Spirochetes & Neisseria Lecture Notes PDF

LECTURE ON; SPIROCHETES AND NEISSERIA FOR; MD2 & BSCN 2  SPIROCHETES Introduction to Spirochetes Long, slender, helically tightly coiled bacteria Gram-negative Aerobic, microaerophilic or anaerobic. Corkscrew motility Can be free living...

LECTURE ON; SPIROCHETES AND NEISSERIA FOR; MD2 & BSCN 2  SPIROCHETES Introduction to Spirochetes Long, slender, helically tightly coiled bacteria Gram-negative Aerobic, microaerophilic or anaerobic. Corkscrew motility Can be free living or parasitic Best-known are those which cause disease: Syphilis and Lyme’s disease  Morphology Have axial filaments, which are otherwise similar to bacterial flagella Filaments enable movement of bacterium by rotating in place  Spirochaetales Associated Human Diseases Genus Species Disease Treponema pallidum ssp. pallidum Syphilis pallidum ssp. endemicum Bejel pallidum ssp. pertenue Yaws carateum Pinta Borrelia burgdorferi Lyme disease (borreliosis) recurrentis Epidemic relapsing fever Many species Endemic relapsing fever Leptospira interrogans Leptospirosis (Weil’s Disease)  GENUS TREPONEMA Regularly coiled with longer a wavelength than Leptospira. Several species and subspecies are important human pathogens, others are members of normal flora especially in the mouth. T.pallidum and its subspecies pertunue and T.caratenum are most important speccies. CHARACTERISTICS OF TREPONEMA Individual cell are too small to visualize by direct light microscopy, can be seen with dark ground (darkfield) illumination or silver impregnation or immunofluorescent. staining cells are actively motile by means of flagella contained within the periplasmic.  LABORATORY IDENTIFICATION T.pallidum and closely related species cannot be grown in artificial media; diagnosis of infections depends upon microscopic examination of fluid from primary lesions and serology DISEASES -T.pallidum;syphills. T.pertunue and T.caratenum the non sexually transmitted treponematoses; yaws and pinta respectively  TRANSMISION Very susceptible to heat and drying, so successful transmission depends upon very close contact. T.pallidum is spread by close sexual contact and may also be vertically transmitted in utero. Yaws and pinta spread by direct contact from infected skin lesions. No animal reservoir. PATHOGENESIS -Study of virulence factors hampered by the inability to grow T.pallidum in artificial culture media  Stages of Syphilis Primary Secondary Latent Tertiary Congenital Syphilis  Primary - Chancre Chancre is most frequently seen on the external genitalia – In women the lesions may form in the vagina or on the cervix. – In men it may be inside the urethra, resulting in a serous discharge. The lesion heals spontaneously after 1-5 weeks. Swab of chancre smeared on slide, examined under dark-field microscope, spirochetes will be present. Thirty percent become serologically positive one week after appearance of chancre, 90% positive after three weeks. Primary Syphilis - Chancre Primary Syphilis - Chancre Differences between chancre and chancroid This a chancroid caused by Haemophilus ducreyi or Streptobacillus Unlike chancre it’s painful and soft. Darkfield Microscopy Fluid From Chancre  Secondary Syphilis Occurs 6-8 weeks after initial chancre, becomes systemic, patient highly infectious. Characterized by localized or diffuse mucocutaneous lesions, often with generalized lymphadenopathy. Primary chancre may still be present. Secondary lesions subside in about 2-6 weeks. Serology tests nearly 100% positive.  Secondary Syphilis A widespread eruption resembling psoriasis or pityriasis rosea which prominently involves the hands should always include the differential diagnosis of secondary syphilis.  Secondary Syphilis Secondary syphilis lesions on back  Latent Syphilis Stage of infection in which organisms persist in the body of the infected person without causing symptoms or signs (asymptomatic). This stage may last for years. One-third of untreated latent stage individuals develop signs of tertiary syphilis. After four years it is rarely communicable sexually but can be passed from mother to fetus.  Latent Syphilis This stage may be further subdivided. – Early latent, initial infection occurred within previous 12 months. – Late latent, initial infection occurred greater than 12 months.  Tertiary Syphilis Divided into three manifestations: – Gummatous syphilis – Cardiovascular syphilis – Neurosyphilis  Tertiary Syphilis - Gummatous Gummas are localized areas of granulomatous inflammation found on bones, skin and subcutaneous tissue. Cutaneous gummas may be single or multiple, generally asymmetric and grouped together. Visceral lesions often cause local destruction of the affected organ. Contain lymphocytes, plasma cells and perivascular inflammation. Tertiary Syphilis Buboe of Neck Tertiary Syphilis Tertiary Syphilis - Gumma  Tertiary - Cardiovascular This condition appears 20 or more years post- infection. Usually involves the aorta. Invading treponemes cause scarring of the tunica media. Over many years, the inflammatory scarring weakens the aortic wall, leading to aneurysm formation, which causes incompetence of the aortic valve and narrowing of the coronary ostia.  Tertiary - Cardiovascular Antibiotic treatment cures the syphilis infection and stops the progress of cardiovascular syphilis. The damage that has already occurred may not be reversed.  Neurosyphilis Caused by invasion of organisms into the CNS. Manifests as an insidious but progressive loss of mental and physical functions and is accompanied by mood alterations. General paresis of the insane: – forgetful, – personality change, – psychiatric symptoms. Onset usually 10-20 years after primary infection. Treatment may not improve symptoms.  Neurosyphilis Neurological complications at this stage include generalized paresis of the insane which results in personality changes, changes in emotional affect, hyperactive reflexes. Tabes dorsalis, degeneration of lower spinal cord, general paresis and chronic progressive dementia often results in a characteristic shuffling gait. Can only be diagnosed serologically by VDRL.  Neurosyphilis Cerebral atrophy, most prominent in frontal lobes seen in general paresis.  Congenital Syphilis Transmitted from mother to fetus. Fetus affected during second or third trimester. Forty percent result in syphilitic stillbirth-fetal death that occurs after a 20 week gestation and the mother had untreated or inadequately treated syphilis at delivery.  Congenital Syphilis According to the CDC, 40% of births to syphilitic mothers are stillborn. 40-70% of the survivors will be infected, and 12% of these will subsequently die prematurely Death from congenital syphilis is usually through pulmonary hemorrhage.  Congenital Syphilis Bone deformities Blindness Deafness Deformed faces Dental deformities Skin rashes Neonatal death  Congenital Syphilis Live-born infants show no signs during first few weeks. – Sixty to 90 % develop clear or hemorrhagic rhinitis. – skin eruptions (rash) especially around mouth, palms of hands and soles of feet.  Congenital Syphilis Early onset syphilis manifests at birth or months after, exhibiting a diffuse infiltration, scabs and fissuring along the periphery of the mouth, which leave sulci in a radiated pattern or rhagades  Congenital Syphilis clear or hemorrhagic rhinitis  Congenital Syphilis Skin eruptions (rash) especially around mouth, palms of hands and soles of feet  Congenital Syphilis Hutchinson’s incisors.  Diagnosis of Syphilis Evaluation based on three factors: – Clinical findings. – Demonstration of spirochetes in clinical specimen. – Present of antibodies in blood or cerebrospinal fluid. More than one test should be performed. No serological test can distinguish between other treponemal infections.  Laboratory Testing Direct examination of clinical specimen by dark-field microscopy or fluorescent antibody testing of sample. Non-specific or non-treponemal serological test to detect reagin, utilized as screening test only. Specific Treponemal antibody tests are used as a confirmatory test for a positive reagin test.  Nontreponemal Reagin Tests Non-specific or non-treponemal serological test to detect reagin, utilized as screening test only. – Reagin is an antibody formed against cardiolipin. – Found in sera of patients with syphilis as well as other diseases. – This type of reagin not to be confused with same word originally used to describe IgE. – Non treponemal tests become positive 1 to 4 weeks after appearance of primary chancre. – in secondary stage may have false negative due to Prozone, in tertiary 25% are negative, after successful treatment will become nonreactive after 1 to 2 years.  Nontreponemal Reagin Tests VDRL RPR USR-unheated serum reagin test RST-reagin screen test ELISA  TREATMENT AND PREVENTION Penicillin is the treatment of choice of Syphills. Tetracycline may be given to penicillin allergic patients. PREVENTION Depends upon detection and treatment of cases, contact tracing and serological testing of pregnant women. Possible cross reaction between T.pallidum and the species causing yaws and pinta must be noted  GENUS BORRELIA Two species of Borrelia are important in humans B.burgorferia cause Lyme disease; B.recurrentis causes relapsing fever. CHARACTERISTICS Less finely coiled than the leptospires. Cell 0.2-0.5macro meter in diameter; stain readily so are visible by using light microscopy  LABORATORY IDENTIFICATION Microaerophilic, complex nutritional requirements, long growth time (weeks) thus culture is not routinely used for identification B.recurrentis demonstrated in blood smear by staining Giemsa or acridine orange. B.burgdorferi much more difficult to visualize culture from biopsy material, possible but difficult diagnosis usually by serology.  DISEASES In relapsing fever the relapsing element may be due to antigen switching. Lyme disease slowly progressive rather than relapsing. Characteristic ‘’bulls eyes’’ skin lesion (erythema chronicum migrans) commonly occurs. Joint pains and fatigue common and latter in untreated cases, neurologic and cardiac manifestations. Erythema chronicum migrans of Lyme Borreliosis  TRANSMISSION B.recurrentis spread from person to person by Lice. Lyme is a zoonosis transmitted to human by hard ticks (lxodes spp). Ticks bite is often unnoticed but less than a minute is required for the organism to enter the host. PATHOGENESIS -Little known about pathogenesis of either disease Antigen switching in B.recurrentis presumably allows evasion of host’s antibody response. TREATMENT AND PREVENTION -Doxycycline, but erythromycin and penicillin have both been used successfully. PREVENTION -Prevention depends upon avoiding contact with vectors.  GENUS LEPTOSPIRA Two species L.interrogans and L.biflexa the former is parasitic the latter contains free living species. Within the species interrogans there are several different serogroups and severals responsible for disease in humans and animals. Leptospira interrogans. Characteristics -Finely coiled spirochetes with hooked ends. Cells 0.1- 0.2macro metre in diameter, up to 20 macro metre in length. -Not visible by direct light microscopy unless stained by silver impregnation or immunofluorescent methods. Dark ground (darkfield) microscopy reveals rotational and directional motility by means of periplasmic flagella.  LABORATORY IDENTIFICATION Direct microscopy of blood and urine possible, but difficult to interpret Leptospira can be grown, with difficulty in special serum containing media. Serologic is usual DISEASE They cause Leptospirosis or Weil’s disease in human and animal. Silver Stain of Leptospira interrogans serotype icterohaemorrhagiae  Obligate aerobes  Characteristic hooked ends (like a question mark, thus the species epithet – interrogans)  TRANSIMISSION Leptospirosis in human is a zoonosis, usual hosts being rodents, bats, cattle, sheep, goats and other domestic animals. Leptospirosis excreted in urine contaminate food and water. Infection occurs by contact. PATHOGENISIS After initial invasion there is hematogenous spread before the organism localized in various organs including the liver and kidney. Subclinical infection is common in endemic areas.  TREATMENT AND PREVENTION Penicillin, doxycycline in penicillin-allergic patients. Disease may be prevented after exposure by doxy cycling. ‘’END FOR SPIROCHETES’’ NEISSERIA  GENUS NEISSERIA This genus contains several or less fastidious species of which two N.meningitidis and N.gonorrhoeae, are important human pathogens. CHARACTERISTICS OF NEISSERIA - They are non-motile Gram negative diplococci with fastidious growth requirement -They are capnophilic (ability to thrive in conjuction with CO2). -N.mengitidis is capsulate while N.gonorrhoeae is not. The capsule is an important pathogenesis factor allowing inhibition of phagocytosis. Neisseria associated diseases  LABORATORY IDENTIFICATION Gram stain of pus or cerebrospinal fluid may reveal Gram negative kidney shaped diplococci, often intracellular (in polymorphs) Require supplemented media for growth(chocolate agar),N.gonorrhoeae easier to isolate on the media containing antibiotics to inhibit other organism of normal flora from sample sites. The two species are differentiated by sugar utilization pattern. kits available to detect N.gonorrhoeae nucleic acid in the specimens. Latex agglutination test for N.meningitidis type A and C.  Disease due to N.gonorrhoeae Gonorrhea is an infection caused by a sexually transmitted bacterium that infects both males and females. Gonorrhea most often affects the urethra, rectum or throat. In females, gonorrhea can also infect the cervix. Gonorrhea is most commonly spread during vaginal, oral or anal sex. But babies of infected mothers can be infected during childbirth. In babies, gonorrhea most commonly affects the eyes.  Symptoms in male Frequent Urination A pus-like discharge from the penis Swelling or redness at the opening of the penis Swelling or pain in the testicles A persistent sore throat  Symptoms in female Discharge from the vagina Pain or burning sensation while urinating Tendency to urinate frequently Heavier periods or spotting Pain during sexual intercourse Sharp pain in the lower abdomen Sore throat Fever Disease due to N.gonorrhoeae  Complications If untreated, it may lead to complications such as: Pelvic inflammatory disease (PID): It can cause severe damage to female reproductive organs. Blockage or scarring of the fallopian tube can occur, which can affect future pregnancy. Scarring in the urethra may be present for men. Painful abscess may develop in the interior of penis. Newborn may get the infection during delivery. Fertilization of egg outside the uterus may occur which would result in ectopic pregnancy. Gonorrhea can also affect your mouth and throat Symptoms may include: sore throat redness in the throat fever swollen lymph nodes in the neck  Identification cont.. -Neisseria is usually isolated on Thayer Martin agar (VPN agar) an agar plate contain antibiotics (vancomycin, colistin, nystatin and TMP-SM) and nutrients that facilitate the growth of Neisseria species while inhibiting the growth of containing bacteria and fungus. -Further testing to differentiate the species include testing for oxidase (clinically all relevant Neisseria show a positive reaction) -Carbohydrate maltose, sucrose and glucose test in which N.gonorrhoeae will only oxidise /utilize the glucose.  TREATMENT AND PREVENTION N.gonnorhoeae resistance to the first line drugs wide spread usual choice is beta-lactamase-stable cephalosporin (cetriaxone). N.mengitidis; penicillin or cetrixone (or equivalent cephalosporin); can be combined with Chloramphenicol. PREVENTION -Prevention of gonorrhoeae requires education;contact tracing.No vaccine available -Rifampicin is used for prophylaxis/prevention of close contact of N.meningitidis. Tetravalent vaccine availble.  Thank you for your participation