Do Not Treat Staphylococcus haemolyticus in Asymptomatic Bacteriuria
In an asymptomatic adult without pyuria or risk factors, Staphylococcus haemolyticus isolated from urine should not be treated. This represents asymptomatic bacteriuria (ASB), and the Infectious Diseases Society of America explicitly recommends against screening for or treating ASB in premenopausal nonpregnant women, diabetic patients, older persons living in the community, elderly institutionalized patients, and catheterized patients while the catheter remains in place 1, 2.
Evidence-Based Framework for Decision-Making
When Treatment Is NOT Indicated (Your Clinical Scenario)
The IDSA guidelines provide Grade A-I (strongest) evidence against treatment in the following populations 1:
- Premenopausal, nonpregnant women – no reduction in symptomatic UTI, mortality, or morbidity with treatment 1, 2
- Diabetic women and men – treatment does not prevent complications or improve outcomes 1, 2
- Older persons living in the community – no benefit demonstrated 1
- Elderly institutionalized patients – treatment increases adverse events without clinical benefit 1
- Catheterized patients while catheter remains in place – 100% develop bacteriuria due to biofilm; treatment is futile 1
Critical Point About Pyuria
The absence of pyuria in your patient further strengthens the recommendation against treatment. The IDSA states with strong recommendation and moderate-quality evidence that pyuria accompanying asymptomatic bacteriuria is not an indication for antimicrobial treatment 1, 3. Even if pyuria were present, it would not change the recommendation 3.
Specific Exceptions Where Treatment IS Required
Treatment is indicated only in these two scenarios 1, 2:
Pregnant women – Screen with urine culture in early pregnancy and treat with 3-7 days of targeted antibiotics if positive (Grade A-I) 1
Patients undergoing urologic procedures with mucosal trauma – Screen before procedure and give 1-2 doses of antimicrobials 30-60 minutes prior to procedure (strong recommendation, moderate-quality evidence) 1, 2
Harms of Unnecessary Treatment
Treating asymptomatic bacteriuria causes measurable harm 2, 4:
- Increases risk of subsequent symptomatic UTI by eliminating protective bacterial strains (hazard ratio approximately 3.09 in randomized trials) 2, 4
- Promotes antimicrobial resistance – S. haemolyticus is already highly resistant, with 77% resistant to three or more agents and 41% resistant to five or six agents 5, 6
- Causes adverse drug reactions without offsetting clinical benefit 2, 4
- Five times more antibiotic exposure days compared to no treatment 2
Organism-Specific Considerations
S. haemolyticus is a coagulase-negative staphylococcus that represents approximately 8.5-13% of coagulase-negative staphylococcal isolates from urine 5, 6. It is characterized by high rates of multidrug resistance, including methicillin resistance in up to 66% of isolates 6. However, the organism identity does not change the management approach – the decision is based on whether the patient is symptomatic and whether they fall into one of the two exception categories 1.
Common Pitfalls to Avoid
- Do not order urine cultures in asymptomatic patients – the result will not alter management and promotes inappropriate prescribing 2, 4
- Do not treat based on laboratory findings alone without clinical symptoms 3, 4
- Do not confuse nonspecific symptoms (delirium, falls in elderly) with symptomatic UTI 4
- Do not treat catheterized patients while the catheter remains in place – all develop bacteriuria and treatment does not prevent symptomatic infection 1
Special Consideration for Catheter Removal
If this patient had a short-term indwelling catheter that was recently removed, antimicrobial treatment of asymptomatic women with catheter-acquired bacteriuria persisting 48 hours after catheter removal may be considered (Grade C-I), though this is a weak recommendation 1. For men, there is insufficient data to make a recommendation 1.