Micro: Respiratory System

what is the most common portal of entry for many infectious agents?

the respiratory system

URT: Mucociliary clearance

the entrapment of microbes and particles in a layer of mucus

-mucus is secreted from goblet cells in the airway epithelium

-ciliated epithelial cells move trapped matter toward the pharynx (move in unison)

-trapped matter is cleared by swallowing or expectorating

what is a primary mechanism for keeping microbes out of the lungs?

mucociliary clearance

URT: Antimicrobial substances

includes lysozyme, lactoferrin, antibodies, and human defensins

URT: Macrophages

immune cells ("big eaters") that clear microbes and dead cells

Primarily LOWER respiratory tract

macrophages are found primarily in the

LOWER respiratory tract

Cells lining the respiratory and alveolar bronchioles are not ___

ciliated

Alveolar fluid location

covers the lower respiratory tract

-contains immunoglobulins and macrophages to clear invaders

what causes Streptococcal Pharyngitis

S. pyogenes

what are the signs and symptoms of S. Pharyngitis

-pharyngitis, fever, headache, swollen lymph nodes, beefy red appearance to pharyngeal tissues

some patients with strep throat may develop...

scarlet fever and may exhibit a rash caused by erythrogenic exotoxins

how to diagnosis S. Pharyngitis

rapid strep test, culture, and/or clinical examination

drug of choice to treat S. Pharyngitis

Penicillin or 1st gen. Cephalosporin, amoxicillin (trmt usually effective within 24 hours)

Streptococcus pyogenes complications: Suppurative

otitis media, sinusitis

Streptococcus pyogenes complications: Non-suppurative

Rheumatic fever, scarlet fever, and glomerulonephritis

In the case of streptococcus pyogenes antibiotics reduce...

-complications

-duration/severity

-transmission

Diphtheria

life-threatening bacterial illness in the throat

Diphtheria is caused by

Corynebacterium diphtheriae

what is the drug of choice to treat Diphtheria?

azithromycin (and antitoxin)

signs and symptoms of Diphtheria

-accumulation of pseudomembrane (can block airway)

-exotoxin which can lead to cardiac arrhythmia and coma

***biggest problem is the toxin!

what is the most commonly infected part of the URT?

nose

Acute sinusitis

-caused by a variety of indigenous microbes of the URT

-Streptococcus, Haemophilus, Moraxella, Staphylococcus

-pain, tenderness, swelling, runny nose

Chronic sinusitis

8-12 weeks. Symptoms are more subtle, and pain occurs less often

Otitis externa

outer ear infection (swimmer's ear)

-caused by Streptococcus, Staphylococcus, or Pseudomonas

treat with ear drops

Acute otitis media

short-term infection of the middle ear

-caused by S. pneumoniae, and H. influenzae, Moraxella catarrhalis

Chronic otitis media

long-term infection, inflammation and damage to the middle ear

what is the drug of choice for Otitis externa, Acute otitis media, and Chronic otitis media?

Amoxicillin +/- clavulanic acid (augmentin)

Most URI are caused by

viruses

so don't use antibiotics

Rhinitis

inflammation and swelling of the mucous membranes of the nose

what are viruses are responsible for the common cold syndrome

Rhinoviruses and Adenoviruses

Rhinovirus

- produces inflammation in the upper respiratory tract

(common cold)

-picornaviridae family

-older children and adults

what do some kids develop from Rhinovirus

Croup - seal bark cough with hoarseness

Adenovirus

(common cold)

-adenoviridae family

-affects infants and young children

-COVID-19 vaccine is non-replicating adenovirus that expresses SARS-CoV-2 spike protein (now discontinued)

what can Adenovirus cause

acute febrile pharyngitis, cough, whitish-gray material appears on throat

Pertussis (whooping cough) is caused by

Bordetella pertussis

-spread through respiratory droplets

-Gm-

-highly contagious

-most cases in children under 5 with most severe cases in infants

describe whopping cough

bunch of rapid coughs in a row, then gasp for air

what does Pertussis do to the body

exotoxin production paralyzes the ciliated cells and impairs mucus movement, potentially causing pneumonia

what are the two stages of Pertussis

Initial (catarrhal) - low-grade fever, increasily severe cough

2nd stage (paroxysmal) - cells and mucus accumulate in the airways and cause labored breathing

what is the drug of choice to treat Pertussis

azithromycin

-DTaP vaccine

what causes Tuberculosis (TB)

Mycobacterium tuberculosis

how do you become infected by TB

small aerosolized droplets

TB infection occurs in 3 stages

-Initial Macrophage Response

-reaches alveoli, reproduce like crazy

-Immune Control (Latent TB)

-balance is restored, stalemate

-not contagious

-Lung Cavitation

-TB bacilli become reactivated and highly contagious

active TB

-immune defenses cannot keep the tubercle bacilli in check

-sputum coughed from the LRT may contain blood

-macrophages in the lung form a tubercle that harbors M. tuberculosis

-if the tubercle breaks apart, bacteria spread throughout body

describe Mycobacterium tuberculosis

-cell wall forms a waxy cell surface that is resistant to drying, chemical disinfectants and antibiotics

-can't be gram stained

-acid fast

what is the most active way to test for TB

X ray and sputum test

-indicates patient is contagious

Acute Bronchitis

inflammation of the bronchi

-viral or bacterial

-bronchitis produces excessive mucus and a narrowing of the bronchi

-abx rarely indicated

Acute Bronchitis can be caused by

URT infection

-M. pneumoniae, C. pneumoniae

Pneumonia

refers to the disease of the bronchioles and alveoli

-lungs are inflamed and filled with fluid which prevents gas exchange

- caused by variety of organisms

Bacterial pneumonia can be classified as

"healthcare-acquired" and "community-acquired"

Atypical pneumonia is caused by

one of the CLaM organisms

Healthcare-Acquired Pneumonia and Ventilator-Acquired Pneumonia

-48 hours after admission - HAP or endotracheal intubation - VAP

-infecting species are showing increased antibiotic resistance

Factors suggestive of HAP or VAP

-new onset fever

-purulent sputum

-leukocytosis (increased WBC)

-decrease in oxygenation

-new lung infiltrate on chest X-ray

Bronchoalveolar lavage

(lung washing) cultures

-75% sensitivity and specificity

-Pneumonia

what causes community-acquired pneumonia?

Most commonly Streptococcus pneumoniae

**most of the time in clinical practice we don't ever find out the actual cause!!

what can cause primary "atypical" pneumonia?

Mycoplasma pneumoniae

"Atypical" pneumonia

often called walking pneumonia

-atypical due to beta-lactam resistance and lack of staining in Gram stain (CLaM)

-common in crowded conditions

community acquired pneumonia can also be caused by

Legionella pneumophila

-transmitted from contaminated water source

Respiratory syncytial (RS) disease is caused by

Respiratory syncytial virus (RSV)

-commonly affects children under 1

-it infects the bronchioles and alveoli of the lungs, causing cells to fuse together

-member of the paramyxociridae family

what is the most common cause of fatal respiratory tract infections in infants under 12 months of age?

respiratory syncytial virus

Severe/Acute Respiratory Syndrome (SARS) spreads through close person-to-person contact and is caused by

SARS-CoV-1 - coronaviridae family

-bats may be natural host

-coronavirus known to produce pneumonia

Middle Eastern Respiratory Syndrome (MERS)

-coronavirus that can produce pneumonia

what are some COVID19 mRNA vaccine adverse effects

- Myocarditis (mostly mild in younger males), 50-100 cases per 1 million doses

- mostly mild: injection reactions, headache, myalgia, fever

Novavax (subunit vaccine) - COVID19

Systemic: fatigue/malaise, headache, and myalgias

--some serious events, but too few to determine if it is due to the vaccine

Parainfluenza infections are usually caused by

human parainfluenza viruses 1 and 3

-infections are milder than influenza (cold symptoms)

-typically affects children under the age of 6 or immunocompromised

Human metapneumovirus (hMPV) are

RSV-like viruses

-mild URT infection

-symptoms are milder than RSV disease

-rarely: ARDS and severe pneumonia

Influenza

-highly communicable Acute Respiratory Infection

-four types of flu (A, B, C, D)

-can develop pneumonia if it gets into the lungs

- part of the orthomyxoviridae family

-transmitted by respiratory dropleps and aerosols primarily but also fomites

Influenza is an upper respiratory disease in most, but some develop severe disease _____

pneumonia - if it gets in the lungs

Influenza contains 2 types of spikes essential to its function:

Hemagglutinin (H) - helps the virion attach and penetrate host cells

Neuraminidase (N) - helps release virions from the host cell after replication and assembly

Guillain-Barre syndrome

occurs when the body damages its own peripheral nerve cells

Reye syndrome often occurs

in children who take aspirin to treat pain and fever

The reason we need new flu vaccines every year is due to

-Antigenic shift

-Antigenic drift

Antigenic shift

the process of RNA segment mixing, producing a new virus

(occurs every 10-15 virus)

-think of the hybrid pig example

Antigenic drift

smaller changes that occur as a result of error prone viral RNA polymerase (occurs constantly)

the flu vaccine is directed against __- and takes __ to produce the vaccine each year

the head of hemaglutinin; 6 months

Complications of the flu virus, such as pneumonia and secondary infections are more common in:

infants, elderly and immunocompromised

how is the flu virus named?

based off the H (18 different) and N (11 different) subtypes

about __% of human flu cases are caused by flu _, the rest are caused by flu __. Flu __ produces mild illness, and _ viruses primarily affect cattle.

70; A; B; C; D

COVID-19 prevention...

- behavioral: social distancing, mask wearing, hand hygiene

- vaccination mRNA (moderna and pfizer) vs subunit (novavax)

the novavax vaccine is based on...

older/more established vaccine technology

the mRNA vaccine for COVID is based on...

entirely new technology with no precedence as an approved vaccine

what are the variants of concern of coronavirus that have evolved over time?

alpha, beta, delta, and omicron (largest area of concern)

pneumonia can involve the entire lung lobe, which is known as

lobar pneumonia

pneumonia can involve the both lungs, which is known as

double pneumonia

pneumonia can involve patches in the respiratory passageways, which is known as

bronchopneumonia

culture of pulmonary secretions is prone to false positives and false negatives because...

-hard to get a good sputum sample

-often contaminated with oral flora

Describe tuberculosis treatment

isoniazid, rifampicion, pyrazinamide, ethambutol, and more

- BCG vaccine used for prevention

-trmt can take 4-6 months

what do the TB blood tests (IGRA) show

measure how the immune system reacts to bacteria that cause TB --measure of exposure, not active disease

what can cause a false positive in the mantoux tb test?

previous TB test or recent TB immunization

about __% of people who carry latent tuberculosis will never develop an active infection

90

what are diseases of the lower respiratory tract

bordatella pertussis, mycobacterium tuberculosis, bronchitis, bacterial pneumonia, SARS-CoV-2

___ children contract at least one ear infection by age 3

3/4

Scarlet Fever as a complication from streptococcus pyogenes...

pink-red rash, sore throat, fever, "strawberry-like inflamed tongue", pastia's lines

- due to pyrogenic exotoxin produced by s. pyogenes

the local microbiota of the respiratory tract supports respiratory health through....

microbe-microbe interaction, certain commensal species promote low-level inflammation and may influence abiotic components like acidity and oxygen availability which could inhibit pathogenic strains

the ___ limit microbe colonization of the lower respiratory tract

the upper respiratory tract chemical and mechanical defenses