Use of plasmid analysis to determine the source of bacterial invasion of the urinary tract

Abstract

SummaryGram negative colonisation and infection of the urinary tract is a well recognised compli cation of the neuropathic bladder caused by sp inal cord injury (S CI). K. pneumoniae accounts for one third of all urinary tract infections in hospitalised SCI patients. Plasmid analysis has been shown to reliably fingerprint bacterial strains, particularly K. pneumoniae, so that growth from two separate locations in or on the body can be accu rately analysed as to migration from a reservoir to a target location.Eighty seven hospitalised SCI patients on intermittent catheterisation for a total of 5 86 patient-weeks were studied. Twice weekly catheterised urine sp ecimens and once weekly rectal swab cultures were taken from each patient. Thirty seven patients experienced at least one clinically significant (colony count> 10 OOOlmL) urinary tract colonisation caused by K. pneumoniae, representing 66 total colonisations. Further analysis of 31 of these 37 patients revealed: K. pneumoniae in all of their stool cultures (p < 0'05) and the identical strain of K. pneumoniae in the urine as well as the stool in 72% of the 66 colonisations (p < 0'05). Analysis of 14 patients without K. pneumoniae urinary col onisations showed absence of faecal K. pneumoniae in 3, and predominant growth in only 4. In 22 of the 37 patients, multiple K. pneumoniae urinary colonisations were noted, representing 27 pairs of colonisation. Fifteen of the pairs were found to be relaps ing (caused by two identical bacterial strains), and 12 were recurrent (caused by two dif ferent bacterial strains). Thirteen of the 1 5 relapsing pairs also had identical urine and stool K. pneumoniae strains (p < 0'05). All colonisations were treated with appropri ate antibiotics based on culture and sensitivity reports. Fourteen of the 15 relapsing colon isation pairs have identical antibiograms (p < 0'05), while all 12 of the recurrent colon isation pairs had different antibiograms (p < 0'05). The differences noted on sensitivity patterns (antibiograms) correlated with differences among strains of K. pneumoniae based up on plasmid analysis. Treatment of bacteriuria did not affect the nature of re peated colonisations regardless of the antibiotic chosen, the route of administration or the duration of treatment.

Characterizing Plasmids in Bacteria Species Relevant to Urinary Health

“…IncF plasmids usually are considered to have a narrow host range, only being transferred and maintained in Enterobacteriaceae ( 44 , 45 ). Plasmids have been identified in in K. pneumoniae isolates from patients with UTI and have been proposed as a fingerprint to identify the origin of infection ( 46 , 47 ).…”