Patho - Lect 2: Infection

What is infection?

A state of tissue destruction resulting from invasion of microorganisms.

What are microorganisms?

Small living forms that include bacteria, fungi, protozoa, viruses.

What is nonpathogenic?

Usually do not cause disease unless conditions change.

What are pathogens?

Disease-causing microbes.

What is normal flora?

Beneficial Microorganisms that live in the GI tract, respiratory tract, genital tract, skin and mucus membranes.

Infectious Diseases

__ - diseases that are transmissible from one person to another.

Communicable

Infectious Diseases

__ - diseases that are not transmissible.

Non-communicable

What are these example of:

• Respiratory infections

• Hepatitis

• STIs

• TB

• Meningitis

Examples of communicable diseases

What are these example of:

• Cardiovascular diseases

• Malignant neoplasms

• COPD

• Diabetes

Examples of non-communicable diseases

What is the prodrome phase of infection?

An early set of symptoms appearing before the onset of a full disease.

Bacteria

__ - gram-negative cell wall → inflammation, fever, septic.

Endotoxin

Bacteria

__ - bacteria produced toxins, usually produced by gram-positive bacteria.

Exotoxins

What is the presence of bacteria in the blood as a result of a failure of the body’s defense mechanisms?

Bacteremia or septicemia

Which major groups of bacteria:

• Rod-shaped organisms

Bacilli

Which major groups of bacteria:

• Include spiral forms and Vibrio spp.

Spirochetes

Which major groups of bacteria:

• Spherical forms

• Diplococci

• Streptococci

• Staphylococci

Cocci

Which basic structure of bacteria:

• Protects and provides a specific shape

• Two types that differ in chemical composition:

  • Gram-positive

  • Gram-negative

• Useful in selecting appropriate antimicrobial therapy

Rigid cell wall

Which basic structure of bacteria:

• Found in some

• Outside the cell wall

• Offers additional protection

External capsule or slime layer

Which basic structure of bacteria:

• One or more attached to cell wall

• Provide motility for some species

Flagella

Which basic structure of bacteria:

• Tiny hairlike structures

• Assist in attachment to tissue

• Transfer of DNA to another bacterium

Pili or fimbriae

Which basic structure of bacteria:

• Inside the bacterial cell wall

• Selectively permeable

Cell membrane

Which basic structure of bacteria:

• Chromosome - One long strand of DNA

• Ribosomes and RNA

• Plasmids - DNA fragments; non-chromosomal; exchange DNA during conjugation

Cytoplasm

Basic Structure of Bacteria:

Exotoxins is usually produced by __.

gram-positive bacteria.

Basic Structure of Bacteria:

Endotoxins is present in the cell of __.

gram-negative bacteria

What is formed by several species and can survive long periods of time in spore state?

Spores

What are small intracellular parasites that dependent on host cells?

Viral Infection

What are cellular effects of viruses?

• Inhibition of host cell DNA, RNA, or protein synthesis

• Disruption of lysosomal membranes

• Promotion of apoptosis

• Fusion of infected, adjacent host cells

• Transformation of host cells into cancerous cells

• Promotion of secondary bacterial infections

Chronic Viral Infection

__ - (dormancy) integrates itself into host cells DNA.

Latency

Which infection is this:

• Common cause of sexually transmitted disease

• Can result in infertility

Chlamydia

Which infection is this:

• Gram-negative

• Transmitted by insect vectors (lice, ticks)

Rickettsia

Which infection is this:

• Lack cell wall

• Cause of atypical type pneumonia

Mycoplasmas

Fungi

__ - from single-celled yeast or multicellular molds.

Fungal or mycotic infection

Fungi can cause __ or mucous membranes but may spread systemically particularly in __.

primary infection on skin, immunosuppressed individual.

Fungal Infection and Injury

__ - single-celled

Yeasts

Fungal Infection and Injury

__ - multi-celled

Molds

What is the pathogenicity of fungal infection?

• Adapt to host environment

• Wide temperature variations, digest keratin, low oxygen

• Suppress the immune defenses

Deep fungal infections can be __.

Ex: Pneumonia, Histoplasmosis, Aspergillosis Vaginal Yeast

life threatening and are commonly opportunistic.

Fungi that invade the skin, hair, or nails are known as __.

Ex: Ringworm, Tinea pedis (athletes foot)

dermatophytes.

What are protozoa?

Single-cell animal organisms, larger then bacteria.

What are these characteristics of:

• Eukaryotic forms

• Unicellular, lack cell wall

• Many live independently, others are obligate parasites

• Pathogens are usually parasites

Protozoa

Protozoa Types

__ - most common water borne disease.

Giardia

Protozoa Types

__ - causes malaria.

Plasmodium

What are these characteristics of:

• Are parasites, not microorganisms

• May be small or up to 1m in length

• Life cycle with at least three stages

  • Ovum, larva, adult

Helminths (flatworms or roundworms)

Helminth Diseases

__ - ova inhaled in dust in fecally contaminated area; common in children worldwide.

Pinworms

Helminth Diseases

__ - larvae enter skin from fecally contaminated soil in tropical areas.

Hookworms

Helminth Diseases

__ - most common form transmitted by larvae in undercooked pork.

Tapeworms

Helminth Diseases

__ - ingested with food that been grown in feces-contaminated soil or prepared with hands that have been in feces-contaminated soil.

Ascaris - giant roundworm

What are prions?

Protein-like agents that change the shape of proteins within host cells.

Principles of Infection

__ - organism is able to reproduce in or on body’s tissues.

Infection

Principles of Infection

__ - in a single individual.

Sporadic

Principles of Infection

__ - continuous transmission within a population.

Endemic

Principles of Infection

__ - higher than normal transmission or spread to new geographical area.

Epidemic

Principles of Infection

__ - transmission has occurred on most continents.

Pandemic

Which transmission of infectious agents:

• Source of infection

• Person with active infection

• Person who is asymptomatic

• Environmental source such as contaminated soil

Reservoir

Which transmission of infectious agents:

• A person may never develop the disease but still is a carrier

• A person with subclinical signs of the disease

Carrier

How do infectious agents leaves?

Portal of exit

What is mode of transmission?

Method whereby the agent reaches a new susceptible host

Ex: air, water, direct contact, food

How do infectious agents enter?

Portal of entry

Virulence and Pathogenicity

__ - capability of a microbe to cause disease.

Pathogenicity

Virulence and Pathogenicity

__ - degree of pathogenicity / (tough to kill)

Virulence

Which modes of transmission:

• No intermediary

• Touching infectious lesion, sexual activity

• Contact with infected blood or bodily secretions

Direct contact

Which modes of transmission:

• Involves intermediary object or organism

• Contaminated hand or food

• Fomite — inanimate object

Indirect contact

Which modes of transmission:

• Respiratory or salivary secretions are expelled from infected individual

Droplet transmission

Which modes of transmission:

• Involve small particles from the respiratory tract

• Suspended in air and can travel farther than droplets

Aerosol transmission

Which modes of transmission:

• Insect or animal is an intermediate host

Vector-borne

What type of infection occur in health care facilities?

Nosocomial Infections

What are factors that decrease host resistance?

• Age (infants and older adults)

• Pregnancy

• Genetic susceptibility

• Immunodeficiency

• Malnutrition

• Chronic disease

• Severe physical or emotional stress

• Inflammation or trauma

• Impaired inflammatory responses

Control of Transmission and Infection

__ - used in all settings with all clients when body fluids may be exchanged.

Standard Precautions

Control of Transmission and Infection

__ - in clients diagnosed with a particular infection — these are used in addition to standard precautions.

Specific Precautions

Which means of disinfection:

• Chemicals - Ethlene oxide, Cidex, (Metricide)

• Heat in an autoclave

Sterilization

Which means of disinfection:

__ - are used on surfaces or objects.

Disinfectants

Which means of disinfection:

__ - are used on the skin and tissues.

Antiseptics

Which physiology of infection:

• Time between entry of organism into the body and appearance of clinical signs of disease

• Vary considerable with different organisms

Incubation period

Which physiology of infection:

• Fatigue, loss of appetite, headache

• Nonspecific — “coming down with something”

• More evident in some infections than others

Prodromal period

Which physiology of infection:

• Infectious disease develops fully

Acute period

What are local signs of inflammation?

Pain, swelling, redness, warmth

What are systemic signs of inflammation?

• Fever may be present

• Fatigue and weakness

• Headache

• Nausea

Diagnostic Tests

__ - Looking for invaders.

Ex: swabs

Antigen identification

Diagnostic Tests

__ - Looking for antibody

Ex. blood test

Antibody titer

What are the guidelines for drug therapy?

Drugs should be administered and taken as directed.

Which classification of antimicrobials:

• Drugs derived from organisms

Antibiotic

Which classification of antimicrobials:

• Antibacterial

• Antiviral

• Antifungal

Antimicrobial

Which classification of antimicrobials:

• Drugs destroy organism

Bactericidal

Which classification of antimicrobials:

• Decrease rate of reproduction

Bacteriostatic

Classification of antimicrobials:

__ - effective against both gram-positive and gram-negative organisms.

Broad spectrum

Classification of antimicrobials:

__ - effective against either gram-positive or gram-negative organisms.

Narrow spectrum

Classification of antimicrobials:

__ - original drug class

First generation

Classification of antimicrobials:

__ - later version, which may be more effective, more tolerable, or more easily administered.

Second generation

Types of Immunity:

__ - antigen is recognized by T cells & B cells → memory cells for cytotoxic T cells & antibody producing plasma B cells are produced.

Naturally Acquired Active

Types of Immunity:

__ - transfer of IgG (pregnancy) or IgA (breastmilk).

Naturally Acquired Passive

Types of Immunity:

__ - introduction of weakened or antigens to trigger body into making cytotoxic T memory cells & antibody plasma B cells (vaccinations).

Artificially Acquired Active

Types of Immunity:

__ - injection of antibodies (serums).

Artificially Acquired Passive