Bacterial Infections of the Genital Tract Lecture 6 PDF

Diagnostic Microbiology Lecture 6 Bacterial Infection of the Genital tract Bacterial Infections of the Genital Tract Sexually transmitted infections (STI) also referred to as sexually transmitted diseases (STD) and venereal diseases (VD), most...

Diagnostic Microbiology Lecture 6 Bacterial Infection of the Genital tract Bacterial Infections of the Genital Tract Sexually transmitted infections (STI) also referred to as sexually transmitted diseases (STD) and venereal diseases (VD), most of which are initially do not cause symptoms. Symptoms and signs of disease may include vaginal discharge, penile discharge, ulcers on or around the genitals, and pelvic pain. Some STIs may cause problems with the ability to get pregnant. More than 30 different bacteria, viruses, and parasites can cause STIs. Bacterial STIs include: - Chlamydia trachomatis - Neisseria gonorrhoeae - Klebsiella granulomatis - Mycoplasma genitalium; - Mycoplasma hominis - Treponema pallidum - Ureaplasma infection While usually spread by sex, some STIs could also spread by non-sexual contact with contaminated blood and tissues, breastfeeding, or during childbirth. Neisseria The genus Neisseria consists of gram-negative aerobic cocci. Two Neisseria species are pathogenic for human Neisseria gonorrhoeae (commonly called gonococcus), the causal agent of gonorrhea and Neisseria meningitidis (commonly called Meningococcus), a frequent cause of meningitis. Gonococci and meningococci are non-motile diplococci that could not distinguish from each other under the microscope. However, they could differentiate in the laboratory by sugar-use patterns, and the site of their primary infections. Both bacteria have classified as pyogenic cocci because infections by these organisms have also characterized by the production of purulent (pus like) material comprised largely of white blood cells. Neisseria gonorrhoeae Gonorrhea is one of the most frequently reported infectious diseases. The causal agent, N. gonorrhoeae, a gram-negative diplococcus, has frequently observed within the polymorphonuclear leukocytes of clinical samples obtained from infected patients. N. gonorrhoeae has usually transmitted during sexual contact or, more rarely, during the passage of a baby through an infected birth canal. It does not survive long outside the human body because it is highly sensitive to dehydration. 1 Diagnostic Microbiology Lecture 6 Bacterial Infection of the Genital tract Laboratory identification: In the male, the finding of numerous neutrophils containing gram-negative diplococci in a smear of urethral exudate permits a temporary diagnosis of gonococcal infection and indicates that the individual should treated. In contrast, a positive culture has needed to diagnosis gonococcal infection in the female as well as at sites other than the urethra in the male. 1-Growth conditions for culture: N. gonorrhoeae grows best under aerobic conditions, and most strains require enhanced CO2. N. gonorrhoeae utilizes glucose as a carbon and energy source but not maltose, lactose, or sucrose. While Neisseria meningitidis utilizes both glucose and maltose. All members of the genus are oxidase-positive, that used to identify Neisseria. 2-Selective media: Gonococci, like pneumococci, are very sensitive to heating or drying. Cultures might have plated quickly or, if not possible, transport media might use to extend viability of the organism to be cultured. Thayer-martin medium (chocolate agar supplemented with antibiotics that inhibit growth of nonpathogenic Neisseriae and other normal flora) has typically used to isolate gonococci. On nonselective media, the normal flora overgrows the gonococci. Culture of N. gonorrhoeae on Thayer-martin agar remains the "gold standard" for diagnosis. Chlamydia is a sexually transmitted infection caused by the bacterium Chlamydia trachomatis. In women, symptoms may include abnormal vaginal discharge, burning during urination, and bleeding in between periods, although most women do not involvement any symptoms. Symptoms in men include pain when urinating, and abnormal discharge from their penis. If left untreated in both men & women, Chlamydia can infect the urinary tract and potentially lead to pelvic inflammatory disease (PID). However, Chlamydia could be treated with antibiotics. Chlamydia trachomatis Chlamydia trachomatis has divided into a number of serotypes, which correlate with the clinical syndrome they cause Chlamydia trachomatis, the major causal agent of sexual transmitted diseases, which is currently the most common reportable infectious disease in the world. In addition, Chlamydia trachomatis could cause eye infections, with symptoms ranging from irritation to blindness. Laboratory identification Chlamydia trachomatis could have demonstrated in clinical material by several direct procedures and by culturing in human cell lines (tissue culture). Samples, particularly from the urethra and cervix in urogenital tract infection and conjunctivae in ocular disease, should obtained by cleaning away overlying exudate and gently scraping to collect infected epithelial cells. 2 Diagnostic Microbiology Lecture 6 Bacterial Infection of the Genital tract 1-Direct tests: Microscopic examination using direct fluorescent antibody staining reveals characteristic cellular cytoplasmic inclusions. Chlamydia trachomatis infections could have detected with high sensitivity and specificity using DNA amplification performed on urine specimens. 2-Culturing methods: Chlamydia trachomatis could have cultivated by tissue culture in human cell lines. The presence of Chlamydial inclusions could have demonstrated after 2 to 7 days of infection. 3-Detection of serotypes: Serotypes of Chlamydia trachomatis could determine by immunofluorescence staining with antibodies. However, the procedure is not widely used because it enhances little of clinical effects. Serological testing for specific antibodies is similarly not helpful except in suspected lymphogranuloma venereum (LGV), in which a single high-titer response is diagnostic. Syphilis is a sexually transmitted infection caused by the bacterium Treponema pallidum subspecies pallidum. The signs and symptoms of syphilis vary depending in which of the four stages it presents (primary, secondary, latent, and tertiary). The primary stage classically presents with a single chancre (painless ulcer). In secondary syphilis a diffuse rash occurs, which frequently involves the palms of the hands and soles of the feet. In latent syphilis, which can last for years, there are little to no symptoms. In tertiary syphilis there are gummas (soft non-cancerous growths), neurological, or heart symptoms. Syphilis has most commonly spread through sexual activity. It has also transmitted from mother to baby during pregnancy or at birth, resulting in congenital syphilis. Diagnosis has usually made by using blood tests, the bacteria can also be detected using dark field microscopy. Treponema pallidum Treponema pallidum subspecies pallidum is a spiral-shaped, Gram-negative, highly movable bacterium. Humans are the only known natural reservoir for subspecies pallidum. It is to survive without a host for more than a few days. Laboratory identification: Syphilis is difficult to diagnose clinically early in its presentation. Confirmation is via either blood tests or direct visual inspection using microscopy. Blood tests have more commonly used, as they are easier to perform. Diagnostic tests are unable to distinguish between the stages of the disease. Definitive diagnosis of syphilis has complicated by the inability to cultivate Treponema pallidum subspecies pallidum in vitro. Clinical manifestations, demonstration of treponemes in lesion material, and serologic reactions have used for diagnosis. If manifestation include one or more cutaneous exudative lesions, 3 Diagnostic Microbiology Lecture 6 Bacterial Infection of the Genital tract motile treponemes could visualized within lesion exudate by dark-field. Treponema pallidum subspecies pallidum is a fastidious organism that exhibits narrow optimal ranges of pH (7.2 to 7.4) and temperature (30 to 37°C). It is rapidly inactivated by mild heat, cold, desiccation, and most disinfectants. Traditionally this organism had considered a strict anaerobe, but it is now known to be microaerophilic. The in vivo generation time is relatively long (30 hours). Treponema pallidum subspecies pallidum had not successfully cultured in vitro. Viable organisms can be maintained for (18 to 21) days in complex media, while limited replication has been obtained by co-cultivation with tissue culture cells. Bacterial causative agent's diseases of genital tract which are genital tract infection manifests as either genital discharge or genital ulceration with or without inguinal lymphadenitis such as: 1- Neisseria gonorrhea: Gonorrhea 2- Chlamydia trachomatis: Urethritis, cervicitis, LGV 3- Ureaplasma urealyticum: Urethritis 4- Gardenella vaginalis: Vaginitis 5- Treponema pallidum: Syphilis Blood tests Blood tests have divided into non-treponemal and treponemal tests. Because of the possibility of false positives with non-treponemal tests, confirmation is required with a treponemal test, such as treponemal pallidum particle agglutination (TPHA) or fluorescent treponemal antibody absorption test (FTA-Abs). Treponemal antibody tests usually become positive two to five weeks after the initial infection. Neurosyphilis is diagnosed by finding high numbers of leukocytes (predominately lymphocytes) and high protein levels in the cerebrospinal fluid (CSF) in the setting of a known syphilis infection. Direct testing Dark ground microscopy of serous fluid from a chancre (painless ulcer) may be used to make an immediate diagnosis. Sensitivity has reported to be nearly 80%; therefore, the test can only use to confirm a diagnosis. Two other tests can carried out on a sample from the chancre: direct fluorescent antibody testing and nucleic acid amplification tests. Direct fluorescent testing uses antibodies tagged with fluorescein, which attach to specific syphilis proteins, while nucleic acid amplification uses techniques, such as the PCR, to detect the presence of specific syphilis genes. These tests are not as time-sensitive, as they do not require living bacteria to make the diagnosis. 4