Streptococcus intermedius is frequently associated with brain and liver abscesses, while pleuropulmonary infections are considered rarer. Even less frequent is the association of lung and brain abscesses due to this agent with infective endocarditis. We describe the case of a 40-year-old man complaining of cough, fever, and headache who was diagnosed with a brain abscess due to S. intermedius, a concomitant lung abscess, and aortic native valve endocarditis. He was treated with surgical drainage of the brain abscess and a 4-week course of intravenous ceftriaxone, followed by oral amoxicillin/clavulanate, obtaining healing of the lesions without relapse of the infection.

Pneumonia remains a leading cause of morbidity and mortality worldwide, with bacterial pathogens contributing significantly to its burden. While Pseudomonas aeruginosa and Acinetobacter baumannii complex are well-recognized non-fermenting Gram-negative bacteria (NFGNB) causing severe pneumonia, particularly in healthcare settings, an expanding array of other, rarer NFGNB species is increasingly implicated. These species include, but are not limited to, Achromobacter spp., Ochrobactrum spp., Burkholderia spp., Aeromonas spp., Roseomonas spp., Elizabethkingia spp., Chryseobacterium spp. Alcaligenes spp., Ralstonia spp., Cupriavidus spp., Sphingomonas spp., Rhizobium spp., Empedobacter spp., and Brevundimonas spp. In this article we aim to provide a focused review of the contemporary epidemiology and specific risk factors for pneumonia caused by this diverse group of rare NFGNB, explicitly excluding P. aeruginosa, Stenotrophomonas maltophilia, and A. baumannii. We seek to delineate the emerging patterns of pneumonia associated with Achromobacter spp., Burkholderia spp., Aeromonas spp., Roseomonas spp., Elizabethkingia spp., Pandoraea spp., Sphingomonas spp., and K. gyiorum. Moreover, we discuss antimicrobial treatment strategies for pneumonia caused by rarer NFGNB including Ochrobactrum spp., Chryseobacterium spp., Alcaligenes spp., Ralstonia spp., Cupriavidus spp., Rhizobium spp., Empedobacter spp., and Brevundimonas spp. A deeper understanding of these specific epidemiological trends and risk factors is important for guiding precise diagnostic approaches, informing antimicrobial stewardship programs, and developing targeted infection prevention and control strategies with the aim of mitigating the impact of these challenging pathogens in the clinical setting.

Arcanobacterium haemolyticum is a facultative anaerobe, catalase-negative, Gram-positive pleomorphic rod, most commonly responsible for pharyngeal infections. Invasive A. haemolyticum infections are rare and typically involve immunocompromised patients; however, severe and invasive infections in immunocompetent patients have also been reported. Here we describe a case of sinusitis complicated by periorbital cellulitis, subdural empyema and cerebritis due to A. haemolyticum in an immunocompetent patient. The patient was initially treated with daptomycin + piperacillin/tazobactam and subsequently with linezolid + meropenem and required multiple surgical interventions to attain source control. Although uncommon, A. haemolyticum should be considered as a causative agent of severe infections complicating pharyngitis or sinusitis that may result from local extension or haematogenous spread, even in an immunocompetent host. We also present a literature review on central nervous system involvement by A. haemolyticum infection.

This is a retrospective observational study including all COVID-19 patients admitted at our Institute throughout three successive pandemic waves, from January 2021 to June 2023. The main in-hospital outcomes (clinical progression [CP], defined as admission to Intensive Care Unit [ICU]/death, and death within 28 days) were compared among participants unvaccinated (NV), fully vaccinated (FV), with one (FV&B1) and two (FV&B2) booster doses. Vaccinated participants were stratified into recently and waned FV/FV&B1/FV&B2, depending on the time elapsed from last dose (≤ and >120 days, respectively). There were 4488 participants: 2224 NV, 674 FV, 1207 FV&B1, and 383 FV&B2. Within 28 days, there were 604 ICU admissions, 396 deaths, and 737 CP. After adjusting for the main confounders, the risk of both in-hospital outcomes was reduced in vaccinated individuals, especially in those who received the booster dose (approximately by 36% for FV and >50% for FV&B1 and FV&B2 compared to NV). Similarly, after restricting the analysis to vaccinated participants only, we observed a risk reduction of approximately 40% for FV&B1 and 50% for FV&B2, compared to FV, regardless of the distance since the last dose. Our data confirm the vaccine’s effectiveness in preventing severe COVID-19 and support the efforts to increase the uptake of booster doses, mainly among older and frailer individuals, still at a greater risk of clinical progression.

Streptococcus intermedius is frequently associated with brain and liver abscesses, while pleuropulmonary infections are considered rarer. Even less frequent is the association of lung and brain abscess due to this agent with left heart endocarditis. We describe the case of a 40-year-old man with a brain abscess due to S. intermedius and concomitant lung abscess and aortic native valve endocarditis. He was treated with surgical drainage of the brain abscess and a 4-week course of intravenous ceftriaxone, followed by oral amoxicillin/clavulanate, obtaining healing of the lesions without relapse of the infection.