Acinetobacter : Oral vs Parenteral Unasyn

• T. Unasyn 375mg(sultamicillin- ampicillin 220mg, Sulbactam 147mg)
• Inj Unasyn 1.5g (ampicillin 1g, Sulbactam 0.5g )

Sensitivity

• β-Lactamase inhibitors, including sulbactam, bind to β-lactamase, thereby increasing the susceptibility of the microorganism to co-administered β-lactam antibiotics.
• most β-lactamase inhibitors do not exert antimicrobial activity if given alone
• Sulbactam, however, has been demonstrated to have antimicrobial properties, including against A. baumannii, which are thought to be mediated by binding to penicillin binding-proteins
• Although the available evidence suggests that sulbactam-based therapies can be effective for the treatment of A. baumannii infection, there is little evidence to suggest that sulbactam-based therapies are more or less effective than alternative therapies

Dose

• Ranges from 3g QID to 3g 3 hourly (suspected MDR pathogens)

Coversions to Oral dose

• No supporting evidence or guidelines on use of oral Unasyn for eradication therapy
• No guides on dose equivalence/conversion of IV to oral for management of Acinetobacter
• As A baumannii is intrinsically multidrug resistant, it is highly recommended to achieve sufficient levels by using therapeutic doses of IV Unasyn ( compared to Oral/ which may not achieve the required sulbacam doses based on usual IV to Oral conversions)

References:

1.   http://www.sciencedirect.com/science/article/pii/S1413867013000718

2.   http://www.globalrph.com/Acinetobacter-baumannii.htm

3.   Guide to Antimicrobial Therapy in Adults 2012

4.   www.uptodate.com

5.   http://emedicine.medscape.com/article/236891-medication