Brief Answer:
Antibiotics that may help and also possible needed tests and examinations discussed below

Detailed Answer:
Hello and welcome to "Ask a Doctor" service,

I carefully read your query and understand your concern.

Normally, according to the recommendations, there should be both symptoms of a urinary infection and a positive urine culture to certainly set the diagnosis of urinary tract infection. A urine culture is positive if it has more than 100,000 bacteria of one kind in 1 ml of urine.

On the other hand, recently it is recognized that if the patient has typical symptoms of a urinary tract infection (fever, pain with urination and frequency) and has at least 1000 bacteria of the same kind, especially if this is E.Coli, it still can be considered a urinary infection. This is even more likely if the simple urinalysis (dipstick) shows some nitrates and leucocytes as well.

To conclude:
- even though the standard diagnosis of urinary tract infection needs a positive urine culture (>100,000 bacteria/ml) in some cases with typical symptoms, a number as low as 1000 E.coli bacteria/ml can be considered positive.

- having the report of the simple urinalysis is helpful as well to check for nitrates and leucocytes (WBC).

- The urine culture in your case should be reconsidered and the lab should be asked to determine the number of the bacteria and what bacteria it is (not just specify it is negative). If you have at least 1000 E.Coli/ml of urine you may decide to discuss with your doctor the chance of having the infection and continue the second stage of the culture, which determines the antibiotic that is effective.

- It is expected that after using an antibiotic, the bacteria may develop resistance so if nitrofurantoin is not helping, you may use another antibiotic which may be determined by the urine culture as explained above or you may choose one of the following: fosfomycin 3g as a single oral dose or Bactrim (TMP-SMX) 980 mg twice a day for 3 days.

- you will also need to have a gynecological examination as sometimes gynecological problems favor recurrent and difficult to treat urinary infections in elderly women (atrophic vaginitis and cystocele or uterine prolapse are all possible risk factors to be ruled out).

- abdominal ultrasound and KUB-Xray may be needed to rule out structural problems of the kidneys and other parts of the urinary tract, which may predispose frequent infections as well.

I hope this answers your query. I remain at your disposal in case further medical assistance is needed.

Kind regards,
Dr. Antoneta Zotaj
General and Family Physician

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