What is the significance of 100,000 Colony Forming Units (CFU) per milliliter (mL) of Citrobacter freundii in a patient's sample, indicating bacteriuria?

From the Guidelines

Citrobacter freundii detected at 100,000 colony forming units per mL in your urine sample indicates a urinary tract infection (UTI) requiring antibiotic treatment. The diagnosis of UTI is based on the presence of at least 50,000 CFUs per mL of a single urinary pathogen, as recommended by the American Academy of Pediatrics 1. Although the traditional threshold for significant bacteriuria was 100,000 CFUs per mL, recent guidelines suggest that a lower threshold of 50,000 CFUs per mL is more appropriate for diagnosing UTI in infants and children 1.

The recommended first-line treatment for UTI is trimethoprim-sulfamethoxazole (Bactrim) 160/800 mg twice daily for 5-7 days, or ciprofloxacin 500 mg twice daily for 7 days if you have sulfa allergies 1. Nitrofurantoin 100 mg four times daily for 7 days is another alternative. While taking antibiotics, it is essential to drink plenty of water, urinate frequently, and complete the entire course even if symptoms improve. Citrobacter freundii is a gram-negative bacterium commonly found in water, soil, and the human intestinal tract that can cause UTIs, particularly in people with compromised immune systems or urinary tract abnormalities. This infection typically causes symptoms like painful urination, frequent urination, cloudy urine, and lower abdominal pain.

Follow-up with your healthcare provider is crucial to ensure the infection has cleared completely. It is also important to note that asymptomatic bacteriuria (ASB) is a common finding in some healthy populations, and treatment of ASB is not recommended unless the patient has specific underlying conditions or is undergoing a urological procedure 1. In this case, since the patient has a symptomatic UTI, antibiotic treatment is necessary to prevent complications and improve quality of life.

Key considerations in managing UTI include:

• Ensuring adequate hydration to promote more frequent urination
• Encouraging urge-initiated voiding and post-coital voiding
• Avoiding spermicidal-containing contraceptives
• Considering topical vaginal estrogens for postmenopausal women with risk factors such as atrophic vaginitis
• Monitoring for signs of complications, such as pyelonephritis or sepsis.

From the FDA Drug Label

Adult Patients: Urinary Tract Infections caused by ... Citrobacter freundii, Skin and Skin Structure Infections caused by ... Citrobacter freundii,

The CITROBACTER FREUNDII is listed as one of the microorganisms that ciprofloxacin (IV) is indicated for in the treatment of various infections, including Urinary Tract Infections and Skin and Skin Structure Infections 2.

• The presence of 100,000 colony forming units per mL of CITROBACTER FREUNDII suggests an abnormal result, indicating a potential infection.
• Ciprofloxacin (IV) may be considered as a treatment option for this infection, given its effectiveness against CITROBACTER FREUNDII.

From the Research

Colony Forming Units per mL of CITROBACTER FREUNDII

• 100,000 colony forming units per mL is considered a significant amount of bacteria, potentially indicating a urinary tract infection (UTI) 3, 4
• However, the presence of CITROBACTER FREUNDII at this concentration does not necessarily confirm an infection, as it can be a contaminant or a commensal organism 3
• Studies have shown that patients with colony counts of 100,000 CFU/mL or more are more likely to have a clinically significant UTI 4

Risk Factors and Treatment

• CITROBACTER FREUNDII infections can be life-threatening, especially in immunocompromised patients, and require antimicrobial therapy based on the sensitivity of the pathogen microorganism 5
• The choice of antimicrobial therapy for Citrobacter infections is challenging due to the increasing resistance to antibiotics 5, 6
• Risk factors for mortality in patients with CITROBACTER FREUNDII bacteremia include the presence of certain resistance genes, such as blaTEM-1 6
• Treatment options for CITROBACTER FREUNDII infections include carbapenems, fourth-generation cephalosporins, amikacin, and quinolones 6

Diagnosis and Interpretation

• The interpretation of colony counts in urine cultures is crucial for the diagnosis of UTIs 3, 4
• Reporting positive results only for patients with 100,000 CFU/mL or more can reduce the number of positive cultures and inappropriate antibiotic use 4
• The diagnosis of UTI should be based on a combination of clinical signs and symptoms, laboratory results, and patient history 4