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Bacteria What diseases are caused by bacteria? Survey of Bacterial Diseases Diseases of the skin Staphylococcus aureus skin infections – the organisms cause both invasive skin diseases characterized by pus production and skin diseases caused by toxin production. Invasive infections: Pimples – are infections of hair follicles (folliculitis). If the hair follicle is an eyelash the disease is called a sty Furuncles (boils) – this is where an abscess develops from a pimple and is characterized by a region of pus surrounded by inflamed tissue Folliculitis Survey of Bacterial Diseases Carbuncles - are a series of interconnected furuncles with more extensive tissue invasion Septicemia – from carbuncles the organism may spread to the bloodstream to cause septicemia Staph. aureus may also cause impetigo (see Strep. skin infections), mainly in newborns Skin conditions due to toxin production: Scalded skin syndrome – this condition occurs when the organism produces an exotoxin called the exfoliative or epidermolytic toxin. The toxin causes the outer skin to peel away in layers. Toxic shock syndrome – exfoliation of the skin may also occur in cases of toxic shock syndrome involving tampon use in menstruating women. This is due to the effects of toxic shock syndrome toxin, type I. Scalded skin syndrome Survey of Bacterial Diseases Streptococcal skin infections –like S. aureus, Strep. pyogenes causes either invasive skin infections or skin conditions caused by toxin production. Invasive skin diseases: Impetigo – the disease is characterized by pustules that become crusted and rupture. This is very contagious and is easily spread from child to child in a day care setting. Impetigo Strep pyogenes infections Wound infections – occasionally causes wound infections following trauma. Usually due to simple contamination of the wound. Cellulitis – infection of subcutaneous tissue and may be accompanied by lymphangitis and abscess formation. Nectotizing fasciitis – when there is destruction of the fiberous tissue deep in skin including destruction of the sheath of tissue that covers the muscle. (“flesh eating bacteria”) Nectotizing fasciitis Strep pyogenes infections Myositis – is a result of Strep. invasion of muscle tissue resulting in extensive muscle necrosis and overwhelming sepsis. This is usually fatal. Scarlet fever Skin conditions due to toxin production The rash seen in scarlet fever is due to an erythrogenic toxin: Strep pyogenes infections Erysipelas – a diffuse, erythematous skin infection that is most often on the face following pharyngitis (due to toxin production) Survey of Bacterial Diseases Propionibacterium acne – involved in the pathogenesis of acne as previously discussed. Bacterial infections of the eye Conjunctivitis – as discussed previously, is an infection of the membranes that cover the eye and lining of the eyelid May be caused by many different organisms Contagious conjunctivitis (pinkeye) is caused by Haemophilus aegyptius. Gonococcal opthalmia neonatorum Caused by Neisseria gonorrhoeae Transmitted to newborns during the birth process as the baby moves down through the birth canal Gonococcal opthalmia neonatorum Neisseria gonorrhea Causes Neonatal Blindness Ophtalmia neonatorum caused by Neisseria gonorrheae Source: Microbiology Perspectives, 1999 Survey of Bacterial Diseases Prevented by giving all newborns eye drops containing antibiotics at birth Trachoma Caused by Chlamydia trachomatis Transmitted by direct contact Is the single most common cause of blindness in underdeveloped countries Trachoma Survey of Bacterial Diseases Bacterial diseases of the respiratory tract Pharyngitis = sore throat Caused mainly by Streptococcus pyogenes (The classic Strep. throat) Transmitted by respiratory secretions Symptoms include inflammation of the throat and fever Can lead to tonsilitis and middle ear infections Pharyngitis Survey of Bacterial Diseases Diphtheria Caused by Corynebacterium diphtheriae that has been lysogenized by a phage encoding the “tox” gene Starts with a sore throat and fever followed by general malaise and swelling of the neck A tough grayish membrane may form in the throat in response to the infection. This can cause suffocation The bacteria are not invasive, but when they liberate their exotoxin, death may occur due to its effects on the heart and kidneys D part of DPT vaccine Diphtheria Survey of Bacterial Diseases Otitis media (middle ear infection) Is an uncomfortable complication of the common cold or any infection of the nose or throat More common in children because the auditory tube is so small Most commonly caused by Strep. pneumoniae, Haemophilus influenzae, Strep. pyogenes, Staph. aurues, and Branhamella catarrhalis Survey of Bacterial Diseases Whooping cough Caused by Bordetella pertussis Transmitted by respiratory secretions The organism is not invasive, but it attaches to respiratory epithelia, impeding their action. This causes a build-up of mucous. The disease occurs in 3 stages Catarrhal stage - symptoms similar to the common cold Paroxysmal stage – characterized by prolonged sieges of coughing as the patient tries to get rid of the mucous that has built up. Gasping of air occurs between the coughs causing a whooping sound. Lasts 1-6 weeks Survey of Bacterial Diseases Convalescent stage – lasts several months P part of DPT vaccine Tuberculosis Both M. tuberculosis and M. bovis can cause Tb, but M. bovis is rare in the U.S. The organism can gain entrance by many portals of entry with inhalation being the most common Tubercle bacilli that reach the alveoli of the lung are ingested by macrophages Enzymes and cytokines are released to start an inflammatory response to wall off the organism (tubercle formation), but the inflammatory response also causes lung damage. Survey of Bacterial Diseases After a few weeks many of the macrophages die, releasing tubercle bacilli and forming a caseous center inside the tubercle. In healthy individuals, the disease is usually arrested at this time and the lesions may may become calcified. Tubercle bacilli may remain dormant in the lesion and serve as a basis for later reactivation of the disease. When the defenses fail, a mature tubercle may form and then the bacilli multiply. The tubercle eventually ruptures, releasing tubercle bacilli that can disseminate throughout the body. This is the progressive form of the disease and symptoms include weight loss, coughing with blood, and loss of vigor. Survey of Bacterial Diseases Pneumonia Characterized by fever, difficult breathing, and chest pain May be caused by many different organisms; Strep. pneumoniae – usually occurs following a primary infection elsewhere Klebsiella pneumoniae – permanent lung damage often occurs Mycoplasma pneumoniae – called walking pneumonia because individuals often do not know that they have the disease. Is also called an atypical pneumonia because the cough is not productive Legionellosis – caused by Legionella pneumpophilia Is transmitted by aerosols from contaminated water More common in older males Survey of Bacterial Diseases Bacterial diseases of the CNS Meningitis Can be caused by many different bacteria, but most cases are caused by: Neisseria meningitidis The disease starts out as a sore throat which progresses to bacteremia and then meningitis which is characterized by a severe headache, neck and back pain and stiffness. The endotoxin causes extensive blood vessel damage with petechiae being a hallmark symptom There is a vaccine against the most commonly encountered virulent types. Petechial rash Survey of Bacterial Diseases Haemophilus influenzae – caused by organisms containing the type b capsule Most commonly seen in children between the ages of two months to four years Hib vaccine Strep. pneumoniae Occurs most in immunocompromised individuals, the very young and the elderly There is a high mortality rate E coli, type K1 and Strep. agalactiae – Are the two most common causes of this disease in newborns The mortality rate is high Survey of Bacterial Diseases Tetanus Caused by Clostridium tetani Disease is due to the toxin tetanospasmin. Spores are found in feces, soil, and dust. Spores enter the body through penetrating wounds where they germinate into vegetative cells and subsequently produce toxin Symptoms begin with cramps and twitching of muscles around the wound. Headache and neck stiffness also occur. These are followed by trismus (lockjaw) and more generalized symptoms. Death, if it occurs, results from respiratory failure Tetanus Survey of Bacterial Diseases Botulism Caused by a toxin produced by Clostridium botulinum In the U.S. botulism usually occurs following ingestion of the toxin in inadequately processed home-canned food. The 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 Survey of Bacterial Diseases Leprosy Also called Hansen’s disease Caused by Mycobacterium leprae The disease is contagious, but requires prolonged, fairly intimate contact for transmission There are two major forms of the disease Tuberculoid – is characterized by lesions of the skin that have lost sensation Lepromatous – is characterized by disfiguring nodules that form mainly on the colder areas of the body – death occurs from complications of other bacterial infections Tuberculous form of leprosy Lepromatous form of leprosy Lepromatous form of leprosy Survey of Bacterial Diseases Bacterial diseases of the cardiovascular system Septicemia – a condition in which bacteria are actively multiplying in the blood. One symptom of this is lymphangitis where red streaks are seen in the skin radiating out from the initial site of infection Septicemia with lymphangitis Survey of Bacterial Diseases Endocarditis – is an inflammation of the endocardium which is the lining of epithelial cells in the heart and its valves Subacute bacterial endocarditis Occurs in individuals with an abnormal heart valve Due usually to viridans group Strep. and follows dental work or a primary infection elsewhere. Clots form and may break off to impair the function of the heart Symptoms include fever, anemia, general weakness and a heart murmur Survey of Bacterial Diseases Acute bacterial endocarditis Occurs in all individuals following a primary infection elsewhere Is characterized by rapid destruction of the heart valves Bacterial endocarditis Survey of bacterial diseases Rheumatic fever Is an autoimmune complication of Strep. pyogenes pharyngitis Can lead to heart damage, arthritis, and death Tularemia Also called rabbit fever because it is usually acquired by contact with infected rabbits Caused by Francisella tularensis Local inflammation may lead to septicemia, pneumonia and abscesses throughout the body Rheumatic fever Survey of bacterial diseases Brucellosis Also called undulent fever Caused by Brucella species Most commonly transmitted by unpasteurized milk A fever spike commonly occurs in the evening Anthrax Caused by Bacillus anthracis Is mainly a disease of grazing animals Can come in through a variety of portals of entry in man (skin, respiratory, GI tract) If it comes in through the skin a characteristic malignant pustules will result at the site of entry. The disease can progress to septicemia and death Death is usually due to the effects of a toxin produced by the organism Anthrax Survey of bacterial diseases Plague Caused by Yersinia pestis which is endemic in the mountains in Southern California There are two forms of the disease – bubonic plaque and pneumonic plague Bubonic plague is transmitted by rat fleas The organism gets into the bloodstream and makes its way to the regional lymph nodes which become painful and enlarged (called buboes and hence the name bubonic plaque). The mortality rate in untreated cases is high. When the organism gets into the lungs it can cause pneumonic plague which is transmitted from person to person via droplet infection. Has a higher mortality rate than bubonic plague (close to 100%) Buboes Survey of bacterial diseases Relapsing fever Caused by Borrelia species other than Borrelia burgdorferi Transmitted by ticks and lice Disease is characterized by high fever, jaundice, and rose colored spots Relapses occur because the organism undergoes antigenic variation. Each relapse is less severe than the preceding one Lyme disease Caused by Borrelia burgdorferi Transmitted by ticks Disease starts with a characteristic rash at the bite site (erythema chronicum migrans) followed by flu-like symptoms ECM – from Lyme disease Survey of bacterial diseases Years later neurological and heart problems as well as arthritis may occur and this is probably due to an immune reaction to remaining organisms Typhus – is characterized by a high, prolonged fever, stupor and small red spots Transmitted by human lice (epidemic) and rat flead (endemic) Caused by Rickettsia prowazekii (epidemic) and R. typhi (endemic) Survey of bacterial diseases Rocky mountain spotted fever Caused by Rickettsia rickettsii Transmitted by ticks Symptoms include high fever, headache, and a rash over the entire body Rocky mountain spotted fever Survey of bacterial diseases Diseases of the digestive system Dental caries – cavities caused by bacteria (species of Strep.) that ferment sugar releasing acid that destroys the enamel and dentin Dysentery = severe diarrhea with blood and/or pus Gastroenteritis = inflammation of the stomach and intestinal mucosa Survey of bacterial diseases Two basic types of disease may occur in the lower intestinal tract; Infection in which the organism attaches, invades, and multiplies. There is a delay in the appearance of symptoms as the organism multiplies. Symptoms include fever, diarrhea (dysentery may occur), nausea and possibly, vomiting. Organisms that may cause infection are Salmonella species, including Salmonella typhi which causes typhoid fever, Shigella species, Vibrio parahaemolyticus, Campylobacter jejuni, and certain strains of E. coli. Intoxication – here disease is due to the ingestion of a preformed toxin or to a toxin produced by an organism which is not invasive, but multiplies at the intestinal mucosa while liberating toxin. Survey of bacterial diseases Symptoms do NOT include fever, but may include abdominal cramps, watery diarrhea, nausea and vomiting. Organisms that may cause this type of intoxication include Staph. aureus, Vibrio cholera, and certain strains of E. coli Bacterial diseases of the urinary and reproductive systems Cystitis is an inflammation of the urinary bladder and symptoms include dysuria (difficult or painful urination) and pyuria (WBCs in the urine) Survey of bacterial diseases The most common cause of cystitis is E. coli, but other enterics as well as G+ bacteria may also cause the infection Gonorrhea Caused by Neisseria gonorrhoeae and usually transmitted by direct sexual contact. Those infected commonly have a concomitant Chlamydia trachomatis infection Asymptomatic infections- Males= 10%, Females= 2075%. The problem with asymptomatic individuals is that they are carriers and can transmit the disease to others. Uncomplicated infections - in males symptoms include acute urethritis with profuse purulent discharge filled with GC. If untreated may spread to cause prostitis and epididymitis Uncomplicated GC infection Survey of bacterial diseases Uncomplicated infections in females - may have increased vaginal discharge, burning or frequency of urination and menstrual abnormalities. Complicated infections Occur more frequently in women - spread from the cervix into the fallopian tubes resulting in endometritis, salpingitis, and peritonitis= pelvic inflammatory disease (PID). Occurs in 10-20% of infected women. Symptoms include lower abdominal pain, abnormal vaginal and cervical discharge, and uterine tenderness. This can result in ectopic pregnancy and infertility. Nongonococcal urethritis – caused by Chlamydia trachomatis with symptoms as above Salpingitis Survey of bacterial diseases Syphilis Caused by Treponema pallidum and is transmitted by direct sexual contact The normal untreated course of the disease occurs in several stages Primary stage – following penetration of the skin or mucous membranes, a characteristic, painless hard chancre develops at the site of entry. The chancre is highly contagious and filled with Treponemes. Simultaneously the organism enters the lymphatics and becomes disseminated. The chancre heals without treatment in a few weeks due to local immunity, but by that time the organism has already disseminated. Primary syphilis Survey of bacterial diseases Secondary stage – 4-8 weeks after the primary stage, the secondary stage develops. Typically there are lesions (filled with treponemes) throughout the body including the skin, mucous membranes, organs, and eyes. Most lesions are on the skin and mucous membranes. The patient may also have a loss of hair, a mild fever, and the development of malaise. This also heals without treatment and the patient may either spontaneously get well or develop a latent infection Secondary syphilis Survey of bacterial diseases Tertiary syphilis – this stage is characterized by granulomatous lesions, called gummas, of the skin, internal organs, CNS, bones, eyes, and cardiovascular system. They are caused by the body’s hyperimmune reaction to remaining spirochetes Tertiary syphilis