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Antibiotics

1. People usually remain healthy and resistant to microorganisms due to the due to the presence of host defenses.

Defenses are:

1. Physical barriers - intact skin, cilia of respiratory tract
2. Physiologic - Gastric acid, antibodies
3. Other defenses are Phagocytic Cells (eat the foreign organisms)

Microorganisms are ubiquitous in the external environment; also present within our bodies.

Beneficial or harmful depending on situation

Bacteria

1. Aerobic vs. Anaerobic
- Aerobic - require oxygen to survive.
- Anaerobic - do not require oxygen to survive.

Bacteria

1. Gram+ vs. Gram-
- Gram+ = very thick cell wall and outer capsule, stains purple.

- Gram- = complex cell wall, difficult to treat, stains red

what are intracellular parasites that survive only in living tissues?

Viruses

Viruses

- intracellular parasites that survive only in living tissues.
- officially classed according to their structure; more commonly described according to origin, disorders, and symptoms they manifest.

what are plant like organisms that exist as parasites on a living host or decaying organic matter?

Fungi

What are single-celled organisms that are the smallest and simplest members of the animal kingdom?

Protozoan

True or False
- When a person's normal host defenses are compromised, the host is susceptible to infection.

True

which of the following are signs and symptoms of infection?
a. Fever
b. Chills,
c. Sweating
d. redness
e. pain & swelling
f. fatigue
g. weight loss
h. increased WBC
i. formation of pus

The classic signs and symptoms of infection are:
- fever, chills, sweating, reness, pain & swelling, redness, fatigue, weight loss, increased WBC, formation of pus

Antibiotics are most effective when coupled with which of the following.
a. Steroids
b. NSAIDs,
c. A functional body defense system
d. consumption of a healthy diet

C. A functional Body Defense System

An infection acquired by a person who has not recently been a patient in the hospital within the last year or had a medical procedure is considered what kind of infection?
a. Nosocomial
b. Community

b. Community

True or False
- As a general rule, community acquired infections are not as severe and usually easier to treat.

True

True or False
- Antibiotic resistant strains are increasing in the communities.

True

What is an example of a bacteria that is increasing in resistance in the communities?

MRSA

What kind of infection is acquired during the course of a hospitalization or procedure?

Nosocomial or healthcare associated infection

True or False
- Nosocomial infections are one of the top 10 causes of death.

True

Nosocomial infections tend to be difficult to treat because the microorganisms have been exposed to what?

They have been exposed to strong antibiotics -->drug resistance and increased Virulence

In addition to increase drug resistance and increased virulence, what also factors into the difficulty of treating nosocomial infections?

Patients are sick and compromised, which also contributes to the difficulty in treating nosocomial infections.

What is the most common hospital associated organism?

MRSA - Methicillin-resistant staphylococcus aureus

What percentage of hospitalized patients develop nosocomial infections?
a. 5%
b. 10%
c. 15%
d. 20%

10%

what is the cost of treating the nosocomial infections annually?

$4-$11 billion annually this is a huge problem

Nosocomial Infections

The most common sites for nosocomial infections are urinary tract infections and incisional infections.

what percentage of nosocomial infections are preventable?
a. 50%
b. 70%
c. 93%
d. 100%

70%

Opportunistic Pathogens

The normal endogenous or environmental flora, which became pathogens in their hosts.
- Usually due to a compromised defense system
- Likely to occur with sever burns (1st line of defense is compromised), CA (chemo/radiation), Indwelling IVs or Urinary catheters, and AIDS

That are the three general uses for antibiotics?

1. Empiric therapy
2. Definitive therapy
3. Prophylactic therapy

- Occurs in the presence of a suspected life threatening infection, I.e. Meningitis.
- An antibiotic capable of killing the microorganism known to be the most common causative is given.
- before the antibiotic is given, cultures must be obtained to identify the causative agent. once the organism is defined through the culture and sensitivity report, the antibiotic therapy can be tailored to the specific organism via a sensitivity report.

Empiric Therapy

- Broad spectrum antibiotics are given with numbers organisms.
- ** Overuse causes resistance
- Narrow spectrum is active with only a few organisms
- THE GOALIS TO USE THE NARROWEST SPECTRUM OF ANTIBIOTICS.

Definitive therapy

- Used to prevent an infection
- Often will see this used before an invasive procedure; i.e. surgery, especially GI surgery, dental work, or suspected STD, pre-op heart valves (left ventricle not working)

Prophylactic surgery

Antibiotics

To optimize the antibiotic therapy, patients should be assessed for therapeutic effects and adverse drug affects.

Therapeutic effects of antibiotics

1. decrease in the signs and symptoms of infections
2. decreased WBCs

Antibiotic Toxicity

- Occurs when the blood levels are too high, or when an allergic or adverse reaction occurs.

Major adverse reaction of antibiotic therapy

- rash, itching, hives, fever, chills, joint pain, and difficulty breathing or wheezing.

Minor reactions to antibiotic therapy

- GI discomfort
- Diarrhea
- Nausea

Occurs when antibiotics reduce or completely eliminate normal flora

Superinfections

Superinfections

- occur when antibiotics reduce or completely eliminate normal flora
- a big issue because the body needs certain bacteria and fungi to maintain normal function--> the opportunity arises for other bacteria to take over-->infection

What is this an example of ?
-Vaginal yeast infections occurs when normal vaginal flora is reduced by antibiotic therapy-->yeast growth goes wild.

A vaginal yeast infection is an example of a superinfection.

What is this an example of?
- pseudomembranous colitis occurs due to the disruption of the normal GI flora-->overgrowth of Clostridium Difficule

Pseudomembranous Colitis (C-Diff) is and example of a superinfection.

what are common signs and symptoms of pseudomembranous colitis (C-Diff)

- Watery diarrhea
- Abdominal Pain
- Fever

In addition to superinfections, Secondary infections may occur also.

- an infections closely following a primary infection and comes from an external source.
ex. a viral respiratory infections develops into a secondary bacterial infection.

Antibiotic Resistance

- Considered a major health problem
- A major cause is the over prescribing of antibiotics and patients not completing their prescribed course of antibiotics.

Antibiotic Resistance: Organisms of concern

- Penicillin resistant streptococcus pneumonia
- methicillin resistant staphylococcus aureus and staphylococcus epidermidis
- vancomycin-resistant resistant enterococcus
- extended-spectrum beta-lactames (ESBL)-producing gram negative bacteria.
- multidrug-resistant tuberculosis (MDR-TB)

what is the primary cause of antibiotic resistance

- overuse of antibiotics

How do they do that?

1. produce enzymes that inactivate the drug
2. modify target sites for antibiotic
3. produce alternative enzyme to bypass antibiotic activity
4. change cell wall structure to decrease permeability

How do we stop antibiotic resistance?

1. reconstruct the antibiotic (very costly, very research and labor intensive, it takes years for drug to get FDA approval, 5-6 years to get on market)
2. Only treat true bacterial infections when necessary
3. Do NOT use antibacterials to treat viral infections, they are of no significant value.

Most common mechanics of antibiotic reaction

1. interference with bacterial cell wall synthesis
2. interference protein synthesis
3. Interference with replication of DNA and RNA
4. Disruption of antimetabolite action inside the bacteria.

what is the goal of antibiotic therapy?

to reduce or remove the presence of bacteria

Sulfonamides

- block synthesis of components necessary for cell metabolism and growth

Penicillins, Cephalosporins, and Vancomycins

- Inhibit formation of cell wall

Fluoroquinolones

- Inhibit DNA gyrase, and enzyme required for reproduction

Aminoglycosides, macrolides, ketolides, tetracyclines, linezolid, and quinupristin/dalfopristin

- bind to ribosomes and inhibit production of essential proteins.

Bactericidal

Kills the organism

Bacteriostatic

Inhibits the growth of the organism

Sulfonamides- Mechanism of Actions

- a bacteriostatic antibiotic (inhibit the growth of susceptible bacteria by preventing bacterial synthesis of folic acid)
- Folic acid is necessary for formation of purine and pyrimidine (precursors of DNA & RNA)

True or False
- Humans produce their own folic acid

False, humans must get folic acid from dietary sources.

True of False
- Bacteria produce their own folic acid

True

Sulfonamides - Indications

- A broad spectrum of activity against both Gram+ and Gram- organisms.
- Often used to treat urinary tract infections
- Commonly susceptible organisms = enterobactor species, Escherichia coli, Klebsiella species, proteus mirabilis, proteus vulgaris, and S. aureus.

Sulfonamides - indications

- used in the treatment of Opportunistic infections in this with HIV (pneumocystis jirovecii)
- sulfamethoxazole/trimethoprim (Bactrim, Septra) used to treat outpatient staphylococcus infections.

Sulfonamides - Contraindications

- Know Drug Allergy to Sulfonamides
- Allergy to Celecoxib (celebrex)
- Pregnant and lactating women and infants younger than 2 months of age - may cause birth defects and Kernicterus (a condition of abnormally high bilirubin which causes irreversible brain damage)

Sulfonamides - Adverse Reactions

- Believed to be immune mediated and involve production of reactive drug metabolites.
- A common cause of allergic reactions; may be described as a "sulfa allergy" by patients
--Typically delayed skin reaction which begin with a fever, followed by a rash.
--Photosensitivity may occur when patient is exposed to sun light causing sever sunburn (use a lot os sunscreen)
- Other reactions are: GI (N/V/D, abdominal pain and stomatitis), Hepatic (renal crystalluria, hematuria, protonuria), and Hematologic

Sulfonamides - Interactions

- May potentiate the hypoglycemic effects of sulfonylureas in diabetics, increase phenytoin toxicity, and enhance anticoagulant effects of warfarin (coumadin)
- May decrease the effects of oral contraceptives

Sulfonamides - 1. Co-trimoxazole (Bactrim)

Dosage is one double strength tablet every 12-24 hours PO
- IV 8-20mg/kg/day as Trimethoprim in divided doses q6-12 hours
- Nursing considerations - make sure culture and specimen report is done. Monitor bowel patterns daily, assess skin for rash, monitor renal, hematological, and hepatic function.

Co-trimoxazole (Bactim) PO Dosage

1 double strength table q12-24 hours PO

Co-Trimoxzole (Bactrim) IV Dosage

8-20mg/kg/day as trimethoprim in divided doses q 6-12 hours

Beta-Lactam Antibiotics

- Very commonly used drugs
- 4 major sublcasses
1. Penicillins
2. Cephalosporins
3. Carbapenms
4. Monobactams
Inhibit the synthesis of cell wall

Beta-Lactam Antibiotics

1. some strains of bacteria lactamase which leads to bacterial resistance. due to this, beta lactamase inhibitors are added to several of the penicillin antibiotics to make the drug powerful agains the beta lactamase producing strains.
Examples:
- ampicillin/subactam (Unasyn)
- Amoxicillin/Clavulanic Acid (Augmentin)
- Ticarcillin/clavulanic acid (Timentin
- Piperacillin/tazobactam (Zosyn)

Penicillins

1. Bactericidal antibiotics
2. discovered by Sir Alexander Flemming in 1928. Introduced in the 1940s WWII.
3. First drug to be effective against syphilis and staphylococcus infections.

Penicillins - Mechanism of actions

1. Inhibition of cell wall synthesis by entering the cell wall.
2. Some penicillins are too large to pass through the cell wall so they must find an appropriate binding site; Penicillin binding proteins.
- Binding with these proteins-->interferes with normal cell synthesis-->defective cell walls that are weak-->cellular death by lysis (rupture)

Penicillins - Indications

1. Used in prevention and treatment of infections
2. Most commonly destroys gram+ organisms, (streptococcus, enterococcus, staphylococcus)
3. Extended spectrum penicillins have very good gram+, gram-, and anaerobic coverage.
- used to treat many hospital acquired infections.

Penicillin - Contraindications

- Drug allergies - you need to also know the reaction, because it is individualized.

Penicillin - Adverse Effects

- Allergic reactions occur in 0.7-14% of treatment courses.
- Most common reactions are: Urticaria, Pruritis, and angiodema.
Unpredictable reactions are: maculopapular eruptions, eosinophilia, stevens-jackon syndrome, exfoliative dermatitis.
- anaphylaxis is less common

Penicillin - Adverse effects

** Problem is: Cross sensitivity may occur with penicillins and cephalosporins.
- patients must be asked to describe their allergic reaction.
**** Those patients whose reactions include hives, and throat swelling should never be given cephalosporins.

Penicillin - Teaching

Have some form of ID, in case you cannot communicate in an emergency.

Penicillin - Interactions

1. Most oral forms of PCN are destroyed by acids.
- avoid taking them with orange juice and cranberry juice.

Penicillin G (prototype) and Penicillin V Potassium

1. IM form is useful in treatment of sexually transmitted disease.
2. Limited use due to many stains which have developed resistance.
PCN G is drug of choice for STREP PHARYNGITIS, reoccurrence of RHEUMATIC FEVER, and NEUROSYPHILIS.
3. PCN G is given IM - destroyed by stomach acid.
4. may cause cardiac arrest
5. contains 1.5mEq of potassium/1 million units--> watch for increased Potassium levels

Penicillin V Potassium

- The same as PCN G, BUT is NOT destroyed by gastric acid.
-- Can only be given orally
125-500mg PO q6-8 hours

Penicillinase-resistant penicillin

- resist breakdown by penicillin destroying enzyme (enicillinase) commonly produced by staphylococci.
-Nafcillin, clxacillin (Apo-Cloxi), dicloxacillin, and oxacillin (Bactocill) are available

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