CH22
MICROBIOLOGY AND PARASITOLOGY | 1NU10 - MID YR - A.Y. 22-23
INFECTIOUS DISEASES AFFECTING THE RESPIRATORY SYSTEM
Upper Respiratory tract:
➢ Mouth
➢ Nose
➢ Nasal Cavity
➢ Sinuses
➢ Throat (Pharynx)
➢ Epiglottis
➢ Larynx
Lower Respiratory tract:
◆
◆
➢
➢
➢
➢
➢
The overall composition of the lung microbiome is
altered in patients suffering from lung disorders
✦
THE RESPIRATORY SYSTEM
DEFENSES
Trachea
Lungs:
Bronch
Bronchioles
Alveoli
DEFENSES: ANATOMICAL
○
Nasal hair
○
Ciliary escalator
○
Mucus
○
Involuntary responses
○
Coughing
○
Sneezing
✶
✶
✶
✶
SECOND & THIRD LINE OF DEFENSES
“Chemical Defenses”
●
●
Complement action in the lungs
Increased levels of cytokines and anti-microbial
peptides
Macrophages inhabit the alveoli of the lungs and
the clusters of lymphoid tissue in the tonsils
Secretory IgA
●
●
NORMAL BIOTA
The respiratory tract harbors a large number of
commensal organisms due to constant contact
with the environment
❖
○
○
●
Prevotella
●
Sphingomonas
●
Pseudomonas
●
Acinetobacter
Secretory IgA
●
Fusobacterium
○
Alveolar macrophages
●
Megasphaera
○
Cytokines
●
Veillonella
○
Complement
●
Staphylococcus
CONCEPT CHECK:
Nasal Hairs
Ciliated Epithelium of trachea and bronchi
(Ciliary Escalators)
Mucus
Coughing
Sneezing
Swallowing
●
Bacteria considered as
normal biota:
●
Streptococcus
○
ANATOMICAL DEFENSES
✶
✶
NORMAL BIOTA
1.
Two anatomical methods of trapping bacteria in the
respiratory tract are: Nasal Hair and Ciliated
Epithelium
2.
Antimicrobial Peptides, Alveolar Macrophages, and
Secretory IgA in the lungs are chemical defenses
against invading pathogens
3.
The larynx is part of the Upper Respiratory tract
4.
Alveoli can be found in the Lower Respiratory tract
5.
TRUE /False: Organisms considered “normal biota” in
the respiratory tract can cause serious disease.
INFECTIOUS DISEASES IN UPPER
RESPIRATORY TRACT
THE COMMON COLD
►
Often called “RHINITIS” (Nose + Inflammation)
Signs & Symptoms
▸
Sneezing, scratchy throat, runny nose
▸
Generally not accompanied by a fever
○ Children experience low fever (less than 102°F or
38.9°C)
Metagenomic analysis reveals that both the
upper and lower respiratory tracts harbor a
large number of bacterial genera
▸
9 Major bacterial genera make up a
significant portion of the normal biota
Infection may predispose patients to secondary
infections
▸
Symptoms are usually due to immune response to
the virus, not to any particular virulence factors
○
Yeasts, such as Candida Albicans, also colonize
mucosal surfaces (Upper Respi. tract)
○
Normal biota plays a significant role in
microbial antagonism
Causative Agents of the Common Cold
▸
Over 200 different kinds of viruses can cause the
common cold
○
99 Serotypes of Rhinoviruses
○
Coronaviruses
Streptococcus pyogenes
○
Adenoviruses
✦ Haemophilus influenzae
○
Respiratory syncytial virus (RSV) - can be more
serious in infants
BACTERIA considered “Normal Biota” can cause
Diseases
✦
✦ Streptococcus pneumoniae
✦ Neisseria meningitidis
✦ Staphylococcus aureus
MARK YPIL | TRANSCRIBED BY
▸
TRANSMITTED BY: DROPLET CONTACT & INDIRECT
TRANSMISSION
▸
No Vaccine & Chemotherapeutic agent
111 I Infectious Disease Affecting the Respiratory System
Infectious Diseases affecting the Respiratory System
COMMON COLD DISEASE TABLE
Prevention
N/A
Approx: 200 Viruses (Rhinoviruses,
Causative Organism
Adenoviruses, Coronaviruses)
Treatment
No antibiotics unless remains
unsolved for for some weeks
Distinctive Features
More common than fungal
Epidemiology
United States: affects 1 of 7 Adults;
between 12-30 mil diagnosis per year
Transmission
Indirect contact or Droplet contact
Virulence Factors
Attachment Proteins
Culture/Diagnosis
Not necessary
Prevention
Hygiene practices
SINUSITIS DISEASE TABLE - _FUNGI_
Treatment
For symptoms only
Causative Organism
Epidemiology
High incidence for Children
Transmission
Introduction by trauma or
opportunistic growth
Culture/Diagnosis
Same
Prevention
N/A
Treatment
Physical removal of fungus. In severe
cases, antifungals are used
Distinctive Features
Suspect in immunocompromised
Epidemiology
Varies in geography. Common in the
US (SE & SW), India, North Africa,
Middle East
SINUSITIS
►
Inflammatory condition of any four pairs of sinuses
in the skull.
►
Can be caused by allergy or infection
►
Patients suffering from cold often develop sinusitis
Signs & Symptoms
Sinus pain, nasal congestion, pressure headache or
toothache
▸
Discharge is opaque and can be yellow or green in
color
▸
Causative Agents of the Sinusitis
ACUTE OTITIS MEDIA (EAR INFECTION)
Common sequelae (complication) of the common
cold
►
Viruses
▸
○
Most common causative agent
○
Same viruses as common cold
Bacteria
▸
○
Most often come from normal biota but represent
only 2% of cases
Fungi
▸
○
Rare, but recognized when antibacterial drugs
fail to alleviate symptoms
VIRUSES
Transmission
Direct or Indirect Contact
Culture/Diagnosis
■
Due to the inflammation of the eustachian tubes
and build up of fluid in the middle ear
■
Bacteria can migrate along the eustachian tubes
increasing the inflammatory response
■
Secretion fluid is called ‘Effusion’
In Chronic Otitis Media, fluid builds up in the
eustachian tubes.
►
■
SINUSITIS DISEASE TABLE - _VIRUS_
Causative Organism
VARIOUS FUNGI
Caused by a mixed biofilm of bacteria attached
to the membrane of the inner ear
Signs & Symptoms
▸
Feeling of fullness or pain in the ear, loss of hearing
Not usually performed; Diagnosis
based on clinical presentation
▸
Young children: irritability, trouble sleeping, eating
or hearing
Prevention
Hygiene
▸
Treatment
None
Infection can cause the eardrum to burst and more
serious infection can result
▸
Distinctive features
More common than fungal
TREATMENT:
Epidemiology
Usually follows common cold
SINUSITIS DISEASE TABLE - _BACTERIA_
Causative Organism
VARIOUS BACTERIA (often mixed
w/ infection
Transmission
Endogenous (Opportunistic)
Culture/Diagnosis
Not usually performed; Diagnosis
based on clinical presentation
Occasional X-ray or other imaging
technique
MARK YPIL | TRANSCRIBED ON [ 07.25.2023]
○
Most often, “Watchful waiting” for 72hrs
○
Tubes can help alleviate symptoms in recurrency
Causative Agents of the Acute Otitis Media
▸
Most commonly caused by the gram-positive
diplococci joined end-to-end bacterium:
Streptococcus pneumoniae
▸
An emerging, and worrying cause is the fungus:
Candida auris
▸
Many different viruses and bacteria
▸
Otitis media is not a communicable disease
121 I
01: Infectious Diseases affecting the Respiratory System
Infectious Diseases affecting the Respiratory System
OTITIS MEDIA DISEASE TABLE
Causative Organism
STREPTOCOCCUS PNEUMONIAE
Streptococcus pyogenes: VIRULENCE FACTORS
▸
Surface antigens of S.pyogenes mimic host proteins
Transmission
Endogenous (May follow other
microorganisms)
▸
M protein aid with resisting phagocytosis and
adhesion
Virulence Factors
Capsule & Hemolysin
▸
Culture/Diagnosis
Usually relies in clinical symptoms
Surface antigens protect the organism from being
affected by lysozymes
▸
Prevention
Pneumococcal conjugate vaccine
(PVC13)
Streptolysin O & Streptolysin S: injure cells and
tissues
▸
Erythrogenic toxin: produced by lysogenic strains
of S. pyogenes, key for scarlet fever.
▸
Some streptococcal toxins act as superantigens
⎼
⎼
Treatment
⎼
Epidemiology
Wait for Resolution
If needed:
═ Amoxicillin (High Resistance)
═ Amoxicillin + Clavulanate or
Cefuroxime
Antibiotic usage reccom. for
babies less than 6 mos old
30% of cases in the United states
OTITIS MEDIA DISEASE TABLE
Causative Organism
Fusobacterium necrophorum
➔
Bacterium that causes 15% of Acute Pharyngitis
cases in the last 15 years.
➔
Gram-negative bacterium
➔
Causes a life-threatening peritonsillar abscess
called Lemierre’s syndrome
CANDIDA AURIS
Transmission
Not known
PHARYNGITIS DISEASE TABLE
Virulence Factors
Biofilm formation
Causative Organism
Culture/Diagnosis
MALDI-TOF or PCR
Transmission
Droplet or Direct contact
Prevention
None
Treatment
Consult CDC (Urgent in Antibiotic
Resistance report)
Virulence Factors
LTA, M Protein,
Hyaluronic acid capsule,
SLS and SLO,
Superantigens,
Induction of autoimmunity
Epidemiology
First appeared in 2009
Culture/Diagnosis
Beta-hemolytic on blood agar
Sensitive to bacitracin
Rapid Antigen test
Prevention
Hygiene Practices
Treatment
Penicillin and Cephalexin (for
penicillin-allergic patient
Distinctive Features
Generally more severe than Viral
Epidemiology
10-20% cases of pharyngitis in the U.S
PHARYNGITIS
►
Inflammation of the throat causing pain & swelling
►
May be caused by same viruses of common cold
►
More serious cases caused by
Streptococcus pyogenes and
Fusobacterium necrophorum
Signs & Symptoms
STREPTOCOCCUS PYOGENES
▸
Inflammatory white packets visible on the walls of
the throat, difficulty swallowing, foul breath.
PHARYNGITIS DISEASE TABLE
▸
Viral sore throat: mild & may lead to hoarseness
Causative Organism
▸
Bacterial: more painful, often accompanied by
fever, headache and nausea
Transmission
Usually endogenous
Virulence Factors
Invasive, endotoxin
Culture/Diagnosis
Culture anaerobically;
CT Scan for abscess(es)
Prevention
?
Treatment
Penicillin
Distinctive Features
Can cause Lemierre’s syndrome
Epidemiology
15% cases of acute pharyngitis in
teens and young adults
Streptococcus pyogenes
COMPLICATIONS
▸
Gram(+) coccus that grows in chains, facultative
anaerobe, produces capsules and slime layer
▸
Serious Complications if untreated:
○
Scarlet fever
○
Rheumatic fever
○
Glomerulonephritis
MARK YPIL | TRANSCRIBED ON [ 07.25.2023]
131 I
FUSOBACTERIUM NECROPHORUM
01: Infectious Diseases affecting the Respiratory System
Infectious Diseases affecting the Respiratory System
PHARYNGITIS DISEASE TABLE
Causative Organism
○
Tracheal cytotoxin:
causes direct destruction of ciliated cells
○
Endotoxin:
leads to the production of a host of cytokinesis
VIRUSES
Transmission
All forms of contact
Virulence Factors
N/A
Culture/Diagnosis
Goal is to rule out S. pyogenes &
F. necrophorum
Prevention
Hygiene Practices
Treatment
Symptom relief only
Distinctive Features
Hoarseness
Epidemiology
Ubiquitous; Responsible for 40-60% of
all pharyngitis cases
Vaccine of Whooping Cough
Pertussis Vaccine:
▸
○
High vaccination rate has kept incidence low
○
Current vaccines are an acellular formulation of
antigens
○
Booster necessary after the age of 11 years
WHOOPING COUGH DISEASE TABLE
Causative Organism
CONCEPT CHECK:
1.
True / FALSE: There is an effective vaccine available
for the common cold
2.
TRUE / False : Sinusitis, Otitis Media, and
Pharyngitis can all be sequelae
3.
Chronic otitis media is considered to be a(n) EAR
INFECTION
4.
Transmission
Droplet Contact
Virulence Factors
FHA (Adhesion)
Pertussis Toxin
Tracheal cytotoxin
Endotoxin
Culture/Diagnosis
PCR or Growth on B-G, charcoal, or
potato glycerol agar;
Diagnosis can be made on symptoms
Prevention
Acellular vaccine (DTaP)
Azithromycin for contacts
Treatment
Azithromycin
Drug resistant B.pertussis is a
concerning threat in the list of
antibiotic resistant threats
Epidemiology
Hundreds of million cases annually
List 3 sequelae of streptococcal pharyngitis
➢
Scarlet Fever
➢
Rheumatic Fever
➢
Glomerulonephritis
INFECTIOUS DISEASES IN BOTH UPPER
AND LOWER RESPIRATORY TRACT
BORDETELLA PERTUSSIS
WHOOPING COUGH
►
Also known as “PERTUSSIS”
► Catarrhal Phase:
■
Bacteria in the respiratory tract cause cold
symptoms
RESPIRATORY SYNCYTIAL VIRUS (RSV)
►
Infects the respiratory tract and produces giant
multinucleated cells (Syncytia)
►
Outbreaks of droplet spread occur around the world,
with peak incidence in the winter and early spring
►
Children 6 months of age or younger, as well
premature babies, are especially susceptible to
serious disease
►
In 2020, with all of the mitigation procedures put in
place for COVID-19, RSV infections were very low
► Paroxysmal Phase:
■
Uncontrollable coughing with whooping sound
■
Can result in broken blood vessels in the eyes,
vomiting, or even hemorrhages in the brain
► Convalescent Phase:
■
Bacteria is decreasing, but ciliated epithelia have
been damaged, requiring weeks/mos of recovery
■
Causative Agents of the Whooping Cough
Bordetella pertussis
▸
Wave of RSV infections in the summer of 2021
after many people stopped wearing masks and
social distancing
Signs & Symptoms
○
Small, Gram(-) rod, strictly aerobic & fastidious
▸
Fever lasting 3 days, rhinitis, pharyngitis, and otitis
○
Filamentous hemagglutinin:
essential for attachment
▸
○
Pertussis toxin:
causes massive mucus production
More serious infections: progress to bronchial tree
and parenchyma, symptoms of croup and difficulty
breathing, and abnormal breathing sounds.
141 I
01: Infectious Diseases affecting the Respiratory System
MARK YPIL | TRANSCRIBED ON [ 07.25.2023]
Infectious Diseases affecting the Respiratory System
○
RESPIRATORY SYNCYTIAL VIRUS DISEASE TABLE
Causative Organism
Respiratory Syncytial Virus
Transmission
Droplet & Indirect contact
Virulence Factors
Syncytia Formation
Culture/Diagnosis
RT-PCR
Prevention
Passive antibody (humanized
monoclonal) in high risk children
Treatment
Ribavirin plus passive antibody in
severe cases
Epidemiology
3-5% mortality in premature infants or
those with congenital heart disease
7x Higher fatality rate in children in
developing countries
ANTIGENIC SHIFT:
▸
○
All cases of influenza are caused by one of three
influenza viruses: A, B, or C belonging to the
Orthomyxoviridae family
►
Reasons to the study the “flu”:
■
Annual flu seasons have the potential for turning
deadly for many people very quickly
■
Many diseases are erroneously termed “the flu”
■
Behavior of influenza viruses illustrates how
viruses can and do cause more serious diseases
than they did previously
○
No recognition by host memory cells
○
Often results in influenza pandemics
Transmission & Epidemiology
The drier air of winter facilitates the spread of the
virus
▸
○
Helping the virus remains airborne for more
extended periods of time
○
Cold air makes respiratory tract mucous
membranes more brittle, facilitating invasion by
viruses
For years the CDC has kept track of the percentage
of deaths caused by Pneumonia and Influenza
▸
○
Headache, chills, dry cough, body aches, fever,
stuffy nose, and sore throat
▸
Extreme fatigue can last for a few days or weeks
▸
Can leave patients vulnerable to secondary
infections, leading to pneumonia
Patients with emphysema or cardiopulmonary
diseases, along with very young, elderly, or
pregnant patients, are more susceptible to serious
complications
▸
INFLUENZA GLYCOPROTEINS
Hemagglutinin (H)
▸
○
Has agglutinating action on red blood cells
○
Binds to host cell receptors of respiratory mucosa
Neuraminidase (N)
▸
○
Breaks down protective mucus coating of the
respiratory tract
○
Assists in viral budding and release
○
Participates in host cell fusion
During the pandemic of COVID-19, it became
necessary to also keep track of the deaths
associated with it
Prevention of Influenza
Three major types of influenza vaccines in the U.S.:
▸
○
An intramuscular inactivated vaccine with three
strains of influenza in it
○
An intramuscular inactivated vaccine with four
strains
Signs & Symptoms
▸
Swapping out of one of the strands of viral RNA
with a gene or strand from a different influenza
virus
■ Infected host has both subtypes of the virus
INFLUENZA
►
Results in decreased ability of host memory cells
to recognize them
▸
The vaccine does not cause the flu
▸
Continuous research of emerging strains to prevent
a pandemic
▸
Several “universal” flu vaccines are in clinical trials
○
Focusing on targeting parts of the H molecule
that do not mutate rapidly
INFLUENZA DISEASE TABLE
Causative Organism
Transmission
Droplet contact
Direct or Indirect contact
Virulence Factors
Glycoproteins spike
Antigenic drift and shift
Culture/Diagnosis
Gold standard is RT-PCR
Prevention
A variety of vaccines are available
and should be received annually
Treatment
Oseltamivir (Tamiflu)
Baloxavir (Xofluza)
Epidemiology
For seasonal flu: Deaths vary per year
U.S.: 17k-52k
International: 250k-500k
MUTATION of GLYCOPROTEINS
ANTIGENIC DRIFT
▸
○
Gradual changing of amino acid composition of
influenza antigens
MARK YPIL | TRANSCRIBED ON [ 07.25.2023]
Influenza A, B, and C viruses
151 I
01: Infectious Diseases affecting the Respiratory System
Infectious Diseases affecting the Respiratory System
CONCEPT CHECK:
1.
True / FALSE: The vaccine against pertussis provides
Extrapulmonary Tuberculosis
lifelong protection
2.
Respiratory syncytial virus is most serious in
PREMATURE babies
3.
4.
Organs most commonly involved:
▸
○
Regional lymph nodes
○
Intestines
○
Kidneys
○
Long bones
True / FALSE: The vaccine against influenza provides
○
Genital tract
lifelong protection
○
Brain
○
Meninges
ANTIGENIC DRIFT refers to minor changes in viral
antigens and ANTIGENIC SHIFT is the result of gene
swapping between different strains of the virus
Secondary (Reactivation) Tuberculosis
Dormant bacteria in the lungs can be reactivated
when immunity wanes
▸
○
INFECTIOUS DISEASES IN THE LOWER
RESPIRATORY TRACT
►
An ancient human disease:
■
Found in mummies from the Stone age, Ancient
Egypt, and Peru
►
After the discovery of streptomycin in 1943, the
rates of the disease significantly decreased
►
Now a reemerging disease:
►
■
HIV Epidemic
■
Drug-resistant strains
■
Nearly 1/3 of the world’s population is infected
The bacterial species Mycobacterium tuberculosis
Infectious dose: 10 Bacteria
▸
Bacteria continue to multiply inside alveolar
macrophages
▸
Tubercles:
○
Granulomas containing a core of TB bacteria in
enlarged macrophages and an outer wall made
of fibroblasts, lymphocytes, and macrophages
○
Can become necrotic caseous lesions
○
Lesions can become calcified
Skin Testing for Tuberculosis
The response of T-cells to M.tuberculosis proteins
▸
○
Causes a cell-mediated immune response
○
Evident in the skin test Tuberculin reaction
■ Mantoux test shows evidence of delayed
hypersensitivity after initial infection with
Tuberculosis
MARK YPIL | TRANSCRIBED ON [ 07.25.2023]
○
Violent coughing
○
Greenish or Bloody sputum
○
Low-grade fever
○
Anorexia
○
Weight loss
○
Fatigue
○
Night sweats
○
Chest pain
The untreated disease has 60% mortality rate
▸
Tuberculosis Causative Agent
Mycobacterium tuberculosis
▸
Primary Tuberculosis
▸
Severe symptoms:
▸
TUBERCULOSIS
Able to remain dormant for weeks, months, years
○
Long, thin acid-fast rod, strict aerobe
○
Generation time 12-20 hr
○
Cord-factor: Lipid component in the
mycobacterial cell wall associated with virulent
strains
■ Mycolic acid and waxes
■ Makes the organism resistant to drying and
disinfections
Mycobacterium avium Complex (MAC)
▸
○
Causes a disseminated tuberculosis infection in
AIDS patients and other immunocompromised
Transmission & Epidemiology
▸
Transmission through fine droplets of respiratory
mucus suspended in the air
▸
Epidemiology vary with living conditions of a
community or area of the world
▸
Factors affecting the susceptibility
○
Inadequate nutrition
○
Debilitation of the immune system
○
Poor access to medical care
○
Lung damage
○
Genetics
161 I
01: Infectious Diseases affecting the Respiratory System
Infectious Diseases affecting the Respiratory System
Tuberculosis Diagnosis
TUBERCULOSIS DISEASE TABLE
Mantoux test:
▸
○
Causative Organism
Purified protein derivative is injected under the
skin and observed for evidence of an induration
indicating delayed hypersensitivity
IGRA:
▸
○
Transmission
Vehicle (airborne)
Virulence Factors
- Lipids in the wall
- Ability to stimulate strong
cell-mediated immunity (CMI)
Culture/Diagnosis
Culture
PCR test (Xpert)
IGRA
Complemented by skin test and chest
x ray
Prevention
Avoiding airborne M.tuberculosi
BCG vaccination
Treatment
- Multiple-drug regimen, may include:
- Pretomanid
- Bedaquiline
- Linezolid
Serious threat category in CDC
Distinctive Features
Much higher fatality rate over shorter
duration
Epidemiology
U.S.: a fewer cases per year
Worldwide: 500k new cases in 2020
Blood test to determine T-cell reactivity to
M.tuberculosis
▸
PCR methods
▸
Acid-fast staining of sputum sample
▸
Chest x-rays verify TB when other tests give
indeterminate results
MDR-TB and XDR-TB
Tuberculosis Treatment
Active tuberculosis:
▸
○
First 2 months: Rifampin, Isoniazid, Ethambutol
& Pyrazinamide
○
4-7 months: uses only two drugs that
susceptibility testing have shown to be effective
Patient non-compliance leads to drug-resistant
strains
▸
○
Multidrug-Resistant Tuberculosis (MDR-TB)
○
Extensively Drug-Resistant TB (XDR-TB)
TUBERCULOSIS DISEASE TABLE
Causative Organism
Vehicle (airborne)
Virulence Factors
- Lipids in the wall
- Ability to stimulate strong
cell-mediated immunity (CMI)
Avoiding airborne M.tuberculosi
BCG vaccination
Treatment
- Isoniazid
- Rifampin
- Pyrazinamide + Ethambutol or
Streptomycin for varying lengths
of time (Always length)
Distinctive Features
Epidemiology
Remains airborne for long periods
Extremely slow-growing, which has
implications for diagnosis &
treatment
U.S.: 10k cases/year 84% ethnic
minorities
International: 1.3 million deaths/year
MARK YPIL | TRANSCRIBED ON [ 07.25.2023]
■
Inflammatory condition of the lung in which fluid
fills the alveoli
■
Can be caused by a wide variety of
microorganisms
⬗ Must be able to avoid phagocytosis or;
Culture
PCR test (Xpert)
IGRA
Complemented by skin test and chest
x ray
Prevention
Anatomical diagnosis:
►
Mycobacterium tuberculosis
Transmission
Culture/Diagnosis
PNEUMONIA
⬗ Avoid being killed once inside macrophages
■
Viral pneumonia is usually (not always) milder
than bacterial pneumonia
■
Fungi can also cause pneumonia
Signs and Symptoms
►
Begin with Runny nose and Congestion, Headache,
and Fever
►
Lung symptoms: Chest pain, Fever, Cough,
Production of discolored sputum
►
Patient appears pale and sickly due to pain and
difficulty breathing
►
Severity and speed of onset of symptoms depend on
the etiologic agent
COMMUNITY-ACQUIRED PNEUMONIA:
Streptococcus pneumoniae
►
Small gram(+) flattened coccus that appears in pairs
►
Alpha-hemolytic
►
50% of healthy people, it is part of normal biota of
the respiratory tract
171 I
01: Infectious Diseases affecting the Respiratory System
Infectious Diseases affecting the Respiratory System
►
►
►
►
Infection occurs:
■
When bacterium is inhaled into the deep areas of
the lung
■
Between two people sharing respiratory droplets
■
The organism used to be called
Pneumocystis carinni
■
Old age
►
It is probably normal biota in healthy people
■
Season
►
Fungus multiplies intracellularly and extracellularly
■
Underlying viral respiratory disease
►
Traditional antifungal drugs are ineffective
■
Diabetes
■
Chronic abuse of alcohol or narcotics
Polysaccharide capsule prevents effective
phagocytosis:
■
Blocks complement
■
Causes inflammatory fluids to build up in the lung
Vaccine is encouraged for children and older adults
Mycoplasma pneumoniae
►
Atypical pneumonia: symptoms do not resemble
those of pneumococcal or other pneumonias
►
Lacks a cell wall, irregularly shaped
►
Transmitted by aerosol droplets among individuals
in close quarters
►
“Walking Pneumonia”
►
Diagnosis through ruling out other cases, PCR, or
serological analysis
Legionella pneumophila
►
Weakly gram(-) displays a variety of shapes
►
Associated with human disease after an American
Legion convention (1976) outbreak
►
Widely distributed in aqueous environments:
■
Tap Water, Cooling towers, Spas, Ponds and
Freshwater
►
Opportunistic: affects the elderly
►
AIRCON LIQUID
Histoplasma capsulatum
►
Agents of Pneumocystis pneumonia
(PCP pneumonia) in patients with AIDS
►
Factors that enhance disease:
► S.pneumoniae is resistant to penicillin, and its
derivatives, macrolides, tetracycline, and
fluoroquinolones
►
Pneumocystis jirovecii
Also known as:
■
Darling’s Disease
■
Ohio Valley Fever
■
Spelunker’s Disease
Can be benign or severe, acute or chronic
■
Most serious forms occur in patient AIDS
■
Chronic pulmonary histoplasmosis: signs and
symptoms similar to Tuberculosis
■
COMMUNITY-ACQUIRED PNEUMONIA DISEASE TABLE
Causative Organism
RHINOVIRUSES
Transmission
Droplet contact
Endogenous transfer
Virulence Factors
N/A
Culture/Diagnosis
Failure to find bacteria or fungi
Prevention
Hygiene
Treatment
None
Distinctive Features
Usually mild
Epidemiology
9% of CAP cases
Streptococcus pneumoniae
Causative Organism
Transmission
Droplet contact
Endogenous transfer
Virulence Factors
Capsule
Culture/Diagnosis
Gram-stain often diagnostic
Alpha-hemolytic on Blood agar
Prevention
PCV-13 or PPSV23 vaccine
Treatment
Doxycycline, Ceftriaxone, with or
without vancomycin; much resistance
Distinctive Features
Patients usually severely ill
Epidemiology
5% of CAP cases; drug-resistant
strains in CDC Serious Threat
Category
Mycoplasma pneumoniae
Causative Organism
Transmission
Droplet contact
Virulence Factors
Adhesins
Culture/Diagnosis
Rule out other etiologic agents,
Serology and PCR
Prevention
No vaccine, no permanent immunity
Treatment
Erythromycin
Distinctive Features
Usually mild; “walking pneumonia”
Epidemiology
N/A
Endemic to all continents except Australia
MARK YPIL | TRANSCRIBED ON [ 07.25.2023]
181 I
01: Infectious Diseases affecting the Respiratory System
Infectious Diseases affecting the Respiratory System
COMMUNITY-ACQUIRED PNEUMONIA DISEASE TABLE
Legionella species
Causative Organism
CAUSATIVE AGENTS:
►
■
Staphylococcus aureus (usually MRSA)
■
Klebsiella pneumoniae
■
Enterobacter
Transmission
Vehicle (water droplets)
Virulence Factors
N/A
■
Escherichia coli
Urine antigen test;
Cultures requires selective charcoal
yeast extract agar
■
Pseudomonas aeruginosa
Culture/Diagnosis
■
Acinetobacter
Prevention
N/A
■
Most cases are polymicrobial origin
Treatment
Fluoroquinolone
Azithromycin
Clarithromycin
Distinctive Features
Epidemiology
Prevention and Treatment of HCA Pneumonia
▸
Most causes are due to aspiration from the upper
respiratory tract
Mild pneumonia in healthy people
Severe in elderly &
immunocompromised
▸
Elevation of patients’ heads to 30-45° angle helps
reduce aspiration of secretions
▸
Deep breathing and coughing
U.S.: 6-8k cases annually
▸
Proper care of ventilation & respiratory equipment
▸
Empiric antibiotic therapy should be started as soon
as health care-associated pneumonia is suspected
Histoplasma capsulatum
Causative Organism
Transmission
Vehicle (inhalation of fungal spores in
contaminated spores)
Virulence Factors
Survival in phagocytes
Culture/Diagnosis
Rapid antigen test & Microscopy
Prevention
Avoid contaminated soil with bird &
bat droppings
Treatment
Itraconazole
Distinctive Features
Many infections asymptomatic
Epidemiology
U.S.: 250k per year;
5-10% Symptomatic
Pneumocystis jirovecii
Causative Organism
Transmission
Vehicle (inhalation of fungal spores)
Virulence Factors
N/A
Culture/Diagnosis
Microscopy
Prevention
Antibiotics given to AIDS patients to
prevent this
Treatment
Trimethoprim / Sulfamethoxazole
Distinctive Features
Majority occur in patients with AIDS
Epidemiology
Almost exclusively in severely
immunocompromised patients
HEALTH CARE-ACQUIRED PNEUMONIA DISEASE TABLE
Causative Organism
Transmission
Endogenous (Aspiration)
Virulence Factors
N/A
Culture/Diagnosis
Culture of lungs fluids
Prevention
Elevating patient’s head, preoperative
education, care of respiratory
equipment
Treatment
Varies by Etiology
U.S.: 300k cases per year; occurs in
0.5-1% of admitted patients
Epidemiology
U.S. and International mortality rate
is 20-50%
HANTAVIRUS PULMONARY SYNDROME
First cases were a cluster of patients in the Four
corners area of New Mexico in 1993
►
■
Most patients were young, healthy adults and
died within a few days
■
Hantavirus: agent previously only been known to
cause severe kidney damage and hemorrhagic
fevers in other parts of the world
■
This emerging disease has a mortality rate of
33%
HEALTH CARE-ASSOCIATED PNEUMONIA
►
About 1% of hospitalized or institutionalized people
developed pneumonia
■ Most often associated with mechanical
ventilation via endotracheal or tracheostomy
tube
■
Gram (-)(+) bacteria from upper
respiratory tract or stomach;
environmental contamination of
ventilator
30-50% mortality rate
MARK YPIL | TRANSCRIBED ON [ 07.25.2023]
191 I
01: Infectious Diseases affecting the Respiratory System
Infectious Diseases affecting the Respiratory System
Signs and Symptoms of Hantavirus Pulmonary
Syndrome
►
CONCEPT CHECK:
1.
Prodromal phase:
In EXTRAPULMONARY tuberculosis, the lymph nodes,
■
Fever
kidneys, long bones, and other organs can become
■
Chills
involved
■
Myalgias (Muscle Aches)
■
Headache
■
Nausea
■
Vomiting
responsible for 40% of all cases of
■
Diarrhea
community-acquired pneumonia
2.
TRUE / False: One third of the world’s population is
infected with Tuberculosis
3.
►
Cough is common, but not a prominent early
symptom
►
Soon, severe pulmonary edema and acute
respiratory distress occur
►
Severe breathing difficulties and a drop in blood
pressure after the hantavirus antigen has spread
through the blood
4.
Streptococcus pneumoniae is the bacterium
Patients requiring mechanical ventilation or who have
tracheostomy tubes are more susceptible to
VENTILATOR - ASSOCIATED PNEUMONIA
Transmission & Epidemiology
►
Airborne via dust contaminated with urine, feces, or
saliva of infected rodents
■
►
Deer mice or other rodents harbor one or more of
the multiple strains of hantavirus
Incidence is increasing in areas of the U.S. west of
the Mississippi river
Treatment & Prevention
►
Diagnosis through detection of IgM antibody to
hantavirus or PCR techniques
►
No treatment other than supportive care
HANTAVIRUS PULMONARY SYNDROME DISEASE TABLE
Causative Organism
HANTAVIRUS
Transmission
Vehicle - Airborne virus emitted from
rodents
Virulence Factors
Ability to induce inflammatory
response
Culture/Diagnosis
Serology (IgM)
PCR identification of antigen in tissue
Prevention
Avoid mouse habitats and droppings
Treatment
Supportive
U.S.: 10-25 cases per year; similar
rates internationally
Epidemiology
Previously thought to be universally
lethal, but now known fatality is
25%-50% Category C Bioterrorism
Agent
MARK YPIL | TRANSCRIBED ON [ 07.25.2023]
1101 I
01: Infectious Diseases affecting the Respiratory System
Infectious Diseases affecting the Respiratory System
TAXONOMIC ORGANIZATION:
MICROORGANISMS CAUSING DISEASE IN
THE RESPIRATORY TRACT
GRAM - POSITIVE
BACTERIA
DISEASE
✦ Streptococcus
pneumoniae
OTITIS MEDIA
PNEUMONIA
✦ Streptococcus
pyogenes
PHARYNGITIS
GRAM - NEGATIVE
BACTERIA
DISEASE
✦ Fusobacterium
necrophorum
PHARYNGITIS
✦ Bordetella pertussis
WHOOPING COUGH
RNA VIRUSES
✦ Respiratory syncytial
virus
RSV DISEASE
✦ Influenza virus A, B,
and C
INFLUENZA
✦ Hantavirus
HANTAVIRUS
PULMONARY
SYNDROME
✦ Rhinoviruses
PNEUMONIA
FUNGI
✦ Legionella spp,
✦ Legionella
pneumophila
OTHER BACTERIA
PNEUMONIA
DISEASE
✦ Mycobacterium
tuberculosis
✦ M.avium (not
considered gram- or
gram+)
TUBERCULOSIS
✦ Mycoplasma
pneumoniae
PNEUMONIA
MARK YPIL | TRANSCRIBED ON [ 07.25.2023]
DISEASE
DISEASE
✦ C. auris
OTITIS MEDIA
✦ Histoplasma
capsulatum
HISTOPLASMOSIS
✦ Pneumocystis
jiroveci
Pneumocystis
pneumonia
1111 I
01: Infectious Diseases affecting the Respiratory System