What are the treatment suggestions for a 24-year-old female with a urinary tract infection (UTI) caused by gram-negative bacilli and Group B streptococcus (GBS)?

From the Guidelines

For a 24-year-old female with a UTI caused by gram-negative bacilli and Group B streptococcus, the recommended treatment is a 3-7 day course of antibiotics that cover both pathogens, with first-line options including fosfomycin 3 grams as a single dose, given its efficacy against gram-negative bacilli and relatively low resistance rates 1. The choice of antibiotic should be guided by local resistance patterns and the patient's medication allergies.

• Fosfomycin is a good option due to its broad spectrum of activity and low resistance rates.
• Other options, such as trimethoprim-sulfamethoxazole (TMP-SMX) or nitrofurantoin, may also be considered, but their effectiveness against gram-negative bacilli may be limited by local resistance patterns.
• If the patient has symptoms of upper UTI (fever, flank pain), an intravenous third-generation cephalosporin, such as ceftriaxone, may be more appropriate as empirical treatment, as recommended by the European Association of Urology guidelines 1.
• The patient should increase fluid intake to help flush bacteria from the urinary tract and can take phenazopyridine 200 mg three times daily for 2 days to relieve painful urination.
• It is essential to note that the treatment of UTIs caused by gram-negative bacilli and Group B streptococcus requires careful consideration of the antibiotic resistance patterns and the patient's clinical presentation, as highlighted in the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) guidelines 1.
• The ESCMID guidelines recommend a carbapenem, such as imipenem or meropenem, as targeted therapy for patients with severe infections due to third-generation cephalosporin-resistant Enterobacterales (3GCephRE), which may be relevant in cases where the gram-negative bacilli are resistant to other antibiotics 1.

From the FDA Drug Label

• Gram-negative bacteria Citrobacter diversus Citrobacter freundii Providencia species (including Providencia rettgeri) Salmonella species (including Salmonella typhi) Shigella species • Gram-positive bacteria Streptococcus agalactiae Table 5 Susceptibility Test Interpretive Criteria for Ceftriaxone

• Susceptibility interpretive criteria for Enterobacteriaceae are based on a dose of 1 gram IV q 24h. ‡ The current absence of data on resistant isolates precludes defining any category other than ‘Susceptible’. Streptococcus pneumoniae isolates should not be reported as penicillin (ceftriaxone) resistant or intermediate based solely on an oxacillin zone diameter of ≤ 19 mm. Pathogen Minimum Inhibitory Concentrations (mcg/mL) Disk Diffusion Zone Diameters (mm) (S) Susceptible (I) Intermediate (R) Resistant Enterobacteriaceae* ≤ 1 2 ≥4 ≥ 23 20 to 22 ≤19 Streptococcus species beta-hemolytic group‡ ≤0. 5 - - ≥ 24 - -

Treatment Suggestions:

• For gram-negative bacilli, ceftriaxone may be effective, as it has shown susceptibility against various gram-negative bacteria, including Enterobacteriaceae.
• For Group B streptococcus (GBS), ceftriaxone may also be effective, as it has shown susceptibility against Streptococcus agalactiae.
• However, it is essential to note that the effectiveness of ceftriaxone depends on the specific strain and susceptibility of the bacteria.
• It is recommended to perform susceptibility testing to determine the most effective treatment option. 2

From the Research

Treatment Suggestions for UTI

• For a 24-year-old female with a urinary tract infection (UTI) caused by gram-negative bacilli and Group B streptococcus (GBS), the treatment suggestions are as follows:

First-Line Empiric Therapies

• A 5-day course of nitrofurantoin 3, 4
• A 3-g single dose of fosfomycin tromethamine 3, 4
• A 5-day course of pivmecillinam 4

Second-Line Options

• Fluoroquinolones 3, 4
• β-lactams, such as amoxicillin-clavulanate 3, 4
• Oral cephalosporins, such as cephalexin or cefixime 4

Treatment Options for Specific Organisms

• For UTIs due to AmpC- β-lactamase-producing organisms: fosfomycin, nitrofurantoin, fluoroquinolones, cefepime, piperacillin-tazobactam, and carbapenems 3, 4
• For UTIs due to ESBL-producing Enterobacteriaceae: nitrofurantoin, fosfomycin, fluoroquinolones, cefoxitin, piperacillin-tazobactam, carbapenems, ceftazidime-avibactam, ceftolozane-tazobactam, and aminoglycosides 3, 4
• For UTIs caused by carbapenem-resistant Enterobacteriaceae (CRE): ceftazidime-avibactam, meropenem/vaborbactam, imipenem/cilastatin-relebactam, colistin, fosfomycin, aztreonam, and ceftazidime-avibactam, aztreonam, and amoxicillin-clavulanate, aminoglycosides including plazomicin, cefiderocol, tigecycline 3, 4

Considerations

• The use of fluoroquinolones for empiric treatment of UTIs should be restricted due to increased rates of resistance 3, 4
• Aminoglycosides, colistin, and tigecycline are considered alternatives in the setting of MDR Gram-negative infections in patients with limited therapeutic options 3, 4
• It is essential to use the new antimicrobials wisely for treatment of UTIs caused by MDR-organisms to avoid resistance development 4