From the FDA Drug Label
For genitourinary or gastrointestinal tract infections other than gonorrhea in men and women, the usual dose is 500 mg q.i.d. in equally spaced doses; severe or chronic infections may require larger doses. In infections caused by haemolytic strains of streptococci, a minimum of 10 days' treatment is recommended to guard against the risk of rheumatic fever or glomerulonephritis
The appropriate treatment for this UTI is ampicillin 500 mg four times a day for a minimum of 10 days 1.
From the Research
For this urinary tract infection with Group B Streptococcus (GBS) at less than 10,000 colonies/mL, the appropriate treatment would be penicillin or ampicillin, which are considered the drugs of choice, as supported by the most recent evidence 2.
Treatment Options
- For penicillin, a typical regimen would be penicillin V 500 mg orally four times daily for 7-10 days.
- Alternatively, ampicillin 500 mg orally four times daily for 7-10 days would also be effective.
- If the patient has a penicillin allergy, cephalexin 500 mg orally four times daily for 7-10 days can be used as an alternative, assuming there is no history of anaphylaxis to penicillins.
Considerations
- It's essential to note that susceptibility testing for beta-lactam antibiotics is not routinely necessary for beta-hemolytic streptococci as resistance is extremely rare, as indicated by studies such as 3.
- The relatively low colony count (less than 10,000 colonies/mL) suggests this may be a less severe infection, but treatment is still indicated if the patient is symptomatic.
- Adequate hydration should be encouraged during treatment, and the patient should complete the full course of antibiotics even if symptoms resolve earlier to prevent recurrence or development of resistance.
Recent Findings
- A recent study 2 highlighted the issue of multidrug resistance in GBS, including resistance to erythromycin, but this does not affect the choice of penicillin or ampicillin as the first-line treatment.
- Another study 4 investigated the hemolytic activity and biofilm formation among clinical isolates of GBS, but the findings do not alter the recommended treatment approach.
- The most recent and highest quality study 2 provides the basis for the recommended treatment, prioritizing penicillin or ampicillin due to their efficacy and the rarity of resistance.