Transcript Lecture 10 - Bacteria2003 - Cal State LA

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