Final answer:
Broad-spectrum antibiotics are often used empirically when the causative agent is unknown, or urgent treatment is required. Narrow-spectrum antibiotics or combination therapy may be employed for specific pathogens if susceptibility is known. An antibiogram can guide therapy to improve appropriateness and reduce resistance.
Step-by-step explanation:
To decide which agents to cover in your empiric therapy without more patient information, the most judicious approach would often be broad-spectrum antibiotics. These types of antibiotics are capable of acting against a wide variety of bacteria and are typically used when the exact causative agent is unknown, or when immediate treatment is necessary, and there is no time for precise identification of the bacteria causing the infection.
For a urinary tract infection (UTI) caused by E. coli, narrow-spectrum antibiotics that specifically target the gram-negative bacteria could be chosen if susceptibility is confirmed via an antibiogram. A wound infection caused by S. aureus may require a targeted staphylococcal antibiotic, unless methicillin-resistant S. aureus (MRSA) is suspected, in which case broader coverage or combination therapy might be needed. A respiratory tract infection caused by P. aeruginosa can be particularly challenging due to this pathogen's known resistance mechanisms; thus, combination therapy using agents with known activity against Pseudomonas may be necessary.
An antibiogram data may guide the selection of empiric therapy, increasing appropriateness by highlighting local patterns of antibiotic susceptibility. Moreover, targeting the causative agent with a narrow-spectrum antibiotic, when possible, minimizes disruption to the microbiota and reduces the likelihood of developing antibiotic resistance.