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Transcript
Bacteria What diseases are caused by bacteria? Overview of Bacterial Infectious Diseases Skin and Soft Tissue Infections Ocular Infections Upper and Lower Respiratory Tract Infections (URTI, LRTI) Infections of Central Nervous System (CNS) Bacteremia and Sepsis Gastrointestinal (GI) Infections Urinary Tract Infection (UTI) and Sexually Transmitted Diseases (STD) Skin and Soft Tissue Infections Staphylococcus aureus Streptococcus pyogenes Propionibacterium Invasive Skin Disease: Staphylococcus Characterized by pus production Pimples – infection of hair follicles (folliculitis); if eyelash disease called sty Furuncles (boils) – abscess develops from pimple, characterized by pus surrounded by inflamed tissue Carbuncles - series of interconnected furuncles with more extensive tissue invasion Septicemia – from carbuncles, MO spread to bloodstream May also cause impetigo in newborns (see Streptococcus) Skin Disease By Toxin: Staphylococcuss Scalded skin syndrome: produces a cytotoxin, exfoliative or epidermolytic toxin causes outer skin to peel away in layers Toxic shock syndrome: exfoliation of skin may occur also involving tampon use in menstruating women due to toxic shock syndrome toxin, type I Invasive Skin Disease: Streptococcus Impetigo – pustules become crusted and rupture, very contagious, easily spread from child to child in day care setting Wound infections – occasional infections following trauma, usually due to contamination of wound Cellulitis – subcutaneous tissue, may be accompanied by lymphangitis and abscess formation Invasive Skin Disease: Streptococcus Nectotizing fasciitis – destruction of fiberous tissue deep in skin including destruction of sheath tissue that covers muscle (“flesh eating bacteria”) Myositis – invasion of muscle tissue resulting in extensive muscle necrosis and overwhelming sepsis, usually fatal Skin Disease By Toxin: Streptococcus Rash seen in Scarlet fever due to erythrogenic toxin Skin Disease By Toxin: Streptococcus Erysipelas – diffuse, erythematous skin disease due to exotoxin, most often on face following pharyngitis Ocular Infections Conjunctivitis Gonococcal opthalmia neonatorum Tracoma Conjunctivitis Infection of membranes cover eye and lining of eyelid By many different MOs Contagious conjunctivitis (pinkeye) Haemophilus aegyptius Gonococcal opthalmia neonatorum Neisseria gonorrhoeae Transmitted to newborns as baby moves through birth canal Prevented by giving all newborns eye drops containing antibiotics at birth Neisseria gonorrhea Causes Neonatal Blindness Ophtalmia neonatorum caused by Neisseria gonorrheae Source: Microbiology Perspectives, 1999 Trachoma Chlamydia trachomatis Transmitted by direct contact Single most common cause of blindness in developing countries Upper & Lower Respiratory Tract Infections Pharyngitis Diphtheria Otitis Media Whooping cough Tuberculosis Pneumonia Pharyngitis Sore throat Mainly by Streptococcus pyogenes (classic “Strep throat”) Transmitted by respiratory secretions Symptoms include inflammation of throat and fever Leads to tonsilitis and middle ear infections Diphtheria Corynebacterium diphtheriae lysogenized by phage encoding “tox” gene Starts with sore throat, fever, followed by general malaise and swelling of neck Tough grayish membrane form in throat, can cause suffocation Bacteria not invasive, liberate exotoxin, death may occur due to effect on heart and kidneys D part of DPT vaccine Otitis Media (middle ear infection) Uncomfortable complication of common cold or any infection of nose or throat More common in children because auditory tube so small Most commonly: Streptococcus pneumoniae Haemophilus influenzae Streptococcus pyogenes Staphylococcus aureus Moraxella catarrhalis Whooping Cough Bordetella pertussis Transmitted by respiratory secretions MO not invasive, attaches to respiratory epithelia impeding action, causes build-up of mucous Disease occurs in 3 stages Catarrhal stage - symptoms similar to common cold Paroxysmal stage – characterized by prolonged sieges of coughing as patient tries to get rid of mucous built up; gasping of air occurs between coughs causing a “whooping” sound, 1-6 weeks Convalescent stage – several months P part of DPT vaccine Tuberculosis Mycobacterium tuberculosis and Mycobacterium bovis can cause Tb, but M. bovis rare in U.S. MO gain entrance by many portals of entry with inhalation being most common Tubercle bacilli reach alveoli of lung are ingested by macrophages Enzymes and cytokines release to start inflammatory response to wall off MO (tubercle formation), but inflammatory response also causes lung damage Tuberculosis After few weeks macrophages die, releasing tubercle bacilli forming caseous center inside tubercle In healthy individuals, disease usually arrested at this time and lesions become calcified; tubercle bacilli remain dormant in lesion and serve as a basis for later reactivation of disease When host defenses fail, mature tubercle form and bacilli multiply Tubercle eventually ruptures, releasing bacilli that disseminate throughout body This is progressive form of disease and symptoms include weight loss, coughing with blood, and loss of vigor Pneumonia Characterized by fever, difficult breathing, and chest pain Many different MOs Streptococcus pneumoniae – usually occurs following primary infection elsewhere Klebsiella pneumoniae – permanent lung damage often occurs Mycoplasma pneumoniae – “walking pneumonia” because individuals often do not know have disease, also called atypical pneumonia because cough not productive Legionellosis – Legionella pneumophilia, transmitted by aerosols from contaminated water into air condition system, more common in older males Infections of CNS Meningitis Tetanus Botulism Hansen’s Disease (Leprosy) Meningitis: Neisseria Meningitis many different bacteria, most by: Neisseria meningitidis Starts as sore throat, progresses to bacteremia, then meningitis characterized by severe headache, neck and back pain, stiffness Endotoxin (Gram-negative MO) causes extensive blood vessel damage with petechiae being hallmark symptom Vaccine against most common encountered virulent types College students living in dorms required/recommended to be vaccinated Meningitis: Other MOs Haemophilus influenzae – have type b capsule Common in children two months to four years Today Hib vaccine prevents most infections Streptococcus pneumoniae Occurs immunocompromised, very young, very old High mortality rate Vaccine to prevent pneumonia is for >30 capsular types E coli, type K1 and Streptococcus agalactiae – Two most common cause of this disease in newborns Mortality rate is high Tetanus Clostridium tetani, neurotoxin tetanospasmin. Spores found in feces, soil, dust; enter body by penetrating wound, germinate into vegetative cells, produce toxin Cramps and twitching of muscles around wound Headache and neck stiffness Followed by trismus (lockjaw) and more generalized symptoms Death, if occurs, results from respiratory failure Botulism Neurotoxin produced by Clostridium botulinum In the U.S., usually occurs following ingestion of toxin in inadequately processed home-canned food First symptoms include nausea, vomiting, and diarrhea Followed by symmetric, descending paralysis (eyes, throat, neck, trunk, and then the limbs) Death is from respiratory failure Hansen’s Disease (Leprosy): Tuberculoid Mycobacterium leprae Contagious but requires prolonged, fairly intimate contact Two major forms of the disease Tuberculoid – characterized by lesions of skin that have lost sensation Hansen’s Disease: Lepromatous Characterized by disfiguring nodules that form mainly on colder areas of body Death occurs from complications of other bacterial infections Bacteremia and Sepsis Septicemia Endocarditis Rheumatic fever Tularemia Brucellosis Anthrax Plague Relapsing fever Lyme disease Typhus Rocky mountain spotted fever Septicemia: Lymphangitis Bacteria actively multiplying and/or releasing toxins into blood One symptom is lymphangitis - red streaks seen in skin radiating out from initial site of infection Subacute Bacterial Endocarditis Inflammation of endocardium, lining of epithelial cells in heart and valves Subacute bacterial endocarditis Occurs individuals with abnormal heart valve Due usually to viridans group Streptococcus, follows dental work or primary infection elsewhere Clots form, may break off to impair function of heart Symptoms include fever, anemia, general weakness, heart murmur Acute Bacterial Endocarditis Individuals following a primary infection elsewhere Characterized by rapid destruction of heart valves Rheumatic Fever Autoimmune complication of Streptococcus pyogenes pharyngitis May lead to heart damage, arthritis, death Tularemia Francisella tularensis Also called rabbit fever, usually acquired by contact with infected rabbits Local inflammation may lead to septicemia, pneumonia and abscesses throughout the body Brucellosis Brucella species Also called undulent fever A fever spike commonly occurs in evening Most commonly transmitted by unpasteurized milk Anthrax Bacillus anthracis Mainly disease of grazing animals Through variety of portal of entry in humans (skin, respiratory, GI tract) If through skin characteristic malignant pustules at site of entry May progress to septicemia and death Death usually due to toxin produced by organism Yersinia pestis Endemic in mountains in Southern California Two forms of disease – bubonic plaque and pneumonic plague Bubonic plague transmitted by rat fleas MO gets into bloodstream, makes its way to regional lymph nodes which become painful and enlarged (called buboes) Mortality rate in untreated cases is high MO gets into lungs cause pneumonic plague, transmitted from person to person via droplet infection, higher mortality rate than bubonic plague (close to 100%) Plague: Bubonic/ Pneumonic Relapsing Fever Borrelia species Transmitted by ticks and lice High fever, jaundice, and rose colored spots Relapses occur because MO undergoes antigenic variation, each relapse less severe than preceding one Lyme Disease Borrelia burgdorferi Transmitted by ticks Starts with characteristic rash at bite site, Erythema Chronicum Migrans (ECM), followed by flu-like symptoms Years later, neurological and heart problems, arthritis may occur, probably due to an immune reaction to remaining MOs Typhus Rickettsia prowazekii (epidemic) and Rickettsia typhi (endemic) High, prolonged fever, stupor and small red spots Transmitted by human lice (epidemic) and rat flea (endemic) Rocky Mountain Spotted Fever Rickettsia rickettsii Transmitted by ticks Symptoms include high fever, headache, rash over entire body GI Tract Infections Dental caries Dysentery Gastroenteritis GI Tract Disease Dental caries – bacteria (Streptococcus mutans) ferment sugar releasing acid that destroys enamel and dentin Dysentery - severe diarrhea with blood and/or pus Gastroenteritis - inflammation of stomach and intestinal mucosa Gastroenteritis: Infection Salmonella species, including Salmonella typhi which causes typhoid fever Shigella species Vibrio parahaemolyticus Campylobacter jejuni Certain strains of E. coli MO attaches, invades, and multiplies. A delay in symptoms as MO multiplies Symptoms include fever, diarrhea (dysentery may occur), nausea, and possibly vomiting Gastroenteritis: Intoxication Staphylococcus aureus Vibrio cholera Certain strains of E. coli Ingestion of preformed toxin, or toxin produced by MO which not invasive but multiplies at intestinal mucosa while liberating toxin Symptoms DO NOT include fever, but may include abdominal cramps, watery diarrhea, nausea and vomiting UTI and STD Cystitis Gonorrhea Nongonococcal urethritis Syphilis Cystitis Most common cause is E. coli Other G(-) enterics as well as G(+) bacteria may also cause infection Inflammation of urinary bladder Dysuria (difficult or painful urination) and pyuria (WBCs in urine) Gonorrhea Neisseria gonorrhoeae Usually transmitted by direct sexual contact Commonly have concomitant Chlamydia trachomatis infection Asymptomatic infections: Males= 10%, Females= 2075% Carriers and transmit disease to others Uncomplicated infections in males: Acute urethritis, profuse purulent discharge filled with GC; untreated may spread to cause prostitis and epididymitis Gonorrhea Uncomplicated infections in females: Vaginal discharge, burning or frequency of urination and menstrual abnormalities Complicated infections more frequently in women: Spread from cervix into fallopian tube Pelvic inflammatory disease (PID) - endometritis, salpingitis, peritonitis Occurs in 10-20% of infected women Symptoms include lower abdominal pain, abnormal vaginal and cervical discharge, and uterine tenderness Can result in ectopic pregnancy and infertility. Nongonococcal urethritis – Chlamydia trachomatis with symptoms as above Syphilis: Primary Treponema pallidum transmitted by direct sexual contact Untreated disease occurs in several stages Primary stage – penetration of skin or mucous membrane, characteristic painless hard chancre develops at site of entry Chancre highly contagious and filled with MOs MO enters lymphatics and disseminated Chancre heals without treatment in few weeks due to local immunity, but MO has already disseminated Syphilis: Secondary 4-8 weeks after primary stage Lesions (filled with MOs) throughout body including skin, mucous membranes, organs, eyes Most lesions on skin and mucous membranes May also have loss of hair, mild fever, malaise Also heals without treatment and patient may either spontaneously get well or develop latent infection Syphilis: Tertiary This stage characterized by granulomatous lesions (gummas) of skin, internal organs, CNS, bones, eyes, and cardiovascular system By body’s hyperimmune reaction to remaining spirochetes