Introduction to Antibiotics Flashcards
What is the most important thing to do before the administration of antibiotic therapy?
Bacterial infection MUST be confirmed
What is the normal flora?
The human body harbors a number of microorganisms that colonize certain body systems called “normal flora”, which are normally harmless bacteria that occur naturally on the skin, and in the respiratory, gastrointestinal, and genitourinary tracts.
What can happen to the normal flora of patients hospitalized for more than 48 hours?
Patients who are hospitalized for more than 48 hours can have their usual normal flora replaced by the “normal flora” of the hospital, which tend to be gram-negative aerobes.
What are the sites of normal flora colonization?
Skin
GI Tract
GU Tract
Respiratory Tract
What are the normal sterile sites?
Blood CSF Pleura Synovium Bone Urine
What is contamination?
Contamination – an organism is introduced into the clinical specimen during the sample acquisition process
What is colonization?
Colonization – an organism is present at a body site but is not invading host tissue or eliciting host responses.
What is infection?
Infection – a pathogenic organism is present at a body site and is damaging host tissues and eliciting host responses and symptoms consistent with infection.
What bacteria is common as a skin pathogen?
Staphylococcus aureus
What bacteria is common as a respiratory tract infection?
Streptococcus pneumoniae
What bacteria is common as a urinary tract infection?
Escherichia coli
Narrow Spectrum
Narrow Spectrum: the antibiotic has activity against a limited group of bacteria (e.g., penicillin has activity against some gram-positive and gram- negative cocci, but not gram-negative bacilli).
Broad Spectrum
Broad Spectrum: the antibiotic has activity against a wide variety of bacteria, such as gram-positive and gram-negative bacteria (e.g., imipenem has activity against gram-positive and gram-negative aerobes and anaerobes).
Minimum Inhibitory Concentration
MIC– the lowest concentration of an antibiotic that prevents visible growth (unaided eye) of a bacteria after 18 to 24 hours of incubation
Minimum Bacteriacidal Concentration
MBC – the lowest concentration of an antibiotic that results in a decrease of > 99.9% of the bacterial inoculum (MIC less than MBC)