What is the appropriate treatment for a patient with a urine culture positive for Pseudomonas aeruginosa, with no sensitivities reported, and currently on Zosyn (Piperacillin-Tazobactam)?

From the Guidelines

Continuing Zosyn (piperacillin-tazobactam) is appropriate while awaiting the full sensitivity panel for a urine culture growing Pseudomonas aeruginosa without sensitivity results yet. Zosyn is typically dosed at 3.375g IV every 6 hours or 4.5g IV every 8 hours for urinary tract infections, with dose adjustments needed for renal impairment, as recommended by the guidelines for the treatment of infections due to multidrug-resistant organisms 1. According to the study published in the Journal of Microbiology, Immunology and Infection, piperacillin/tazobactam is one of the recommended treatment options for infections due to carbapenem-resistant Pseudomonas aeruginosa (CRPA) and difficult-to-treat P.aeruginosa (DTR-PA) 1.

Some key points to consider in the management of such infections include:

• Monitoring for clinical improvement, including resolution of symptoms such as dysuria, frequency, and fever
• Considering a repeat urine culture after treatment completion to confirm eradication, especially if the patient has risk factors for complicated UTI
• Evaluating for structural abnormalities, foreign bodies (catheters), or immunocompromise, as Pseudomonas in urine often indicates complicated infection or healthcare exposure
• Being prepared to adjust the antibiotic regimen based on the sensitivity results and local resistance patterns, with options such as fluoroquinolones, carbapenems, or ceftazidime, as suggested by the guideline endorsed by the Italian Society of Infection and Tropical Diseases (SIMIT) 1

Treatment duration typically ranges from 5-14 days depending on infection severity and clinical response, as indicated in the guidelines 1. It is crucial to tailor the treatment approach based on the most recent and highest quality evidence, such as the 2022 study published in the Journal of Microbiology, Immunology and Infection 1, to optimize outcomes in terms of morbidity, mortality, and quality of life.

From the FDA Drug Label

1. 2 Nosocomial Pneumonia Piperacillin and tazobactam for injection, USP is indicated in adults and pediatric patients (2 months of age and older) for the treatment of nosocomial pneumonia (moderate to severe) caused by beta-lactamase producing isolates of Staphylococcus aureus and by piperacillin and tazobactam-susceptible Acinetobacter baumannii, Haemophilus influenzae, Klebsiella pneumoniae, and Pseudomonas aeruginosa (Nosocomial pneumonia caused by P. aeruginosa should be treated in combination with an aminoglycoside) [see Dosage and Administration (2)]. 2.2 Dosage in Adult Patients with Nosocomial Pneumonia Initial presumptive treatment of adult patients with nosocomial pneumonia should start with piperacillin and tazobactam for injection at a dosage of 4. 5 g every six hours plus an aminoglycoside, [totaling 18 g (16 g piperacillin and 2 g tazobactam)], administered by intravenous infusion over 30 minutes.

The patient has a urine culture with Pseudomonas aeruginosa and is being treated with Zosyn (piperacillin/tazobactam).

• The FDA drug label for Zosyn indicates that it is effective against Pseudomonas aeruginosa in the treatment of nosocomial pneumonia.
• However, the label also states that nosocomial pneumonia caused by P. aeruginosa should be treated in combination with an aminoglycoside.
• Since the patient has a urine culture with Pseudomonas aeruginosa, it is likely that the infection is not limited to the lungs, and the treatment may need to be adjusted accordingly.
• The dosage of Zosyn for nosocomial pneumonia is 4.5 g every six hours, and it should be administered in combination with an aminoglycoside.
• The patient's treatment should be guided by culture and susceptibility results, and the dosage and combination of antibiotics may need to be adjusted based on these results 2.

From the Research

Urine Culture with Pseudomonas Aeruginosa

• Pseudomonas aeruginosa is a common cause of complicated urinary tract infections, particularly in patients with underlying urinary tract diseases or those with indwelling urinary catheters 3.
• The treatment of Pseudomonas aeruginosa infections can be challenging due to its inherent resistance to many antibiotics and its ability to develop resistance to ongoing treatments 4, 5.

Treatment Options for Pseudomonas Aeruginosa Infections

• Piperacillin-tazobactam (Zosyn) is a commonly used antibiotic for treating Pseudomonas aeruginosa infections, and extended-infusion dosing strategies have been shown to improve clinical outcomes 6.
• Other treatment options include ceftazidime, carbapenems, and newer antibiotics such as ceftolozane-tazobactam and ceftazidime-avibactam, which may be effective against multidrug-resistant strains 4, 7, 5.
• The choice of antibiotic should be guided by the patient's risk factors, the site of infection, and the local epidemiology of antibiotic resistance 4, 5.

Sensitivity Testing and Antibiotic Resistance

• Sensitivity testing is crucial in guiding antibiotic therapy for Pseudomonas aeruginosa infections, as the bacteria can develop resistance to multiple antibiotics 3, 7.
• The emergence of multidrug-resistant and extensively drug-resistant Pseudomonas aeruginosa strains highlights the need for wise antibiotic use and the development of new treatment strategies 4, 5.