From the Research
Yes, a patient can have a urinary tract infection (UTI) even with no bacteria present in the urinalysis. This situation is known as a "culture-negative UTI" or "sterile pyuria." Several factors can explain this discrepancy, including the patient having already started antibiotics before the sample was collected, which can reduce bacterial counts below detectable levels 1. Some bacteria require special culture techniques not used in standard urinalysis, such as anaerobic bacteria, mycobacteria, or fastidious organisms. Certain pathogens like Chlamydia or Mycoplasma won't grow on standard culture media. Additionally, the infection might be located higher in the urinary tract, with bacteria not consistently shed into the urine.
Key Points to Consider
- The absence of pyuria in urinalysis cannot exclude UTI in patients with suggestive clinical findings 1.
- Pyuria might be lacking in UTIs associated with certain pathogens, such as Klebsiella spp. and Enterococcus spp. 1.
- Urine culture tests should be performed in patients with suspected UTI, even in the absence of pyuria, to avoid delay in diagnosis and treatment 1.
- Contemporary automated urinalysis indices were often abnormal in a disease-free population of women, even using ideal collection technique, which could lead to false-positive UTI diagnosis 2.
Empirical Treatment
In cases where UTI symptoms are present but standard cultures are negative, clinicians may still treat empirically with antibiotics like nitrofurantoin (100mg twice daily for 5-7 days), trimethoprim-sulfamethoxazole (one DS tablet twice daily for 3 days), or fosfomycin (3g single dose) based on symptom presentation 3. If symptoms persist despite treatment, further investigation with specialized cultures or imaging may be warranted to rule out other conditions that can mimic UTI symptoms. The choice of antibiotic should be guided by local resistance patterns and the patient's clinical presentation 3, 4.