Molecular Detection of HpmA and HlyA Hemolysin of Uropathogenic Proteus mirabilis

Abstract

Urinary tract infection (UTI) is one of the bacterial infections frequently documented in humans. Proteus mirabilis is associated with UTI mainly in individuals with urinary tract abnormality or related with vesicular catheterism and it can be difficult to treat because of the formation of stones in the bladder and kidneys. These stones are formed due to the presence of urease synthesized by the bacteria. Another important factor is that P. mirabilis produces hemolysin HpmA, used by the bacteria to damage the kidney tissues. Proteus spp. samples can also express HlyA hemolysin, similar to that found in Escherichia coli. A total of 211 uropathogenic P. mirabilis isolates were analyzed to detect the presence of the hpmA and hpmB genes by the techniques of polymerase chain reaction (PCR) and dot blot and hlyA by PCR. The hpmA and hpmB genes were expressed by the RT-PCR technique and two P. mirabilis isolates were sequenced for the hpmA and hpmB genes. The presence of the hpmA and hpmB genes was confirmed by PCR in 205 (97.15 %) of the 211 isolates. The dot blot confirmed the presence of the hpmA and hpmB genes in the isolates that did not amplify in the PCR. None of the isolates studied presented the hlyA gene. The hpmA and hpmB genes that were sequenced presented 98 % identity with the same genes of the HI4320 P. mirabilis sample. This study showed that the PCR technique has good sensitivity for detecting the hpmA and hpmB genes of P. mirabilis.

Urinary tract infections: epidemiology, mechanisms of infection and treatment options

“…P. mirabilis produce two toxins, haemolysin (HpmA) and Proteus toxic agglutinin (Pta), which are implicated in tissue damage and dissemination to the kidneys, initiating acute pyelonephritis 16,72 . HpmA is a Ca + -dependent pore-forming cytolysin that destabilizes the host cell by inserting itself into the cell membrane and causing a Na + efflux 16 (FIG.…”

Pathogenesis of Proteus mirabilis Infection

“…For example, hpmA was found by Southern blot in 63/63 isolates tested, and correlated with hemolytic activity (102); likewise, a survey of 211 isolates using a combination of PCR and dot blot found that all encoded hpmA (103). Zap protease is also widespread, including all P. mirabilis tested from a diverse O-serogroup collection (104).…”

“…The calcium-independent hemolysin is encoded by two genes comprising a two-partner secretion system: hpmA , which produces a 166 kDa secreted exoprotein, and hpmB , which produces a 63 kDa translocase protein that is required for both the activation and secretion of HpmA through cleavage of an N-terminal peptide (209). HpmA is the predominant hemolysin in Proteus species and appears to be the only hemolysin encoded by P. mirabilis , present in 268/274 (98%) of P. mirabilis clinical and fecal isolates from Brazil and the United States while none of these isolates encoded hlyA (102, 103). Similarly, hpmA is present in all 7 complete P. mirabilis genome sequences available through NCBI as of May 2017.…”

Proteus mirabilisand Urinary Tract Infections

“…The hemolysin is encoded by hpmA , while a second gene, hpmB , encodes a membrane transporter; both genes are highly conserved across P. mirabilis isolates (220). The levels of hemolysin in P. mirabilis correlate with its ability to invade cultured kidney cells, and an isogenic P. mirabilis Δ hpmA mutant is minimally invasive in cultured cells (136, 137).…”