Lecture 11 Flashcards
Infectious Diseases and Epidemiology
Klebsielle Pneumoniae 225
-Example given at start of class of bacteria that is resistant to EVERYTHING except imipenem and fluoroquinolones
Bacteria
- Bacteriology
- Prokaryotic
- Single cell organisms
- Most antimicrobials target bacteria
- Ex: strep, staph, pneumonia
Fungi
- Mycology
- Eukaryotic Cells
- Single or multi-cell organisms
- Chemotherapy is more limits
- Ex: Candida, athlete’s foot, aspergillus
Virus
-Virology
-Non-cellular
-Obligate, intracellular pathogen
-Infectious
-Anti-viral development challenging
Ex: Chicken pox, measles, mumps, shingles
Parasites
- Parasitology
- Tape worms
- Trichomoras
- Dracunules medinensis
Prions
-Non-cellular
-Pathogen protein
-Driven by amount of glycosylation, possibly
Animals: Mad Cow Disease, Chronic Wasting Disease
Humans: Kuru, Fatal Familial Insomnia
Infectious Disease
- Noncommunicable Disease
- Nosocomial Infections
Noncommunicable Diseases
- Caused by microbiota
- E. Coli or microbiota in improper places (deep tissues, mouth biota in heart, etc.)
- Food poisoning due to pre-formed toxins or botulism in adults are examples
- Transmitted by common source - Legionnarie’s disease from HVAC or Pseudomonas in water
- Diseases from pathogens in environment can also be a source (fungal spores, tetanus, etc.)
Spread Methods (2)
- Vertical
- Horizontal
Vertical Spread of Infectious Disease
- Mother-to-child
- Transplacental (child birth)
- Breast milk
- Rubella, AIDS, Herpes
Horizontal Spread of Infectious Disease
- Other routes
- Saliva, skin to skin, fecal-oral, vector transmitted, zoonoses
Direct Spread
-Moves without help from one person to another, close contact is required, travels within a meter of distance
-Saliva/respiratory droplets are means or transport
Ex: common cold or influenza
Skin-to-Skin Contact Spread Example
MRSA (occurs in athletes commonly)
Blood-borne Spread Examples
Hepatitis A & B, AIDS
-Requires inoculation of blood/blood products
Fecal-Oral Spread
- Intestinal pathogens spread via this method
- Increased risk with children in daycare, holding children, and even shaking hands
- E. Coli, Shigella, Campylobacter, Salmonella
Indirect - Respiratory Infection
-Air particle over distance greater than a meter
-Fomites - inanimate objects that spread disease
Ex: Flu or cold
Indirect - Intestinal Infection Paths
-Contaminated water, food, and fomites
Indirect - Blood-borne Infection Paths
-Needle sticks and scalpel cuts tend to allow for pathogens to infect
Biological Vectors
- Indirect infection via anthropods
- Ex: Malaria, Lyme Disease, Rocky Mountain Spotted Fever, Plague
- Passed via mosquitos, ticks, lice, etc.
Animal Infections
- Zoonoses
- Diseases transmitted from animals to humans
- Direct contact - rabies, anthrax, etc.
- Indirect contact - Lyme Disease, plague
- Travel: Vertebrate»_space; Vector»_space; Human
Patterns of Incidence (4)
- Sporadic
- Endemic
- Epidemic
- Pandemic
Sporadic
Observed only occasionally and without geographic concentration
Endemic
Low, constant levels (smoldering infection)
Epidemic
Higher levels of infection in a short time in a geographic location
Pandemic
Widespread (possibly worldwide) infection with high attack rates
Nosocomial Infections
- Health-care associated
- NOT present at time of admission
- Develops during hospitalization (5-15% patients)
- Can occur from contact with health care professionals, contaminated equipment, ventilators, IV, catheters, spread of normal flora, or surgery
- High mortality rate - people infected are already sick and have weakened immune defenses. Most of these infections are resistant to drugs though they rarely infect health individuals
Primary Pathogen
Disease causing pathogen in health, strong individuals
Opportunistic Pathogen
Disease causing pathogen in compromised host
Pseudomonas Aerginosa
- Can be part of normal microbiota
- Serious and life-threatening infections in burn patients, those on respirators, eye infections with contacts, and outer ear infections
Are opportunistic pathogens avirulent?
Far from it, usually contain a multitude of virulence factors.
Infectious Dose
Amount of pathogen needed to infect 50% of patients. Usually measured for diarrheal pathogens
Newly Discovered Infections
Hantavirus, HIV, Ebola, West Nile Virus, SARS, and MERS
Evolving/Re-emerging Threats
Community-acquired MRSA, Pan-resistant bacteria, E. Cola O157H7
Superbugs Problems
- Pan-resistant bacteria is on the rise
- Pipeline of new antibiotic development is dwindling
- Resistance to new drugs is rapid
How to Avoid Antibiotic Resistant Pathogens?
- Slow evolution of resistance
- Appropriate use of antibodies
- Drug combinations
- Attack virulence factors
- Hospital Infection Control
Miama Superbug Outbreak
- Admission file: XDR bacteria
- Only sensitive to colistin and gentamicin
- Overlooked and ignored
- 9 more patients came in over 3 months with identical cases
- Overall impact: 5 died, 2 survived with kidney failure, 3 survived without kidney failure
