Bacterial Infections of the Lower Respiratory System

lower bacterial vs upper bacterial infection differences

lower are less common but more serious (life-threatening)

examples of lower respiratory infections

pneumonias, whooping cough, TB, Legionnaires

Pneumoccal pneumonia

bacterial pneumonia

Pneumoccal pneumonia signs and symptoms

cough, sudden chills and fever, shortness of breath, chest pain, cyanosis, resut-colored sputum from blood

incubation period of Pneumoccal pneumonia

1-3 days

causative agent of Pneumoccal pneumonia

Streptococcus pneumonia (Gram + diplococcus) = pneumococcus

how does Pneumoccal pneumonia resist phagocytosis

thick polysaccharide capsule interferes with the action of C3B (prevents opsonization)

do strains of Streptococcus pneumonia that lack a capsule cause disease?

no

pathogenesis of Pneumoccal pneumonia

inhalation of infected droplets

colonization of alveoli triggers and inflammatory response

fluid and inflammatory cells fill alveoli

produce pneumolysin -> pleurisy

pneumolysin

membrane damaging toxin that destroys ciliated epithelium & activates inflammatory response

what can happen if Pneumoccal pneumonia enters the bloodstream?

septicemia

endocarditis

meningitis

What are the carrier rates for pneumococcal pneumonia?

High

What conditions increase the risk of pneumococcal pneumonia?

Alcoholism, narcotic use, and viral infections impairing the mucociliary escalator

Which chronic diseases increase the risk of pneumococcal pneumonia?

Chronic lung disease, chronic heart disease, diabetes, and cancer

prevention of Pneumoccal pneumonia in children under 2, adults over 65, and immunocompromised

PCV13 - conjugate vaccine against 13 serotypes

prevention of Pneumoccal pneumonia in adults over 65 and high-risk individuals (2+)

polysaccharide vaccine againt 23 serotypes

NOT FOR CHILDREN <2

treatment for Pneumoccal pneumonia

antibiotics

penicillin

What type of bacteria is Klebsiella species?

Enterobacteria

What is the shape and Gram stain of Klebsiella species?

Gram-negative rods with a large capsule

What condition does Klebsiella species commonly cause?

Pneumonia, especially if host defenses are impaired

Are Klebsiella pneumonia common hospital-acquired pathogens?

Yes - cause most of the deaths from HAIs

signs and symptoms of Klebsiella pneumonia

chest pain, cyanosis, blood jelly-like sputum

IMPORTANT factors for Klebsiella pneumonia

bloody jelly-like sputum

mucoid colonies that string out when touched

Gram - bacteria

incubation period of Klebsiella pneumonia

1-3 days

causative agent of Klebsiella pneumonia

Kiebsiella pneumoniae, encapsulation enterobacterium

in what way is pathogenesis of Klebsiella pneumonia similar to S. penumoniae?

capsule is essential virulence factor

Klebsiella pneumonia pathogenesis

inhalation of colonized mucus droplets

destruction of lung tissue and abscess formation (in liver and brain)

infection spreads to blood

case fatality rate of Klebsiella pneumonia

50% even with treatment

where do Klebsiella pneumonia colonize in humans?

throat, GI tract, skin

can become part of normal microbioata

Klebsiella pneumonia causes

endotoxic or septic shock

permanent lung damage, death (even with antibacterials)

Klebsiella pneumonia produces

siderophore - induces inflammation and enhances the spread of bacterium

Klebsiella pneumonia v. Pneumococcal pneumonia tissue damage

Klebsiella pneumonia results in more damage

Klebsiella pneumonia epidemiology

attack very young, old, alcoholics, nursing home residents, and immunocompromised persons

treatment of Klebsiella pneumonia

combination of antibiotics

resistance is an issue

surgery (drain abscesses)

prevention of Klebsiella pneumonia

no vaccine available

Mycoplasmal pneumonia are most common in which group of people

children, young adults (college students), military recruits

greatest in crowded conditions

Mycoplasmal pneumonia is also known as

walking pneumonia bc disease is usually mild

considered an atypical pneumonia

Mycoplasmal pneumonia signs and symptoms

gradual onset of dry cough

tiny colonies with fried egg appearance

incubation period of Mycoplasmal pneumonia

2-3 weeks

Mycoplasmal pneumonia causative agent

Mycoplasma pneumonia

lacks cell wall

grows slowly and aerobic

tiny colonies with fried egg appearance

pathogenesis of Mycoplasmal pneumonia

inhalation of infected droplets

damage to respiratory epithelium, inflammatory response and destruction of cells via CARD toxin

inflammatory response to M. pneumonia causes

thickening of walls of the bronchial tubes and alveoli

Virulence factor of M. pneumonia

community acquired respiratory distress syndrome (CARDS) toxin

epidemiology of Mycoplasmal pneumonia

mild infections common

infected people spread the disease

treatment of Mycoplasmal pneumonia

antibiotics - excluding cell wall synthesis

prevention of Mycoplasmal pneumonia

NO VACCINE

avoid crowding in school and military facilities

Mycoplasmal pneumonia spread by

aerosolized droplets of respiratory secretions

Whooping cough is also known as

pertussis

signs and symptoms of Whooping cough

incubation period 1-2 weeks and characterized by 3 stages: Catarrhal, Paroxysmal, and convalescent

Catarrhal stage

inflammation of mucous membranes

duration of Catarrhal stage

1-2 weeks

signs and symptoms of Catarrhal stage

runny nose, sneezing, low fever, mild cough

patients are most contagious in which stage of whooping cough?

Catarrhal stage

paroxysmal stage of whooping cough length

2-4 weeks

paroxysmal stage is characterized by

frequent burst of violet, uncontrollable coughing

cough is dry and followed by forceful attempts to inhale (gasping)

what severe effects can the pertussis cough cause?

rupture eyes blood vessels, cause tongue to protrude out & neck veins to stand out

vomiting and seizures - patient can become cyanotic

convalescent stage of whooping cough

recovery - no longer contagious

coughing attacks less frequent

What is the causative agent of pertussis?

Bordetella pertussis

What type of bacteria is Bordetella pertussis?

Tiny Gram-negative rod that is encapsulated

What is the oxygen requirement for Bordetella pertussis?

It is strictly aerobic.

How does Bordetella pertussis respond to drying and sunlight?

It is sensitive to drying and sunlight.

How quickly does Bordetella pertussis die inside the host?

It quickly dies inside the host.

What is the first step in the pathogenesis of whooping cough?

Colonization of ciliated respiratory tract surfaces

What type of substances are produced by the bacteria in whooping cough?

Destructive toxins

What are the effects of whooping cough on mucus and ciliary action?

Increased mucus along with decreased ciliary action results in severe coughing spasms

What happens to air in the bronchioles during whooping cough?

Air can enter bronchioles but not escape

epithelial attachment of whooping cough is aided by which two colonization factors

1. Filamentous hemagglutinatinin

2. pertactin

filamentous hemagglutinin

a pilus that extends from the bacterial surface

pertactin

acts as an adhesin

3 toxins produced by whooping cough

1. pertussis toxin

2. adenylate cyclase toxin

3. tracheal cytotoxin

pertussis toxin

A-B toxin that causes increased production of cAMP which interferes with cell signaling pathways

what does pertussis toxin result in

1. marked increase in mucus output

2. decreased killing ability of phagocytes

3. massive release of lymphocytes into the blood

4. ineffectiveness of NK cells

5. low blood sugar

adenylate cyclase toxin

membrane damaging toxin and enzyme that converts ATP to cAMP

adenylate cyclase toxin results

reduces phagocytosis by lysis of leukocytes

Tracheal cytotoxin

causes release of fever-inducing cytokine (IL-1) & sloughing & death of ciliated epithelial cells

epidemiology of whooping cough

inhalation of infected droplets - highly contagious

older children and adults have mild symptoms

severe in infants

treatment of whooping cough

certain antibiotics given before coughing spasms start

prevention of whooping cough

acellular vaccine (DTap) for immunization of infants and children

Tdap booster for adolescents, pregnant women, and adults every 10 years