection.

Abnormal looking cervix can be seen commonly in gynecology in day to day practice. It becomes necessary to differentiate between normal physiological changes brought by normal menstrual cycle from the anatomical and pathological disorders. Colposcopic examination of cervix with a stereoscopic binocular magnifying glasses is extremely helpful for identification of the possible etiology behind and exclusion of any cancerous growth to establish the diagnosis. The etiologic reasons of abnormal cervix can be physiological, infectious, abnormal growth and iatrogenic. This article provides a step-by-step approach to differentiating them.