Obligate Intracellular Bacteria PDF

Obligate Intracellular Bacteria  * Course contents 1- Obligate Intracellular Bacteria 2- Cell Wall-Deficient Bacteria, Rickettsiae & Chlamydiae 3- Mycology 2/8  3/8 Obligate Intracellula...

Obligate Intracellular Bacteria  * Course contents 1- Obligate Intracellular Bacteria 2- Cell Wall-Deficient Bacteria, Rickettsiae & Chlamydiae 3- Mycology 2/8  3/8 Obligate Intracellular Bacteria Spirochetes “Spiral form” Bacteria 3 Genera: Treponema, Borrelia & Leptospira 1- Treponema pallidum * Characters: 1- Thin, filamentous, motile 2- Not stained by ordinary staining 3- Seen by dark-field microscopy 4- Composition: external envelope, cytoplasm, cytoplasmic membrane & fibrilis * Growth requirements: Saprophytic Treponemes: cultivable, anaerobic & require BSA or volatile FAs Pathogenic Treponemes: Not grown in vitro; survive days under anaerobic conditions in media contain BSA, pyruvate, albumin * Pathogenesis: Syphilis ; Sexually transmitted disease or Congenital * Stages: 1ry & 2ry; MOs demonstrated in specimens c.f. 3ry stage: autopsy only  1ry Syphilis 2ry Syphilis 3ry (late) Syphilis Hard chancre appears after - Hard chancre ulcerative lesion heals - In 1/3 of untreated patients 3 wks of exposure after 6-8 wks - Localized in some organs or tissues - 2ry syphilis lesions appear Firm & ulcerated lesion on Organisms invade blood & disseminated Chronic granuloma (gummata) may genitalia to organs & tissues appear in skin, bones or organs Inguinal lymph nodes - Generalized rash: skin & mucous - CNS & cardiac manifestations occur late enlarged - Mucous patches in mouth - MO is latent in deep tissues: (Patients - Condylomata on genitalia Non-infectious & MOs Not demonstrated) - Lesions are highly infectious - Treponemas seen from abraded skin - Serological detection: +ve * Congenital syphilis: 1- From syphilitic mother to fetus 2- MOs found in large No. in blood & organs * Diagnosis: - Specimen: lesion exudates in 1ry & 2ry syphilis - Examination: by dark-field microscope - Staining: Silver impregnation, immunofluorescence 4/8 * Serodiagnosis: A- Non-treponemal or Reagin test: Detect Non specific Abs or Reagins: react with lipid Ag 1- Venereal Disease Research Laboratory (VDRL): Slide test Serum + cardiolipid ---> Flocculation 2- Wassermann reaction: Complement-fixation test Serum + lipid extract of animal heart B- Treponemal tests: Detect Treponemal Abs: react specifically with T. pallidum 1- T. pallidum immobilization (TPI) test: Serum + Motile Nichols strain of T. pallidum ---> Dark-field microscope ---> motility loss 2- Fluorescent Treponemal Ab-Absorption (FTA-ABS) test: Serum + Nichols strain ---> detected with Fluorophore-labeled Anti-human Abs * Treatment: Penicillin: early stages Erythromycin & tetracycline: penicillin allergy 5/8  2- Borrelia * Characteristics: Spiral, microaerophilic, stained with aniline dyes Borrelia recurrentis * Disease: Relapsing fever (acute, febrile illness) * Transmission: Louse bite * Pathogenesis: MOs enter blood ----> lesions in spleen, liver & GIT Relapsing fever: Severe febrile septicemia (3-7 d) ---> afebrile interval (days to wks) ---> a relapse occurs (due to antigenic variation) * Diagnosis: Specimen: Blood Examination: Dark-field microscopy Animal inoculation: helpful * Identification: - Lab. ONLY reports Borrelia as demonstrated in blood or inoculated animals - Serology is NOT successful due to marked antigenic instability * Treatment: Tetracycline (Drug of choice) No vaccine 6/8  3- Leptospira icterohaemorrhagiae * Morphology: Spiral, hooked (one or both ends), motile * Disease: Leptospirosis (infectious jaundice) * Transmission: Infected animal urine [Primarily parasites of rodents, dogs & cattle] * Pathogenesis: 1- Asymptomatic infection of kidney 2- MOs enter blood, invade various organs (Kidney, liver, meninges,…) 3- Occupational disease: prevails in mine laborers, sewage & agricultural workers * Symptoms: Muscular pain, fever & chills May result in infectious jaundice or meningitis * Treatment: Tetracycline, erythromycin or penicillin 7/8 Thanks 8 Mycoplasma, Rickettsiae & Chlamydiae  Cell Wall-Deficient Bacteria Mycoplasma * Characteristics: 1- Smallest organisms capable of growth & reproduction outside host on artificial media with cholesterol. 2- Pleomorphic (lack rigid cell wall); instead (3-layered membrane containing sterol) 3- Pass bacterial filter 4- Form tiny colonies “fried-egg” look. 1- Mycoplasma pneumoniae * Disease: Primary Atypical Pneumonia (PAP) * Virulence factors: 1- Specific receptor protein ---> host cell attachment 2- H2O2 -----> hemolytic & destruction of tracheal epithelial cells * Symptoms: - Pneumonia, chills, fever & general malaise - Major symptoms disappear, chest infiltration & cough continue 1-2 m * Diagnosis: 1. Specimen: sputum (Culture: E-agar e penicillin) 2. Microscopy: difficult; sputum is scanty , non-purulent & pathogen stains poorly 3. Serodiagnosis 4. CFT 5. PCR * Treatment: azithromycin, doxycycline & levofloxacin 2/9  Genital Mycoplasma * 3 MOs: M. hominis, U. urealyticum & M. genitalium * Sexually transmitted infections: as NGU or puerperal infections (infections connected with or immediately following childbirth) M. hominis & Ureaplasma urealyticum M. hominis U. urealyticum * General - Common inhabitants of GU tract characters - Grow more rapidly than M. pneumoniae - Degrades arginine - Hydrolyses urea * Properties - Resistant to erythromycin - Referred as “T strain”: produces tiny colonies not visible to naked eye - Postpartum or postabortal fever - Urethritis (men) * Disease - Endometritis (women) * Treatment - Doxycycline Mycoplasma genitalium * Disease: NGU (males) & cervicitis & PID (women) * Diagnosis: PCR * Treatment: Azithromycin NGU: Nongonococcal urethritis PID: pelvic inflammatory disease in females 3/9  Rickettsiae * 3 genera: Rickettsia, Ehrlichia & Coxiella * General characteristics: 1- Coccobacilli & stain poorly 2- Obligate intracellular parasites, not grown on artificial media 3- Fastidious bacteria; require growth cofactors by host (e.g. acetyl CoA, NAD, ATP, ions; K & Mg) 4- Plasma membrane is leaky ---> permeable to host nutrients & coenzymes * Pathogenesis: transmitted by arthropods (fleas, ticks, mites & lice) ---> taken into cells (similar by phagocytosis) ----> multiply -----> Host cells killed ---> spread via blood or lymphatics * Diseases: - Fever, headache, malaise, prostration, skin rash (except Q-fever) - Enlarged liver & spleen. 4/9  1- Typhus fever 2- Endemic 3- Rocky Mountain 4- Q- fever (Epidemic typhus) typhus spotted fever * Etiology Rickettsia prowazekii R. typhii R. rickettsii Coxiella burnetii *Transmission - Human body louse - Bite of rat fleas - Bite of dog tick - Arthropod vector not m.o excreted in feces essential for transmission - Inhaling contaminated aerosols & dust, drinking milk, handling animals * Disease Most severe & world Similar, but milder - Fever, malaise, rash * Characters: symptoms - Survives 60°C /1 hr. so widely distributed than epidemic - Resembles typhus pasteurization > 60°C typhus fever, however, rash (62.9°C). - Acidophilic, multiply within appears first on phagolysosome extremities - Heat & drying resistant (endospore formation). * Pathogenesis: - Fever, headache, fatigue, No rash. * Complications: - Pneumonitis & endocarditis * Diagnosis a) CFT b) Microagglutination (MA) test c) Immunofluorescence test d) Weil-Felix test: Agglutination (macroagglutination) using OX-19, OX-2, OX-K strains of P. vulgaris by Abs produced by rickettsia due to cross reactivity. * Treatment Doxycycline (drug of choice), except for pregnant women; chloramphenicol 5/9  Chlamydiae * Characters: G -ve, Non-motile, [Obligate intracellular; Energy parasites (use host ATP & NAD+ )] - Cell envelope (2 lipid bilayers) with cell wall similar to G -ve bacteria, No peptidoglycan or muramic a * Differences from Viruses: 1- Contain both DNA & RNA 2- Multiply by binary fission & seen by ordinary microscope 3- Possess ribosomes --> sensitive to ABs inhibit protein synthesis as tetracyclines & macrolides 4- Have enzymes & restricted metabolic capacity * Unique life cycle: 6/9  Chlamydia psittacii C. trachomatis Disease Psittacosis (ornithosis) 1- Non-gonococcal urethritis (NGU) - C. trachomais serotypes D - K - Zoonotic & occupational disease Symptoms - Urethritis (male) - Cervicitis, urethritis, sterility (female) - Discharge is more mucoid & fewer pus cells (C.F; N. gonorrhoeae) 2- Trachoma - C. trachomatis serotypes A, B, Ba & C cause chronic keratoconjunctivitis ---> blindness Transmission - Inhalation: dust contaminated e respiratory * Contact: Contaminated fingers or towels & clothing & secretions or feces of infected birds Symptoms - Affects LRT, flulike symptoms - Pulmonary infiltrates Scarring in eyelid ----> Turned-in eyelashes ----> - Enlarged liver & spleen mechanical abrasion ----> Cornea damage -----> lesions & blindness Diagnosis 1- Specimen: sputum & other clinical material. * Conjunctival scrapings, urethral discharges, cervical swabs 2. Culture: cell culture or embryonated chicken eggs 3. Microscopy 4. Serology: IFA Treatment Doxycycline or erythromycin Azithromycin & tetracycline 7/9  3- Lymphogranuloma venereum (LGV) - C. trachomatis serotypes L1, L2, L3 * Transmission: sexual contact * Symptoms: - lesions on genitalia, enlarged & painful lymph nodes - chronic inflammation ---> fibrosis, lymphatic obstruction * Diagnosis: - Specimen: pus, aspirated suppurative lymph node. Biopsy from enlarged lymph node - Serodiagnosis: CFT & Immunofluorescence * Treatment: tetracyline, sulfonamides or erythromycin 4- Chlamydia pneumoniae * Disease: pharyngitis, laryngitis, bronchitis or pneumonia * Treatment: doxycycline & erythromycin 8/9 Thanks 9 Medical Mycology 1  Mycology * Def: Science that studies fungi * Fungi: Eukaryotic heterotrophic Mos; may be saprophytic or parasitic Unicellular (Yeast) Multicellular (Filamentous) Dimorphic Oval, spherical or elongated Branched hyphae can form spores Yeast & hyphae forms Mycoses A- Cutaneous B- Subcutaneous C- Systemic (deep) - Limited to epidermis - Penetrates beneath skin - Deep within body or disseminated to internal organs Apple-green fluorescence Dermatophytes * Include 3 genera: Trichophyton, Epidermophyton & Microsporum * Infection site: keratinized tissues (nail, hair & skin); keratin as nutrition source * Disease: ringworm or tinea Target Class (drug) * Transmission: by infected skin scales Cell wall Echinocandins Polyenes (Amphotericin B , Nystatin) * Diagnosis: - Culture: on SDA & microscopy Cell - UV lamp (Wood's lamp examination): fluorescence Azoles (Fluconazole) membrane - Skin test: Ag-Ab reaction Allylamines (Terbinafine) DNA/RNA Fluorinated pyrimidines (Flucytosine) * Treatment: - Removal of infected & dead tissue Mitosis Griseofulvin - Antifungal: Topical (miconazole or clotrimazole) or oral (griseofulvin & itraconazole) 2/8  I. Cutaneous mycoses Name Site/Symptoms - Itching, blisters, rupture, discharge of fluids T. pedis (Athlete’s foot) - Skin fissures can lead to 2ry bacterial infections - Non-hairy skin: ring-like lesions T. corporis (body ringworm) scaly center inflamed periphery T. cruris (groin ringworm) - Can spread from upper thighs to genitals T. capitis (scalp ringworm) - Scalp: redness, edema, scaling, vesicle formation T. versicolor - Neck, trunk & arms: brownish red scaling - Nail: deformed, discolored & brittle T. ungium - Terbinafine (drug of choice) T. barbae Beard regions (face & neck) 3/8  II. Subcutaneous Mycoses 1- Sporotrichosis 2- Mycetoma *Causative Sporothrix schenckii Madurella grisea & Actinomadura madurae agent * Morphology Transmission: - Morphology: Dimorphic & Transmission Through traumatic lacerations or wounds - At 25°C: Thin, septate, twisted hyphae - At 37°C: as yeast, buds appear * Pathogenesis - Lesion: ulcerate , pus filled, spread to - localized abscess -> discharges pus, serum & blood & Diagnosis lymphatics, may be chronic - May lead to bone deformities - Microscopy: budding yeast or pseudohyphae - Defining characteristic: presence of colored grains - Culture on SDA: 25°C (hyphae), at 37°C (yeast) composed of compacted hyphae in exudate * Treatment - Oral itraconazole (drug of choice) - Surgical excision 4/8  III. Systemic mycoses - Pathogens; A- True: infect healthy individuals B- Opportunistic: infect immunocompromised - Dimorphic fungi: exhibit both yeast & mycelial forms 1- Coccidiomycosis 2- Histoplasmosis *Causative agent Coccidioides immitis Histoplasma capsulatum * Transmission - Inhalation of arthrospores - Inhalation of conidia * Pathogenesis - Airborne arthrospores enter lungs & - Airborne conidia enter lungs & germinate germinate - Pulmonary infections: - Can spread to bones & CNS ----> A- Acute but self-limiting meningitis B- Chronic, progressive & fatal - Dissemination is rare ---> invasion of cells of reticuloendothelial system (only fungus that exhibit intracellular parasitism). * Diagnosis Morphologic identification Exo-antigen test: Ags detected by immunodiffusion assay. DNA hybridization: measures degree of genetic similarity between DNA sequences. * Treatment - Amphotericin B & flucytosine - Ketoconazole, fluconazole, itraconazole 5/8  IV. Opportunistic Mycoses * Susceptible patients: diabetic, AIDS, cancer, taking immunosuppressive drugs, long use of broad spectrum ABs - N.B: competing bacterial flora are eliminated by antibacterial ABs, allowing yeast to overgrow 1- Candidiasis * Causative agent: Candida albicans * Diseases: 1- Oral candidiasis 2- Vaginal candidiasis 3- Cutaneous candidiasis 4- Systemic candidiasis (Mouth thrush) Symptoms - Raised, white - Itching, burning pain - Hand infections due to - Life-threatening. plaques on oral vulva & vagina. long immersion in water mucosa, tongue, - Thick or thin white - May involve GIT, or gums discharge - In moist warm skin; red, kidneys, liver & spleen. vesicular. - skin around nails: swollen, red & painful * Diagnosis - Gram- staining: oval cells, germ tubes & hypha - Culture on SDA: creamy colonies * Treatment - Topically: Nystatin or clotrimazole - Orally: ketoconazole, fluconazole & itraconazole * Germ tube: Tube-like outgrowth produced by germinating cells -----> develops into hypha. ** Pseudohypha: Chain of yeast cells; result of budding -----> forming hypha-like filament 6/8  2- Cryptococcosis 3- Aspergillosis *Causative agent Cryptococcus neoformans Aspergillus fumigatus * Transmission - Inhalation of spores * Pathogenesis - Occur in immunosuppression - Non-invasive (Aspergilloma) or Acute aspergillosis - Infections in lungs, can transmits to - Acute aspergillosis: most severe, fatal, infection of other organs e.g. CNS --> meningitis lung --> disseminated to brain, GIT & organs Mucoid, glistering colonies * Diagnosis A- microscopically: - Specimen: - Sputum shows septate branched hyphae - Specimens: (spinal fluid, sputum or (V-shaped branches); septate hyphae that branch at a skin lesion) --> stained e India ink ---- 45-degree angle. > encapsulated yeast - Tissue sections or biopsy: B- Serology:1- Agglutination test shows fungus ball 2- IF: detects Ag in tissue - Serology - PCR * Treatment Amphotericin B & flucytosine 1- Amphotericin B 2- Surgical removal of fungal masses or infected tissue 7/8 Thanks 8  Miscellaneous Fastidious G – ve rods  Miscellaneous Fastidious G – ve rods 1) Brucella * Zoonotic disease: animals are reservoir B. abortus: Cattle & Buffalo B. melitensis: Goats & Sheep B. suis: Swine B. canis: Dogs * Transmission: Ingestion (milk & meat) Contact: Through skin abrasions & mucous in farmers & butchers Inhalation 2/8 * Pathogenesis: Brucella is facultative intracellular -> granulomata (Immune response) * Disease: Brucellosis (Undulant or Malta or Mediterranean fever” - Acute: Intermittent fever (high afternoon & low at night), chills, malaise, headache, sweating, anorexia & wt loss - Systemic illness: may include Liver: hepatosplenomegaly & granulomas Papulonodular lesions Genitourinary tract: abortion in women & Orchitis in men Lung: lesions Heart: endocarditis Skin: papulonodular lesions Eye: visual disturbance & Uveitis Joints: arthritis CNS: encephalitis & meningitis 3 * Laboratory diagnosis: Specimens: blood, bone marrow, biopsy of spleen & liver. Culture: Blood agar in presence of 5 to 10% CO2 for 4-5 days. Identification a- Gram stain: small Gram –ve coccobacilli b- Biochemical tests: Urease, oxidase, catalase positive, H2S production c- PCR d-Serodiagnosis: tube agglutination test or ELISA * Treatment: Doxycycline + rifampin 4 Thanks 5