LECOM Microbiology Lecture 6

causative factor of scarlet fever

pyrogenic exotoxin

What is the bacterial cause of pharyngitis?

Streptococcus pyogenes; Group A beta hemolytic strep (GAbS)

streptococcus pyogenes grams stain, catalase, and blood agar results

- Gram Positive, cocci

o Catalase negative

o Beta-hemolytic on blood agar plate (complete, clear)

Transmission of pharyngitis

respiratory droplets

symptoms of pharyngitis

· Abrupt onset fever, sore throat (scratchy throat) with exudate (pus- WBCs, white patches in the back of throat), difficulty swallowing, may have abdominal pain, nausea, vomiting.

o Suppurative infection- produces pus

how to diagnose pharyngitis?

rapid strep test

at risk population for pharyngitis

children and teenagers

what causes the common cold?

Rhinovirus

What is the viral family that causes the common cold?

Picornaviridae

genomic: Naked, (+) ssRNA

special characteristics for rhinovirus

prefers 33-35 degrees

ICAM-1 receptors on cells

what are the signs and symptoms for the common cold (rhinovirus)

sore throat, rhinorrhea (runny nose), coughing, sneezing, body aches, malaise, headache.

how to prevent the common cold?

wash hands and avoid touching face

what is the treatment for the common cold?

supportive care- rest, hydration, antihistamines, nasal decongestants

what complications can arise from the common cold?

otitis media (ear infection), sinusitis, chronic bronchitis, exacerbations of reactive airway disease (asthma, COPD, etc.)

how does the common cold transmit

aerosols

Adenovirus causes what disease?

Acute respiratory disease

Adenovirus characteristics

dsDNA virus, naked

transmission of adenovirus

aerosols, fecal matter

What makes acute respiratory disease deadly?

pneumonia (this disease is deadly in health individuals)

what is the common population for Acute Respiratory Disease?

military recruits, serotypes 4, 7

what are the signs and symptoms of Acute respiratory disease?

Fever, runny nose, cough, pharyngitis, and possible conjunctivitis

what is the vaccine/prevention method for acute respiratory disease and who is it used for?

· Live attenuated, oral vaccine (specific for only military recruits)

o Causes immune response in mucosal tissue, goes right to target.

§ Mucosal tissue (in intestine) has IgA antibody.

· Causes the symptoms.

virulence factors of streptococcus pyogenes

*M protein (antiphagocytic-evades immune system macrophages)

*SPE=strep. pyrogenic exotoxins (fever inducing exotoxins, encoded by phage)

what are the clinical symptoms of scarlet fever?

§ 1-2 days after pharyngitis

§ Sandpaper rash

· Starts on face spreads to body, NOT on palms or soles

· 1 week duration then desquamation (skin peeling)

§ Strawberry tonguey wine song")

what are the potential complications from untreated strep throat?

Scarlet fever and rheumatic fever

what is a causative agent for rheumatic fever?

cross-reactivity of M protein

Cross-reactivity of M protein mechanism of action (rheumatic fever)

§ Antibodies made against S. pyogenes M protein (during original pharyngitis infection) cross react with:

· Protein on heart valves

o Damage heart valves over time

o Endocarditis

· Joints

o Polyarthritis

oral candidiasis is caused by what

candida albicans (yeast)

Decrease in bacteria = Increase yeast

at risk populations for oral candidiasis

· Infants, elderly, dentures, broad spectrum antibiotics

· AIDS patients, chemotherapy

signs and symptoms of oral candidiasis

· difficulty swallowing, eating, painful, white patches.

o Thrush

§ Characteristic white patches "cottage-cheese"

§ Overgrowth in the mouth and throat

what is the treatment for oral candidiasis

§ clotrimazole, nystatin, fluconazole

· People in chemotherapy are prescribed a mouth wash to prevent oral thrush.

what are the characteristics of and the gram stain/ catalase results for Corynebacterium diphtheriae

gram positive, club-shaped bacteria, catalase positive

non-motile

what is the transmission for Corynebacterium diphtheriae

human reservoir

what are the two causative agents for Diphtheriae

· Respiratory- transmission respiratory aerosols

· Cutaneous- transmission skin contact

what are the virulence factors for diphtheira

· Diphtheria toxin- phage-mediated

· Produced at site of infection (back of the throat)

· Disseminates through the blood

o Receptors on heart and nerve cells

mode of action for diphtheria

· Same as P. aeruginosa Exotoxin A

· ADP-ribosyl transferase

o Inactivates elongation factor 2

o Inhibits host protein synthesis

- B cell binds to host cell membrane facilitating entry of A subunit

- A subunit ADP-ribosylates EF2 to inhibit protein synthesis

What are the signs/symptoms for Respiratory diphtheria

formation of thick gray pseudomembrane, enlarged lymph nodes, bull neck appearance, malaise, sore throat, fever, exudative pharyngitis

mechanism of action for respiratory diphtheria

· Attach and multiply in the pharynx

· Exotoxin causes tissue damage

potential complications of respiratory diphtheria

myocarditis and neurotoxicity

mode of action of cutaneous diphtheria

· Skin contact

· Gains entry to subcutaneous tissue through break in the skin

signs and symptoms of cutaneous diphtheria

chronic, non-healing ulcer

diagnosis of Diphtheria

· Culture:

o Selective agar- cystine tellurite blood agar

§ Tinsdale agar

§ Tellurite- grayish black colonies

§ Cystine- brown halos surrounding colonies

o PCR

Vaccination of diphtheria

· Vaccine is given in a series

· Part of DTaP- children

· Target the toxin

o Toxoid- inactive toxin, doesn't cause damage

Antibodies to toxoid block the toxin from causing harm

what are the characteristics of Haemophilus influenzae?

· Gram-negative short fat rod

· Normal flora of the Upper Respiratory tract

· Capsule, adhesins, endotoxin

what is the diagnosis of heamophilus influenzae

·Microscopy/Gram stain

· Culture: fastidious ("picky")

· Requires X (heme) factor and V (NAD) factor

· Chocolate agar

· Wont grow on MacConkey

what causes epiglottis

Haemophilus influenzae type B

what are the signs and symptoms of epiglottis

§ severe inflammation and edema (can't breathe or swallow due to these), difficulty breathing, drooling, fever, sitting forward ("Catcher's stance")

· Other influenza strains causes otitis media, meningitis, pneumonia

what is the prevention for epiglottis

vaccine that targets the capsule

what is the treatment for epiglottis

intubation, antibiotic- ceftriaxone

what is the characteristics of Bordetella pertussis

§ Gram negative coccobacillus

§ Aerobic

what disease does Bordetella pertussis cause

"Whooping cough"

· Highly contagious disease

· Uncontrolled violent coughing (causative)

High risk population for pertussis

· Unvaccinated children

· Vaccinated teens (middle and high school age)

Virulence factors for pertussis

· Attachment: bind to ciliated epithelial cells (lungs)

o Pertactin

o Filamentous hemagglutinin

· Tissue damage (once factors are bound)

o Pertussis toxin-

§ ADP ribosylating activity of G proteins, increase cAMP, increase respiratory mucus

o Tracheal cytotoxin

§ Leads to pneumonia

§ Affinity for cilia

§ Causes ciliostasis (cilia becomes paralyzed) or death of cells

· Leads to characteristic cough.

· Stimulates IL-1 resulting in fever

pathogenesis of pertussis

· Exposure: aerosol droplet inhalation

o Human reservoir

· Attachment to ciliated epithelial cells

o Pertactin

o Filamentous hemagglutinin

· Proliferation

· Tissue damage

o Pertussis toxin

o Tracheal cytotoxin

What are the three phases (clinical manifestations) of pertussis

catarrhal, paroxysmal, and convalescence

Catarrhal phase

o cold-like symptoms, runny nose, sneezing, malaise, low fever, loss of appetite

§ High transmissible in this phase, high # of bacteria

paroxysmal phase

o damage ciliated cells, impaired mucus clearance

§ Prolonged coughing fits with inspiratory whoop 40-50 times/day, vomiting exhaustion, ruptured blood vessels in the eyes

convalescence phase

o recovery

§ Symptoms: diminished paroxysmal cough, development of secondary complications (pneumonia, seizures, encephalopathy)

diagnosis for pertussis

· Nasopharyngeal aspirate beat

· Classic: Bordet-Gengou medium ("Bordetella")

· Current: Regan-Lowe agar

o Inoculate at bedside

o 7-12 days incubation

· PCR

Vaccines for pertussis

· Acellular vaccine

o Currently recommended

o Inactivated pertussis toxin + filamentous hemagglutinin + pertactin

· Part of DTaP

o Children

o Given in a series

define pneumonia

o Inflammation of the lungs accompanied by fluid filled alveoli and bronchioles

§ May involve: hemoptysis (coughing up blood)

§ Most common cause of death from infection in the elderly

What is the transmission for pneumonia

o Inhalation of aerosols

o Aspiration of normal flora

§ Upper respiratory tract

§ GI

o Hematogenous spread from another site of infection.

What bacterial strain causes Nosocomial pneumonia

pseudomonas aeruginosa (also S. aureus, H. influenzae)

What are the enteric strains for causing pneumonia

§ Enterobacter

§ Klebsiella

§ E. coli

§ Serratia marcescens

what are the characteristics of pseudomonas aeruginosa

§ Gram-negative rods

§ Ubiquitous (found anywhere)

§ Capable of growing on many substrates

§ Temperatures 4-42 degrees Celsius (4= refrigerator temp)

§ Forms a biofilm

· Alginate capsule

§ Motile

· Flagella and pili

§ Oxidase positive

-Highly antibiotic resistant

what is the virulence factor of pseudomonas aeruginosa

same as diphtheria

-Exotoxin A

-ADP ribosyl transferase inactivates EF2, inhibiting protein synthesis

What are the risk factors for pseudomonas aeruginosa infections

cystic fibrosis, VAP infections, pulmonary disease

What is the causative agent of typical pneumonia

Streptococcus pneumoniae (also Klebsiella pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus)

what are the signs and symptoms of typical pneumonia

· Similar to pneumococcal pneumonia

· Abrupt onset, fever, chills, congestion, shortness of breath, cheat pain

· Productive cough (cough up sputum)

what are the characteristics of streptococcus pneumoniae

o AKA pneumococcus

o Lobar pneumonia- infection in only one lobe

o Gram positive, pairs or chains

§ Capsule, adhesin, IgA protease

§ Pneumolysin- lyses ciliated epithelial cells

o Blood agar- Alpha-hemolytic

o Rust-colored sputum- blood in sputum

· Seasonal: winter and fall

· Community Acquired

What are predisposing factors (at risk populations) for typical pneumonia infections

o Viral infection

§ Influenza and HIV

o Alcoholism

o Children and elderly

o Splenectomy

§ Also functional splenectomy- spleen still present but does not function

how to diagnose typical pneumonia infections

o Sputum sample- rust colored

o Microscopy

§ Gram positive cocci and numerous PMNs

o Antigen agglutination

§ Secreted in urine as well as sputum

o Hemolysis

o Optochin sensitive

§ Type of antibiotic chemical only used in labs

§ Doesn't grow in oxygen

what are the vaccine types for typical pneumonia

o Both types target capsule -> prevent the adhesion of the capsule

o Can prevent meningitis as well

o Pneumovax- 23 most common capsule serotypes

§ PPSV23

§ Adult

o Pneumococcal conjugate vaccine

§ PCV13

§ Children 2-59 months

What bacterial strains cause atypical pneumonia

§ Mycoplasma pneumoniae, Chlamydophila spp., legionella pneumophila, Coxiella burneti

· Organism not seen with gram stain (Except Lp)

what are the signs and symptoms of atypical pneumonia

· Fever, headache, malaise, myalgia, nausea, diarrhea

· Non-Productive cough (dry-hacking cough)

Mycoplasma pneumoniae characterisitics

o Smallest free-living microbe

o No cell wall

o Capsule

o Adhesion- attachment to base of cilia

· May last several weeks or months- "Walking Pneumonia"

o This is due to patients not seeking treatment right away

what is the target population for atypical pneumonia

high school and college age students

What is the transmission for atypical pneumonia

inhalation of aerosols

what are the diagnostics for atypical pneumonia

o Can not see bacteria with microscope

o Large number of PMNs

o Grows very slowly in culture (2-6 weeks)

o Cold agglutinins

o PCR

what is the treatment for atypical pneumonia

o Macrolide

§ Azithromycin (Z-Pack), erythromycin

o Doxycycline

characteristics of Chlamydophila pneumonias

o Gram negative "in structure" as it doesn't gram stain

o CAP

o *Obligate intracellular bacteria

diagnostics for Chlamydophila pneumonias

o Microscopy/Gram stain

§ No organisms seen

§ Large numbers of PMNs

o ELISA

what are the two stages for Chlamydophila pneumonias

o 1. Elementary body

o 2. Reticulate Body (for replication)

o These stages prevent phagosome from binding to lysosome= no degradation

what is the transmission for Chlamydophila pneumonias

respiratory droplets

what are the signs and symptoms for Chlamydophila pneumonias

o Mild fever, sore throat, malaise, persistent cough

o Tends to be mild infection

what is the treatment for Chlamydophila pneumonias

same as atypical pneumonia (caused by mycoplasma pneumonia)

o Macrolide

§ Azithromycin, erythromycin

o Doxycycline

what bacterial strain causes psittacosis (parrot fever) and what is it

· Chlamydophila psittaci

o Parrot fever

o Disease of birds can be transmitted to humans

§ Zoonoses: bird to humans

o Obligate intracellular

o Treatment

§ Doxycycline

§ Azithromycin

Legionnaire's Disease bacteria characteristics

o Gram negative- however it does NOT gram stain well

o Water cooling towers and air conditioning units

§ People in the same building can all get the disease

o Intracellular

§ Environment- amoeba

§ Human- alveolar macrophages

what is the transmissions for Legionnaire's Disease

inhalation of aerosolized droplets

what are the symptoms of Legionnaire's Disease

o Abrupt onset of feer, headache, pleurisy, chills, myalgia, dry cough

o Complications involving GI tract, CNS, liver and kidneys are common.

What are the risk factors (or at risk population) for Legionnaire's Disease

o Smokers, COPD, high alcohol consumption, elderly, immunosuppressed, renal transplant patients or dialysis patients

what are the diagnostics for Legionnaire's Disease

o Culture: fastidious

§ *Buffered charcoal yeast extract agar (BCYE agar)

· Iron salts and cysteine

o Fluorescent antibody staining

§ Antigen can be detected in urine

what is the bacterial strains responsible for ventilator-associated pneumonia (VAP) and cystic fibrosis

pseudomonas aeruginosa and Burkholderia cepacian

Describe the risk factors, symptoms, and treatment associated with pneumonia caused by anaerobic bacteria

o Aspiration of respiratory (oral) or gastric material (GI)

o Risk factors

§ Dental work- Oral

§ Loss of consciousness- GI

o Mixture of Bacteroides and Fusobacterium

§ Necrotizing

§ Lung abscesses

o Copious amounts of foul-smelling sputum

o Treatment:

§ Metronidazole

§ 2-4 months

what are the characteristics of the bacterial strain responsible for Anthrax

bacillus anthracis

o Gram positive rods ("Box-car" like arrangement) occurring in chains

o Aerobic, non-motile

o Forms resistant endospores

o Spores remain viable for years in soil, dried or processed hides

§ Main concern: inhaling spores

o Present in air, water, soil, and vegetation

what are the 3 types of anthrax

1. Cutaneous

2. Inhalation (pulmonary)

3. Gastrointestinal

inhalation anthrax virulence factor

o Capsule (protein: poly-glutamic acid)

o Anthrax toxin

§ Major virulence factor secreted by B. anthracis

§ Encoded by plasmid pXO1 carrying 3 toxins

§ A/B toxin

§ Three component proteins

· Protective antigen (PA)- binding portion

· Edema factor (EF) and Lethal factor (LF)

o PA + EF or PA + LF combinations will form protein

o Increase in EF= Increase in cAMP (lead to edema)

o Increase in LF= cell death

what is the transmission of inhalation anthrax

inhalation of endospores (spores have no taste)

what are the initial and after several days worth of symptoms

o Initial

§ Sore throat, mild fever, myalgia, cough

o After several days

§ Severe coughing, nausea/vomiting, lethargy, confusion, confusion, shock, death

· Damage caused by anthrax spores and bacilli to the central chest cavity causes chest pain and difficulty breathing

what occurs once spores enters the lymph nodes for anthrax

o Spores germinate into active bacilli, multiplying and eventually bursting the macrophages

§ This releases more bacilli into bloodstream to be transferred to entire body

o Once in bloodstream, these bacilli release three substances:

§ LF, EF, and PA

· These toxins are the primary agents of tissue destruction, bleeding, and death of host