Latency, Anti-Bacterial Resistance Pattern, and Bacterial Infection-Related Glomerulonephritis.

Background and objectives Bacterial infection-related glomerulonephritis occurs concurrent to or following known or unknown infections. It's important to understand the clinical implications of the bacterial isolates, anti-microbial resistance patterns and impact of latency-based classification on kidney and patient outcomes. Design, setting, participants, and measurements 501 consecutive adults diagnosed with bacterial infection-related glomerulonephritis between 2005-2017 were included from biopsy registry of 15545 patients at a single center in South India and follow up data collected from electronic medical records till December 2019. Latency was defined as time between resolution of infection and onset of glomerulonephritis and was classified as para-infectious, peri-infectious and post-infectious glomerulonephritis. Longitudinal kidney and patient outcomes were studied. Results The mean age of the cohort was 40 (15) years, 6% were above 65 years and 330 (66%) were men. Diabetes was present in 93 (19%) of patients. 70% (353/501) patients had known infections, with the median latent period for para-infectious (115/353, 33%), peri-infectious (97/353, 27%) and post-infectious (141/353, 40%) glomerulonephritis being 0, 5 (4-7) and 15 (10-31) days respectively. The most common predisposing organism was Streptococcus pyogenes (137/353, 39%). Drug resistant non-streptococcal bacteria were methicillin resistant Staphylococcus aureus 25% (4/16), extended-spectrum beta-lactamases 20% (12/59) and carbapenem resistant organisms 10% (6/59). 20/22 (91%) of the drug resistant organisms were isolated from para-infectious group. The most common site of infection was skin in peri- (23/97, 24%) and post-infectious glomerulonephritis (61/141, 43%), and urinary tract in para-infectious glomerulonephritis (35/115, 30%). Out of 321 patients with more than three months follow-up, 48 (15%) developed kidney failure over a median period of 10 (2-37) months and 14 (4%) died. Para-infectious glomerulonephritis, eGFR <30 ml/min/1.73m2, moderate to severe interstitial fibrosis and tubular atrophy, and non-treatment with renin angiotensin system blockers were significant risk factors for progression to kidney failure by Cox proportional-hazards model. Conclusions Along with clinical and histological predictors, para-infectious glomerulonephritis caused predominantly by non-streptococcal and drug resistant bacterial infections was associated with poor kidney prognosis.