Chapter 7 · General principles

Antimicrobial therapy and prevention of resistance

General principles

In severe systemic infection, start empirical therapy without unjustified delay. Obtain microbiological samples before antibiotics only if this does not postpone treatment.
Drug selection is based on illness severity, local resistance patterns, previous cultures, allergies, and kidney function.
Intravenous administration is preferred in severe infection.
Once susceptibility results are available, de-escalate to the narrowest-spectrum active agent.

High risk of ESBL-producing organisms.
Drug penetration into renal tissue and urine must be considered.
For infected stones, treatment duration and drug combinations depend on illness severity, the pathogen, susceptibility, clinical response, and adequacy of drainage. The presence of a stone alone does not justify indefinitely prolonged or combination therapy.

Asymptomatic bacteriuria in a patient with an indwelling catheter is not usually an indication for antibiotics. The main exceptions are pregnancy and preparation for a urological procedure involving mucosal injury.
Pyuria, cloudy urine, and odor without clinical symptoms do not establish catheter-associated infection.
In symptomatic catheter-associated infection, obtain a culture before antibiotics, provided this does not delay treatment, and remove or replace the catheter as indicated.
Assess the need for the catheter daily. Maintain a closed drainage system and do not disconnect it without an indication.

Asymptomatic candiduria does not usually require antifungal therapy, except in established high-risk groups and before urological intervention.
In patients with fever, pain, obstruction, a stent, or a nephrostomy, assess for ascending infection, a fungus ball, and impaired urinary drainage.
Restoration of drainage is mandatory in fungal obstruction; at the same time, consider stent or nephrostomy replacement or removal and targeted antifungal therapy.

Step	Action
1	Assess severity, systemic signs, allergies, kidney function, and MDR risk
2	Obtain microbiological samples, provided this does not delay treatment
3	Start empirical therapy according to the local formulary and antibiogram
4	Identify and address obstruction, an abscess, or an infected device
5	Once culture results are available, narrow therapy to the narrowest-spectrum active agent
6	Determine duration according to clinical response and adequacy of source control
7	Assess the need for the catheter, stent, and nephrostomy daily