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What diseases are What diseases are caused by caused by bacteria?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

Ophtalmia neonatorum caused by Neisseria gonorrheaeSource: Microbiology Perspectives, 1999

Neisseria gonorrhea Causes Neonatal Blindness

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

Plague: Bubonic/

Pneumonic

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%)

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=

20-75% 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