What is the appropriate antibiotic treatment for a 78-year-old male patient with a urinary tract infection (UTI) caused by Morganella morganii and Proteus, with a recent history of an indwelling Foley catheter and current symptoms of dysuria?

Treatment of Catheter-Associated UTI with Morganella morganii and Proteus

Ceftriaxone is the most appropriate antibiotic treatment for this 78-year-old male with catheter-associated UTI caused by Morganella morganii and Proteus species. 1

Rationale for Treatment Selection

• The European Association of Urology strongly recommends an intravenous third-generation cephalosporin as first-line empirical treatment for complicated UTIs, including catheter-associated UTIs 1
• The patient's urine culture shows Morganella morganii (>100,000 CFU) and Proteus (<10,000 CFU) with susceptibility to ceftriaxone (MIC ≤1) 1
• Ceftriaxone provides excellent coverage against both identified organisms and is particularly effective for catheter-associated UTIs which typically involve more resistant organisms than uncomplicated UTIs 1, 2
• Recent research indicates that treatment of M. morganii infections should include a third-generation cephalosporin to which the organism is susceptible 2

Alternative Treatment Options

• Ciprofloxacin is another appropriate option as the susceptibility testing shows sensitivity (MIC ≤0.25) and it's FDA-approved for UTIs caused by Morganella morganii and Proteus 3, 1
• Trimethoprim-sulfamethoxazole could be considered as the organism shows susceptibility (MIC ≤2/38) and it's indicated for UTIs caused by Morganella morganii 4, 5
• Ampicillin/sulbactam is also a potential option based on the susceptibility results (MIC ≤4/2) 6

Treatment Duration

• The Infectious Diseases Society of America recommends treating catheter-associated UTI for 7 days if symptoms resolve promptly 1
• Consider extending treatment to 10-14 days for this elderly patient with delayed response or if prostatitis cannot be excluded 1
• Since the patient is 78 years old with multiple comorbidities including diabetes (A1c 7.3), a 10-14 day course may be more appropriate to ensure complete resolution 6, 1

Catheter Management

• The catheter should be replaced if it has been in place for ≥2 weeks prior to initiating antimicrobial therapy 1, 7
• Removing or replacing the catheter will hasten symptom resolution and reduce the risk of subsequent infection 1, 8
• Discontinuation of catheter use alone may result in eradication of candiduria in almost 40% of patients, but is less effective for bacterial UTIs like this case 6, 7

Important Clinical Considerations

• The patient's diabetes (A1c 7.3) and advanced age are risk factors for complicated UTI and may affect treatment response 8, 7
• M. morganii has high potential to develop multidrug resistance, so adherence to the full course of antibiotics is essential 2, 9
• Monitor for clinical response within 72 hours of treatment initiation; if symptoms persist, consider extending treatment duration or switching antibiotics based on susceptibility 1, 2
• The alkaline urine (pH 8.5) is consistent with urease-producing organisms like Proteus and Morganella, which can lead to stone formation and catheter encrustation if not properly treated 7

Follow-up Recommendations

• Consider a follow-up urine culture after completion of antibiotic therapy to confirm eradication of infection 6, 1
• Address the patient's other medical issues, including sleep disturbance and recently prescribed melatonin, after resolving the acute infection 1
• Evaluate for any underlying urological abnormalities that may predispose to recurrent infections 1, 10