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Urine Stasis Predisposes to Urinary Tract Infection by an Opportunistic Uropathogen in the Megabladder (Mgb) Mouse.

Becknell B, Mohamed AZ, Li B, Wilhide ME, Ingraham SE - PLoS ONE (2015)

Bottom Line: Bladder stones were analyzed by x-ray diffractometry.Bladders and kidneys were subject to histologic analysis.Cutaneous vesicostomy prior to CONS inoculation significantly reduces the quantity of CONS recovered from Mgb-/- urine, bladders, and kidneys.

View Article: PubMed Central - PubMed

Affiliation: Nephrology Section, Nationwide Children's Hospital, Columbus, OH, United States of America; Department of Pediatrics, Ohio State University School of Medicine, Columbus, OH, United States of America; Center for Clinical and Translational Research, The Research Institute at Nationwide Children's, Columbus, OH, United States of America.

ABSTRACT

Purpose: Urinary stasis is a risk factor for recurrent urinary tract infection (UTI). Homozygous mutant Megabladder (Mgb-/-) mice exhibit incomplete bladder emptying as a consequence of congenital detrusor aplasia. We hypothesize that this predisposes Mgb-/- mice to spontaneous and experimental UTI.

Methods: Mgb-/-, Mgb+/-, and wild-type female mice underwent serial ultrasound and urine cultures at 4, 6, and 8 weeks to detect spontaneous UTI. Urine bacterial isolates were analyzed by Gram stain and speciated. Bladder stones were analyzed by x-ray diffractometry. Bladders and kidneys were subject to histologic analysis. The pathogenicity of coagulase-negative Staphylococcus (CONS) isolated from Mgb-/- urine was tested by transurethral administration to culture-negative Mgb-/- or wild-type animals. The contribution of urinary stasis to CONS susceptibility was evaluated by cutaneous vesicostomy in Mgb-/- mice.

Results: Mgb-/- mice develop spontaneous bacteriuria (42%) and struvite bladder stones (31%) by 8 weeks, findings absent in Mgb+/- and wild-type controls. CONS was cultured as a solitary isolate from Mgb-/- bladder stones. Bladders and kidneys from mice with struvite stones exhibit mucosal injury, inflammation, and fibrosis. These pathologic features of cystitis and pyelonephritis are replicated by transurethral inoculation of CONS in culture-negative Mgb-/- females, whereas wild-type animals are less susceptible to CONS colonization and organ injury. Cutaneous vesicostomy prior to CONS inoculation significantly reduces the quantity of CONS recovered from Mgb-/- urine, bladders, and kidneys.

Conclusions: CONS is an opportunistic uropathogen in the setting of urinary stasis, leading to enhanced UTI incidence and severity in Mgb-/- mice.

No MeSH data available.


Related in: MedlinePlus

Histopathology of Mgb-/- bladders and kidneys with spontaneous infection and struvite stones.(A) WT bladders exhibit a multilayered but compact urothelium over the connective tissue of the lamina propria, and thick bundles of smooth muscle comprising the muscularis propria. Green dashed line demarcates the urothelial basement membrane. White dotted line indicates the boundary between submucosa and muscularis propria. H&E, 20x objective. (B) Uninfected Mgb-/- bladders demonstrate a thickened urothelium and submucosa, and lack the muscularis propria due to the Mgb mutation. Detached urothelium as well as other cellular and non-specific debris are found in the bladder lumen. H&E, 20x objective. (C)Mgb-/- bladders exhibit luminal stones (S) and detached urothelium, urothelial thickening, and a submucosal inflammatory infiltrate. Green dashed line demarcates the urothelial basement membrane. H&E, 20x objective. (D) Mixed inflammatory cellular infiltrate in a spontaneously infected Mgb-/- bladder urothelium and submucosa, with vacuolated cell remnants (inset) within the urothelium. Submucosal fibrosis is also evident. Trichrome, 20x objective, inset 40x. (E) A spontaneously infected Mgb-/- kidney demonstrates focal areas (yellow dashed lines) of intense interstitial leukocyte infiltration consisting of monocytes, lymphocytes, and plasma cells (inset). These areas are surrounded by normal-appearing renal parenchyma, consistent with a focal pyelonephritis. H&E, 5x objective; inset 40x objective. (F) In another spontaneously infected Mgb-/- kidney, the renal medulla demonstrates diffuse inflammatory infiltrate in the interstitium and suburothelial space. Medullary collecting ducts (*) are markedly dilated with cytoplasmic flattening, reactive nuclei, and luminal acute cellular degeneration consistent with acute tubular necrosis. Green dashed line demarcates the urothelial basement membrane. Trichrome, 20x objective.
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pone.0139077.g003: Histopathology of Mgb-/- bladders and kidneys with spontaneous infection and struvite stones.(A) WT bladders exhibit a multilayered but compact urothelium over the connective tissue of the lamina propria, and thick bundles of smooth muscle comprising the muscularis propria. Green dashed line demarcates the urothelial basement membrane. White dotted line indicates the boundary between submucosa and muscularis propria. H&E, 20x objective. (B) Uninfected Mgb-/- bladders demonstrate a thickened urothelium and submucosa, and lack the muscularis propria due to the Mgb mutation. Detached urothelium as well as other cellular and non-specific debris are found in the bladder lumen. H&E, 20x objective. (C)Mgb-/- bladders exhibit luminal stones (S) and detached urothelium, urothelial thickening, and a submucosal inflammatory infiltrate. Green dashed line demarcates the urothelial basement membrane. H&E, 20x objective. (D) Mixed inflammatory cellular infiltrate in a spontaneously infected Mgb-/- bladder urothelium and submucosa, with vacuolated cell remnants (inset) within the urothelium. Submucosal fibrosis is also evident. Trichrome, 20x objective, inset 40x. (E) A spontaneously infected Mgb-/- kidney demonstrates focal areas (yellow dashed lines) of intense interstitial leukocyte infiltration consisting of monocytes, lymphocytes, and plasma cells (inset). These areas are surrounded by normal-appearing renal parenchyma, consistent with a focal pyelonephritis. H&E, 5x objective; inset 40x objective. (F) In another spontaneously infected Mgb-/- kidney, the renal medulla demonstrates diffuse inflammatory infiltrate in the interstitium and suburothelial space. Medullary collecting ducts (*) are markedly dilated with cytoplasmic flattening, reactive nuclei, and luminal acute cellular degeneration consistent with acute tubular necrosis. Green dashed line demarcates the urothelial basement membrane. Trichrome, 20x objective.

Mentions: We next examined the histology of bladders and kidneys of Mgb-/- mice with bladder stones. In the absence of bladder stones and bacteriuria, the Mgb-/- bladder exhibits distinct features compared to WT controls: detrusor hypoplasia, urothelial thickening, and luminal debris (Fig 3A and 3B), consistent with previous reports.[7,10] Mgb-/- bladders with stones displayed increased urothelial thickening, mucosal detachment, and histologic evidence of luminal stones (Fig 3C). A mononuclear and neutrophilic infiltrate occupied the urothelium and submucosa, with submucosal fibrosis evident on Trichrome stain (Fig 3D). Cytoplasmic vacuoles within the urothelium indicated acute cellular degeneration (Fig 3D inset). Infected Mgb-/- kidneys exhibited interstitial nephritis in the cortex and medulla (Fig 3E). Medullary collecting ducts were markedly dilated with cytoplasmic flattening, reactive nuclei, and luminal cellular degeneration consistent with acute tubular necrosis (Fig 3F). As in the bladder, trichrome staining identified collagen deposition immediately beneath the renal urothelium (Fig 3F). These features of cystitis or pyelonephritis observed in Mgb-/- urinary tracts with bladder stones were not evident in tissues from culture-negative Mgb-/-, Mgb+/- or WT mice (Fig 3A and 3B; data not shown).


Urine Stasis Predisposes to Urinary Tract Infection by an Opportunistic Uropathogen in the Megabladder (Mgb) Mouse.

Becknell B, Mohamed AZ, Li B, Wilhide ME, Ingraham SE - PLoS ONE (2015)

Histopathology of Mgb-/- bladders and kidneys with spontaneous infection and struvite stones.(A) WT bladders exhibit a multilayered but compact urothelium over the connective tissue of the lamina propria, and thick bundles of smooth muscle comprising the muscularis propria. Green dashed line demarcates the urothelial basement membrane. White dotted line indicates the boundary between submucosa and muscularis propria. H&E, 20x objective. (B) Uninfected Mgb-/- bladders demonstrate a thickened urothelium and submucosa, and lack the muscularis propria due to the Mgb mutation. Detached urothelium as well as other cellular and non-specific debris are found in the bladder lumen. H&E, 20x objective. (C)Mgb-/- bladders exhibit luminal stones (S) and detached urothelium, urothelial thickening, and a submucosal inflammatory infiltrate. Green dashed line demarcates the urothelial basement membrane. H&E, 20x objective. (D) Mixed inflammatory cellular infiltrate in a spontaneously infected Mgb-/- bladder urothelium and submucosa, with vacuolated cell remnants (inset) within the urothelium. Submucosal fibrosis is also evident. Trichrome, 20x objective, inset 40x. (E) A spontaneously infected Mgb-/- kidney demonstrates focal areas (yellow dashed lines) of intense interstitial leukocyte infiltration consisting of monocytes, lymphocytes, and plasma cells (inset). These areas are surrounded by normal-appearing renal parenchyma, consistent with a focal pyelonephritis. H&E, 5x objective; inset 40x objective. (F) In another spontaneously infected Mgb-/- kidney, the renal medulla demonstrates diffuse inflammatory infiltrate in the interstitium and suburothelial space. Medullary collecting ducts (*) are markedly dilated with cytoplasmic flattening, reactive nuclei, and luminal acute cellular degeneration consistent with acute tubular necrosis. Green dashed line demarcates the urothelial basement membrane. Trichrome, 20x objective.
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Related In: Results  -  Collection

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pone.0139077.g003: Histopathology of Mgb-/- bladders and kidneys with spontaneous infection and struvite stones.(A) WT bladders exhibit a multilayered but compact urothelium over the connective tissue of the lamina propria, and thick bundles of smooth muscle comprising the muscularis propria. Green dashed line demarcates the urothelial basement membrane. White dotted line indicates the boundary between submucosa and muscularis propria. H&E, 20x objective. (B) Uninfected Mgb-/- bladders demonstrate a thickened urothelium and submucosa, and lack the muscularis propria due to the Mgb mutation. Detached urothelium as well as other cellular and non-specific debris are found in the bladder lumen. H&E, 20x objective. (C)Mgb-/- bladders exhibit luminal stones (S) and detached urothelium, urothelial thickening, and a submucosal inflammatory infiltrate. Green dashed line demarcates the urothelial basement membrane. H&E, 20x objective. (D) Mixed inflammatory cellular infiltrate in a spontaneously infected Mgb-/- bladder urothelium and submucosa, with vacuolated cell remnants (inset) within the urothelium. Submucosal fibrosis is also evident. Trichrome, 20x objective, inset 40x. (E) A spontaneously infected Mgb-/- kidney demonstrates focal areas (yellow dashed lines) of intense interstitial leukocyte infiltration consisting of monocytes, lymphocytes, and plasma cells (inset). These areas are surrounded by normal-appearing renal parenchyma, consistent with a focal pyelonephritis. H&E, 5x objective; inset 40x objective. (F) In another spontaneously infected Mgb-/- kidney, the renal medulla demonstrates diffuse inflammatory infiltrate in the interstitium and suburothelial space. Medullary collecting ducts (*) are markedly dilated with cytoplasmic flattening, reactive nuclei, and luminal acute cellular degeneration consistent with acute tubular necrosis. Green dashed line demarcates the urothelial basement membrane. Trichrome, 20x objective.
Mentions: We next examined the histology of bladders and kidneys of Mgb-/- mice with bladder stones. In the absence of bladder stones and bacteriuria, the Mgb-/- bladder exhibits distinct features compared to WT controls: detrusor hypoplasia, urothelial thickening, and luminal debris (Fig 3A and 3B), consistent with previous reports.[7,10] Mgb-/- bladders with stones displayed increased urothelial thickening, mucosal detachment, and histologic evidence of luminal stones (Fig 3C). A mononuclear and neutrophilic infiltrate occupied the urothelium and submucosa, with submucosal fibrosis evident on Trichrome stain (Fig 3D). Cytoplasmic vacuoles within the urothelium indicated acute cellular degeneration (Fig 3D inset). Infected Mgb-/- kidneys exhibited interstitial nephritis in the cortex and medulla (Fig 3E). Medullary collecting ducts were markedly dilated with cytoplasmic flattening, reactive nuclei, and luminal cellular degeneration consistent with acute tubular necrosis (Fig 3F). As in the bladder, trichrome staining identified collagen deposition immediately beneath the renal urothelium (Fig 3F). These features of cystitis or pyelonephritis observed in Mgb-/- urinary tracts with bladder stones were not evident in tissues from culture-negative Mgb-/-, Mgb+/- or WT mice (Fig 3A and 3B; data not shown).

Bottom Line: Bladder stones were analyzed by x-ray diffractometry.Bladders and kidneys were subject to histologic analysis.Cutaneous vesicostomy prior to CONS inoculation significantly reduces the quantity of CONS recovered from Mgb-/- urine, bladders, and kidneys.

View Article: PubMed Central - PubMed

Affiliation: Nephrology Section, Nationwide Children's Hospital, Columbus, OH, United States of America; Department of Pediatrics, Ohio State University School of Medicine, Columbus, OH, United States of America; Center for Clinical and Translational Research, The Research Institute at Nationwide Children's, Columbus, OH, United States of America.

ABSTRACT

Purpose: Urinary stasis is a risk factor for recurrent urinary tract infection (UTI). Homozygous mutant Megabladder (Mgb-/-) mice exhibit incomplete bladder emptying as a consequence of congenital detrusor aplasia. We hypothesize that this predisposes Mgb-/- mice to spontaneous and experimental UTI.

Methods: Mgb-/-, Mgb+/-, and wild-type female mice underwent serial ultrasound and urine cultures at 4, 6, and 8 weeks to detect spontaneous UTI. Urine bacterial isolates were analyzed by Gram stain and speciated. Bladder stones were analyzed by x-ray diffractometry. Bladders and kidneys were subject to histologic analysis. The pathogenicity of coagulase-negative Staphylococcus (CONS) isolated from Mgb-/- urine was tested by transurethral administration to culture-negative Mgb-/- or wild-type animals. The contribution of urinary stasis to CONS susceptibility was evaluated by cutaneous vesicostomy in Mgb-/- mice.

Results: Mgb-/- mice develop spontaneous bacteriuria (42%) and struvite bladder stones (31%) by 8 weeks, findings absent in Mgb+/- and wild-type controls. CONS was cultured as a solitary isolate from Mgb-/- bladder stones. Bladders and kidneys from mice with struvite stones exhibit mucosal injury, inflammation, and fibrosis. These pathologic features of cystitis and pyelonephritis are replicated by transurethral inoculation of CONS in culture-negative Mgb-/- females, whereas wild-type animals are less susceptible to CONS colonization and organ injury. Cutaneous vesicostomy prior to CONS inoculation significantly reduces the quantity of CONS recovered from Mgb-/- urine, bladders, and kidneys.

Conclusions: CONS is an opportunistic uropathogen in the setting of urinary stasis, leading to enhanced UTI incidence and severity in Mgb-/- mice.

No MeSH data available.


Related in: MedlinePlus