Providencia are gram negative motile rods and are considered as opportunistic bacterial pathogen of clinical significance. The sources of Providencia are varied and with each species of Providencia having a preferred habitat. P. alcalifaciens and P. rustigianii have been isolated from the colon and feces, P. stuartii from wounds, urinary tract and respiratory tract and P. heimbachae from feces of penguins. The most commonly isolated Providencia in human being is P. stuartii and it leads to urinary tract infections and bacteremia in intensive care unit. The P. rettgeri has been isolated from poultry, feces of reptiles and amphibians and surface waters. It is rarely isolated from human feces and urinary tract. The bacterial urease causes alkalization of urine leading to encrustation of catheters. P. rettgeri has also been reported to cause wounds, burns and blood infection [3,4,5,6,7].
Proteeae comprises of three genera namely Proteus, Morganella and Providencia. Providencia is differentiated from other two members because of its ability of using citrate and fermenting d-mannitol . The different strains of Providencia spp. have peritrichate flagella leading to its motility at 20–25°, but at temperature of 37° they are less motile. Providencia strains do not swarm, have fruity smell and requires neither niacin nor pantothenic acid for growth. The biochemical properties of Providencia family include positive for Indole production, Methyl Red, Citrate, Phenylalanine deaminase, growth in potassium cyanide, acid production from mannose, inositol, salicin, l-rhamnose, d-mannitol, adonitol, d-arabitol, and erythritol and negative for Voges-Proskauer reaction. P. rettgeri strains are genetically diverse when compared to other Providencia strains and are differentiated with other strains because of their property to ferment mannitol and degrade urea. Biogroups of P. rettgeri can be distinguished by their reactions in rhamnose, salicin and erythritol. Approximately 3/4th of isolates of P. rettgeri have the ability to acidify erythritol which is unique only to this species when compared to other members of Proteeae .
Infection caused by Providencia are rare and are mostly hospital acquired. The different infection caused by Providencia species are urinary tract infection, bacteremia, endocarditis, surgical site infection, soft tissue infection, brain abscess, meningitis, burn site infection, intravascular device infection, ocular infection, xanthogranulomatous pyelonephritis, peritonitis, intra-abdominal infection, and automatic implantable cardioverter-defibrillator pocket infection. The proposed pathogenesis of Providencia sepsis is ascending infection through the urinary tract and subsequent bacteremia leading to systemic infection and meningitis [3, 4, 9,10,11,12,13].
Providencia rettgeri is often resistant to multiple antibiotics like gentamicin, first-generation cephalosporins, nitrofurantoin, fosfomycin, tigecycline, polymyxins and ampicillin. Imipenem, amikacin and cefepime are the most active agents for more than 90% of the isolates [1, 14,15,16]. There is emergence of isolates that are carbapenemase producers carrying the New Delhi metallo-β-lactamase (NDM) gene bla NDM-1 . Tshisevhe et al. reported outbreak of carbapenem-resistant Providencia rettgeri involving four patients in South Africa with isolates being resistant to Meropenem, Imipenem and Ertapenem .
Maiti et al. published case series of three patients having age of 3, 34 and 40 years with central nervous system infections caused by P. rettgeri. The organism was isolated from cerebrospinal fluid in two patients and from subdural empyema in one patient. The patients were treated successfully with antibiotics and were discharged . There are no published case report till date that have reported Providencia rettgeri as cause of neonatal sepsis.