Anti-microbial General Principles Flashcards
Which type typically attack the cell wall- bacteriocidal or bacteriostatic?
Bacteriocidal attack the cell wall to kill the organism
Bacteriostatic stop growth, work on proteins and ribosomal subunits
What is the minimum inhibitory concentration (MIC)?
Lowest concentration of ABX required to prevent growth
Can you compare the potency different ABX based on their MIC for a given organism?
No
What is minimum bactericidal concentration (MBC)?
Lowest concentration required to kill bacteria
MIC or MBC: Reported on the culture and sensitivity report?
MIC
What is concentration-dependent killing?
Want to get a high peak concentration and then allow concentration to drift down over time. Examples aminoglycosides and fluoroquinolones
What is time-dependent killing?
Want the MIC to be longer period of time. Trough values are typically important for ABX the are time dependent killing.
Example is beta lactams, monobactams, macrolides
Is post-antibiotic effect demonstrated in all antimicrobials?
Yes; demonstrated in virtually all antimicrobials
What is Post-antibiotic effect (PAE)?
ABX continue to suppress the growth of bacteria even after the ABX is no longer detectable
PAE decreased or increased in acidic environments?
Decreased in acidic (infected) media
T/F: Post-antibiotic effect is especially present in concentration dependent ABX?
True
What four things contribute to antimicrobial resistance?
- Overuse for inappropriate indications
- Broad Spectrum
- Poor infection control
- Inappropriate dose or duration
T/F: All gram positive bacteria have intrinsic resistance to vancomycin?
False, all gram negative bacteria
Intrinsic or Acquired resistance definition: reflects a genetic alteration in the bacteria that renders a once effective antimicrobial ineffective?
Acquired
What are the four mechanisms through which acquired resistance is achieved?
- Decreased permeability (Stops the ABX from entering the organism)
- Increased efflux pumps (form pumps to “kick out” ABX)
- Inactivation (ex. beta lactamase)
- Modification of antimicrobial target
T/F
The more board the spectrum, the greater chance of resistance
True
T/F
Continuous infusion has been shown to be more effective than intermittent boluses
FALSE
has not been shown
Should 2 ABX with different MOA be used?
Yes to inhibit emergence of resistant strains of an organism. Creates synergistic effect
Ex. beta lactam and aminoglycoside (BL breaks down bacterial cell wall and allows easier entry for aminoglycoside)
Treatment of an established infection with an effective therapy of ABX agents is based upon what three things?
- Delivery of a concentration of drug to the site of infection
- Concentration sufficient to kill or inhibit growth of the offending organism
- Sufficient period of time to eradicate the infection
What 5 clinical situations is bactericidal therapy considered necessary for clinical cure?
- CV infection (particularly endocarditis or prosthetic valves)
- Meningitis and cerebral abscess.
- Severe neutropenia
- Osteomyelitis
- Tx of prosthesis or vascular access related infections w/o removing the device
Vascular access devices typically grow what type of bacteria?
Gram Positive
Lung infections typically grow what type of bacteria?
Gram Negative
What is an antibiogram?
A chart demonstrating the resistance patterns in your specific hospital/facility/region and compares bacterial strains and how susceptible they are to each ABX available
What are examples of impaired host defense?
- Anatomical (ulceration)
- Neutropenia
- Aspleenia
- Malignancy
- HIV
- Immunosuppresant therapy
How are the pharmacokinetics of pregnant patients changed?
Increased volume of distribution and increased GFR
T/F: Penicillins, Tetracyline, Cephalosporins, and Erythromycin are all considered safe for pregnant patients?
False; Tetracycline should always be avoided
What medications are to be avoided in pregnant patients?
- Metranidazole
- Ticarcillin
- Rifampin
- Trimethoprim
- Fluoroquinolones
- Tetracyclines
Canadian Population Study determined which three ABX had no increased risk to fetus or mother?
Amoxil, Cephalosporins, Macrobid
Why is tetracycline contraindicated in pregnant patients?
Associated with acute fatty necrosis of liver, pancreatitis, and possible renal injury
If patient contracted itchy red areas with previous ABX treatment, should that medication be used again?
Yes; as long as not raised rash
Per 2018 CDC data, ____in____ hospitalized patients will develop an infection?
1 in 31
Rank central line location sites from most likely to least likely to get infected
Femoral>I.J.>Subclavian
Risk increase the further the site is from the heart
What is the disease associated with altered bowel flora?
Pseudomembranous enterocolitis caused from Clostridium difficile over growth
What two toxins mediate C.Diff pathogenesis?
- Enterotoxin A
2. Cytotoxin B
How is C Diff diagnosis confirmed?
With detection of one of the toxins
What percent of successfully treated C Diff patients have relapse infection?
10%
What is treatment for C.Diff?
- Oral Vanco (1st line treatment for mild, mod, sever)
- Dificid (fidaxomicin) (1st line treatment for mild, mod,severe)
- Fecal Transplant
Don’t use Flagyl anymore d/t SE’s (more than 2 rounds and get neuro damage)
Which ABX has the highest risk of developing C Diff?
Second Highest risk?
Rarely?
1st Cleocin
2nd Cephalosporins
Rarely- Vancomycin and Flagyl
T/F: PPI and H2 Antagonist therapy does not increase risk of developing C Diff?
False; while PPI is associated with higher risk, both increase risk of developing C Diff infection
What is the “best way” (per emily) to cure C Diff?
Fecal Transplant (99% cure rate)
What happens if an obese patient donates feces for fecal transplant?
The recipients have been shown to increase weight
What percentage of Surgical Site Infections (SSI) are considered preventable?
50%
Why is cefazolin chosen so frequently for SSI?
- Low cost
- Broad spectrum
- Low incidence of allergic reaction
Gross GI spillage is an example of what wound class?
Class III
Perforated viscera or old wound with devitalized tissus is an example of what wound class?
Class IV
Surgery in areas known to harbor bacteria is an example of what wound class?
Class II
Surgery on traumatic wounds is an example of what wound class?
Class III
T/F: Class IV wound is the only wound class that REQUIRE ABX?
False; Class III and Class IV are required, while Class II should be considered
Which organism is most common species on clean wounds?
Staphylococcal
What are recommendations for patients at high or moderate risk undergoing procedures involving infected tissues or receiving prosthetic cardiac valves?
- Include anti-staphylococcal ABX for cellulites and osteomyelitis
- Coverage for active infections
(i dont even know wtf this slide means)
What are recommendations for fungal infection prophylaxis?
Little data to support it
Difficult to prove fungal infection
Issue complicated by fluconazole resistant C Albicans emerging and other changing resistant fungal species
(Per Emily) When should ancef be given for SSI?
60 mins prior to incision
(Per Emily) when should vanco be given for SSI?
120 mins prior to incision
What is typical dose of vancomycin?
15mg/kg on Actual Body Weight up to around 2.5g
Elderly and morbidly obese patients have a volume of distribution close to __, so if we are using .7 to dose them with Vanco we are ____ them
1
underdosing
What two ABX’s should be given to pregnant patients only if necessary?
Aminoglycosides
Isoniazid
What reactions are considered “true allergic reactions” to ABX?
Anaphylaxis
Steven-Johnson syndrome
Allergic interstitial nephritis
3 most common types of nosocomial infections
Urinary
Respiratory
Blood
T/F
Antibiotic impregnated catheters will always decrease risk of bactermia
FALSE
may decrease the risk….proven to be not that great
What percentage of the population are natural carriers of c.diff?
10%
they are at a higher risk of infection
T/F
You can get c.diff infection with a single dose on Ancef
True
What surgical wound class is atraumatic, has no break in sterile technique and no entry into the respiratory, GI, GU tracts?
Class I
If a procedure is long, you want to redose your prophylactic ABX after __ half-lives
2
So,
Ancef (t= 2hrs) after 4 hours
Cleocin (t =3hrs) after 6 hours
Vanco (t = 8hrs) after 16 hours