Bacteria and disease

1. The suspected organism must be absent in healthy individuals but present in those with the disease

2. The suspected organism must be isolated from the infected host and grown in pure culture

3. The organisms grow from pure culture must produce the same disease as that of the infected source when inoculated to a susceptible animal

4. The same causative agent must then be reisolated from the inoculated diseased organism

Give me the Koch’s 4 postulate

etiologic agent

host

environment

The development of an infectious disease is a consequence of the interaction among three components:

1. _____

2. _____

3. _____

Reservoir

Continual source of disease-producing microorganisms

Site where infectious agent normally resides and multiplies

Animal reservoir

zoonotic infections: from animal to humans (ex. plague, and rabies)

Human reservoir

from one individual to another (ex. Respiratory pathogens & sexually transmitted infections)

Carriers

developed the disease, got well but still harbor the organism thereby transmitting them to others

asymptomatic/ healthy carriers

incubatory

chronic

convalescent

forms of carriers

mechanical transmission

biological transmission

2 types of vector transmission

Immune status

most important factor that can affect development of disease process

mechanical / invasiveness

chemical / toxin production

immunologic

3 ways in how organisms produces disease

adhesins

facilitates adhesion to specific target cells

colonization

ability to evade host immune defenses

production of extracellular substances to promote invasion

3 ways of Mechanical / invasiveness

Staphylococcus aureus

secretes coagulase enzyme which helps hide from surveillance cells

Mycobacterium tubercolosis

____- can survive and multiply in macrophage by phagosome -lysosome fusion

Neisseria gonorrheae

______multiplies within the host cell and is extruded to infect other host cells.

- causes direct destruction of the host cells

Clostridium perfingers

produces collagenase - development of disease called gas gangrene.

Toxins

poisonous substances that contribute to disease production.

Lipid A

Polysaccharide

Component responsible for activity of endotoxins are Lipopolysaccharide ( LPS) made of 2 components:

1.________toxic activity

2.________Antigen

lysis

Exert effect: when bacteria dies, cell walls undergo ______

Endotoxins

Integral components of Gram negative bacteria

Exotoxins

Intracellular products as part of their growth and metabolism.

• Mainly proteins and enzymes

• Soluble in body fluids, easily diffused in the blood.

cytotoxins

neurotoxins

enterotoxins

3 principal types of exotoxins

Immunologic

Consequence to the immune response of the host to the microorganism or its product.

1. how they behave within a host and within a population

2. Source of microorganism

3. occurence of disease

4. Severity / duration of disease

5. extent of host involvement

Classification if infectious disease

Contagious disease

if the disease easily and rapidly spread from one person to another.

Fulminant infection

if the infection results in the death of the patient over a short period of time.

Exogenous

Endogenous

Classification of infectous disease based on the source of the microorganism

Exogenous

if the source of the infectious agent is from outside the body (e.g., cholera)

Nosocomial infection

Also called Hospital acquired infections, an exogenous infection, obtained from the hospital environment.

Endogenous

if the source of the causative agent is from inside the body (e.g., Escherichia coli)

40
20
15
6
8
11

Give the percentage of the frequency of nosocomial infection

UTI’s ______

Surgical Site infection _____

Lower respiratory infection ______

Bacterimia via Iv and cath. ______

Cutaenous Infection ______

other _____

Sporadic

endemic

Epidemic

Pandemic

Classifications of Infectous disease based on Occurence of a disease

Sporadic

a disease that occurs occasionaly (e.g., rabies, tetanus)

Endemic disease

a disease that is constantly present in a population at low levels (e.g., Malaria in Palawan)

Epidemic Disease

if a great number of people in a given locality develop infectious disease in a relatively short time ( ex. influenza)

Pandemic Disease

type of disease that has a worldwide occurence or involves at least 3 regions in the worls (ex. Sars)

Acute

Latent

Chronic

Classifications of Disease based on the severity or duration of a disease

Acute disease

develops rapidly but lasts only for a short period of time

Chronic Disease

develops more slowly and occurs for long periods of time.

Latent disease

the causative organisms remains inactive for a time but can become active again and produce symptoms of the disease.

Localized infection

systemic infection

focal infection

primary infection

secondary infection

Subclinical/ Innaparent infection

Classification of infectous disease based in the extent of host involvement

Localized infection

invading organisms are limited to a relatively small area of the body.

systemic infection

or Generalized infection, where causative organism or their products are spread through out the body through blood/ lymph

Focal infection

causative agents of a localized infection may enter a blood or lympathic vessel, spread to specific parts of the body and become confined to specific areas

Primary infection

an acute infection that causes initial illness.

Secondary infection

caused by opportunistic pathogens after the primary infection has weakened the body’s defenses.

Subclinical/ inapparent infection

one that does not cause noticeable illness.

Incubation period

prodromal period

period of illness

period of decline

period of convalescence

Stages of infectous disease

Incubation period

time between initial appearance symptoms

Prodromal period

Characterized by appearance of first mild signs and symptoms

Period of illness

Disease at its height : all disease signs and symptoms apparent

Period of decline

Signs and symptoms subside

Period of convalescence

Body returns to pre-diseased state, heakth is restored

Disease

Result of an undesirable relationship b/w host and pathogen interruption on the normal functioning of body part/s

Infection

Invasion of the body by pathogenic microorganisms

Symbiosis

Prolonged and close interaction b/w organisms of different species

Virulence

Describes the degree of pathogenicity of an organism or the degree to which an organism can produce disease

Contamination

Presence of unwanted materials where they should not be or at concentrations above the normal

Pollution

Presence of contaminants that can cause adverse biological effects to humans and communities

Bacterimia

Presence of bacteria in the blood

Pyemia

Presence of pus-producing bacteria in the bloodstream

Viremia

Presence of virus in the blood

toxemia

Presence of toxins in the blood