Spirochetes Microbiology Unit 18 PDF

Microbiology Unit 18 Spirochetes Ve más allá 1 GENERAL FEATURES • Cylindrical • Helical • Thin and mobile: locomotion, flexion and rotation • Gram-negative, cell wall flexibility • Elements of mobility: axial filaments (periplasmic endoflagella) • Sometimes not visible at optical microscope (lo...

Microbiology Unit 18 Spirochetes Ve más allá 1 GENERAL FEATURES • Cylindrical • Helical • Thin and mobile: locomotion, flexion and rotation • Gram-negative, cell wall flexibility • Elements of mobility: axial filaments (periplasmic endoflagella) • Sometimes not visible at optical microscope (long but very narrow): darkfield microscopy or fluorescence microscopy required (marked with fluorochromes) • Resistant to rifampicin • Great host specificity GENERAL FEATURES Periplasmic flagella Cytoplasmic membrane Outer membrane Peptidoglycan CLASSIFICATION Spirochaetales Order Families Spirochaetaceae Leptospiraceae Extremities Not incurved Respiration Aerobe/anaerobe Aerobe Source of carbon Carbohydrates and Fatty acids and energy amino acids Genus Treponema Borrelia Incurved Leptospira GENERAL FEATURES Genera of clinical interest Treponema syphilis, yaws, pinta, bejel Borrelia relapsing fever, Lyme disease Leptospira leptospirosis Treponema  Long and thin bacteria that can not be seen with Gram stain. Fluorescence microscopy  Anaerobes  Some are microbiota of the mouth, intestines and genital tract Treponema Species of the commensal microbiota:  Strictly anaerobic  Cultured in vitro  Intestine, genitals and mouth (oral treponemes) Pathogenic:  Uncultivable  Mucous slime layer (virulence factor)  T. pallidum spp. pallidum: syphilis (worldwide distribution)  Other species: various tropical diseases. Oral Treponemes • Strict anaerobes • Many nutritional requirements • Usually difficult to culture • They can be divided according of how they obtain their energy, from amino acids or carbohydrates. Amino acids Carbohydrates T. denticola T. socranskii T. orale T. macrodentium T. vincentii Oral Treponemes Ecology • Deep areas of supragingival plaque and gingival sulcus (anaerobic conditions) • They need synergy with other bacteria in plaque (use compounds excreted by them) Oral Treponemes Virulence factors • Endotoxin • Mobility, ability to penetrate T. denticola: • In vitro: inhibition of PMN functionality • Decreased lymphocyte response:↓Ab • Trypsin-like enzyme that degrades gelatin Oral Treponemes Pathology • Related to periodontal disease. Probably secondary pathogens, almost opportunistic (to an already established periodontal disease) • Vincent's infection or trench mouth: acute necrotizing ulcer gingivitis (ANUG), necrotizing ulcerative process that affects the oral cavity and pharynx. Oral Treponemes Vincent's infection or trench mouth • Microbiology: Treponema vincentii, Fusobacterium, and other microorganisms (Selenomonas, Prevotella intermedia, other treponemes etc.) • Predisposing factors: States of stress, immunosuppression, malnutrition, poor oral hygiene, smoking, throat infections, teeth or mouth • Affects people: 15 to 35 years and immunosuppressed • Symptoms: crater-like ulcers between the teeth, unpleasant taste in the mouth, reddened and swollen gums, grayish film on the gums, gum pain, gum bleeding in response to any pressure or irritation Oral Treponemes Vincent's infection or trench mouth: Differential diagnosis: herpetic, gonococcal, syphilitic or non infectious gingivostomatitis. Treatment: • Chlorhexidine • In severe infections: metronidazole or penicillin • Remove necrotic tissue Prevention: • Good health, good nutrition, good oral hygiene including tooth brushing and flossing, learn ways to cope with stress, regular professional evaluation and dental cleaning, quit smoking. Oral Treponemes Oral treponemes: laboratory diagnosis • Subgingival plaque sample • Microscopy: darkfield, direct immunofluorescence • T. denticola: positive BANA test (unspecific): is used to determine the proteolytic activity of certain oral anaerobes that contribute to oral malodor. • Detection of:  DNA  Specific Ag (immunofluorescence with monoclonal Ab) • Difficult cultivation: in liquid media with specific nutrients for treponemes and antibiotics that kill other microorganisms. Oral Treponemes BANA test: Porphyromonas gingivalis Trypsin-like enzyme Bacteroides forcytus Treponema denticola Trypsin breaks down argininechromophore binding Arginine linked to a chromophore Colored reaction The release of the chromophore produce a color change Treponema pallidum Treponema pallidum spp. pallidum • Spirochete with 6-12 deep spires. • Not cultivable in vitro. • Not visible with conventional microscopy. • Very sensitive to desiccation or temperature changes. • Causative agent of syphilis • Transmission only by sexual contact or through the placenta to the fetus (congenital syphilis). • Worldwide distribution. Syphilis Sexually Transmitted Infection (STI) Transmission by direct contact of active lesions Exclusive to humans Compulsory notifiable disease Different stages of the disease: Early syphilis Late syphilis Treponema pallidum pallidum - SYPHILIS Early syphilis • Sexual Transmitted Disease (STD) • Cutaneous-mucosal lesions • If untreated, relapses • It is divided into 2 periods: primary syphilis and secondary syphilis. Primary syphilis: indurated and ulcerated lesion at the site of inoculation (chancre), regional lymphadenopathy. Disappears spontaneously within 4-6 weeks. Treponema pallidum pallidum - SYPHILIS Early syphilis Secondary syphilis: 2-12 weeks after the disappearance of the chancre. Treponemes pass to blood. Mucocutaneous lesions and flu-like syndrome. Disappears spontaneously, latent phase of 3-30 years.  Characteristic sign: exanthema with macular or maculopapular lesions on the trunk. Predilection for palms and soles where it can indurate (syphilitic cloves). May affect mucous membranes: oval plaques, raised edges. Disappears spontaneously after 2-12 weeks without treatment. Treponema pallidum pallidum - SYPHILIS Early syphilis Tertiary syphilis: Only in a few patients (1/3 of untreated) After 15 to 20 years. • Diffuse and chronic inflammation in organs and tissues. • Granulomatous lesions (gummas) in skin, bone and other tissues. • Cardiovascular syphilis • Neurosyphilis Treponema pallidum Oral Syphilis Possible manifestations of syphilis in the oral cavity Primary: chancre. Secondary: mucosal erosions Tertiary: gummas Treponema pallidum Congenital Syphilis • Transplacental transmission • Possibility of transmission between 40-70% • Intrauterine death • Congenital anomalies • Silent infection (may not be evident until 2 years) Treponema pallidum Diagnosis Direct: • Detection of treponemes in mucocutaneous lesions or chancre (dark-field microscopy, IFD assay with monoclonal Ab) • PCR Indirect: serology tests • Nonspecific or nontreponemal • Treponemal or specific Treponema pallidum Diagnosis Nonspecific or nontreponemal: • Measure of reagins, antibodies against a lipid complex released by cells in the early stage of the disease.  RPR (rapid plasma reagin)  VDRL (Venereal disease research laboratory test). • Positive in primary, secondary and latency Syphilis. • Negative in tertiary Syphilis and after effective treatment (treatment control). • False positives in other infectious or inflammatory diseases. Treponema pallidum Diagnosis Treponemal or specific • Detect antibodies (Ab) against specific T. pallidum-antigens (Ag). • To confirm a positive nontreponemal test. • Positive in primary, secondary, tertiary and latency Syphilis. • Also positive after effective treatment, not useful for treatment control. Treponema pallidum Treatment • Penicillin as early as possible. • Allergy to penicillin: doxycycline or chloramphenicol. • Serological screening of pregnant women to prevent congenital syphilis. THANKS FOR YOUR KIND ATTENTION