Acute Infection-Related Glomerulonephritis and Disseminated Gonococcal Infection Case Study

Vocabulary terms and clinical definitions based on a case report of a 13-year-old girl with concurrent disseminated gonococcal infection and acute glomerulonephritis.

Infection-related glomerulonephritis (IRGN)

A condition resulting from glomerular immune complex deposition due to various pathogens such as bacteria, viruses, fungi, and parasites, occurring during an acute illness or after a latent period.

Poststreptococcal glomerulonephritis (PSGN)

The best-known example of IRGN, typically occurring $1-3$ weeks after pharyngitis and $2-4$ weeks after skin infection with beta-hemolytic group A Streptococcus.

Disseminated gonococcal infection (DGI)

A rare complication of Neisseria gonorrhoeae infection ($0.5\%-3\%$ incidence) characterized by fever, petechiae, tenosynovitis, polyarthralgias, and asymmetric polyarthritis.

Tenosynovitis

Inflammation of a tendon sheath, identified in this case by erythema and tenderness on the dorsum of the right foot.

Hypocomplementemic glomerulonephritis

A form of nephritis associated with active complement consumption, characterized in this patient by low levels of $C3$ (initial value $12\,mg/dL$), $C4$ ($14\,mg/dL$), $C5$, and $C8$.

"Starry sky" pattern

A characteristic granular immunofluorescence staining pattern for $C3$ involving the glomerular capillary walls and mesangium, indicative of infection-related glomerulonephritis.

Subepithelial electron-dense humps

Abundant hump-shaped immune deposits without spike formation seen on electron microscopy, typical of acute postinfectious glomerulonephritis.

Por A and Por B

Two immunochemically distinct groups of porin proteins used to classify Neisseria gonorrhoeae into 26 and 32 serovers respectively, indicating broad strain diversity.

Molecular mimicry

A proposed mechanism for glomerular injury where a gonococcal antigen cross-reacts with a component of the glomerular capillary wall, stimulating the production of antibodies that bind in situ.

Anasarca

Severe, generalized edema resulting from fluid overload and fluid retention, as observed in the patient on hospital day 3.

Chocolate blood agar

Specific medium required for the culture of the fastidious organism Neisseria gonorrhoeae, which also requires a humid and carbon dioxide-rich atmosphere for viability.

Nephritogenic strains

Specific strains of a pathogen (such as group A streptococci or potentially Neisseria gonorrhoeae) that possess properties capable of inducing glomerular injury.

Anti-DNAase B

A streptococcal antibody test which, when normal ($<310\,U/mL$) alongside a negative throat swab, helped exclude recent streptococcal infection in this patient.

Endocapillary proliferative and exudative glomerulonephritis

A pathological finding on light microscopy showing global obliteration of glomerular capillaries by hypercellularity and many infiltrating neutrophils.