Tazocin (Piperacillin/Tazobactam) Antimicrobial Coverage
Tazocin provides broad-spectrum coverage against most Gram-positive and Gram-negative aerobic bacteria plus anaerobes, making it particularly effective for polymicrobial infections, but it does NOT cover MRSA, ESBL-producing organisms reliably, or AmpC-hyperproducing bacteria. 1, 2
Gram-Positive Coverage
- Methicillin-susceptible Staphylococcus aureus (MSSA): Excellent activity with MIC 0.12-0.5 mcg/mL 3
- Streptococcus species: Inhibits all strains at ≤16 mcg/mL, including penicillin-resistant strains 3
- Enterococcus species (vancomycin-susceptible): 85.7% susceptibility, though activity is suboptimal compared to other pathogens 3
- Does NOT cover MRSA: Requires addition of vancomycin, linezolid, or daptomycin for MRSA coverage 4
Gram-Negative Coverage
Enterobacteriaceae
- Escherichia coli and Klebsiella pneumoniae: 80-84% susceptibility against standard strains 5
- Proteus, Enterobacter species: Covered in nosocomial infections 4
- ESBL-producing organisms: Controversial and unreliable coverage; carbapenems are superior 4, 3
- AmpC-hyperproducing organisms (Enterobacter, Citrobacter): Only 68.8% susceptible; tazobactam does NOT inhibit Class I beta-lactamases 2, 3
Non-Fermenters
- Pseudomonas aeruginosa: Most active beta-lactam against multidrug-resistant strains (79.5% susceptibility), but requires higher doses and often combination with aminoglycoside 4, 3, 5
- Acinetobacter baumannii: Covered per FDA labeling 1
- Haemophilus influenzae: 100% susceptibility including beta-lactamase producers 3
Anaerobic Coverage
- Bacteroides fragilis group: Excellent activity against B. fragilis, B. ovatus, B. thetaiotaomicron, B. vulgatus 1, 2
- Other anaerobes: Broad anaerobic spectrum, making metronidazole unnecessary when using piperacillin/tazobactam 4
FDA-Approved Indications
The following infections are specifically FDA-approved 1:
- Intra-abdominal infections (adults and pediatrics ≥2 months)
- Nosocomial pneumonia (adults and pediatrics ≥2 months)
- Skin and soft tissue infections (adults)
- Female pelvic infections (adults)
- Community-acquired pneumonia (adults)
Clinical Context by Infection Type
Severe Intra-Abdominal Infections
Piperacillin/tazobactam is recommended as monotherapy for severe community-acquired and nosocomial intra-abdominal infections requiring broad Gram-negative and anaerobic coverage 4. It provides coverage against P. aeruginosa, Enterobacter, and Proteus species needed for nosocomial infections 4.
Diabetic Foot Infections
Useful for broad-spectrum coverage with TID/QID dosing, though P. aeruginosa is uncommon in diabetic foot infections except in special circumstances 4.
Necrotizing Soft Tissue Infections
Appropriate for empiric Gram-negative coverage in polymicrobial necrotizing infections when combined with MRSA coverage 4.
Sepsis and Septic Shock
Acceptable as part of multidrug empiric broad-spectrum therapy for septic shock, often combined with vancomycin and/or antifungal agents 4.
Critical Limitations and Pitfalls
What Tazocin Does NOT Cover:
- MRSA: Always add vancomycin, linezolid, or daptomycin if MRSA suspected 4
- ESBL-producing Enterobacteriaceae: Use carbapenems instead 4, 2, 3
- Carbapenem-resistant organisms: No activity 4
- AmpC-hyperproducers: Unreliable; only 68.8% susceptible 2, 3
- Candida species: Requires separate antifungal coverage 4
Dosing Considerations:
- Higher doses required for P. aeruginosa: Standard dosing may be inadequate 4
- Combination with aminoglycoside recommended for severe P. aeruginosa infections and febrile neutropenia 4, 6, 7
- Renal adjustment mandatory: Half-life increases twofold (piperacillin) to fourfold (tazobactam) when CrCl <20 mL/min 1
Geographic Resistance Patterns:
Always check local antibiograms before empiric use, as resistance rates vary significantly by institution and region, particularly for P. aeruginosa and Enterobacteriaceae 4, 5.