Download Bacteriology - UAB School of Optometry

Bacteriology:
1. Staphylococcus aureus
a. It is β-hemolytic, catalase-positive, coagulase-positive, and gram-positive.
b. GI: Produces heat-stable enterotoxins in poorly refrigerated, high-protein
foods. It is spread to food from the nares or from lesions of food
preparers.
c. Clinically, has rapid onset with nausea, GI pain, vomiting, and diarrhea.
d. Heart: Causes bacterial endocarditis (usually acute). It has properties that
allow it to adhere to heart valves as well as prosthetic replacement valves.
e. Clinically, the infection rapidly damages the heart. Coagulase allows
formation of platelet and fibrin clots. Cytolytic toxins damage heart cells
(common in IV drug users).
f. Skin: It is the major cause of infections in hospitalized patients. It has a
high resistance of drug resistance and is controlled primarily by
phagocytic destruction.
g. Clinically, skin infections include inpetigo (often bullous), boils
(furuncles), carbuncles, styes, and surgical wound, burn, or traumaticlesion infections. Scalded skin syndrome occurs in children younger than
five. Other infections include toxic shock syndrome, food poisoning,
pneumonia, osteomyelitis, and endocarditis.
2. Staphylococcus epidermidis
a. It is coagulase-negative and is sensitive to novobiocin. It has a remarkable
ability to adhere to artificial materials in the body.
b. Clinically, associated with bacterial endocarditis in the heart. It occurs
generally with prosthetic valves or IV drug users, and it is chronic.
3. Staphylococcus saprophyticus
a. It is catalase-positive and gram-positive. It is nonhemolytic, coagulasenegative, and resistant to novobiocin. It is nitrite negative. It adheres to
uroepithelial cells.
b. Clinically, causes urinary tract infections in sexually active young women
(“honeymoon cystitis”).
4. Streptococcus pneumoniae
a. It is gram-positive, α-hemolytic, and a lancet-shaped diplococcus. It
possesses a group-specific carbohydrate common to all pneumococci,
which can be precipitated by a C-reactive protein found in the plasma
during an inflammatory response. Types can be distinguished by swelling
of the capsule in the presence of type-specific antiserum (quellung
reaction).
b. Differentiated from other streptococci because it is sensitive to optochin,
sensitive to bile, and ferments inulin.
c. Clinically, associated with lower respiratory tract infections. Infants,
elderly, immunosuppressed persons, and chronic alcoholics are most
vulnerable.
d. Self-infection can occur by aspiration after epiglottal reflexes have been
slowed due to chilling, anesthesia, morphine, alcohol, virus infection, or
increased pulmonary edema.
e. Manifestations include abrupt onset, fever, chills, chest pain, and
productive cough. Recovery is often associated with the appearance of an
anticapsular antibody.
f. The disease is identified by culture of lung sputum, followed by typing via
the quellung reaction.
g. Treatment includes penicillin and other antibiotics. An effective vaccine
for adults is also available.
5. Streptococcus pyogenes
a. It occurs as single, paired, or chained gram-positive cocci, depending on
the environment. It is a facultative anaerobe. It causes multiple clinical
conditions.
b. It is classified as group A of the 21 Lancefield groups of streptococci,
because it contains group A-specific carbohydrate and several antigenic
proteins (M, T, and R antigens) in the cell wall.
c. It is classified into the β-hemolytic group. It is sensitive to bacitracin, an
antibacterial polypeptide, in contrast to other streptococci. It is catalasenegative.
d. Clinically, in upper respiratory tract infections, it is responsible for
streptococcal pharyngitis, scarlet fever, and rheumatic fever.
e. Streptococcal pharyngitis is characterized by sore throat, fever, headache,
nausea, cervical lymphadenopathy, and leukocytosis. It can result in
complications; it can also result in intense pharyngeal redness, edema of
the mucous membranes, and a purulent exudate. It can be treated by
penicillin.
f. Scarlet fever exhibits symptoms resembling those of streptococcal
pharyngitis. It is accompanied by a rash caused by phage-coded
erythrogenic toxins.
g. Rheumatic fever follows group A streptococcal throat infections in
genetically predisposed people. It results in a systemic inflammatory
process involving the connective tissue, heart, joints, and CNS, and may
lead to progressive chronic debilitation. It may damage heart muscles and
valves, with mitral stenosis as a lesion hallmark. It should be treated
promptly with penicillin.
h. In skin and soft tissue infections, it can result in impetigo, cellulitis and
erysipelas, or fasciitis.
i. Impetigo is an easily spread exudative infection of the epidermis occurring
primarily in children. It may result in nephritis as a complication. It
should be treated with penicillin.
j. Cellulitis and erysipelas are initiated by infection through a small break in
the skin. Cellulitis applies if the lesion is confined; erysipelas applies if
the lesion spreads.
k. Fasciitis is a rapidly spreading, dangerous infection of the fascia. It tends
to occur in diabetic patients who are particularly susceptible. Infections
necessitate rapid surgical debridement of necrotic tissue followed by
therapy with antibiotics.
6. Streptococcus agalactiae
a. It is a β-hemolytic, gram-positive cocci. It occurs frequently as part of the
normal vaginal and oral flora in adult women. The colonization of the
female genital tract predisposes newborns to infection, sepsis, and
meningitis.
b. Clinically, it is a central nervous system infection and can occur as
early-onset neonatal sepsis or late-onset neonatal sepsis.
c. In early-onset neonatal sepsis, it occurs readily in newborns, but only 1 in
100 infected newborns become ill. It is associated with obstetric
complications, premature birth, and respiratory distress (50% fatality rate).
d. In late-onset neonatal sepsis, it is characterized by meningitis, and
commonly leads to permanent neurologic damage. It has a fatality rate of
15-20%.
e. Penicillin G generally is given for treatment.
7. Viridans streptococci
a. They are α-hemolytic, are uninhibited by optochin, and are not bile
soluble. They predominate in the normal human oral cavity. Unlike other
streptococci, they cannot be classified by group-specific antigens. They
include 19 species (most common are Strep. salivarius, Strep. mutans,
Strep. mitis, and Strep. sanguis).
b. Organisms are generally non-invasive opportunists, and no attributes of
pathogenicity have been identified.
c. Clinically, on access to the blood stream, they are the most frequent cause
of subacute bacterial endocarditis. They are a major cause of dental
caries.
d. Treatment is with penicillin, which generally is effective.
8. Enterococcus faecalis
a. It is a β-hemolytic, gram-positive coccus that occurs as part of the normal
intestinal and oral flora in humans and animals. It is a facultative
anaerobe.
b. Organisms are generally noninvasive opportunists; however, they are a
leading cause of nosocomial infections.
c. Clinically, disease includes urinary tract infections, septicemia, and
associated endocarditis.
d. The organisms are relatively resistant to many antibiotics; it is inhibited
but not killed by penicillin.
9. Listeria monocytogenes
a. It is a gram-positive, facultative-intracellular bacillus that has tumbling
motility at room temperatures and is a psychrophile. Exposure comes
from vertebrate feces contaminating dairy products, deli meats and
cheeses, unheated hotdogs, and uncooked cabbage.
b. Its pathogenicity is intracellular. It “reorganizes” host cell actin; the
resulting actin trails propel Listeria directly into other cells.
c. Clinically, infections in pregnant women result in flu-like symptoms with
fever and the potential of transplacental transfer of listeria to the fetus.
Granulomatosis infantiseptica (from in utero infection) results in widely
distributed abscesses and granulomas in the fetus. The fatality rate is 30100%.
d. Meningoencephalitis occurs in neonates, patients with malignancy,
immunocompromised patients, and adults older than 40 years of age. It is
the most common meningitis to occur in immunocompromised patients.
e. Septicemia occurs in the same population.
f. Focal lesions results from direct contact, generally as eye or skin lesions.
g. Treatment is ampicillin (intravenous) for infected pregnant women. The
prognosis is poor.
h. Pasteurization kills Listeria in milk.
10.Corynebacterium diphtheriae
a. It is a gram-positive, club-shaped rod often occurring in V- and L-shaped
arrangements that produce large volutin granules.
b. It is a potent A-B exotoxin, with the B component binding to specific cell
membrane receptors required to trigger uptake of the A component by the
cell.
c. Clinically, it causes upper respiratory diphtheria (pseudomembranous
pharyngitis). It is rare, and begins as a mild pharyngitis with slight fever
and chills. It then spreads up to the nasopharynx or down to the larynx
and trachea. The bacteria themselves do not disseminate but elaborate the
diphtheria exotoxin, which circulates and causes additional symptoms
such as hoarseness and stridor. It causes cervical adenitis and edema.
d. Treatment is with antitoxin and erythromycin. Prevention is by proper
vaccination, although it does not prevent colonization.
11.Bacillus anthracis
a. It causes anthrax. It is a spore former. Spores play an important role in
transmission.
b. Clinically, cutaneous anthrax results from entry of spores unto a cut or an
abrasion; the fatality rate is 10%. Pulmonary anthrax occurs in 5% of
anthrax cases and results from entry of spores into the lungs; the fatality
rate is 50%.
c. Treatment is with intravenous penicillin.
d. End of first quiz material.
12.Neisseria meningitidis
a. It is a gram-negative, oxidase-positive bacterium with the ability to use
both glucose and maltose. It colonizes upper respiratory membranes
before causing meningococcemia.
b. There are nine different capsular serogroups; most infections in the U.S.
are caused by B, C, and Y serogroups.
c. It possesses a capsular polysaccharide that inhibits phagocytosis. It also
possesses an LPS, causing extensive tissue necrosis, hemorrhage,
circulatory collapse, intravascular coagulation, and shock. It also
possesses an IgA protease that degrades IgA1.
d. Clinically, the disease begins as mild pharyngitis with occasional slight
fever. In the susceptible age-group, organisms disseminate to most
tissues, resulting in a fulminant meningococcemia (fatal in 1-5 days).
Initial signs and symptoms are fever, vomiting, headache, and stiff neck.
A petechial eruption then develops that progresses from erythematous
macules to frank purpura. Waterhouse-Friderichsen syndrome is
fulminating meningococcemia with hemorrhage, circulatory failure, and
adrenal insufficiency.
e. Treatment requires early diagnosis and prompt hospitalization to be
successful. Treatment is with high-dose intravenous penicillin and
requires supportive measures against shock and intravascular coagulation.
13.Neisseria gonorrhoeae.
a. It is an oxidase-positive, gram-negative diplococcus with a “kidney bean”
morphologic appearance. It is epidemic, with the highest incidence in the
most sexually active group (15-25 year olds).
b. It does not ferment maltose.
c. It possesses a plasmid that codes for penicillinase production. It also
possesses pili, which are protein surface fibrils that mediate attachment to
the mucosal epithelium. It produces an IgA protease that degrades IgA1.
d. Clinically, it results in mucous membrane infections, primarily in the
anterior urogenital tract. It is absent in 20-80% of women and 10% of
infected men (these asymptomatic carriers may transmit the bacteria).
Repeated infection may cause scarring with subsequent sterility. There
are various types of infections, including:
i. Urethritis in men is characterized by thick, yellow, purulent
exudate; frequent, painful urination; and possibly an erythematous
meatus.
ii. Endocervicitis or urethritis in women is characterized by a purulent
vaginal discharge; frequent, painful urination; and abdominal pain.
iii. Rectal infections (prevalent in gays) are characterized by painful
defecation, discharge, constipation, and proctitis.
iv. Pharyngitis is characterized by purulent exudate; the mild form
mimics viral sore throat, whereas the severe form mimics
streptococcal sore throat.
v. Disseminated infection (blood stream invasion) is infection in
which organisms initially localize in the skin, causing dermatitis,
then spread to the joints, causing overt, painful arthritis.
vi. Infant eye infection (ophthalmia neonatorum), which is contracted
during passage through the birth canal, is characterized by severe,
bilateral purulent conjunctivitis that may rapidly lead to blindness.
e. For treatment, ceftriaxone should be given, followed by a tetracycline. In
about 50% of cases, pelvic inflammatory disease is severe enough to
warrant hospitalization.
14.Chlamydia trachomatis
a. It is an obligate intracellular pathogen. It has a cell wall, but the cell wall
lacks peptidoglycan. It is differentiated into 15 serotypes.
b. Clinically (subtypes D-K), it causes a sexually transmitted disease that
may involve associated inclusion conjunctivitis. It is a prominent cause of
nongonococcal urethritis in men and urethritis, cervicitis, salpingitis, and
pelvic inflammatory disease in women.
c. Clinically (subtypes L1, L2, L3), it causes a sexually transmitted disease
called lymphogranuloma venereum, which is characterized by a
suppurative inguinal adenitis. It may cause lymphadenitis to progress to
lymphatic obstruction and rectal strictures if untreated.
d. Clinically (subtypes A-C), it causes a chronic keratoconjunctivitis
(trachoma) that can progress to conjunctival and corneal scarring and
blindness. It is frequently accompanied by a concomitant secondary
bacterial infection.
e. Treatment is with doxycycline or erythromycin.
15.Chlamydia psittaci
a. Characteristics are similar to C. trachomatis. It exists in two forms:
i. An elementary body, which is infectious.
ii. A reticular body, which is the intracellular reproductive form.
b. Clinically, it is a natural disease of birds. It is also a zoonotic human
disease of the lower respiratory tract that ranges from subclinical to fatal
pneumonia. It is an occupational disease associated with the raising and
processing of poultry.
16.Chlamydophila pneumoniae
a. It was formerly known as the TWAR agent. It has the same characteristics
as those listed for C. psittaci.
b. Clinically, it causes various lower respiratory tract infections, including
bronchitis and pneumonia. It causes “walking pneumonia” in young
adults.
17.Treponema pallidum
a. It is a corkscrew-shaped, motile organism with unusual morphologic
appearance of the outer envelope, three axial filaments, a cytoplasmic
membrane-cell wall complex with endotoxin, and a protoplasmic cylinder.
It causes chronic, painless infections that may last 30-40 years if
untreated. It causes syphilis, which is sexually transmitted, epidemic
worldwide, and may affect any tissue.
b. Clinically, vascular involvement leads to endarteritis and periarteritis,
resulting in inhibited blood supply and necrosis. Lymphocyte and plasma
cell infiltration occurs at sites of infection. The pathogenesis of syphilis is
generally divided into three stages:
i. Primary – localized infection with erythema, induration with a firm
base (hard chancre), and ulceration.
ii. Secondary – disseminated infection with lesions in almost all
tissues; mucocutaneous rash; may recur if untreated.
iii. Tertiary – aortitis and CNS problems may be fatal.
c. In utero infection has severe manifestations, including abortion, stillbirth,
birth defects, or latent infection with the snuffles followed by a rash and
desquamation.
d. Treatment is with long-acting penicillin. In pregnant patients, serologic
syphilis tests should be performed during the first and third trimesters.
18.Borrelia burgdorferi
a. It is a large, motile spirochete that causes Lyme disease. It is carried by
Ixodes ticks.
b. Clinically, it is a blood stream infection that seeds other tissues, especially
the brain, heart, and joints.
i. Stage 1. The hallmark is erythema (chronicum) migrans, an
annular lesion with a rashy border and central clearing that spreads
out from the site of the tick bite. Malaise, fatigue, headache, fever,
chills, stiff neck, aches, and pains occur for several weeks.
ii. Stage 2. Neural and cardiac problems arise, including meningitis,
cranial neuropathy, radiculoneuropathy, and some cardiac
dysfunction.
iii. Stage 3. Joint problems occur, especially in large joints, producing
oligoarthritis. Intermittent bouts of arthritis may recur for 3-7
years. Neural dysfunction may lead to dementia and paralysis.
c. Treatment for primary infection is with doxycycline, amoxicillin, or
cefuroxime.
19.Leptospira
a. It is a spiral and an obligate anaerobe that grows in artificial media
supplemented by rabbit serum (may require four weeks)
b. Clinically, it is associated with liver disease.
20.Rickettsia rickettsii
a. It is a weakly staining gram-negative, obligate intracellular bacterium with
a specific predilection for endothelial cells of capillaries. It causes a
zoonotic disease in which ticks are vectors of human disease. It induces
variable clinical manifestations, ranging from benign and self-limiting to
highly fulminant, which is highly fatal.
b. Clinically, multisystemic diseases of endothelial cells occur, resulting in
hyperplasia, thrombus formation, inhibited blood supply, angiitis, and
peripheral vasculitis. General rickettsial manifestations involve abrupt
onset of high fever, chills, headache, and myalgias. Rocky Mountain
spotted fever initially causes a rash on the extremities, which spreads to
the trunk. The fatality ranges from 20-30%.
c. As for treatment, doxycycline is the drug of choice.
21.Bacteroides fragilis
a. It is a gram-negative, anaerobic rod, usually pleomorphic, with vacuoles
and swelling. It is a non-spore-forming anaerobe. It contains levels of
superoxide dismutase and catalase, which makes it somewhat resistant to
short exposure to oxygen.
b. It is a part of the normal flora of the upper respiratory tract, intestinal tract,
and female genital tract.
c. Clinically, it causes cellulitis and necrotizing fasciitis, especially in
diabetic patients, similar to group A streptococci. Infection is treated with
surgical debridement and drainage, followed by treatment with
metronidazole.
d. Clinically, also causes abscess formation with mixed anaerobic and
facultative anaerobic bacteria.
22.Prevotella melaninogenica
a. It is a small, gram-negative, anaerobic coccobacillus with occasional long
forms. It has distinctive black colonies on agar. It produces a potent
endotoxin and a collagenase.
b. Clinically, it cause lung abscesses; putrid sputum is a clue to anaerobic
lung infection. It also causes infections of the female genital tract.
23.Fusobacterium nucleatum
a. They are gram-negative, polymorphic, long, slender filaments and
fusiform rods. They are non-spore-forming anaerobes sensitive to oxygen.
b. They are usually present in mixed infections but may be the sole agent.
They are present in both the upper respiratory tract and the intestinal tract.
c. Clinically, they act synergistically with oral spirochetes, resulting in an
ulcerating, necrotizing gingivitis (Vincent’s angina, or trench mouth).
24.Actinomyces israelii
a. It is a gram-positive anaerobic bacillus. It is slow-growing and difficult to
isolate. It causes extensive soft tissue involvement crossing tissue plane
and involving multiple organ systems.
b. Clinically, it can cause cervicofacial actinomycosis (lumpy jaw), which
most commonly begins after dental work is performed.
c. It also causes mycetoma, which is an infection of the limb, with swelling,
sinus tract formation and draining, with “sulfur granules.”
25.Propionibacterium
a. It is a gram-positive anaerobic bacillus. It is an unusual cause of infection
which is part of the normal flora of the skin. It may be difficult to
determine the role of blood isolates in disease.
26.Lactobacillus
a. It is a gram-positive anaerobic bacillus. It is part of the normal flora of the
vagina. It is also a rare cause of disease.
27.Clostridium tetani
a. The clostridium genus is the only genus of anaerobes that forms
spores.
b. C. tetani is a gram-positive, spore-forming anaerobe. It is characterized
by in vivo toxin production.
c. Clinically, infection follows minor trauma or occurs as umbilical cord
stump infection in a neonate. Manifestations include muscle stiffness,
tetanospasms of lockjaw and back arching, and short, frequent spasms of
voluntary muscles.
28.Clostridium botulinum
a. It is a gram-positive spore-forming anaerobic rod.
b. Clinically, food poisoning follows ingestion of the preformed toxin in
contaminated food.
29.Clostridium perfringens
a. It is a large gram-positive, anaerobic, spore-forming rod. It produces 12
exotoxins causing food poisoning.
b. Clinically, it causes myonecrosis (gas gangrene) or destruction of
traumatized tissue and surrounding healthy tissue. This is associated with
phospholipase C (α-toxin) and H2 and CO2.
c. Clinically, it also causes food poisoning following ingestion of
contaminated food containing a preformed enterotoxin.
30.Clostridium septicum
a. This is associated with malignancy and neutropenia.
31.Clostridium difficile
a. It produces two toxins: an enterotoxin that causes gastrointestinal upset
and a cytotoxin that kills mucosal cells.
b. Clinically, it occurs as severe gastroenteritis, termed pseudomembranous
colitis or antibiotic-associated colitis, and follows antibiotic therapy to
treat other bacterial infections.
32.Haemophilus influenzae
a. It is a gram-negative, pleomorphic rod. It is “blood-loving.” It is a
facultative anaerobe, and is non-hemolytic.
b. Pathogenesis: It has a polysaccharide capsule that is antiphagocytic (type
B) that is a major virulence factor. It has IgA protease. It also has
endotoxins that activate macrophages and damage respiratory epithelium,
leading to bacteremic spread.
c. It is detectable on chocolate agar, but not on blood or MacConkey agar. 510% CO2 is required, as well as X (hemin) and V (NAD) growth factors,
which are both found in red blood cells but must be released by lysis. It is
also satellitic with S. aureus.
d. Clinically, the common infections include otitis media and sinusitis in
individuals of any age, and bronchitis and pneumonia in people with
COPD. Rare infections include acute bacterial meningitis and epiglottitis
in unvaccinated children. The biotype aegyptius causes bacterial “pink
eye,” which is an epidemic, purulent conjunctivitis that occurs often in
school-age children but also spreads to adults.
e. Prevention: Hib conjugate vaccine (the type B polysaccharide capsule
complexed to protein).
33.Bordetella pertussis
a. It is a strict aerobic, gram-negative coccobacillus. It is slow-growing,
encapsulated, fastidious, non-fermentative, and it oxidizes amino acids.
b. Clinically, it causes whooping cough. This disease is localized only in the
respiratory tract and is highly contagious. There are three distinct stages:
i. Catarrhal stage: mild upper respiratory tract infection with
c.
d.
e.
f.
sneezing, slight cough, low fever, and runny nose (lasts 1-2
weeks).
ii. Paroxysmal stage: extends to the lower respiratory tract, with
severe cough; little time to breathe causes anoxia and vomiting
(lasts 1-6 weeks).
iii. Convalescent stage: less severe cough that may persist for several
months.
In the laboratory, complete blood count may reveal lymphocytosis.
Recovery confers immunity.
Pathogenesis: Attaches to ciliated respiratory epithelium by various
adhesins, which include filamentous hemagglutins and the pertussis toxin.
Evasion of the host defense results in impaired chemotaxis. Local tissue
damage and systemic disease are caused by exotoxins.
Detection is with a nasopharyngeal (NP) swab collected at bedside and
plated on Regan-Lowe or Bordet-Gengou media. It is identified by
immunofluorescence or slide agglutination.
Prevention is with an acellular vaccine (DTaP) during infancy.
34.Legionella pneumophila
a. It is a gram-negative, rod-shaped bacterium that may form longer
catalase-negative?
filaments. It is fastidious,
, facultatively
intracellular, non-fermentative, and stains poorly with safranin.
b. Pathogenesis: The organism is inhaled from the environment, grows
intracellulary, and fails to activate the alternate complement pathway.
c. Clinically, it causes pneumonia (legionnaires’ disease), which is acquired
by inhalation of the organism from environmental sources. It is most
common in smokers and in the presence of an organ transplant, T-cell
defect, or chronic lung disease. Infections peak in frequency from July to
October (AC cooling towers). It is not transmitted by person-to-person
contact. There is a purulent, alveolar exudate, and there are GI and renal
manifestations. There is no vaccine. Prevention is by decontaminating
cooling towers, shower heads, etc.
35.Moraxella catarrhalis
a. It is a gram-negative coccus that may be carried in the URT of healthy
children. It causes bronchitis, CAP, sinusitis, and otitis. Occasionally, it
causes non-respiratory infections. Most strains produce beta lactamase.
36.Mycoplasma pneumoniae
a. Mycoplasma pneumoniae and all mycoplasmata are the smallest of the
bacteria (>150 species). Only four are human pathogens, though.
b. M. pneumoniae lacks a cell wall (pleomorphic) and requires cholesterol
for growth. It is an extracellular, mucous membrane pathogen that does
not invade other tissues.
c. Pathogenicity: It attaches to human mucosal cells by the P1 protein
(cytadherence). It releases H2O2 (cytotoxicity hemolysin – ciliostasis),
damaging epithelial cells and producing a long-lasting, hacking cough. It
possesses altered macromolecular synthesis. Fusion of the mycoplasma
membrane with the host may deposit mycoplasma antigens, which then
play a role in autoimmune-like reactions.
d. Clinically, it causes pharyngitis and tracheobronchitis. It also causes
primary atypical pneumonia (walking pneumonia). This is the most
common cause of pneumonia from 5-15 years of age. There may be a role
in asthma. Re-infection is common (there is no protective immunity).
e. Detection is with enriched agar medium (SP4 + serum) and growth is slow
(5-20 days).
37.Mycoplasma genitalium
a. Clinically, it causes commensals in lower urogenital tract in normal
sexually active adults.
b. Detection is with a culture good for rapid growth. PCR is needed for M.
genitalium.
38.Yaddi yaddi
39.