Surg 126--Chapter 5 Flashcards
What are antimicrobial agents used for?
To prevent and to treat infections caused by pathogenic microorganisms.
What does pathogenic mean?
Disease-causing
Antibiotics take their name what 2 Greek words?
Anti and bios
What does “anti” mean?
Against
What does “bios” mean?
Life
What are antibiotics?
Natural chemicals (or metabolites) produced by microorganisms that inhibit the growth of other microorganisms.
The natural substances that make up antibiotics include _____ and _____.
Fungi (and molds) and bacteria
What percentage of antibiotics in the U.S. are prescribed for prophylaxis of infections?
30 – 50%
For the surgical patient, antibiotics are prescribed _____, _____, or _____.
Preoperatively, intraoperatively, or postoperatively
Potential complications of every surgical intervention because any such procedure penetrates the body’s first line of defense: the skin.
Postoperative wound infections (SSI’s)
SSI’s may range from _____ to _____.
Minor to serious
TJC has developed a national quality partnership called the _____.
Surgical Care Improvement Project (SCIP)
Created by TJC and focuses on reducing SSI’s.
Surgical Care Improvement Project (SCIP)
What are the goals of SCIP?
Increase compliance for measures related to the use of antibiotics such as:
- The selection of the antibiotic
- The time an antibiotic is received before the incision
- The time an antibiotic is discontinued after surgery
- The ID of the person responsible for these actions and for verifying antibiotic names, times of administration, and documentation
What measure was developed by the WHO and includes antibiotics and surgical patient safety?
Surgical Patient Checklist
What are the 3 sections of the Surgical Patient Checklist?
Before the induction of anesthesia, before the skin incision, and before the patient leaves the OR.
Contains a list of tasks to be accomplished and verified.
Surgical Patient Checklist
How are SSI caused?
By the introduction of pathogenic microorganisms into a susceptible host via a route of transmission.
The pathogen must have a _____, _____, and _____.
Source, a means of transmission, and a host to cause an infection
The source of pathogenic organisms may be _____ or _____.
Endogenous or exogenous
The infectious microbe comes from the patient’s own bacteria.
Endogenous
The infectious microbe comes from outside the patient.
Exogenous
What are two common methods to identify pathogens?
Culture and sensitivity (C&S) and gram staining
Describe culture and sensitivity (C&S).
The process of growing microbes in culture to determine the infecting pathogen and the exposure of the pathogen to various antibiotics to determine which agent will best inhibit the pathogen’s growth.
Describe gram staining.
A rapid identification test that assists the physician in prescribing an initial course of antibiotic therapy based on the probable pathogen causing the infection.
A fluid or tissue specimen is obtained with a swab from the infection site and placed in one or more culture tubes for transport to the microbiology lab.
Culture and sensitivity (C&S)
Bacteria occur in many different shapes, what are the three major groups.
- Spirilla (spiral shaped)
- Bacilli (rod or oblong shaped)
- Cocci (round or spherical shaped)
To be effective, an antimicrobial agent must have _____.
Selective toxicity
What is selective toxicity?
Acts against pathogenic organisms with harming host cells.
Antibiotics must target structures and functions in _____ that differ from those of _____.
pathogenic microorganisms
host cells
The actual goal of antibiotic administration is to _____.
assist the patient’s immune system to subdue the infection.
Name two ways antimicrobial agents are classified.
bactericidal and bacteriostatic
What is bactericidal?
The agent kills the bacteria.
What are examples of bactericidal agents?
Aminoglycosides, cephalosporins, and penicillins
What are bacteriostatic agents?
Inhibit bacterial growth, relying on the host’s own immune system to take over once the pathogenic microorganism is suppressed.
What are examples of bacteriostatic agents?
Erythromycins and tetracyclines
What is a broad spectrum antibiotic?
Has a wide range of activity–usually effective against both gram-negative and gram-positive bacteria.
What is a narrow spectrum antibiotic?
Have a smaller range of activity–often effective against only one category of microorganisms, gram-negative or gram-positive.
What is a limited spectrum antibiotic?
Are effective against just one species of microorganism.
What is antibiotic resistance?
The ability of some strains of pathogenic microbes to prevent or overcome the activity of antimicrobial agents.
What are the four categories of antibiotic resistance mechanisms?
- The microorganism may manufacture microbial enzymes that inactivate the antibiotic.
- The cell membrane may be altered to prevent the antibiotic from entering the cell.
- The target area, such as ribosome, may be altered so that the agent is no longer effective.
- The microorganism may add a substance to the antibiotic, which inhibits its ability to reach its desired binding site.
What are the methods of antimicrobial action (how do they work against the pathogenic microorganisms)?
- Inhibit cell-wall synthesis
- Interfere with protein synthesis
- Alter cell membrane function
- Inhibit production of nucleic acids (RNA or DNA)
- Interfere with cell metabolism
What does MRSA stand for?
methicillin-resistant Staphylococcus aureus
What is MRSA?
Methicillin was developed to treat some of the gram-positive pathogenic microbes. A strain of S. aureus developed a resistance to is. This became know as MRSA.
What does VRE stand for?
vancomycin-resistant enterococci
What is VRE?
A group of enteric (digestive tract) bacteria has developed resistance to vancomycin.
The rapid development of resistant pathogens is linked to _____.
the misuse of antimicrobial agnets
What are ways antimicrobial agents are misused?
- Inappropriate prescribing (colds and viral infections)
- Patients do not take antibiotic as prescribed
- Antibiotics in the food chain
What are the major groups of antibiotics?
- Aminoglycosides
- Cephalosporins
- Fluoroquinolones
- Macrolides
- Oxazolidinones
- Penicillins
- Tetracyclines
Aminoglycosides
- derived from various strains of Actinomyces bacteria
- interfere with protein synthesis by binding to bacterial ribosomes
- bactericidal
- narrow in spectrum
- generally only active against aerobic, gram-negative bacteria
- can provide some activity against some gram-positive bacteria such as Staphylococcus, including methicillin resistant strains
All aminoglycosides are contraindicated if the patient has a history of _____.
hypersensitivity or toxic reaction to any aminoglycoside
Major adverse effects of aminoglycosides include _____.
nephrotoxicity and ototoxicity (can damage kindey cells and cause hearing loss)
Aminoglycosides are poorly absorbed _____, but are almost completely absorbed when applied _____ during surgical procedures.
orally
topically
What are the most common administration routes for aminoglycosides?
intramuscular or intravenous injections
Aminoglycosides are indicated for _____.
short-term treatment of serious infections due to susceptible organisms
Aminoglycosides can be used to treat _____.
bacterial septicemia as well as infections of the respiratory tract, bones and joints, CNS (meningitis), skin, and soft tissue, and intra-abdominal infections.
What are examples of aminoglycosides?
- Amikacin
- Gentamicin
- Streptomycin
- Tobramycin
- Neomycin
Cephalosporins
- broad spectrum antibiotics derived from the fungus Cephalosporium acremonium
- bactericidal, targeting cell-wall synthesis
- block an enzyme needed to strengthen the bacterial cell wall, causing lysis (rupture)
- classified into 4 (5) generations based on different ranges of activity
Cephalosporins-first generation
-active against many gram-positive and some gram-negative microbes
Cephalosporins-second generation
-effective on a wider variety of gram negative, but fewer gram-positive organisms
Cephalosporins-third generation
- wider range of activity against gram-negative microbes that 2nd generation agents, but are less effective on gram-positive
- may be used to treat some hospital acquired infections
Cephalosporins-fourth generation
- have an expanded spectrum on both gram-positive and gram-negative microorganisms
- many can cross the blood-brain barrier and are effective against meningitis
- also used against Pseudomonas aeruginosa
Cephalosporins-fifth generation
- Zeftera, Zevtera, reportedly has powerful antipseudomonal characteristics
- potent against MRSA and some strains of Streptococcus pneumoniae
Administration of cephalosporins is _____, _____, or _____.
oral, intramuscular, or intravenous
What are examples of 1st generation Cephalosporins?
Ancef, Kefzon, Keflex, Keflin
What are examples of 2nd generation Cephalosporins?
Mefoxin, Ceclor, Zinacef
What are examples of 3rd generation Cephalosporins?
Suprax and Rocephin
What are examples of 4th generation Cephalosporins?
Maxipime
What are examples of 5th generation Cephalosporins?
Ceftobiprole
Macrolides
- includes erythromycins
- broad-spectrum agent
- inhibits bacterial protein synthesis by binding to the prokaryotic ribosomal subunit
- bacteriostatic for most bacteria
- bactericidal for several gram-positive bacteria such as Legionella
What are examples of macrolides?
Erythromycin
What was the first true antibiotic?
penicillin
Penicillin is available in many _____ and _____ forms.
natural and semisynthetic
Penicillin
- effective against a wide variety of gram-positive and gram-negative microbes
- bactericidal
- MRSA is resistant to all penicillinase-restistant penicillins
Semisythetic penicillin includes ____.
ampicillin, amoxicillin, and bacampicillin
What was the first broad-spectrum antibiotics?
tetracyclines
Tetracyclines
- originally obtained from cultures of Streptomyces
- bacteriostatic in action against many gram-positive and gram-negative bacteria
What are examples of tetracyclines?
vibramycin and aureomycin
Clindamycin (Cleocin)
- the synthetic analogue of the natural antibiotic lincomycin
- active against gram-positive and anaerobic bacteria
- may be used to treat serious respiratory, pelvic and intra-abdominal infections caused by anaerobic bacteria
What is used to treat infections in patients who are allergic to penicillin?
Clindamycin (Cleocin)
Metronidazole (Flagyl)
- synthetic antibiotic intended for intravenous administration
- often used for prophylaxis in colorectal procedures when contamination from enteric bacteria is possible
- also used to treat postoperative SSI’s caused by susceptible anaerobic bacteria
Bacitracin
- similar properties to penicillin
- effective against staphylococci and streptococci
- used in combination with other medications (such as polymyxin B) in a topical form to treat ophthalmic and other types of infections
Vancomycin
- used to treat infections caused by MRSA
- administered intravenously
- active against staphylococci, streptococci, and enterococci
- due to its toxicity, use is restricted to critically ill patients