Indications for antibiotics include: Never prescribe antimicrobial, unless you did culture and sensitivity - except at life threatening infection
- Prophylaxis: as in giving treatment from suspected infection that has not developed such meningitis case, that could transmit to everyone in class. or such as surgery, to prevent infection that is highly suspected in that case, e.g. tooth extraction (6 capsule amoxicillin 500mg) , mastectomy.
-
Trimethoprim / sulfamethoxazole (TMP/SMX) to prevent Pneumocystis cranii (jirovecii pneumonia )in a patient on cyclosporine and prednisone after a liver transplant or HIV patients
-
Cefazolin given before surgery to prevent a staphylococcal skin infection of the surgical site
- Empiric Therapy: suspicion, due to presenting symptoms, sampling, culture would take long time. giving empiric medication, and waiting for results for specific treatment according to sensitivity and culture. Using broad spectrum drug - then using definitive therapy
Examples
-
Levofloxacin initiated for a patient with presumed community-acquired pneumonia
-
Ceftriaxone given for the treatment of suspected pyelonephritis
Empiric therapy_is given to patients who have a proven or suspected infection, but the responsible organism(s) has or have not yet been identified i.e before specific culture information has been reported or obtained .
It is the type of therapy most often initiated in both outpatient and inpatient settings. After the clinician assesses the likelihood of an infection based on physical exam, laboratory findings, and other signs and symptoms, he or she should generally collect samples for culture and Gram staining.
The process of culturing the sample begins around the time that the clinician performs the Gram stain. After a day or so, testing will reveal the identification of the organism, and eventually the organism can be tested for its susceptibility to various antibiotics. However, this process takes several days, so empiric therapy is generally initiated before the clinician knows the exact identification and susceptibilities of the causative organism. Empiric therapy is our best guess of which antimicrobial agent or agents will be most active against the likely cause of infection. Sometimes we are right, and sometimes we are wrong. The significance of making a correct guess differs depending on the severity of the infection; a wrong choice for an uncomplicated urinary tract infection (UTI) results in an annoyed patient, whereas the wrong choice for meningitis is fatal. Keep in mind that empiric therapy should not be directed against every known organism in nature—just those that cause the infection in question. Her we use use more “broad spectrum” anti-microbials.
- Definitive Therapy: (usually after empiric)
After culture and sensitivity results are known, the definitive therapy phase of treatment can begin. Unlike empiric therapy, with definitive therapy we know on what organisms to base our treatment and which drugs should work against them. At this phase, we choose antimicrobial agents that are safe, effective, narrow in spectrum, and cost-effective. This helps us avoid unneeded toxicity, treatment failures, and the possible emergence of antimicrobial resistance; it also helps manage costs. In general, moving from empiric to definitive therapy involves decreasing the spectrum of coverage, because we do not need to target organisms that are not causing infection in our patient. In fact, giving overly broad-spectrum antibiotics can lead to the development of superinfections: infections caused by organisms resistant to the anti-biotics in use that occur during therapy.
So,
- Organism(s) identified and specific therapy chosen
- More “narrow” spectrum
Examples of Definitive Therapy
-
Transitioning from piperacillin /tazobactamto, ampicillin in a patient with a wound infection caused by Enterococcus faecalis, which is susceptible to both drugs
-
statient with a UTI caused by Klebsiellapneumoniae that is resistant to ceftriaxone but susceptible to ciprofloxacin