Overview The presence or absence of specific enzymes can be used to distinguish bacteria in the laboratory urease catalase coagulase oxidase Urease Catalyzes the hydrolysis of urea into carbon dioxide and ammonia Increase in urine pH leads to renal calculi Urease positive bugs ("Urease Contaminates Kidneys. Now Peeing HurtS.") Proteus spp. Helicobacter pylori Klebsiella pneumoniae Ureaplasma urealyticum Nocardia spp. Cryptococcus neoformans S. epidermis and S. saprophyticus Catalase Decomposes hydrogen peroxide before the host can use it to fight infection H2O2 normally converted to microbicidal products by the enzyme myeloperoxidase particularly a problem in people with chronic granulomatous disease (NADPH oxidase deficiency) diseased host does not make enough H2O2 Catalase positive Staphylococci (all species) "they have enough 'staff' to make catalase" Nocardia spp. Pseudomonas Listeria Aspergillus Candida E. coli Burkholderia cepacia Serratia marcescens H. pylori Aspergillus spp. Catalase negative Streptococci (all species) most anaerobes Coagulase Coagulase positive Staphylococcus aureus Yersinia pestis Oxidase Oxidase positive Neisseria spp. most Gram-negative bacteria Oxidase negative Enterobacteriaceae