Transcript 10 M301 Bacteria 2011 - Cal State LA

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
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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
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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
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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
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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
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UTI and STD
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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