CLASS 14 - INFECTION AND RELATED THERAPIES, SKIN + RESPIRATORY EXEMPLARS Flashcards
What is an infection?
The invasion and growth of foreign pathogens in the body.
Describe the chain of infection.
Infectious diseases result from the interaction of agent, host, and environment. Transmission occurs when the agent leaves its reservoir or host through a portal of exit, is conveyed by some mode of transmission, and enters through an appropriate protal of entry to infect a susceptible.
Identify the 4 types of pathogens that may cause an infection in the body.
Bacteria
Fungi
Virus
Parasite
What is pathogenicity? What does it depend on?
The ability to cause disease.
Pathogenicity depends on the microbes’ speed of reproduction and ability to bypass body defenses.
What are opportunistic pathogens?
Opportunistic pathogens rely on a suppressed immune system for successful infection.
Identify the 4 stages of infectious disease.
- Incubation Period
- Prodromal Period
- Acute Period
- Convalescent Period
What causes inflammation?
How does the process of inflammation impact a patient during an infection?
How can the inflammatory process negatively impact the body during an infection (excess inflammation)?
Inflammation occurs when chemicals from WBCs enter your blood or tissues. This raises the blood flow to the area of infection.
It can cause redness and warmth, and some chemicals cause fluid to leak into your tissues, resulting in swelling.
Excess inflammation is associated with tissue damage.
What is virulence?
Virulence is a measure of pathogenicity.
A highly virulent microbe can produce disease in very small numbers. The primary characteristics of virulence are invasiveness and toxicity.
Define invasiveness
Invasiveness is the ability to grow extremely rapidly and cause direct damage to surrounding tissue by sheer numbers.
How do bacterial exotoxins harm cells in the body?
Exotoxins damage or destroy body cells. When some gram-ve bacteria die, their cell wall releases endotoxins that induce macrophages to release large amounts of cytokines caysing rapid inflammation, fever, and chills.
What are subclinical infections?
If an infectious disease is subclinical, this means that it progresses from infection to resolution w/o the appearance of clinical symptoms.
What is bacteremia?
Bacteremia occurs when detectable amounts of bacteria enter the blood stream; usually asymptomatic, but can cause secondary infections particularly in the presence of cardiac valve disease or a prosthetic joint
Define sepsis.
What are the clinical manifestations?
Sepsis occurs when circulating bacteria cause systemic inflammation.
Signs include fever, hypotension, tachycardia, tachypnea, and leukocytosis.
Describe severe sepsis.
Severe sepsis includes all signs of sepsis + multi-organ failure.
What is septic shock?
What pathogens can cause septic shock in the body?
Septic shock is a combination of severe sepsis and refractory hypotension.
- Mainly gram- bacteria that release endotoxins,
- Staphylococcus aureus and streptococcus pyogenes that can produce toxic shock syndrome toxin.
Why does a patient become hypotensive during septic shock?
With a systemic response, all blood vessels dilute which causes the blood pressure to drop.
Instead of assisting in fighting the infection, the body’s response to sepsis actually slows down the blood flow, whcih makes our immune system less effective.
The bacteria can damage vital organs, and a lack of blood flow can result in organ failure.
What are the local signs of infection (4)?
Local signs of infection include:
1) signs of inflammation (redness, pain, heat, swelling)
2) presence of exudate or pus
3) lymphadenopathy (swollen + tender lymph nodes)
4) system-specific signs
- GI infections: vomiting, diarrhea
- Resp tract infections: sneezing, coughing, dyspnea
What are the systemic / general signs of infection (5)?
1) fever (or subnormal temperatures with some viral infections)
2) fatigue
3) headache
4) anorexia, nausea
5) malaise + myalgia (joint + muscle pain)
Which lab results are used to diagnose an infection in the body?
CBC
- increased WBC count
- blood lactate
- increased CRP
- increased segmented neutrophils
- increased band neutrophils
- increased monocytes
- increased basophils
- increased eosinophils
What does an increased blood lactate count indicate in terms of infection?
Increased blood lactate indicates an increased sign of sepsis in the body.
What does an increased level of CRP indicate in the body?
sign of general inflammation
what does an increased level of segmented neutrophils in the blood indicate in the body?
sign of bacterial infection
what does an increased level of band neutrophils in the blood indicate in the body?
sign of bacterial infection
what does an increased level of lymphocytes in the blood indicate in the body?
sign of viral + bacterial infection
what does an increased level of monocytes in the blood indicate in the body?
sign of recovery from severe infections
what does an increased level of basophils in the blood indicate in the body?
sign of parasitic infection
what does an increased level of eusinophils in the blood indicate in the body?
sign of parasitic infection
What is a neutrophil band shift to the left? What does it tell us about the patient?
A left shit indicates the presence of immature neutrophils in the blood.
An increase in immature band neutrophils typically means that the bone marrow has been signaled to release more WBCs and increase the production of WBCs.
This is an indication of a bacterial infection.
Identify the 4 sources of health-care associated infections.
Client flora
Invasive devices
medical personell
medical environment
What is a community acquired (CA) infection?
What is a hospital acquired infection?
CA infection is contracted less than 48 hours after hospital admission.
HA infection is contracted more than 48 hrs after admission, usually more virulent + resistant.
Identify the lab results for a patient with a viral infection
increased lymphocytes
Identify the lab results for a patient with a bacterial infection
increased segmented neutrophils
increased band neutrophils
increased lymphocytes
Identify the lab results for a patient with a parasitic infection
increased basophils
increased eusinophils
What is an anti-infective medication?
What are they further specified as?
Anti-infective medications are considered to be any medications that are effective against pathogens.
Further specified as:
- antibacterial
- antifungal
- antiviral
What is the purpose of anti-infective treatment?
- used prophylactically (to prevent infection)
- reduces the bacterial load enough to give the immune system a better chance to fight it off
What is an antibiotic?
Antibiotics are naturally produced by microorganisms to kill other microorganisms (only works on bacteria).
Can we use antibiotics on parasites, viruses, or fungi?
No, because antibiotics only work against bacteria.
What the 2 general categories used to classify anti-infective drugs?
- Classification by susceptible organism
2. Classification by MOA
Describe how anti-infective drugs are classified by susceptible organism.
This classification is used to describe the drugs that are effective against certain pathogens.
Drugs can be classified as antibacterial, antifungal, or antiviral.
These types can be further divided into narrow spectrum and broad spectrum.
What is a narrow spectrum antibiotic?
What is a broad spectrum antibiotic?
which type is preferred?
active only against a few specifi organisms (preferred)
actibe against a wide variety of organisms
describe the process of graim staining.
Bacteria stained with crystal violet, then KI solution used.
Destaining is done with water + alcohol
bacteria is gram +ve if stain does not come out
bacteria is gram -ve if stain comes out.
describe the composition of gram+ve bacteria in terms of peptidoglycan and their plasma membrane.
outer thick peptidoglycan later, inner plasma membrane
describe the composition of gram+ve bacteria in terms of peptidoglycan and their plasma membrane.
outer membrane, middle thin peptidoglycan later, inner plasma membrane.
Define aerobic bacteria.
require oxygen for their growth
Describe obligate aerobic bacteria and give an example.
cannot survive in the absence of oxygen
ex - TB
Describe microaerophilic bacteria and give an exmaple.
require lower concs of oxygen such as 2-10%
ex - Helocobacter pylori
Define anaerobic bacteria.
do not require oxygen for their growth
Describe obligate anaerobic bacteria and give an example.
cannot survive in the presence of oxygen
ex - tetanus
Describe facultative anaerobic bacteria and give an example.
can grow w / o oxygen, but use it if it’s present.
ex - E.coli
Describe aerotolerant bacteria.
cannot use oxygen for their growth, but arent harmed by its presence.
Antibiotics are selectively toxic. What does this mean?
They attempt to kill the invading bacteria without harming host cells.
Define bacteriocidal.
Define bacteriostatic.
Bacteriocidal = kills bacteria
Bacteriostatic = slows bacterial growth
What might cause the host to not tolerate an antibiotic?
allergy
drug becomes toxic to host in high doses
metabolites of drug may be toxic to liver in high doses.
What are the 5 ways in which antibiotics target bacterial cells?
- inhibit cell wall synthesis
- increase cell membrane permeability
- inhibit protein synthesis
- inhibit bacterial synthesis of DNA and RNA / disrupt DNA function
- antimetabolite activity
What is a biofilm? Why is it important for anti-infective therapy?
A biofilm is a jelly-like substance where thousands of bacterial cells are suspended inside.
The antibiotics must diffuse through the biofilm to reach all the bacterial cells.
Some cells that are buried deep within the biofilm are exposed to only a fraction of the antibiotic that reached the surface.
What is antibiotic resistance?
Antibiotic resistance occurs when bacteria continue to grow in the presence of the drug.
What is innate resistance?
use penicillin as an example
innate ability of a bacterial species to resist activity of a particular antimicrobial agent through its inherent structural or functional characteristics, which allow tolerance of a particular drug or antimicrobial class.
example: penicillin innately does not work very well of gram -ve bacteria since these bacteria have very little cell wall.
what is acquired antibiotic resistance?
resistance develops through random mutations that are occasionally advantagoeus resulting in survival.
By killing susceptible strains of a bacterial population through excessive use of antibiotics, resistant strains are allowed to survive and eventually dominate that bacterial population.
What are nosocomial infections?
Infections acquired in a hospital or other healthcare setting.
Often resistant to common antibiotics.
Identify the 4 Common Mutations bacteria undergo to become resistant to antibiotics.
1) Enzymes in the bacteria eat and deactivate antibiotics
2) Antibiotics are ejected from the bacteria
3) bacterial wall prevents antibiotics from entering
4) bacteria adopts a new way of processing energy (some antibiotics interfere w the energy process)
Describe how enzyme production can lead to the acquiring of antibiotic resistance.
Enzyme can destroy or deactivate the drug such as beta-lactamase
Enzymes can deactivate a drug as it crosses over the cell membrane
What is Beta-Lactamase?
Beta-Lactamase is an enzyme produced by many staphylococcus bacteria that metabolizes penicilin.
Beta-Lactamase breaks down the B-Lactam ring of penicillin.
B-Lactamase gene can be shared through genetic exchange between bacteria.
What is a solution for the problem of Beta-Lactamase and penicillin?
Penicillins are combined with Beta-Lactamase inhibitors ro combat this resistance.
Describe the removal by resistance pumps as a mechanism of antibiotic resistance.
Resistant bacteria have developed several types of pumps that removes the antibiotic before it causes its effect
Describe alteration of the drug’s target site as a mechanism of antibiotic resistance.
The bacteria changes the shape of the target receptor so the drug cannot bind.
How can we prevent the formation of resistant strains of bacteria?
- prevent infections when possible
- diagnose + treat the infection properly
- use antibiotics wiselg. Prescribe only when there is a clear rationale .
- prevent transmission of infection
What are the 2 common resistant strains of bacteria?
MRSA (methicillin-resistant staphylococcus aureus)
VRE (vancomycin-resistant enterococci)
Which patients are susceptible to MRSA?
Immunocompromised patients
Occurs in healthy people through skin infections
Where are VRE naturally found? Where else are they found?
VRE found notmally in GI tract and female GU tract
Found in wounds, ulcers
In which scenarios would an anti-infective agent be used prophylactically?
High risk patients
High risk procedures
High risk of exposure
Protocol driven
ex - antibiotic eye drops post-birth to prevent chlamydia and gonorrhea eye infections
ex - antibiotics prior to dental procedures for patients with mechanical heart valves
anti-malarial drigs for travellers in high risk areas
What are some host factors that need to be considered prior to the administration of anti-infective therapy?
Immunocompetence
Local tissue conditions like sinuses or CNS infections, need longer tx w abx to reach target tissue.
Allergy history
Recent use of Abx
Age, pregnancy or breastfeeding, genetics
What is a super/suprainfection?
How does this occur?
A new, secondary infection caused by antibiotic use.
Some microbes produce natural antibacterial substance or toxins that kill other microbes. Antibiotics cannot distinguish between host and hostile flora, and killing the host flora can leave an opportunity for hostile flora to grow.
What is microbial antagonism?
helps to protect the host from being overrun by pathogenic organisms. They compete with them for nutrients and space.
What should we monitor a patient for to ensure that a suprainfection is not occurring?
Monitor for diarrhea, bladder pain, painful urination, or abnormal vaginal discharge.
What are the 3 ways in which organisms that cause pneumonia can reach the lungs?
Aspiration
Inhalation
Hematogenous spread from primary infection
What is lobar pneumonia?
Continuous inflammation in the lobe(s) or entire lung.
What are the 4 stages of bacterial pneumonia?
Congestion (24 hrs)
Red Hepatization (days 2-4)
Gray Hepatization (days 5-9)
Resolution
what is bronchopneumonia?
infection starts in the bronchi and spreads as pathcy, bilateral inflammation.
what are the 8 classes of antibiotics?
penicillins cephalosporins aminoglycosides tetracyclines macrolides sulfonamides glycopeptides fluroquinolones
Describe the function of urinary antiseptics and provide an example.
Exclusively used for urinary tract infections.
Concentrate in the kidney and travel to the bladder for anti-bacterial action in the urine.
ex - Nitrofurantoin - treat acute cystitis (bladder infections) or prophylaxis of recurrent UTIs.
Describe the function of Anti-fungal drugs (azoles) Fluconazole and Nystatin
Fluconazole: Narrow spectrum (used for only candida albicans), systemic and superficial fungal infections
Nystatin: primarily used for candida albicans infections of the vagina, skin, and mouth ; travels through GI tract without being absorbed.
What is the difference between fungal cells and human cells?
fungi have steroid in their plasma membrane, drugs inhibit steroid synthesis which makes the membranes leaky.
In which population are opportunistic fungal infections most common in?
Immunocompromised patients.
Describe the function of anti-protozoans using metronidazole (Flagyl) as an example.
What is a potential side effect?
Metronidazole is effective against protozoans and some bacteria
- anti-amebic: amebic dysentery
- antiprotozoan: Giardiasis (GI) and trichomoniasis (vaginal)
- antibacterial: helocobacter pylori (bacteria) infections of the stomach
Antabuse like reaction when taken with alcohol
Describe the function of Anti-Viral drugs such as Acyclovir (Zovirax).
Acyclovir is the drug of choice for anti-herpesvirus
prevents viral DNA sysnthesis
Decreases the duration and severity of herpes episodes.
