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Transcript
Diagnostic microbiology lecture: 17 CHLAMYDIA Abed ElKader Elottol MSc. Microbiology 2010 1 Abed ElKader ElOttol General Characteristics • Obligate intracellular bacteria. • Have ribosomes like bacteria. • Are metabolically deficient. Morphology • Small rounded organism. • Multiply by binary fission. • Cell wall consists of inner & outer membranes but differ from that of Gram negative bacteria by absence of peptidoglycan. 2 Abed ElKader ElOttol 3 Abed ElKader ElOttol Important Species C. psittaci C. pneumoniae C. trachomatis Cultural Characters Grow in: Yolk sac of chicken embryo Tissue culture (McCoy cells) PATHOGENESIS • Infect epithelial cells of mucous membranes & lungs Virulence is due to: • Resistance to phagocytic killing by lysosomal enzymes • Heat-labile toxin • Competition with host cell for nutrients • Host’s immune response may account for inflammation & tissue destruction. 4 Abed ElKader ElOttol C. trachomatis inclusion bodies (brown) in a McCoy cell culture . CHLAMYDIA PSITTACI A zoonotic respiratory disease. Natural habitat : birds Transmitted through inhalation of : Respiratory secretions & dust from faeces of infected birds Common in poultry workers Disease : Pneumonia (Psittacosis) Diagnosis Isolation of organism from sputum by tissue culture Complement fixation test to detect specific Abs Treatment Tetracycline in adults Erythromycin in babies 6 Abed ElKader ElOttol CHLAMYDIA PNEUMONIAE Also known as TWAR (TW – Taiwan & AR – acute respiratory) Cause atypical pneumonia like Mycoplasma pneumoniae Treatment Tetracycline in adults Erythromycin in babies 7 Abed ElKader ElOttol CHLAMYDIA TRACHOAMATIS 15 serotypes (A-L) C. trachomatis includes three human biovars: trachoma (serovars A, B, Ba or C), urethritis (serovars D-K), and lymphogranuloma venereum (LGV, serovars L1, 2 and 3). Transmission: Through close personal contact like: • Sexual • Passage through birth canal • Finger to eye or fomite to eye (Trachoma) DISEASES 1. Trachoma • Caused by serotypes A, B, Ba & C • One of the leading causes of blindness in developing countries with dry & hot weather • Chronic conjunctivitis : leads to scarring of eye lids and cornea Abed ElKader ElOttol 8 spread by direct contact with eye, nose, and throat secretions from affected individuals, or contact with fomites 2. Genital Tract Infections (Serotypes D-K) • Non-gonococcal urethritis in men • A common cause of non-gonococcal urethritis • Mucopurrulent urethral discharge • May progress to epidydmitis & orchitis (testes inflamation) • Cervicitis & Vaginitis • Mucopurrulent vaginal discharge • Pelvic Inflammatory Disease (PID) • May lead to secondary infertility 10 Abed ElKader ElOttol 3. Neonatal Infections (Caused by serotypes D-K) • Acquired from mother’s birth canal • Inclusion Conjunctivitis • Profuse mucopurrulent discharge 7-12 days after birth • Pneumonia. 4. Lymphogranuloma Venereum (LGV) • Caused by serotypes L1, L2 & L3 • A STD with lesions on genitalia & LNs (buboes) 5. Reiter’s Disease An autoimmune disease caused by Abs formed against C. trachomatis which cross react with antigens on cells of urethra & joints(arthritis, redness of the eyes, and urinary tract signs). 11 Abed ElKader ElOttol LAB DIAGNOSIS • Specimens from urethra, conjunctiva, sputum & cervix. • Microscopy. • Chlamydial “cytoplasmic inclusions” are detected by: • Giemsa staining • Fluorescent Ab staining • PCR • Cell Culture • Sero-diagnosis TREATMENT Tetracycline in adults Erythromycin or Azithromycin in babies 12 Abed ElKader ElOttol Calymmatobacterium granulomatous Klebsiella granulomatis GRANULOMA INGUINALE 13 Abed ElKader ElOttol The disease is commonly known as donovanosis Small, painless nodules appear after about 10–40 days of the contact with the bacteria. Later the nodules burst, creating open, fleshy سميك, oozing رشحlesions. General characteristics Capsulated short Gram-negative rod A STD with higher incidence in homosexuals Clinical Features Initially papules appear on external genitalia which ulcerate and extend widely – ulcer formation Base of ulcer is “BEEFY”; spreads by contact so is known as “KISSING ulcers” Lymph Nodes may enlarge Treatment : Tetracycline 14 Abed ElKader ElOttol MYCOPLASMA An older name was Pleuropneumonia-Like Organisms PPLO 15 Abed ElKader ElOttol GENERAL CHARACTERISTICS The smallest free-living organism (0.3 μ diameter). Have no cell wall. Insensitive to penicillins & cephalosporins. Poorly stained by Gram-staining. Cytoplasmic membrane contains cholesterol. Slow growth on specialized artificial culture media (a week). Typical “fried-egg” appearance of colonies by a plate microscope 16 Abed ElKader ElOttol Formulae Difco™ PPLO Agar Approximate Formula* Per Liter Beef Heart, Infusion from 50 g ................................... 6.0 g Peptone ................................................................... 10.0 g Sodium Chloride ........................................................ 5.0 g Agar ......................................................................... 14.0 g 17 Abed ElKader ElOttol MYCOPLASMA PNEUMONIAE MAIN DISEASE • Primary atypical pneumonia • Common in late summer and early autumn PATHOGENESIS & EPIDEMIOLOGY • Droplet infection. • Organism adhere to respiratory epithelium. • Inhibit ciliary motion. • Damage epithelium. • Common in chidren & young adults • Increased incidence in winter 18 Abed ElKader ElOttol CLINICAL FEATURES Sore throat, fever & headache. Cough with small amount of whitish non-purulent sputum. Some extrapulmonary symptoms. Opacities on chest X-Rays. IMMUNITY Incomplete: second episode can occur. 19 Abed ElKader ElOttol UREAPLASMA URELYTICUM 20 Abed ElKader ElOttol Differentiated from mycoplasma due to urease enzyme production Like mycoplasma produce “fried egg” colonies on specialized medium. Diseases • Non-gonococcal, non-chlamydial urethritis in men. • Post-partum fever in women. • Transmitted by sexual contact. MYCOPLASMA & UREPLASMA LAB DIAGNOSIS Culture : “Fried egg” colonies on specialized medium Cold Agglutinin detection A titer of 1:128 or higher – indicates recent infection TREATMENT Tetracycline OR Spectinomycin 21 Abed ElKader ElOttol RICKETTSIA & COXIELLA 22 Abed ElKader ElOttol Rickettsiae – A genus of small, rod-shaped, round to pleomorphic microorganisms . – gram-negative – cultivable only in living tissues. – Transmitted by lice قملand ticksقراد, they cause disease in humans and domestic animals but are also found in the cytoplasm of tissue cells of lice, fleas, ticks and mites سوس, which may act as reservoirs and vectors Pathogenesis 1. Insect vectors for human transmission: arthropods such as fleas, ticks, mites عث, or lice 2. Rodents, humans, or arthropods: all can serve as reservoirs 3. Multiply in salivary glands of ticks & gut of lice/fleas 4. Site of Bite = Eschar (encrusted متقشرulcer) → necrotic tissue: Site of bite = point at which Rickettsia enters the body becomes blackened 1. Following bite, organisms taken into body by “phagocytosis process 2. Organisms multiply in both nucleus & cytoplasm of host cell. • Typhus Group Louse borne (epidemic) Typhus. – Etiological agent = Rickettsia prowazekii – Transmission: person-to-person by infected human body louse that excretes organisms in feces • Introduction of pathogen form lice facilitated by scratching the louse bites – high fever, chills, rash possible – Duration of Disease: ~2 weeks; more severe in ederly – Complications: CNS dysfunction and myocarditis Rock Mountain Spotted Fever Etiological agent = Rickettsia ricketsii Reservoir = rodents (mice, rats) Vector = Tick Bite Rickettsia in saliva of tick, transfer to humans after bite Human infection High fever & malaise, then rash – initially, but becomes petechial or hemorrhagic Rash starts on extremities, then rapid spread to entire body. Untreated cases – vascular disturbances with myocardial or renal failure possible Coxiella • • • • • Etiological agent = Coxiella burnetti Q fever Reservoir = cattle, sheep, rodents, ticks Vector = contaminated aerosol C. burnetti enters the body via mucous membranes, abrasions & GIT via consumption of milk for infected animals – Zoonosis becouse animal direclty transmits the organism to humans – high fever, cough, pneumonia, hepatitis – all selflimiting usually; rarely – endocarditis (scarring of hrt. valves) and scarring of liver – complicated by hepatitis, myocarditis, or encephalitis Growth characteristics • Grow only in eukaryotic cell like • Tissue cultures OR embryonated eggs • 33 Abed ElKader ElOttol RICKETTSIA & COXIELLA : LAB DIAGNOSIS • Serology • PCR • Tissue culture • Weil-Felix Reaction • Antigens of several species of Rickettsiae cross-react with cell wall O antigen of Proteus OX-2, OX-19, OX-K. • These Proteus antigens can be used in lab to detect presence of specific antibodies against certain Rickettsia in patients serum. • Reaction negative in Q fever TREATMENT • Tetracycline • Chloramphenicol 34 Abed ElKader ElOttol End of Lecture 35 Abed ElKader ElOttol