Providencia rettgeri (PR) has been frequently associated with colonization of indwelling urinary catheters and urinary tract infections, bacteremias, skin infections, traveler's diarrhea, etc [3, 4]. To the best of our knowledge, this microorganism has never been implicated in infections of automatic ICD, being this case the first one ever reported in the literature as evidenced by a MEDLINE database search. Axillae, human feces, urine, throat and perineum could serve as potential reservoirs for Providencia species, mainly in chronic debilitated patients. Exogenous sources include sewage contaminated natural waters [5]. A probable key feature in the pathogenesis of this patient's infection was the formation of a biofilm composed mainly of host adhesins (fibrinogen, fibronectin, collagen) and bacteria that may have occurred soon after the insertion of the ICD [6]. The skin of our patient could have been colonized with PR before the adherence of the bacterium to the device since no foley catheter insertion had been reported on prior admissions.
PR is a facultative anaerobe, Gram-negative, motile, opportunistic bacterium that belongs to the genus Providencia, tribe Proteeae (along with the genus Proteus and Morganella), Enterobacteriaceae family. PR was first isolated by Rettger in 1904 during an epidemic of fowl cholera, but it was only studied in detail later in 1918 when it was called Bacterium rettgerei [7]. In 1951, Kauffmann applied the term Providencia to the genus described by Stuart et al. at Brown University in Providence, Rhode Island [8]. Many taxonomic changes of genus Providencia have taken place since then, which included a frequent overlap between the Gram-negative genera belonging to the tribe Proteeae. Currently, the genus Providencia includes five species: P. stuartii, P. rettgeri, P. alcalifacens, P. rustigianii and P. heimbachae. Providencia stuartii has been described as the commonest isolate in residents of nursing homes diagnosed with bacteremia [9]. In a recent epidemiologic study in a Canadian population, the incidence of isolates for the genus Providencia was found to be 3.4⁄100 000⁄year, with more infections reported as people aged and were residing in nursing homes [10].
Nosocomial outbreaks of highly resistant strains of PR causing urinary tract infections and bacteremias have been described. Epidemiologic factors included the intensive concomitant use of antibiotics and indwelling urinary catheters; while the use of gloves by personnel showed to be an effective control measure [11, 12]. Our patient was kept on contact isolation until the end of the admission with no further cases reported on the same medical ward.
Resistant Enterobacteriaceae is a recent major health hazard. The transmission of resistance is frequently acquired through plasmids from other Gram-negative rods and it has been associated with the increasing use of antibiotics. The frequent isolation of extended spectrum beta-lactamase in Providencia species alarms about the risk of future nosocomial epidemics caused by this multi-resistant organism and is a considered an emerging problem [13, 14]. The natural antibiotic susceptibility of PR includes numerous beta-lactam, fluoroquinolone and aminoglycoside antibiotics and a less resistant pattern than that of P. stuartii[15].