Clin Med 1 Infectious Disease 2

Bacteria Pathophysiology

Invasion of tissue

Release Exotoxins and Endotoxins

What are exotoxins?

Poisonous substances secreted by bacteria

What do exotoxins do?

Cell lysis, degradation of extracellular matrix, cell dysfunction

What are endotoxins?

Inflammatory/immune response

Cellular and tissue destruction

Viruses pathophysiology direct pathway

Produces a protein that damages the cell membrane

Virus pathophysiology indirect pathway

Produces a protein that is incorporated into the cell membrane

Immune system mounts a response to this protein

True or False: Sepsis is a syndrome associated with severe infection?

True

Is sepsis a systemic response to infection?

Yes, it enters the bloodstream

How is sepsis caused?

The release of bacterial endotoxins and/or exotoxins

Sepsis triggers the activation of what?

Inflammation cascade, coagulation cascade, complement system

Sepsis cycle

Infection

Bacteremia

Sepsis

Septic Shock

Multi-organ failure

What is the bacteremia stage?

Bacteria in the bloodstream

What is the sepsis stage?

2 or more of:

Temp>100 degrees, <96 degrees

HR>90

RR>20

WBC >12k, <4k

What is the septic shock stage?

Hypotension

Perfusion abnormalities

Altered mental status

What is the multi-organ failure stage?

Failure of the kidneys, lungs, heart, liver, clotting, and CNS

What are the treatments for sepsis?

Treat primary infection

Fluid resuscitation

Medications to vasoconstrict, improve heart function

Treat organ failure

Immune modulators

What is the definition of a pathogen?

The parasite or microorganism responsible for arousing a pathologic response

Ex: bacteria or virus

What is the definition of infectivity?

Pathogen's ability to invade and replicate in a host; how likely is the pathogen to infect someone

Ex: common cold and HIV

What is the definition of pathogenicity?

Ability of organism to cause disease; certain conditions or some disease can happen at any time.

Ex: Epstein-Bar has monolike symptoms (15%)

What is the definition of virulence?

Potency of pathogen and producing severe disease; how bad it will be

Ex: the common cold has a low virulence and Ebola has a high virulence

What is the definition of antigenicity?

The pathogen's ability to stimulate an immune response

Experience condition once (Chicken pox)

Large immune response

Low antigenicity: TB, syphilis, HIV

What is are the sequences of infection?

Transmission

Contact

Airborne

Enteric

Vector-borne

What is contact transmission?

Host is in direct/indirect contact with infection

Ex: touch face w/ disease, common cold lives on surface, touch disease that is on a door knob

What is airborne transmission?

Pathogen is inhaled in through contaminated droplets

Ex: pneumonia, TB, COVID

What is the enteric transmission?

Fecal/oral route

Ex: Underdeveloped countries virus in fecal to oral route

What is the vector-borne transmission?

Indirect, intermediate, insects transmit the disease

Ex: malaria

What is the sequence of infection?

Inoculation/portal of entry

Incubation

Prodromal period

Clinical disease

Convalescence

Recovery

What is the inoculation/portal of entry period?

Pathogen fights past 1st line of defense

Nasal passage

What is the incubation period?

The period of time from when the pathogen enters until symptoms occur

Replication

Host may/not be contagious

What is the prodromal period?

Mild non-specific symptoms

Ex: fatigue

What is the clinical disease period?

Body's response - immune, inflammation

true symptoms

What is the convalescence period?

Resolution - body defeats pathogen

What is recovery?

No longer having the pathogen

What are the symptoms of infection?

Fever, chills, sweating, malaise (general fatigue and feeling ill), nausea, vomiting

What are the symptoms in elderly for infection?

Confusion, memory loss, difficulty concentrating

What are the signs of infection?

Fever, rash, lymphadenopathy (swelling of lymph), and lymphangitis

What is this a picture of?

Lymphangitis

What is this picture of?

Lymphangitis

What is the ancillary testing for infection?

Direct visualization of the organism

Culture and sensitivity

Detection of microbial antigen or antibody

Clues that infection may be present

Detection of specific microbial nucleotide sequences

What is direct visualization of the organism?

Gram staining - finding certain bacteria

Used by sputum or urinalysis

What is the difference between culture and sensitivity?

Culture is different because each bacteria grow differently. Cultures are 24 hours. Sensitivity is 48 hours. Sensitivity is different by seeing how long infected tissue grows, antibiotics are treatments.

What does the detection of microbial antigen or antibody help do?

Identify viral rapid strep test

What clues that infection may be present?

X-ray and WBC in urinalysis

What is the detection of specific microbial nucleotide sequences?

Viral and bacterial infections

How do we treat infection?

Local methods: Heat, incision and drain

Antibiotics - bacterial

Antivirals - viruses

Antifungals - fungals

What are the antibiotic mechanisms?

Destroy the cell wall

Inhibit protein synthesis

Inhibit DNA synthesis

Inhibit RNA synthesis

What does inhibiting the protein synthesis do?

Bacteria can't replicate

What does inhibiting DNA and RNA synthesis do?

Prevent function and replicate

Antiviral medications do what for the body?

Inhibit viral replication

Frequent resistance

Often use multiple medications

What are the preventions for infection?

Handwashing

Disinfecting tables/equipment

Personal protective equipment (PPE)

Vaccinate healthcare workers

Follow isolation procedures

If ill, avoid treating high-risk patients