Proteus morgani is less frequently associated with urinary tract infections than Proteus mirabilis--an explanation

The metabolic activities of faecal and urinary strains of Proteus morgani and P. mirabilis were compared. Regardless of origin, the generation time of P. morgani strains in urine was approximately twice as long as that of the P. mirabilis strains. Urease synthesis was constitutive in P. morgani strains but required induction with urea in the P. mirabilis strains. In the presence of urea, the P. mirabilis strains liberated ammonia more rapidly and produced alkaline conditions more quickly than P. morgani strains, although they synthesized much less urease. These characteristics may place P. morgani strains at a disadvantage in comparison with P. mirabilis strains in their ability to cause urinary tract infections.