β-lactamases hydrolyze primary and extended-spectrum penicillins and cephalosporins, thus making P. penneri strains naturally resistant to penicillin G, amoxicillin, cephalosporins (i.e. cefaclor, cefazoline, cefuroxime, and cefdinir), oxacillin, and most macrolides. Susceptibility profile Most isolated P. penneri strains are multiple-drug resistant, with 12 being the highest drug-resistance number reported. P. penneri has a distinguishing susceptibility profile, based on the production of the chromosomally induced β-lactamase HugA. HugA determines resistance to aminopenicillins and first- and second-generation cephalosporins, including cefuroxime. However, HugA does not affect cephamycins or carbapenems and is inhibited by clavulanic acid. Similar to other Proteus species, P. penneri is resistant to tetracyclines and nitrofurantoin. Presently, all tested strains of P. penneri have been found to be highly susceptible to: ceftizoxime ceftazidime moxalactam cefoxitin gentamicin tobramycin netilmicin Most strains with a few exceptions are also susceptible to: amikacin piperacillin cefoperazone All tested strains have been found resistant to: penicillin ampicillin tetracycline chloramphenicol co-trimoxazole Treatment Information on the treatment of P. penneri infections is limited, but the use of gentamicin, tobramycin, netilmicin, and amikacin have been indicated as possible drugs of choice for the treatment of systemic infections caused by susceptible P. penneri strains. In vitro studies of ceftizoxime, ceftazidime, moxalactam, and cefoxitin suggest these agents also may prove to be clinically useful in treating infections caused by P. penneri. See also Proteus vulgaris References External links Type strain of Proteus penneri at BacDive - the Bacterial Diversity Metadatabase Gram-negative bacteria Bacteria described in 1982