Lecture 8 Other Gram Negative Rods 2022 PDF

Other Gram- negative rods Presented Click to by: Dr. Fahad edit Master subtitle style Alsaab Objectives  By the end of this session the student should be able to: Describe the clinical significance of Haemophilus, Pseudomonas, and Brucella infections List the...

Other Gram- negative rods Presented Click to by: Dr. Fahad edit Master subtitle style Alsaab Objectives  By the end of this session the student should be able to: Describe the clinical significance of Haemophilus, Pseudomonas, and Brucella infections List the laboratory identification and some virulence factors for these organisms Describe the pathogenesis, clinical features, and laboratory identification of Neisseria gonorrhoeae, Treponema pallidum, and Chlamydia species 2 General features  Gram negative  LPS  Grow in the presence of oxygen  Pathogens of the human respiratory tract:  Haemophilus species  Bordetella species  Legionella species  Opportunistic pathogen:  Pseudomonas species  Animal pathogens that cause human infection (zoonotic):  Brucella species  Yersinia species 3  Haemophilus species Gram negative (Coccobacilli or rods (pleiomorphic)).  Require certain factors for growth Hemin (X factor) NAD+ (V factor)  Haemophilus influenzae – major pathogen:  Encapsulated type B (Hib) causes severe disease.  Non-encapsulated (not typeable): Less severe and part of respiratory tract Normal flora 4  H. influenzae pathogenesis H. influenzae (encapsulated type B – Hib) H. influenzae (non-encapsulated)  Common cause of meningitis in  These strains are major pathogens that children between 6 months and 2 colonize the human respiratory tract. years  Causes:  **Vaccination** is with type B Otitis media polysaccharide components (HiB)  Causes: Sinusitis Meningitis Broncho-pneumonia Epiglottitis Septic arthritis 5  Identification: Haemophilus species Isolation from sterile sites, blood, cerebrospinal fluid (CSF), or synovial fluid (critical) Rapid diagnosis is important especially if a CSF sample is obtained Chocolate agar (X, V factors) Prevention: **Vaccination** Antibiotics 6  Pseudomonas species Motile, encapsulated and obligate aerobe Found in soil, water, plants and animals Can colonize without causing disease but can cause severe opportunistic infections (nosocomial infections) Can grow in many water containing vessels Pseudomonas aeruginosa – primary human pathogen Can grow in laboratory water baths, wet IV tubing, & other water-containing Capsule vessels. 7  P. aeroginosa Pathogenesis  Disease starts with attachment to and colonization of host tissue  Pili – important for adherence  Capsule – protects from host defense  Host tissue damage facilitates adherence and colonization  Many toxins and extracellular products are produced to promote local invasion and spread.  2 kinds of infection  Localized  Systemic (mostly immunocompromised patients) 8  Clinical Significance – P. aeruginosa Localized infections. Respiratory Tract: External otitis keratitis Localized or swimmer's ear Pneumonia in patients with chronic lung Eye infection infections Ear infection disease, congestive heart failure, cystic endophthalmiti s fibrosis. Elderly diabetic Gastrointestinal Tract: patients/trauma patients Necrotizing Mild diarrhea in children. Otitis externa Necrotizing enterocolitis. Hot tub skin rash CNS: Localized infections can lead to systemic infections Meningitis and brain abscesses.  Bacteremia (usually immunocompromised patien  Bone & joint infections  Endocarditis 9  Identification: Pseudomonas species  Identification  Blood agar plates.  MacConkey plates  Biochemical & Diagnostic tests  Treatment  Antibiotic treatment challenging because of resistance.  Immunocompromised individuals need a combination of antibiotics. 10  Brucella species  Disease: Brucellosis:  Animal pathogen (zoonotic)  B. abortus (cattle), other species  Epidemiology:  Transmission to humans: animal contact or consumption of contaminated products (dairy, meat)  Sterility & abortion in animals.  Pathogenesis:  Entry: skin cuts, GI tract, inhalation of aerosols.  Moves via lymphatic system and spreads via blood to different organs. 11  Clinical Significance & Identification: Brucella species Incubation: 5 days – several months Flu-like symptoms Develop undulant fever (temperatures repeatedly rise & fall). Complications: may Identification: involve GI tract, skeletal, neurological,  Detailed history of patient cardiovascular,  Cultured from blood, body fluids, tissue specimens on pulmonary systems blood agar Occupation hazard for Treatment: Combination antibiotic therapy employees in the meat industry 12  Neisseria gonorrhoeae Gram negative, aerobic cocci (diplococci) Transmission Sexual contact During the passage of a baby through an infected birth canal PRESENTATION TITLE 13  N. gonorrhoeae - Pathogenesis Structure: Pathogenesis:  Attach & colonize epithelial cells of the urethra, rectum,  Pili cervix, pharynx or conjunctiva. Hair-like surface  IgA protease – destroys IgA. appendages that enhance Colonizes mucous membranes of the GU and/or rectum. attachment to host cells. Localized infections are characterized by pus. Resistance to May lead to tissue invasion and chronic inflammation. phagocytosis. Females are often asymptomatic:  Lipooligosaccharide (LOS)  Act as reservoirs for maintaining and transmitting  Opacity proteins gonococcal infections. Mediate attachment. Often more than one sexually transmitted disease is acquired at the same time requiring treatment for more than 1 pathogen. 14  N. gonorrhoeae – Clinical Significance Genitourinary tract infections: Pharyngitis  Males: yellow, purulent urethral discharge &  Oral-genital contact  purulent pharyngeal painful urination exudate  Females: infection in the endocervix which Opthalmia neonatorium extends to the female genital tract (greenish-  Infection of conjunctival sac acquired during yellow discharge) birth Can progress to the uterus, causing  May lead to blindness if untreated salpingitis (inflammation of the fallopian tubes  infertility ~ 20%), pelvic Disseminated infection (results from gonococcal inflammatory disease & fibrosis) bacteremia).  Fever, painful arthritis, small pustules on the skin Rectal infections  More common in women  Prevalent in male homosexuals  Patients treated should also receive treatment  Symptoms: constipation, painful defecation & for Chlamydia purulent discharge 15  N. gonorrhoeae – Identification & Treatment Identification: Treatment:  Male: neutrophils containing gram  Cephalosporins negative diplococci in urethral  Partners in relationships should discharge allows for treatment. be treated.  Females: urethral discharge,  No effective vaccine available. positive culture  Disseminated gonococcal infection  No natural immunity.  culture confirmation required.  Prevention: safe sexual practices  Culture of skin lesions, joint fluid or (especially with multiple blood. partners).  Thayer – Martin chocolate agar. PRESENTATION TITLE 16  Treponema pallidum Sexually transmitted infection caused by the spirochete Treponema pallidum (T. pallidum). Gram negative bacilli, corkscrew or helical shape Causes Syphilis Transmission:  Spirochete morphology Sexual contact or transplacental (congenital syphilis). T. pallidum cannot survive outside of the host for long. Syphilis occurs in 3 stages:  Primary Syphilis.  Secondary Syphilis.  Tertiary Syphilis. 17  T. pallidum – Clinical significance (i) Primary Syphilis: Secondary Syphilis:  Rashes and papules on almost any part of the  Hard, painless genital or oral chancre at body (the palms of the hands and soles of the feet, site of inoculation. in mouth and armpits).  3 weeks between infection and appearance  Primary & secondary lesions extremely infectious. of chancre.  Other organs may also be involved – liver, brain,  Lesions heal but organism continues to kidneys. spread via lymph & blood. Tertiary Stage (40% of individuals):  Asymptomatic period for up to 24 weeks.  After healing of secondary lesions, the disease enters a latent period, this stage can last many years.  Degeneration of the nervous system & lesions (granulomatous lesions = gummas) in deep organs like the heart, liver, skin. 18  T. pallidum – Clinical significance (ii) Congenital syphilis:  T. pallidum is transmitted through the placenta to a fetus after the first 10-15 weeks of pregnancy.  Death & spontaneous abortion, or still birth.  Infected infants who live develop a condition similar to secondary syphilis including a variety of CNS & structural abnormalities.  Treatment: Treatment of the mother with appropriate antibiotics prevents this disease. PRESENTATION TITLE 19  T. pallidum – Identification & Treatment Identification:  Cannot be easily cultured.  Immunofluorescent staining and dark-field microscopy.  Antibody titers – ELISA. Treatment:  Penicillin.  No vaccine available.  Safe sexual practices.  Multiple Diseases may need to be treated. PRESENTATION TITLE 20  Chlamydia species Gram negative and obligate intracellular parasite. Small, round-to-ovoid organisms They synthesize their own proteins which make them sensitive to inhibitors of protein synthesis such as tetracyclines & macrolides. Do not grow on laboratory media (obligate intracellular parasite!!). - Require living cells for growth (embryonated eggs or in tissue culture cells). Genitourinary tract and eye infections - Chlamydia trachomatis  Respiratory tract infections - Chlamydia psittaci - Chlamydia pneumoniae 21  Chlamydia species - Pathogenesis Elementary Unique Life cycle body Infectious form Elementary body: initiates Reticulate body an infection & once phagocytosed prevents fusion of the phagosome Elementary and lysosome, protecting body itself. Reproductive form Reticulate body: multiplies by binary fission to increase in number. PRESENTATION TITLE 22  Chlamydia Trachomatis -Clinical significance (i) C. Trachomatis causes a range of Genitourinary tract and Eye Infections Chlamydial NGU is like infections caused by Nongonococcal urethritis (NGU) Neisseria gonorrhea > 4 million cases/year in the U.S. (most common STD)except: Males: urethra is affected Longer incubation Females: cervicitis and/or urethritis period (2-3 weeks) Infections can be asymptomatic Discharge is more Infections may spread: mucoid (less pus cells) Men: Epididymis Treatment: NGU and Women: Fallopian tubes & adjacent tissues (pelvicNeisseria gonorrhea inflammatory disease) 23  Chlamydia Trachomatis -Clinical significance (ii)  Lymphogranuloma venereum (LGV):  Papules on external genitalia, followed by painful swelling of inguinal & perirectal lymph nodes  Trachoma:  Chronic keratoconjunctivitis often leads to blindness  Transmitted by personal contact  Eye to eye via droplets  Contaminated surfaces touched by hands  Persistent or repeated infection leads to blindness  Neonatal conjunctivitis 24  C. trachomatis – Identification & Treatment  Identification: Fluorescent antibody Samples from Urethra & cervix (GU) staining and conjunctivae (ocular) Fluorescent antibody staining (immunofluorescence) PCR – polymerase chain reaction to amplify DNA Culture: does not grow on media (tissue C. trachomatis grown in tissue culture culture – human cell lines)  Treatment: Erythromycin, Azithromycin, Doxycyline 25  Chlamydia psittaci, Chlamydia pneumonia  C. psittaci: Psittacosis or Ornithosis  Zoonotic disease transmitted to humans from the inhalation of dust contaminated with respiratory secretions or feces of infected birds  Affects the lower respiratory tract  Flu-like symptoms – enlargement of liver and spleen  Severity: asymptomatic to fatal (rare)  Workers who deal with birds (high risk)  C. pneumonia: Pharyngitis, followed by Laryngitis, bronchitis or pneumonia  Significant cause of community-acquired respiratory infection  Diagnosis: antibody titers by immunofluorescence  Treatment: Doxycycline or Erythromycin 26 Thank you PAGE 27