Microbial Diseases of the Reproductive System I, Summaries of Microbiology

Download Microbial Diseases of the Reproductive System I and more Summaries Microbiology in PDF only on Docsity! Reproductive System Infections II Mr. Mohamed Yusuf Abdi M.Sc. Medical Microbiology and Immunology Learning Objectives • Describe the clinical features of gonorrhea infection, including potential complications in untreated women. • Name the agent that causes syphilis and describe the clinical features of each infection • Outline the clinical features of chancroid and genital herpes. • Explain the clinical features of human papilloma viruses (HPVs). • Describe the Pap smear method and its clinical applications in preventive care • Describe the clinical features of chlamydia, including potential complications in untreated women. • Summarize the life cycle of Chlamydia trachomatis. • Describe the clinical and epidemiological features of lymphogranuloma venereum. Discharge Diseases • Discharge diseases are those in which the infectious agent causes an increase in fluid discharge in the male and female reproductive tracts. • Examples are trichomoniasis, gonorrhea, and chlamydia infection. • The causative agents are transferred to new hosts when the fluids in which they live contact the mucosal surfaces of the receiving partner. • In this section, we cover the two major discharge diseases: gonorrhea and chlamydia infection. Gonorrhea • Gonorrhea is a sexually transmitted disease involving infection of the epithelial cells that line the mucosa of the cervix and urethra. Etiology: • Neisseria gonorrhoeae (also known as gonococcus (singular), or gonococci (plural)), which is a gram-negative diplococcus that has flattened surfaces between the adjacent individual cocci (shaped similar to a kidney bean or a coffee bean). • Gonorrhea often co-existent with Chlamydia. Pathogenesis and Virulence Factors • Successful attachment is key to the organism’s ability to cause disease. • Following attachment, the gonococci rapidly multiply and spread through the cervix in women, and up the urethra in men. • The gonococci invade non-ciliated epithelial cells, which internalize the bacteria and allow them to multiply within intracellular vacuoles, protected from phagocytes and antibodies. • Also, the gonococci produces an IgA protease helps to protect them from the host’s secretory antibodies Signs and Symptoms • At least 50% of all infected women have only mild symptoms or are completely asymptomatic. A mucopurulent (containing mucus and pus) or bloody vaginal discharge occurs in about half of the cases, along with painful urination if the urethra is affected. • In 10–20% of untreated women, infection spreads up the genital tract to cause PID and damage to the fallopian tubes. • If the mother is infected with gonorrhea, the eyes of the infant can become infected as it passes through the birth canal. This condition, ophthabnia neonatorum, can result in blindness. Signs and Symptoms • Serious consequences of gonorrhea can occur outside of the reproductive tract. • About 5% of people with disseminated infection have deficiencies in the complement proteins [C5–C8]. • Rare complications of gonococcal bacteremia are meningitis and endocarditis. Diagnosis of Gonorrhea • The best method for diagnosis is a PCR test of secretions. • A gram stain of male secretions usually yields visible gonococci inside polymorphonuclear cells, but this procedure is not considered sensitive enough to rule out infection if no bacteria are found. • The gonococcus is very sensitive to adverse environmental influences and survives poorly outside the body. • Cultivation has the advantage of allowing determination of antibiotic sensitivity. Nongonococcal Urethritis (NGU) • Non-gonococcal urethritis (NGU), also known as nonspecific urethritis (NSU), refers to any inflammation of the urethra not caused by neisseria gonorrhoeae. Etiology: • Chlamydia trachomatis is the most frequent cause of NGU, but there are a number of other organisms that can cause the infection including ureaplasma urealyticum, mycoplasma genitalium, trichomonas vaginalis, gardnerella vaginalis, and HSV. Chlamydia • The chlamydiae are very small bacteria that are obligate intracellular pathogen. • They have a more complicated life cycle than free-living bacteria because they can exist in different forms: A. The elementary body (EB): is infectious but dormant extracellularly. B. The reticulate body (RB): is non-infectious but metabolically active for intracellular multiplication. • C.trachomatis serotypes D–K cause STDs FIGURE: Chlamydia trachomatis life cycle This bacterium is an obligate intracellular pathogen that cycles between an elementary body form and a reticulate body form. Signs and Symptoms • In men, the bacteria are a leading cause of nongonococcal urethritis. Recall that in men the urethra is part of the urinary and reproductive system, so this infection would affect both systems. In women the bacteria mainly target the cervix, but can spread to the uterus and fallopian tubes. • Chlamydia infections are often asymptomatic; about 50 percent of men and 75 percent of women are asymptomatic. When symptoms do develop they can differ between the sexes. • In men symptoms include dysuria, burning and itching around the opening of the penis, and swelling or pain in the testicles. There can also be a white, yellow, or green discharge from the penis. Signs and Symptoms • In women, symptoms may include bleeding/spotting between menstrual periods and/or after sex, dysuria, vaginal discharge with an odor, itching or burning around the vagina, pain during sexual intercourse, and pelvic pain that may be accompanied by fever. • However, in patients who do develop symptoms, chlamydia and gonorrhea are indistinguishable from each other based solely on signs and symptoms. • Therefore, it’s recommended that clinicians order tests for both when working up a patient diagnosis. Signs and Symptoms • However, the fact that most cases are asymptomatic means they go undetected and can lead to complications. For women, complications include pelvic inflammatory disease. • Women with an untreated infection can also transmit this bacterium to their newborn as the baby passes through the birth canal. This perinatal exposure, or exposure during delivery, may lead to bacterial conjunctivitis and/or neonatal pneumonia. • Male complications include chronic epididymitis (swelling of the epididymis), which can also cause infertility. Diagnosis • Direct fluorescent antibody detection is also used. • Serology is not always reliable. In addition, antibody to Chlamydia is very common in adults and often indicates past, not present infection. • Isolating the bacterium and growing it in cell culture is the best method for detecting this bacterium Treatment and Prevention • Patients with NGU can be treated with azithromycin or doxycycline. • All sexual partners should be examined for STIs and promptly treated to prevent recurrences of NGU. Genital Ulcers • Three common infectious conditions can result in lesions on a person’s genitals: I. Syphilis II. Chancroid III. Genital herpes • One very important fact to remember about the ulcer diseases increases the chances of infection with HIV because of the open lesions. Signs and Symptoms • Untreated syphilis is marked by distinct clinical stages designated as primary, secondary, and tertiary syphilis. • The disease also has latent periods of varying duration during which it is quiescent. • The spirochete appears in the lesions and blood during the primary and secondary stages and, thus, is transmissible at these times. • Syphilis is largely non transmissible during the “late latent” and tertiary stages. Primary Syphilis • The earliest indication of syphilis infection is the appearance of a small hard ulcer (chancre) at the site of entry of the pathogen. • The chancre is painless, and an exudate of serum forms in the centre. • This fluid is highly infectious, and examination with a darkfield microscope shows many spirochetes. • The chancre heals spontaneously without scarring in 3 to 6 weeks due to a strong cellular immune response. • Lymph nodes in affected region become enlarged and firm. Primary stage: Chancre appearing at the initial infection site Second stage: Disseminated rash Secondary Syphilis • Swollen lymph nodes, sore throat, patchy hair loss, fever, muscle aches, or malaise may also occur. Sometimes people don’t even notice these symptoms. • These symptoms usually disappear within 3 months and the pathogen enters a latent period that lasts for months to years before it launches the final, tertiary stage. Latent Period • During this period, the results of a serologic test are positive for syphilis in the absence of any clinical symptoms. • After 2 to 4 years of latency, the disease is not normally infectious, except for transmission from mother to fetus. • The majority of cases do not progress beyond the latent stage, even without treatment. • latent period can last for 20 years or longer. Congenital Syphilis • Congenital syphilis results when maternal syphilis is transmitted in utero to the fetus. Damage to mental development and other neurological symptoms are among the more serious consequences. • This type of infection is most common when pregnancy occurs during the latent period of the disease. • A pregnancy during the primary or secondary stage is likely to produce a stillbirth. Diagnosis of Syphilis • laboratory diagnosis hinges on microscopy and serology. Microscopy: • Microscopy are important for screening for primary syphilis because serological tests for this stage are not reliable. • Exudate from the primary chancre should be examined by either: Dark-feld microscopy immediately after collection Ultraviolet microscopy after staining with fluorescein-labelled anti-treponemal antibodies. • T.pallidum is very thin and cannot be seen in Gram-stained preparations. Diagnosis of Syphilis Serology: • At the secondary stage, when the spirochete has invaded almost all body organs, serological tests arc reactive. • They are divided into: A. Non-specifc tests (non-treponemal tests or regain tests): are used for screening and to determine treatment efficacy. B. Specifc tests (treponemal tests) are used to confirm a positive non- treponemal test. Table 22.5 Serological tests for syphilis and conditions associated with false-positive results Non-specific Viral infection, collagen vascular (non-treponemal) disease, acute febrile disease, VDRL postimmunization, pregnancy, RPR leprosy, malaria, drug misuse Specific Diseases associated with increased (non-treponemal) or abnormal globulins, lupus FTA-ABS erythematosus, Lyme disease, TP-PA autoimmune disease, diabetes TPHA mellitus, alcoholic cirrhosis, viral infections, drug misuse, and pregnancy FTA-ABS, fluorescent treponemal antibody absorption test; MHA-TR microhaemagglutination assay for 7 pallidum; RPR, rapid plasma reagin test; TPHA, TF. pallidum haemagglutination test; TP-PA, 7 pallidum particle agglutination test; VDRL, Venereal Disease Research Laboratory test. Specific Tests (Treponemal Tests) • Treponemal-type serological tests that react directly with the spirochete. • Treponemal-type tests are used for confirmatory testing. • Tests in common use include: I. The enzyme-linked immunosorbent assay (ELISA), which detects IgM and IgG. II. The fluorescent treponemal antibody absorption (FTA-ABS) III. The micro-haemagglutination assay for T. Pallidum (MHA-TP). Treatment • Penicillin is the drug of choice for treating people with syphilis and their contacts • For patients who are allergic to penicillin, treatment with doxycycline should be given. • Prevention of secondary and tertiary disease depends upon early diagnosis and adequate treatment. • Congenital syphilis is completely preventable if women are screened serologically early in pregnancy (<3 months) and those who are positive are treated with penicillin. Inguinal Lymphadenopathy • Genital infections are common causes of inguinal lymphadenopathy (swelling of lymph nodes in the groin) among sexually active people. • Syphilis and gonorrhoea have been discussed above. • Lymphogranuloma venereum, chancroid and donovanosis are more common in tropical and subtropical countries than in Europe and the USA but may be imported by travellers Inguinal Lymph Nodes Inguinal Lymphadenopathy Donovanosis • Donovanosis (granuloma inguinale or granuloma venereum) is rare in temperate climates, but common in tropical and subtropical regions. • The infection is characterized by nodules, almost always on the genitalia, which erode to form granulomatous ulcers that bleed readily on contact. • The pathogen is a gram-negative rod, previously called klebsiella granulomatis • Donovanosis is diagnosed by microscopy and treated with doxycycline Lymphogranuloma venereum • The tertiary stage can lead to severe destruction of the genitalia as tissues experience progressive edema (swelling) and permanent fibrosis (scarring). • Cell culture methods, immunofluorescence, or nucleic acid-based tests are used for diagnosis. • Treatment with doxycycline or erythromycin is recommended. Genital Herpes Genital Cold Sores • Genital herpes is a recurrent lifelong inflammatory viral disease of the male and female genital tracts. Aetiology: • Genital herpes is caused by herpes simplex virus type 2 (HSV-2). Also unprotected oral sex can transmit HSV-1 to the genital area. Manifestations: • The herpes virus enters epithelial cells after contact with an infected person’s lesions or genital fluid. Manifestations • It usually causes an initial, severe outbreak of ulcers as quickly as three days after transmission on the penis or vulva, that soon breakdown to form painful shallow ulcers. • The early appearance of the lesions is sometimes called “dewdrop on a rose petal,” describing the look of the clear pustule above a reddened base. • Local lymph nodes are swollen, and there may be constitutional symptoms including fever, headache and malaise. • Occasionally the lesions are on the urethra, causing dysuria or pain on micturition. First ae as small Blisters turn into soft wet ulcers. Herpes white blister Herpes nlrtie virus nyo New layer of skin begins to form, fewer virus copies Skin surface again normal, in sore but virus remains in body Virus migrati Fa to other parts of body Herpes appearance Genital herpes lesion Diagnosis and Treatment • Diagnosis of genital herpes can be done by culture of the virus taken from a vesicle; however, PCR testing of such samples has proven more sensitive and is potentially faster. If there are no lesions to be sampled, serological testing can identify HSV infections or confirm clinical diagnosis by symptoms. • Although the antiviral drug acyclovir can shorten outbreaks and suppress flare-ups to reduce the risk of transmission, there is not a cure for herpes. Genital Warts Causative agent: • Human papilloma viruses cause the most common STI in the world. • There are over 200 known subtypes of HPV; about 40 of them are sexually transmitted. • HPV types 6 and 11 are the most common types that cause genital warts. HPV-16 and HPV-18 are the most common causes of cervical and penile carcinoma, HPV causes about 90 percent of cervical cancers. Signs and Symptoms • The genital warts may also be painful, friable, and pruritic. • It may be present on skin, external genitalia, perineum, perianal, and intra-anal regions. • Those who cannot resolve the infection may experience outbreaks of genital warts and may have an increased risk of cancer. The sexually transmitted forms of HPV can cause anal and genital warts and some cause cancer—especially cervical, anal, vaginal, vulvar, penile, and oropharyngeal cancers (mouth/throat cancer). Diagnosis • Diagnosis of the cauliflower-like lesions of HPV is usually clinically determined. Diagnosis of genital warts can be confirmed by biopsy. • A Papanicolaou test, or “PAP” smear as it is often called, should be performed to determine if there is koilocytosis in the cells obtained from the cervix. • A definitive diagnosis of HPV infection is based on detection of viral nucleic acid or capsid protein in samples taken from the cervix or penis.