Estimated hospitalization rate for diseases attributable to Streptococcus pneumoniae in the Veneto region of north-east Italy

Variation in pneumococcal invasiveness metrics is driven by serotype carriage duration and initial risk of disease

Streptococcus pneumoniae is an opportunistic pathogen that, while usually carried asymptomatically, can cause severe invasive diseases like meningitis and bacteremic pneumonia. A central goal in S. pneumoniae public health management is to identify which serotypes (immunologically distinct strains) pose the most risk of invasive disease. The most common invasiveness metrics use cross-sectional data (i.e., invasive odds ratios (IOR)), or longitudinal data (i.e., attack rates (AR)). To assess the reliability of these metrics we developed an epidemiological model of carriage and invasive disease. Our mathematical analyses illustrate qualitative failures with the IOR metric (e.g., IOR can decline with increasing invasiveness parameters). Fitting the model to both longitudinal and cross-sectional data, our analysis supports previous work indicating that invasion risk is maximal at or near time of colonization. This pattern of early invasive disease risk leads to substantial (up to 5-fold) biases when estimating underlying differences in invasiveness from IOR metrics, due to the impact of carriage duration on IOR. Together, these results raise serious concerns with the IOR metric as a basis for public health decision-making and lend support for multiple alternate metrics including AR.

The Burden of Streptococcus pneumoniae-Related Admissions and In-Hospital Mortality: A Retrospective Observational Study between the Years 2015 and 2022 from a Southern Italian Province

Streptococcus pneumoniae (SP) has high worldwide incidence and related morbidity and mortality, particularly among children and geriatric patients. SP infection could manifest with pneumonia, bacteremia, sepsis, meningitis, and osteomyelitis. This was a retrospective study aimed at evaluating the incidence, comorbidities, and factors associated with in-hospital mortality of pneumococcal disease-related hospitalization in a province in southern Italy from the years 2015 to 2022. This study was performed in the Local Health Authority (LHA) of Pescara. Data were collected from hospital discharge records (HDRs): this database is composed of 288,110 discharge records from LHA Pescara's hospitals from 2015 to 2022. Streptococcus Pneumoniae-related hospitalizations were about 5% of the hospitalizations; 67% of these were without comorbidities; 21% were with one comorbidity; and 13% were with two or more comorbidities. Regarding mortality of SP infection, the most affected age group was older people, with the percentage of cases among the over-65s being more than 50% compared to the other age groups. HDRs represent a valid and useful epidemiological tool for evaluating the direct impact of pneumococcal disease on the population and also indirectly for evaluating the effectiveness of vaccination strategies and directing them.

Epidemiology of invasive and non-invasive pneumococcal infections in hospitalised adult patients in a Lebanese medical centre, 2006-2015

This is a retrospective medical file review of adult inpatients with Streptococcus pneumoniae infections admitted to a Lebanese hospital between 2006 and 2015. We revisited the clinical scenarios of these infections in view of increasing antibiotic resistance in Lebanon. One hundred and three patients were included; 92% were eligible for pneumococcal vaccination, yet none were vaccinated. Non-invasive pneumococcal disease (non-IPD) represented 64% of these infections. Superinfections caused by antibiotic-resistant bacteria were documented in 17.5% of the patients, with the predominance of ventilator-associated pneumonia (12.6%). Kidney disease and septic shock were positive predictors for mortality [adjusted odds ratio (OR) = 14.96, 95% confidence interval (CI) 2.34-95.45, P = 0.004; OR = 5.09, 95% CI 1.33-19.51, P = 0.02, respectively]. Herein, the differences in clinical success, S. pneumoniae infection-related death, and total mortality were not statistically significant between invasive pneumococcal disease (IPD) and non-IPD subgroups (59.5% vs. 77.3%, P = 0.056; 21.6% vs. 9.1%, P = 0.08; and 35.1% vs. 22.7%, P = 0.174; respectively). Upon comparing antibiotic susceptibility of S. pneumoniae during the first two years of the study (2006-2007) (n = 32 isolates) and the last two (2014-2015) (n = 14 isolates), there was an increasing non-susceptibility to penicillin (34.4%-50.0%, P = 0.25), and a decreasing susceptibility to erythromycin and clindamycin (81.3%-78.6%, P = 0.67 and 90.6%-85.7%, P = 0.65; respectively).