What is the appropriate intravenous treatment for a patient with a urinary tract infection, as indicated by positive nitrite and few bacteria in the urinalysis, who is allergic to Penicillin (penicillin)?

From the Guidelines

For a patient with urinalysis showing WBC 6-10, few bacteria, elevated urobilinogen, and positive nitrite, along with elevated CO2 (32) and glucose (132), I recommend intravenous antibiotic therapy with a non-penicillin alternative, specifically ceftriaxone 1-2g IV daily, as the first-line treatment, due to its efficacy and low cross-reactivity with penicillin allergy, as suggested by the European Association of Urology guidelines 1.

The patient's presentation suggests a urinary tract infection (UTI) with gram-negative bacteria, given the positive nitrite and presence of WBCs. The elevated urobilinogen may indicate some liver involvement or hemolysis, but this does not alter the primary approach to treating the UTI.

Given the patient's allergy to penicillin, alternatives must be considered. The European Association of Urology guidelines 1 recommend using a combination of antibiotics for complicated UTIs, including an intravenous third-generation cephalosporin as empirical treatment. Ceftriaxone is a suitable option due to its broad spectrum of activity and low rate of cross-reactivity with penicillin allergy, which is around 1-2% 1.

Other options for patients with severe penicillin allergy include aztreonam 1-2g IV every 8 hours, which has virtually no cross-reactivity with penicillin, or a fluoroquinolone such as ciprofloxacin 400mg IV every 12 hours or levofloxacin 750mg IV daily, provided the local resistance rate is <10% 1. Gentamicin 5-7mg/kg IV daily (with renal monitoring) is another option for patients with concerns about other beta-lactams.

Treatment should continue for 7-14 days, depending on the clinical response, with consideration for switching to oral therapy once the patient improves. It is also crucial to ensure adequate hydration and glucose management, as the patient's hyperglycemia can complicate infection recovery.

Key points to consider in management include:

• The choice of antibiotic should be guided by local resistance patterns and the severity of the infection.
• Urine culture and susceptibility testing should be performed to tailor the antibiotic regimen appropriately.
• The patient's allergy status, particularly to penicillin, must be considered when selecting an antibiotic.
• Monitoring for signs of complications, such as sepsis or worsening renal function, is essential.
• Adjustments to the treatment plan may be necessary based on the patient's response to therapy and the results of culture and susceptibility testing.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION: Gentamicin injection may be given IM or IV. The patient’s pretreatment body weight should be obtained for calculation of correct dosage. The recommended dosage of gentamicin injection for patients with serious infections and normal renal function is 3 mg/kg/day, administered in three equal doses every eight hours

The patient has a complicated urinary tract infection, as indicated by the urinalysis results (wbc urine 6-10, bacteria few, urobilinogen 4, nitrite positive) and is allergic to penicillin.

• Treatment: Gentamicin (IV) is a possible treatment option.
• Dosage: The recommended dosage for adults with normal renal function is 3 mg/kg/day, administered in three equal doses every eight hours 2.
• Administration: The IV administration of gentamicin may be particularly useful for treating patients with bacterial septicemia or those in shock.
• Monitoring: It is desirable to measure both peak and trough serum concentrations of gentamicin to determine the adequacy and safety of the dosage 2.

From the Research

Treatment Options for Urinary Tract Infections (UTIs)

Given the patient's allergy to penicillin, the following treatment options can be considered:

• For acute uncomplicated bacterial cystitis, options include a 5-day course of nitrofurantoin, a 3-g single dose of fosfomycin tromethamine, or a 5-day course of pivmecillinam 3
• For UTIs due to ESBL-producing Enterobacteriales, parenteral treatment options include piperacillin-tazobactam (for ESBL-E coli only), carbapenems, ceftazidime-avibactam, ceftolozane-tazobactam, and aminoglycosides including plazomicin 3
• For UTIs caused by carbapenem-resistant Enterobacteriales (CRE), treatment options include ceftazidime-avibactam, meropenem/vaborbactam, imipenem/cilastatin-relebactam, and colistin 3

IV Treatment Options

For patients who require IV treatment, the following options can be considered:

• Piperacillin-tazobactam
• Carbapenems (e.g. meropenem/vaborbactam, imipenem/cilastatin-relebactam)
• Ceftazidime-avibactam
• Ceftolozane-tazobactam
• Aminoglycosides (e.g. plazomicin) 3
• Cefepime 4
• Gentamycin 4

Considerations for Treatment

When selecting a treatment option, it is essential to consider the patient's allergy to penicillin and the potential for antibiotic resistance. The choice of antibiotic should be guided by local susceptibility patterns and the severity of the infection 3, 4. Additionally, the use of fluoroquinolones should be avoided due to the high risk of resistance and adverse events 5, 6, 7.