MIC305 Spirochetes, Acid Fast Bacteria, Atypical Bacteria PDF

1 Spirochetes Acid Fast Bacteria Atypical Bacteria Asst.Prof.Dr. Acharawan Thongmee; October 17-18, 2024; MIC305  2 Spirochetes Treponema Leptospira Borrelia  3 3...

1 Spirochetes Acid Fast Bacteria Atypical Bacteria Asst.Prof.Dr. Acharawan Thongmee; October 17-18, 2024; MIC305  2 Spirochetes Treponema Leptospira Borrelia  3 3 3 Spirochetes  Long, slender, helically shaped cells  Actively motile by means of flagella-like filaments called axial filaments.  Gram negative (Gram stain is rarely used to identify spirochetes.)  best recognized by dark field microscopy  4 Spirochetes  Three genera are human pathogens:  Treponema  causes syphilis, bejel, yaws, pinta and, in the oral cavity, acute necrotizing ulcerative gingivitis (together with fusobacteria)  Leptospira  causes leptospirosis  Borrelia  causes relapsing fever and Lyme disease  5 Treponema Treponema pallidum  Tryponema live in the oral cavity, intestinal tract, and perigenital regions of humans and animals  Pathogens are strict parasites with complex growth requirements  Extremely fastidious and sensitive; cannot survive long outside of the host  Require live cells for cultivation  Sexually transmitted and transplacental 5 Syphilis  6 Syphilis  Primary syphilis – appearance of hard chancre at site of inoculation; chancre heals spontaneously  Secondary syphilis – fever, headache, sore throat, red or brown rash on skin, palms, and soles; rash disappears spontaneously Spirochete appears in lesions and blood during primary and secondary stages – communicable Primary syphilis lesion, chancre Symptom of secondary syphilis 6  7 Syphilis Latent stage  The infection remains dormant (latent)  Usually 2 years  Without any clinical symptoms (asymptomatic) but with positive serology  Tertiary syphilis – about 30% of infections enter in tertiary stage; can last for 20 years or longer; numerous pathologic complications occur in susceptible tissues and organs  Neural, cardiovascular symptoms, 7  8 Spirochetes Syphilis  Congenital syphilis  skin eruptions, bone deformation, nervous system abnormalities Congenital syphilis 8  9 Syphilis: Diagnosis –symptoms, history, –T. pallidum cannot be cultured. Microscopic examination –Dark-field microscopic identification of bacteria –Staining with fluorescent-labeled, monoclonal antibodies 9  10 Syphilis: Diagnosis Serological diagnosis  Nontreponemal tests  measure anti-treponemal antibody using a cross reactive cardiolipin as an antigen rather than the actual bacterial antigens.  VDRL (Venereal Disease Research Laboratories)  RPR (Rapid Plasma Reagin)  Treponemal antigen tests  rely upon antigens derived directly from T. pallidum.  TPHA : Treponema pallidum hemagglutination assay  FTA-ABS or fluorescent treponemal 10 antibody-absorption test  11 Leptospira  Leptospira interrogans and Leptospira biflexa are the recognized species  Leptospira are found in damp environments such as still water and wet soil.  The kidneys of some rodents and domestic animals act as a reservoir for L. interrogans.  The urine of these animals serves as a vehicle of transmission of human leptospirosis.  The symptoms of leptospirosis are vary from mild febrile illness to fatal attacks of jaundice and renal failure.  12 Leptospira Transmission  infected urine rodents - Bacteria multiply in proximal convoluted farm animals tubules of kidney, shed in urine - infected urine --means of transmission  water - humans recovering from leptospirosis shed organisms for days to weeks  through broken skin. - domestic animals, rodents may shed  Incubation period for life  Average 10 days (4-20 days) 12  13 Leptospira : Leptospirosis symptoms - flu-like - severe systemic disease * kidney brain Liver : hepatitis, jaundice Eye: red eye Leptospira interrogans  14 Leptospirosis : Diagnosos  Dark-field microscopy  serology  most readily culturable of spirochetes – culture still extremely difficult  Blood specimen (1st week) --> aseptic meningitis, hepatitis, jaundice and hemorrhage in liver  Uremia and bacteriuria in kidney  Urine specimen (2nd and 3rd week) 14  15 Borrelia  Borrelia burgdorferi  Found in ticks and small mammals, particularly deer. Transmission is by a tick vector.  The agent of Lyme disease, a generalized infection with neurological and cardiac manifestations and arthritis. bull's eye rash  16 17 Borrelia  17 Acid Fast Bacteria Mycobacterium  18 Mycobacterium Acid fast bacilli [AFB] Thick, lipid-rich, waxy cell wall Mycobacterium tuberculosis Mycobacterium leprae Mycobacterium avium-intracellulaire complex (MAC) or (M. avium)  19 Lipid-Rich Cell Wall of Mycobacterium Mycolic acids Unusual cell wall lipids (mycolic acids,etc.) (Purified Protein Derivative) 19  20 Mycobacterial Clinical Syndromes 20  21 Mycobacterium tuberculosis  Facultative intracellular pathogen  survive within unactivated macrophage  uses phagocytic vacuole for survival and replication  prevents fusion of phagosome with lysosome  22 Mycobacterium tuberculosis Tuberculosis (TB)  Tuberculosis is a chronic granuloma, chronic inflammation lesion with many types of cells  Usually affects lung, but many other organs may be affected.  Incidence is increasing due to emergence of AIDS cases.  Immune response is cell-mediated immunity.  23 How Is Tuberculosis (TB) Transmitted?  Person-to-person through the air by a person with TB disease of the lungs Source: CDC, 2000  24 24 24 Progression of Tuberculosis M. tuberculosis can survive within unactivated macrophages Activated macrophages can kill the bacteria Individual’s immunological response determines the outcome of exposure Healthy individual exposed to low dose activated macrophages stop infection Individuals unable to mount a rapid response bacteria multiply in lung macrophages phagocytes attracted to site of infection  25 225 26 Mycobacterium tuberculosis Progression of Tuberculosis Bacteria in tubercles may survive for decades (latency) Suppression of immune system may allow bacteria to break out of lesions and multiply (reactivation) Old age, cancer, immunosuppressive drugs and HIV infection can lead to reactivation  26 Typical Progression of Pulmonary Tuberculosis  Granuloma formation with fibrosis  Caseous necrosis Tissue becomes dry & amorphous (resembling cheese) Mixture of protein & fat (assimilated very slowly)  Calcification Ca++ salts deposited 26  27 Mycobacterium tuberculosis  Primary infection / not all bacilli died some remain dormant  Few cases  disseminate  meninges, bone, joint, kidney (Miliary Tuberculosis) Post-Primary Tuberculosis  Reactivation or Reinfection  Same granulomatous reaction but more tissue necrosis  Bacilli gain access to sputum  28 Spread of TB to Other Parts of the Body 1. Lungs (85% all cases) 2. Central nervous system (e.g., brain, meninges) 3. Lymph nodes 4. Genitourinary system 5. Bones and joints 6. Disseminated (e.g., miliary) 28  29 Clinical Symptoms of Tuberculosis  severe weight loss  night sweats  chronic cough (often with blood)  Fever  malaise (loss of energy)  progressive lung damage  30 Laboratory Diagnosis Eight Week Growth of Mycobacterium tuberculosis on Lowenstein-Jensen Agar Nucleic acid probes 30 Nucleic acid sequencing  31 Mycobacterium tuberculosis Tuberculin Test Test done by using Purified Protein Derivative [PPD] Intracutaneous injection  Mantoux method Used to identify patients who are infected, they may or may not have the disease Tuberculin + (skin test) means person has cell mediated immunity to M. tuberculosis * active infection * have been vaccinated * prior infection  32 Treatment and Control of Tuberculosis Treatment Regimen  Rifampicin + Isoniazid + Pyrazinamide + ehambutol Control of Tuberculosis  Early detection & effective treatment  Vaccination/ BCG a living attenuated vaccine - -Derived from M. bovis  Chemoprophylaxis Persons contact with active TB  Isoniazid alone  Skin test  33 Mycobacterium leprae Leprosy  Infection often causes severe disfigurement & deformity  Incubation periods; 2-20 years. Description  Acid fast bacilli  Cannot grow in any type of artificial media or in vitro  34 Mycobacterium leprae Pathogenesis  Target is nerve cells  Nerve damage  The progression of the disease is determined by immune response to the bacilli  Tuberculoid Leprosy  few bacilli & strong immune reaction  Lepromatous Leprosy  Many bacilli & no immune response 35  35 Forms of leprosy -Tuberculoid leprosy * organisms in well-contained granulomatous lesions in tissue Lepromatous Leprosy (Early/Late Stages) - Lepromatous leprosy * more serious disfigurement, nodular swelling * related to slow fibrosis of peripheral nerves, with anesthesia * shortening of toes and fingers in response to repeated unfelt trauma: spontaneous amputations often occur (sloughing) 35  36 36 36 Laboratory Diagnosis Smears from sub-epidermal skin sections Acid fast stain lepromin skin test -----> positive - tuberculoid leprosy negative - lepromatous leprosy  37 Mycobacterium avium-intracellulaire Complex 37 37  38 M. avium-intracellulaire Complex (MAC) Progression vs. CD4 Count in AIDS Patients 38  39 Atypical Bacteria Rickettsiae, Chlamydia, Mycoplasma a miscellaneous group of organisms with properties common to both bacteria and viruses 39  40 Rickettsia  Obligate intracellular parasites  Gram stain poorly, but appear to be Gram-negative cell wall  Non motile pleomorphic rods or coccobacilli 0.3-0.7 µm x 1.5-2 µm  cannot be grown on laboratory media  obligate intracellular parasites that can grow in both phagocytic and nonphagocytic cells.  Ticks, fleas, and lice are involved in their life cycle  transmitted by the bite of an infected arthropod vector  Rickettsia :  typhus fever,  spotted fever  41 The Rickettsiae Typhus (ไข้รากสาดใหญ่), spotted fever; transmitted by the bite of an infected arthropod vector vesicular with pox-like progression - rickettsial pox Diagnosis serology Weil-Felix test antibodies cross-react with antigens from Proteus 41  42 Chlamydia  Small obligate intracellular parasites  Alternate between 2 stages:  Elementary body – small, metabolically inactive, extracellular, infectious form released by the infected host  Reticulate body – noninfectious, actively dividing form, grows within host cell vacuoles  43 Developmental Cycle of Chlamydia  EB bind to host cells  Epithelial  Macrophage  Reorganization into RB  Growth of RB  Reorganization into EB  Inclusion bodies  Release of EB  44 Chlamydia trachomatis  Trachoma (ริดสีดวงตา) – attacks the mucous membranes of the eyes, genitourinary tract, and lungs  Ocular trachoma – severe infection, deforms eyelid and cornea, may cause blindness  Inclusion conjunctivitis – occurs as baby passes through birth canal; prevented by prophylaxis  Sexually transmitted diseases (STD) – second most prevalent STD; urethritis, cervicitis, Pelvic inflammatory disease (PID), infertility  Lymphogranuloma venereum – disfiguring disease of the external genitalia and pelvic lymphatics  45 Chlamydia trachomatis  Trachoma  Inclusion conjunctivitis  Associated with genital chlamydia  Mucopurulent discharge  Corneal infiltrates, vascularization and scarring can occur  In neonates infection results from infected birth canal  Apparent 5-12 days after birth  Ear infection and rhinitis often accompany ocular disease 45  46 Lymphogranuloma Venereum C. Trachomatis (Biovar: LGV)  First stage  Small painless vesicular lesion at infection site  Fever, headache and myalgia  Second stage  Inflammation of draining lymph nodes  Fever, headache and myalgia  Buboes (rupture and drain)  Ulcers  47 Mycoplasma - Smallest known free-living organisms (0.15-0.3 µm.)  2 medically important species  M. pneumoniae – primary atypical pneumonia; pathogen slowly spreads over interior respiratory surfaces, causing fever, chest pain, and sore throat  M. hominis - Genital tract infections  Morphology and cultural characteristics  Do not possess the distinctive cell wall of bacteria  Having sterols in the cytoplasmic membrane  highly pleomorphic  Require special lipids from host membranes  48 Mycoplasma pneumoniae - Infects upper and lower respiratory tract - Primary atypical pneumonia : walking pneumonia : slow to develop : incubation period up to 3 weeks : fever, headache, cough Common in children and young adults - Mechanism of transmission : Sneezing, coughing 48  49 Mycoplasma pneumoniae  Clinical significance  the major cause of primary, atypical pneumonia (walking pneumonia)  Transmitted by droplet infection  After a 2-3 week incubation, the disease begins as a mild, upper respiratory tract infection and progresses to fever, headache, malaise, and a dry cough which is usually mild and self-limited.  3-10% develop clinically apparent pneumonia with occasional complications of arthritis, rashes, cardiovascular problems, or neurological problems.  50 Mycoplasma pneumoniae LABORATORY DIAGNOSIS 1. Culture - throat swab, sputum - selective agar supplemented with serum and antibiotics - colonies ----> “fried egg” appearance 2. Serodiagnosis - antibody titer - Cold agglutinin test - Complement fixation test 3. Rapid diagnosis - Immunoassay - DNA probe, PCR 50  51 Mycoplasma pneumoniae LABORATORY DIAGNOSIS  Cold agglutinin test – a nonspecific test in which the patient produces cold reacting antibodies that agglutinate type O human RBCs at 40 C, but not at 370 C  A single titer of 1:128 is significant and occurs in 7 days and disappears in 6 weeks.  52 Recommended Reading 53