* Bacteroides spp., including B. fragilis
* Enterobacter spp.
* Escherichia coli
* Haemophilus influenzae
* Klebsiella species
* Morganella morganii
* Neisseria gonorrhoeae
* Proteus mirabilis
* Proteus vulgaris
* Providencia rettgeri
* Pseudomonas spp., including P. aeruginosa
* Serratia marcescens