What is a good antibiotic regimen for a 36-year-old female with an 8.5 cm intrauterine loculated abscess, who underwent IR (Interventional Radiology) drainage with drain placement, and has a wound gram stain showing gram-positive and gram-negative rods, as well as gram-positive cocci?

From the FDA Drug Label

PIPRACIL is indicated for the treatment of serious infections caused by susceptible strains of the designated microorganisms in the conditions listed below: Intra-Abdominal Infections including hepatobiliary and surgical infections caused by E. coli, Pseudomonas aeruginosa, enterococci, Clostridium spp., anaerobic cocci, or Bacteroides spp., including B. fragilis. Gynecologic Infections including endometritis, pelvic inflammatory disease, pelvic cellulitis caused by Bacteroides spp., including B. fragilis, anaerobic cocci, Neisseria gonorrhoeae, or enterococci (E. faecalis). Piperacillin has been shown to be active against most strains of the following microorganisms, both in vitro and in clinical infections as described in the INDICATIONS AND USAGE section Aerobic gram-positive microorganisms Enterococci, including Enterococcus faecalis Streptococcus pneumoniae Streptococcus pyogenes Aerobic gram-negative microorganisms Acinetobacter species Enterobacter species Escherichia coli Haemophilus influenzae (non-β-lactamase-producing strains) Klebsiella species Morganella morganii Neisseria gonorrhoeae Proteus mirabilis Proteus vulgaris Providencia rettgeri Pseudomonas aeruginosa Serratia species

A good antibiotic regimen for the patient would be Piperacillin/Tazobactam (IV), as it is effective against a broad spectrum of gram-positive and gram-negative aerobic and anaerobic bacteria, including those that may be causing the patient's intrauterine loculated abscess 1, 1. Key points to consider when using Piperacillin/Tazobactam (IV) include:

• The patient's wound gram stain showed gram-positive and gram-negative rods, as well as gram-positive cocci, which are susceptible to Piperacillin/Tazobactam (IV)
• The patient has a serious infection, which is an indication for the use of Piperacillin/Tazobactam (IV)
• Piperacillin/Tazobactam (IV) has been shown to be effective in the treatment of gynecologic infections, including endometritis and pelvic inflammatory disease 1 Important considerations for the use of Piperacillin/Tazobactam (IV) include:
• Appropriate cultures should be made for susceptibility testing before initiating therapy and therapy adjusted, if appropriate, once the results are known
• The prophylactic use of Piperacillin/Tazobactam (IV) should be stopped within 24 hours, since continuing administration of any antibiotic increases the possibility of adverse reactions 1

From the Research

For a 36-year-old female with an 8.5 cm intrauterine loculated abscess with IR drainage and a wound gram stain showing gram-positive and gram-negative rods plus gram-positive cocci, I recommend a broad-spectrum antibiotic regimen of Piperacillin-Tazobactam 4.5g IV every 6 hours plus Vancomycin 15-20 mg/kg IV every 12 hours (adjusted based on levels). This combination provides coverage for the polymicrobial infection suggested by the gram stain, as supported by studies such as 2 which demonstrate the efficacy of piperacillin/tazobactam against a broad spectrum of bacteria, including those commonly found in intrauterine infections.

The choice of Piperacillin-Tazobactam is further reinforced by its effectiveness in treating intra-abdominal infections, as shown in studies like 3 and 4, which, although older, provide a foundation for its use in similar infection types. More recent studies, such as 5, highlight the safety and tolerability of administering piperacillin/tazobactam via IV push, which could be beneficial in certain clinical scenarios, though the standard administration method should be followed unless specific circumstances dictate otherwise.

Key considerations in managing this patient include:

• Monitoring for signs of clinical improvement, such as resolution of fever, decrease in white blood cell count, and reduction in C-reactive protein levels.
• The drain should remain in place until output is minimal, typically less than 10-20 mL/day, indicating resolution of the abscess.
• Culture results, when available, should guide the narrowing of antibiotic coverage to reduce the risk of resistance development and minimize side effects.
• The regimen should continue for at least 14 days, with potential transition to oral antibiotics after significant clinical improvement, based on both clinical judgment and culture results.

This approach prioritizes the patient's morbidity, mortality, and quality of life outcomes by aggressively treating the infection while minimizing the risk of antibiotic resistance and side effects.