Microbiology Chapter 22

alveoli

Which portion of our respiratory system would have the least microbes in a healthy individual?

Upper Respiratory Tract Diseases Caused by Microorganisms

Rhinitis (common cold)

- Rhinoviruses (50%)

- Coronaviruses (15-20%)

- Adenoviruses

common cold

What is the most common disease of humans living in temperate climates?

Common cold symptoms

sneezing, scratchy throat, runny nose, begin 2-3 days after infection, generally no fever

Common cold transmission

- Droplet transmission

- Indirect transmission

a single rhinovirus deposited on the nasal mucosa is sufficient to cause a cold

Common cold treatment

none; working on vaccines (Rhinoviruses attach to ICAM-1 on nasal mucosa)

Sinusitis

- Commonly called a sinus infection

- Most commonly caused by allergy

- Can also be caused by infections or structural problems

- Generally follows a bout with the common cold

Sinusitis symptoms

nasal congestion, pressure above the nose or in the forehead, feeling of headache or toothache, facial swelling and tenderness

Sinusitis (Bacterial Infection)

opaque discharge with a green or yellow color

Sinusitis (Allergic)

clear discharge accompanied by itchy, watery eyes

Droplet transmission

transmission via airborne droplets

Indirect transmission

transmission of blood or body fluids through contact with an intermediate contaminated object

Acute Otitis Media

• Ear infection

• Also a common sequel of rhinitis

• Chronic otitis media

• Common in children

Chronic Otitis Media

when fluid remains in the middle ear for indefinite periods of time, may be caused by biofilm bacteria

Acute Otitis Media symptoms

sensation of fullness or pain in the ear, loss of hearing; untreated or severe infections can lead to eardrum rupture

Eustachian tubes, bacterial multiplication

Viral infections of the upper respiratory tract lead to inflammation of the _____________________ , and buildup of fluid in the middle ear can lead to _____________________________ in the fluids

leads to pus production and continued fluid secretion (effusion)

Migration of bacteria along the eustachian tube from the upper respiratory tract and multiply rapidly

Pharyngitis (Strep Throat)

- Caused by Streptococcus pyogenes

- Can cause infection when immune system is weakened by fatigue, stress, poor diet, drug therapy (cancer), other diseases

- 50% of all cases of severe sore throat

True

Streptococcus pyogenes is frequently isolated from healthy people (True/False)

Pharyngitis (Strep) symptoms

inflammation of the throat, incubation period 2-5 days, pain and swelling, reddened mucosa, swollen tonsils, white packets of inflammatory products, mucous membranes swell, foul-smelling breath

swelling of the mucous membranes

What symptom of pharyngitis can affect speech and swallowing?

Pharyngitis (Strep) diagnosis

- Blood Agar contains red blood cells

- Streptococcus pyogenes secretes hemolysin that lyses RBC’s

* ELISA: rapid

antibiotics

Pharyngitis (Strep) treatment

Complications of S. pyogenes

scarlet fever, rheumatic fever, glomerulonephritis

Scarlet Fever

Systemic toxin

Rheumatic Fever

- Autoimmune complication of S. pyogenes

- Joint inflammation, heart valve damage

Glomerulonephritis

Acute, can cause kidney damage

Rheumatic Fever

Which of these is most likely to result in damage to the heart valves following a bacterial infection?

Diphtheria

• Caused by Corynebacterium diphtheria

• Spread by the respiratory route

• Symptoms initially experienced in the upper respiratory tract

• 5 cases or fewer annually in U.S.

Diphtheria symptoms

Sore throat, lack of appetite, low-grade fever; pseudomembrane forms on the tonsils or pharynx

Diphtheria complications

- Certain strains produce diphtheria toxin, which inhibits protein synthesis in host cells

- If toxin reaches vital organs, severe damage can occur and lead to death

Diphtheria treatment

Penicillin kills pathogen, antitoxin inactivates toxin

ELISA (Enzyme Linked Immunosorbant Assay)

- uses antibodies and enzymes to detect and measure the amount of a substance in a liquid sample

- a common way to detect antibodies, antigens, proteins, and hormones

Antigen

foreign substance that causes immune response

Antibody

proteins produced by B-lymphocytes

Scarlet fever

If the S. pyogene strain produces erythrogenic toxin

Erythrogenic toxin

produced by S. pyogenes, obtained through lysogenic conversion, resulting in the rash of scarlet fever

Whooping Cough (Pertussis)

- Caused by Bordetella pertussis which grows in upper respiratory tract

- Spread by the respiratory route

- Pertussis Toxin kills ciliated epithelial cells lining upper respiratory tract

- 2 distinct symptom stages

Pertussis symptoms

- Catarrhal stage

- Paroxysmal

- Convalescent

Catarrhal stage of Pertussis

• After incubation from 3 to 21 days

• Bacteria in the respiratory tract cause cold symptoms (runny nose)

• Lasts 1 to 2 weeks

Paroxysmal stage of Pertussis

• Severe and uncontrollable coughing

• Violent coughing spasms can result in burst blood vessels in the eyes or even vomiting

Convalescent phase of Pertussis

- Complete recovery requires weeks or even months

- Other microorganisms can more easily cause secondary infection

Pertussis prevalance

- Occurs mostly in children under 1 year of age

- Milder in older children and adults, can be overlooked as cold

- Immunization (DTaP vaccine) has reduced cases from > 200,000 to 1000-6000 cases/year

Diphtheria

What was the leading infectious killer of children in the United States until 1935?

Corynebacterium diphtheriae

Which organism produces a tough grayish membrane in the throat?

DTaP

diphtheria, tetanus, and acellular pertussis vaccine

DTaP booster

TDaP

Tuberculosis

- Mycobacterium tuberculosis

- Reservoir: humans

- Transmission: inhalation on aerosolized pathogen or contaminated dust

Tuberculosis prevalance

- 1/3 of total population, 1.3 million deaths

- 10-12 million infected, most latent, 20,000 new cases a year

Tuberculosis information

- Humans are easily infected but are often resistant

- Only about 5% of infected people actually develop a clinical case

- Untreated TB progresses slowly

Tuberculosis manifestations

primary tuberculosis secondary tuberculosis, and disseminated tuberculosis

Primary tuberculosis

initial infection

Secondary (Reactivation) tuberculosis

tubercle ruptures and re-establishes an active infection, can disseminate and turn into crhonic

Disseminated (Extra-Pulmonary) tuberculosis

When infection spreads throughout the body

• Outside of the lungs

• More common in immunosuppressed patientsand young children

• Regional lymph nodes, kidneys, long bones,genital tract, brain, and meninges

• Complications are usually grave

Latent infection of Tuberculosis

organism in lungs but no symptoms, can stay inactive or reactivate

Latent to reactivation TB

Live bacteria can remain dormant and become reactivated weeks, months, or years later

Chronic (Active) tuberculosis

tubercles filled with bacteria expand and drain into bronchial tubes and upper respiratory tracts

Chronic tuberculosis symptoms

violent coughing, greenish or bloody sputum, low-grade fever, anorexia, weight loss, extreme fatigue, night sweats, chest pain

TB skin test (Mantoux)

- minute amount of extract of pathogen (PPD) is injected into the skin

- Positive: red, raised lesion within 24-48 hrs

Sputum stain

acid fast stain reveals pathogen

Chest x-ray

reveals calcified tubercles

IGRA

blood test detects presence of T cells

BCG Vaccine

Anyone who has had this will have a positive skin test and must be evaluated by a chest radiograph

TB treatment

Treatment for six months

Can cause side-effects like nausea and vomiting

- Isoniazid - kills fast growing pathogen

- Ethambutol

- Rifampin

- Pyrazinamide

previous BCG vaccine given

A friend of yours from Asia tested positive for the tuberculin skin test, but had a negative chest X-ray. What is most likely the cause of these results?

Pneumonia

• Inflammatory condition of the lung in which fluid fills the alveoli

• Can be caused by a wide variety of different microorganisms

• Viral pneumonias milder than bacterial

• Community-acquired vs. nosocomial pneumonias•

Pneumonia symptoms

• Upper respiratory tract symptoms, including runny nose and congestion

• Headache

• Fever

• chest pain, fever, cough, discolored sputum

Dyspnea

labored breathing

Rales

Crackles; wet crackling noise in lungs

Community-acquired

contracted outside of the hospital

Nosocominal pneumonias

hospital acquired

Streptococcus pneumoniae

- diplococcus

- most common bacterial pneumonia (60%)

- preexisting lung disease

- macrophage, dead cell, and fluid accumulation reduce lung capacity

- chest pain, bloody sputum, labored breathing

Hemophilus influenzae

less common; occurs in individuals with cancer, diabetes, poor nutrition, and alcoholism

Mycoplasma pneumonia

- causes walking pneumonia, a mild form that infects upper respiratory tract

- Symptoms: low-grade fever, cough, chest pain, headache; all persist 3 weeks or longer

Streptococcus pneumoniae

What is the leading cause of community acquired bacterial pneumonias?

Legionnaires Disease

- Caused by Legionella pneumophila

- Reservoir: natural waters, cooling towers of large air conditioners

Transmission: contaminated aerosolized water (small droplets, spray)

- Healthy individuals quite resistant

- Treatment with Macrolides

1976 American Legion Convention in Philadelphia

Where was the first outbreak of Legionnaires Disease?

Legionnaires Disease

What bacterial pneumonia cannot be transmitted from one person to another?

Legionnaire's Disease (1000 reported, estimated 25,000)

What disease often goes unreported?

Legionnaire's Disease transmission

Upon breathing aerosolized water, pathogen lodges in and near the alveoli --> engulfed by macrophages --> pathogen multiplies --> inflammation --> fluid accumulation

Legionnaire's Disease symptoms

- Headache, malaise, rapid rise in temperature, chills

- Later, dry cough develops with coughing upblood

Heavy smokers, alcohol abusers and the chronically ill

Who is most susceptible to Legionnaire's Disease?

Neuraminadase, Hemaglutinin

Antigens for Influenza

Antigenic Drift

Influenza changes in H and N spikes

variation of H and N spikes

How are viral strains of Influenza identified?

Influenza treatment

• Vaccine for high-risk individuals (developed each year)

• Zanamivir (Relenza) - inhaled (inhibit neuramindase)

• Oseltamivir phosphate (Tamiflu) - oral

Influenza

• Begins in the upper respiratory tract; serious cases may also affect the lower respiratory tract

• 1-4 day incubation period

• Symptoms begin very quickly: headache, chills, dry cough, • • • • Body aches, fever, stuffy nose, and sore throat• Extreme fatigue can last a few days or a few weeks

Respiratory Syncytial Virus

• Produces giant multinucleated cells (synctia) in the respiratory tract

• Most prevalent cause of respiratory infection in the newborn age group (4500 DEATHS)

• First symptoms: fever that lasts approximately3 days, rhinitis, pharyngitis, and otitis

coughing, wheezing, dyspnea, rales, bronchitis, pneumonia

More serious RSV infections give rise to symptoms of croup, which include

RSV diagnosis

Serologic (blood) test for viruses and antibodies

RSV Treatment

- Synagis and Beyfortus (RSV-monoclonal antibody for preemies)

- Ribavirin for severe cases; administered by aerosol

- Arexvy and Abrysvovaccines for age 60+ and 3rd trimester of pregnancy

COVID-19

• The S proteins protrude from the viral surface resembling a crown, or corona

• SARS-CoV-2

• Transmitted from human-to-human (droplet) through coughing, sneezing, singing, or talking

• Spreads mainly through respiratory droplets within 6 ft

Stage 1 COVID-19

• Asymptomatic state

• Incubation time - median 4 to 5 days, range 2 to 14 days

• Virus is detected by a nasal swab

Stage 2 COVID-19

• Clinical manifestations

• 2 to 14 days post-exposure include cough, fever, shortness of breath, chills, muscle pain, loss of taste and/or smell, sore throat, nausea, diarrhea.

• Up to 80% of COVID-19 cases will be either asymptomatic or will arrest at this stage.

Stage 3 COVID-19

• Hypoxia, progression ARDS within 8-12 days

• Critical care/hospitalization necessary

• Manifestations - pneumonia, difficulty breathing, persistent chest pain/pressure, confusion, inability to stay awake, bluish lips or skin.

• Oxygen levels fall as lungs become filled with fluid, white blood cells, mucus, and cellular debris.

• Cytokine storm leads to dramatic drop in blood pressure, leaky blood vessels, formation of blood clots, organ failure.

COVID-19 Treatment

• Drugs

• FDA approved - remdesivir sold under the trade name of VEKLURY

• Baricitinib (CIMZIA®) used in conjunction with remdesivir for hospitalized adult and pediatric patients (not approved as a stand-alone treatment)

• Paxlovid - combination of nirmatrelvir and ritonavir

• National Institutes of Health formally concluded that chloroquine/hydroxychloroquine provides no clinical benefit to patients with COVID-19

Convalescent plasma treatment for COVID-19

• Treatment - Convalescent Plasma

• Donated plasma for patients suffering from life-threatening COVID-19.

• Reports from patients state their condition improved significantly after the plasma was transfused.