Infectious Disease Concepts and Pathogens for Nursing Students

Infectious Diseases (IDs)

Disorders in which tissue damage or dysfunction is produced by a microorganism.

Endemic

Used to describe a disease that exists all the time in certain communities; e.g., 'malaria is endemic to parts of Africa.'

Epidemic

An outbreak of a disease that spreads within a certain time frame to people of one or several communities; e.g., 'There is often a yearly flu epidemic in some U.S. communities.'

Pandemic

The disease outbreak spreads from being epidemic (a few communities) to being worldwide; e.g., 'The Spanish flu of 1918 began as an epidemic amongst soldiers at U.S. army bases, then became pandemic when they went to Europe during WWI.'

Infection

Presence & multiplication of a living organism on or in the host.

Pathogen

An organism that causes harm.

Types of Pathogens

Viruses, bacteria, fungi, protozoan, nematodes, and microsporidia.

Immunocompetence

Are the host's defense mechanisms adequate, non-defective, fully functional, etc.?

Virulence Factors

Toxins, adhesion factors, invasion factors, evasive factors of the infecting organism.

Cellulitis

An infection of the skin and underlying tissues.

Botulism

A rare but serious illness caused by a toxin produced by the bacterium Clostridium botulinum.

Tetanus

A bacterial infection characterized by muscle spasms, caused by Clostridium tetani.

Rabies

A viral disease that causes inflammation of the brain, transmitted through the bite of an infected animal.

Malaria

A disease caused by parasites transmitted to humans through the bites of infected mosquitoes.

Zika Virus

A virus transmitted primarily by Aedes mosquitoes, causing fever, rash, and joint pain.

Ebola

A severe and often fatal illness in humans and nonhuman primates caused by the Ebola virus.

Strep Throat

A bacterial infection that causes inflammation and pain in the throat.

Diphtheria

A serious bacterial infection affecting the mucous membranes of the throat and nose.

Pertussis

Also known as whooping cough, a highly contagious respiratory disease caused by the bacterium Bordetella pertussis.

Mumps

A contagious disease caused by a virus that leads to painful swelling of the salivary glands.

Measles

A highly contagious viral disease characterized by a distinctive red rash.

Pox Diseases

A group of diseases characterized by the formation of pustules on the skin.

Influenza

Commonly known as the flu, a viral infection that attacks the respiratory system.

Standard precautions

Basic infection prevention measures used during every patient interaction whether a known or suspected infection is present.

Hand hygiene

Washing hands before/after every patient contact, before/after every meal, after using the toilet.

Personal protective equipment (PPE)

Gowns, gloves, face masks worn when anticipating exposure to infectious material.

Respiratory hygiene and cough etiquette

Cover cough or sneeze with arm, not the hand.

Safe injection practices

Dispose used needles in a special container.

Disinfecting soiled surfaces and equipment

Disinfect shared equipment, such as blood pressure cuffs, between each patient use.

Contact precautions

Used when any patient has diarrhea, stool incontinence, draining wounds or sores, uncontrolled secretions, vomiting, draining body fluids, skin rashes or sores.

Droplet precautions

Used when droplets generated by an individual during coughing, sneezing, or talking can invade the host's nasal mucosa, conjunctiva, or mouth.

Airborne precautions

Used when any individual has a suspected or known infection that is transmitted by the airborne route.

Incubation period

Phase during which the pathogen begins active replication but doesn't produce signs and symptoms; varies in length: salmonella—6 to 8 hrs, hep B—50 to 180 days.

Prodromal stage

Initial appearance of signs and symptoms; may be mild.

Acute stage

Maximum impact, with very pronounced and specific signs and symptoms.

Convalescent period

Containment of infection and resolution of signs and symptoms.

Resolution

Total elimination of pathogen without remaining signs and symptoms.

Chronic disease

Disease that has a protracted and irregular course.

Subclinical or subacute form

Some diseases progress without many clinical signs and symptoms or with less severe signs and symptoms.

Fulminant illness

Abrupt onset with little or no prodrome.

Antibiotic resistance

Microorganisms changing to become resistant to the anti-infective drugs that used to kill or disable them.

Beta lactam antibiotics resistance

A type of antibiotic resistance where bacteria become resistant to beta lactam antibiotics.

Vancomycin resistance

A type of antibiotic resistance where bacteria become resistant to vancomycin.

Beta-lactam antibiotics

Penicillin and its derivatives that have a molecular structure called a beta-lactam ring.

Beta-lactamase

An enzyme developed by certain microbes that can destroy beta-lactam antibiotics by dismantling the beta-lactam ring.

MRSA

Methicillin-resistant Staphylococcus aureus, a strain of staph bacteria that has become resistant to the beta-lactam antibiotic methicillin.

Fomite

An inanimate vector that can transmit infections.

Subcutaneous

Referring to the area under the skin.

Nosocomial disease

An infection that is acquired in a hospital setting.

Community-acquired MRSA

A new strain of MRSA found in wounds of people who have not been in a hospital setting.

Vancomycin

An antibiotic that is effective against MRSA.

Resistant Streptococcus pneumoniae

A strain of bacteria that was once easily treated with penicillin but has developed resistance due to over-treatment.

Otitis media

An ear infection most commonly caused by Streptococcus pneumoniae.

VRE

Vancomycin-resistant enterococcus, another hospital-associated infection.

Enterococci faecalis

A normal bowel flora that can migrate to the urinary tract in hospitalized individuals.

Pathogenesis of cellulitis

Occurs when an organism like Staphylococcus aureus gains deeper entry after a laceration or puncture.

Impetigo

A milder staph infection of the skin characterized by an eruption of blisters around the nose and mouth.

Vector-borne disease

Diseases transmitted via bite, sting, or puncture of a host creature that introduces a disease-causing organism into a new body.

Examples of vectors

Mosquitoes, ticks, rats, bats, dogs, etc.

Mutated gene in VRE

A change in one small part of a protein on the enterococcus cell wall that prevents Vancomycin from binding.

Heavy-duty alternative antibiotics

Antibiotics that are now required to treat infections caused by VRE due to resistance.

MRSA colonization

Occurs in the nares of healthcare workers and can spread through direct patient contact.

Infections caused by MRSA

Typically invade wounds and can colonize sites such as the bladder and blood.

Over-treatment of ear infections

Contributes to the development of resistant strains of Streptococcus pneumoniae.

Cellulitis Treatment

Tx (treatment) for cellulitis—abx (antibiotics).

Botulism Mechanism

Toxin heads for neuromuscular nerve synapses & blocks acetylcholine muscle receptor cells.

Botulism Symptoms

Typical S&S is a descending, symmetric paralysis, including respiratory.

Floppy Baby Syndrome

Ex—'floppy baby syndrome'—seen in infants (<1 year) that eat honey contaminated with C. botulinum.

Botulism Bioterrorism

Considered one of top candidates for bioterrorism use.

Botulism Treatment

Tx—temporary mechanical ventilation, other supportive tx.

Tetanus Pathogenesis

Caused by Clostridium tetanii, a bacillus which can live in soil as a spore → when deposited in a wound, will then germinate.

Tetanus Toxin

As it becomes active, will release exotoxin tetanospasmin→ blocks inhibitory neurotransmitters & causes uninterrupted nerve impulses to muscle cells→ can cause jaw muscle tightening called trismus (lockjaw), or more severe tetany.

Tetanus Treatment

Tx—antibx & TIG.

Rabies Mechanism

Virus travels via peripheral nervous system (PNS) to the brain & spinal cord (central nervous system -- CNS) and causes brain inflammation→ leads to S&S of anxiety, agitation, confusion, convulsions.

Rabies Symptoms

Other S&S include production of large amount saliva, plus dysphagia = 'foaming at the mouth' & 'hydrophobia' (not really a fear of water, just can't swallow).

Rabies Treatment

Treatment needs to begin within first 14 days with post-exposure prophylaxis (PEP) -- one dose of rabies immunoglobulin and four doses of rabies vaccine.

Rabies Prognosis

If not treated within this time, the rabies virus will continue its 'trip' all the way up to the CNS—once CNS infected, there is no cure.

Malaria Cause

Caused by protozoa that is transmitted via mosquito vector.

Malaria Mechanism

Protozoa reproduces in liver cells (hepatocytes) and then is released into blood, where it infects RBCs & causes them to rupture (hemolysis)→ as the RBCs rupture, they trigger a flooding of acute phase reactants into blood→ causes S&S.

Malaria Symptoms

S&S - high fever, chills, arthralgia, anemia, splenomegaly, cerebral ischemia, heart failure.

Malaria Treatment

Tx—Prevention with malaria vaccination in children, or with quinine-based drugs, mosquito nets, use of insect repellant that contains DEET. Antiparasitic or IV antimalarial drugs once diagnosed.

Zika Symptoms

Signs and symptoms may be mild and are similar to the S&S seen with the flu. People usually don't get sick enough to go to the hospital, and they rarely die of Zika. However, Zika infection during pregnancy can cause birth defects such as microcephaly (brain and head smaller than normal).

Zika Transmission

Transmission (spread) occurs from mosquito bites or -person-to-mosquito-to-person; from a pregnant woman to her fetus; or by sexual transmission.

Zika Prevention

Prevent Zika by using insect repellants that contain DEET, use of light-colored clothing when outdoors, use of window/door screens and mosquito nets, removal of standing water where mosquitos reproduce.

Zika Sexual Precautions

Sexual abstinence or condom use should be considered for 8 weeks to 6 months.

Zika Risk for Pregnant Women

Pregnant women or those wishing to become pregnant should avoid areas where a Zika outbreak is known.

Zika Diagnosis

Blood or urine test can confirm a diagnosis.

Zika Treatment

Supportive care includes fluids, rest, and acetaminophen.

Strep Throat Symptoms

Red, sore throat, often with white patches on tonsils.

Scarlet Fever

Can occur with certain strains of strep, characterized by fever and rash covering the whole body.

Importance of Early Antibiotics

Early and thorough treatment of antibiotics will lessen the chance of autoimmune diseases like rheumatic fever.

Diphtheria Symptoms

Sore throat, fever, and pseudomembrane across tonsils and throat.

Whooping Cough

Also known as pertussis, characterized by violent coughing fits that can lead to malnourishment.

Mumps Complication

Main complication is infertility in males.

Titer

Done to measure the level of antibodies to specific diseases; high titer indicates lots of antibodies.

Measles Symptoms

Dense red maculopapular rash starting on head, fever, cough, runny nose, conjunctivitis.

Measles Complications

Can include serious complications such as encephalitis.

Rubella

Milder virus with mild symptoms like fever, rash, and swollen glands.

Rubella Risks in Pregnancy

Can cause baby to be born with problems like mental retardation, eye problems, and hearing problems.

Rubella Vaccination

Child-bearing age women should have a rubella titer done; if low, need to be vaccinated.