Escherichia coli bloodstream infections are common and associated with high mortality. A key feature of E. coli is the lipopolysaccharide (LPS) O-antigen, which contributes to immune evasion during invasive infection. We analyzed serial isolates from patients with relapsed E. coli bacteremia and identified frequent disruption of O-antigen synthesis due to mutations in wbbL, resulting in a rough LPS phenotype. Rough LPS isolates were more serum sensitive and less pathogenic in mice. Despite this apparent attenuation, 11 of 61 (18%) E. coli sequence type 131 bloodstream isolates in our cohort harbored disruptive wbbL mutations and were associated with significantly worse clinical outcomes, including septic shock and mortality. Using a murine model of recurrent bacteremia, we show that rough LPS isolates partially evade protective immunity generated against smooth LPS E. coli, highlighting the importance of host immune context in invasive disease.

Streptococcus pneumoniae remains a leading cause of invasive bacterial infection worldwide and is classically associated with community-acquired pneumonia. However, fulminant pneumococcal septic shock in the absence of radiographic pneumonia is uncommon and may delay diagnosis and treatment. We present the case of a 48-year-old immunocompetent female who developed severe septic shock secondary to Streptococcus pneumoniae bacteremia despite initially negative chest imaging for focal pneumonia. The patient presented with profound hypotension, lactic acidosis, thrombocytopenia, acute kidney injury, and acute hypoxic respiratory failure requiring vasopressor support and intensive care admission. Blood cultures grew Streptococcus pneumoniae. Initial chest radiography and computed tomography angiography of the chest demonstrated no focal consolidative pneumonia, although delayed bibasilar pulmonary infiltrative changes developed later during hospitalization. Extensive evaluation did not identify alternative infectious sources including endocarditis or meningitis. The patient improved rapidly with aggressive resuscitation and targeted antimicrobial therapy. This case highlights the importance of recognizing invasive pneumococcal disease even in the absence of classic radiographic findings and emphasizes that early imaging may underestimate evolving pulmonary infection in severe sepsis.

Community lineages of Staphylococcus aureus emerging in hospitals, such as CC398, have raised concerns. S. aureus CC398 isolates from bloodstream infections (BSI) and nasal colonization of hospitalized patients, during the COVID-19 pandemic, between March/2020 and September/2021, were characterized for antimicrobial susceptibility by disk diffusion test. Spa types and Sequence Type (ST) were analyzed by PCR/sequencing, and genes of resistance, virulence, and human immune evasion cluster (IEC) were accessed by PCR. Of a total of 118 CC398 isolates, 104 were from nasal swabs (4 MRSA and 100 MSSA), and 14 MSSA were from BSI. Forty (33.9%) patients presented COVID-19, and prior antimicrobial use was common among those colonized (p < 0.05). High resistance rates were found for penicillin (PEN, 92.4%), erythromycin (ERY, 95.8%), clindamycin (CLI, 90.7%) and gentamicin (GEN, 51.7%), and the iMLSB phenotype was commonly detected. All four nasal MRSA and 47.4% of MSSA isolates were multidrug-resistant. The CLI/ERY/GEN/PEN/ermT/ermC and CLI/ERY/ermT resistance profiles were frequent in nasal (45.2%) and BSI (57.1%) isolates, respectively. The ermC gene was more found in nasal (93.3%) than in BSI (7.1%) isolates (p < 0.05). Most of 95% of the isolates presented the fnbA, fnbB, cna, and ermT genes. The spa type t1451 was detected in 91.5% of isolates, and the human clade was associated with 98.3%, with IEC type C being prevalent. MSSA-CC398 isolates of the human clade were predominant among hospitalized patients during the pandemic. The increased selective pressure exerted on these isolates, previously resistant to macrolides, may have favored their dissemination in the environment.

Neonatal intestinal perforation is a life-threatening surgical emergency that is more commonly described in preterm or low-birth-weight infants. Isolated descending colonic perforation in a term neonate is rare and may be difficult to recognize when symptoms are non-specific. We report a male newborn delivered at 37+2 weeks, weighing 2.6 kg, with Apgar scores of 9 and 9 at 1 and 5 minutes. Breastfeeding was started at two hours and was initially tolerated. At 12 hours, he developed poor feeding and brownish vomiting, while stool passage was present from day one. Initial laboratory tests and chest and abdominal X-ray findings were not diagnostic. He later developed persistent bilious nasogastric aspirate, rising inflammatory markers, thrombocytopenia, Escherichia coli bacteremia, and respiratory deterioration. A contrast study did not show malrotation or intestinal obstruction. In view of further clinical deterioration and abdominal distension, an abdominal X-ray was repeated and demonstrated pneumoperitoneum. Emergency laparotomy revealed fecal peritonitis and multiple isolated left descending colon perforations. Histopathology showed a necrotic, perforated descending colon and excluded Hirschsprung disease. After Hirschsprung disease, necrotizing enterocolitis, and intestinal obstruction were considered less likely, idiopathic colonic perforation was considered the most likely explanation. Later, severe sepsis may have aggravated the bowel injury rather than caused the initial perforation. This case emphasizes the importance of repeated clinical assessment and imaging, and early surgical reassessment in deteriorating neonates.

Clostridium perfringens (C. perfringens) bacteremia complicated by massive intravascular hemolysis (MIH) is rare, rapidly progressive, and often fatal even before microbiological confirmation is available. We present the case of an 85-year-old man initially presenting with symptoms suggestive of an acute cardiovascular event. Within hours, however, his condition deteriorated significantly, necessitating intubation and admission to the ICU, while severe hemolysis repeatedly rendered his blood samples unsuitable for analysis. At that time, review of the patient's peripheral blood (PB) film revealed bacillary forms within a neutrophil, providing a significant, early clue to overwhelming toxin-mediated bacterial sepsis, later confirmed to be due to C. perfringens, which, despite broad-spectrum antibiotic treatment and intensive supportive care, led to the patient's death within hours of ICU admission. This report highlights the importance of urgent PB film review in septic patients with otherwise unexplained hemolysis, in order to enable a timely and effective antibiotic regimen, optimized supportive care, and assessment for source control when possible.

A 91-year-old woman with chronic tophaceous gout presented with worsening left foot pain, swelling, and purulent drainage after several months of presumed gout flares treated with prednisone and antibiotics. At presentation, she was septic with leukocytosis, elevated inflammatory markers, and imaging consistent with first metatarsophalangeal (MTP) osteomyelitis. Blood cultures grew methicillin-sensitive Staphylococcus aureus (MSSA). Further imaging demonstrated T12/L1 discitis and lumbar epidural phlegmon/abscess extending from L3/L4 to L5. Echocardiography showed a small filamentous structure on the mitral valve where vegetation could not be excluded. This case showcases diagnostic uncertainty when infection mimics gout and the need for early reassessment when symptoms fail to respond to conventional treatments.

Ignatzschineria spp. bacteria are emerging pathogens whose vectors historically have not been clearly identified. We used molecular methods to establish a relationship between the black blow fly (Phormia regina) and human Ignatzschineria bacteremia in persons experiencing homelessness in Vancouver, British Columbia, Canada, validating a novel transmission pathway in a vulnerable urban population.

BACKGROUNDEnhancing surveillance of bloodstream infections (BSIs) by extracting data from electronic health records (EHR) is often the first step in automating the surveillance of healthcare-associated infections (HAIs).AIMWe assessed existing BSI surveillance systems and the progress in implementing EHR-BSI surveillance within the ECDC project Surveillance from Electronic Health Data (SUREHD).METHODSWe summarised information on BSI surveillance systems through meetings with national representatives and review of national surveillance protocols and reports.RESULTSOf the 30 EU/EEA countries invited to join the SUREHD project, 17 actively participated from March 2023 to March 2025. All 17 countries conducted BSI surveillance within HAI or antimicrobial resistance programmes, and EHR-BSI surveillance was being implemented nationally (n = 9), regionally (n = 2) or at hospital level (n = 6). Reported challenges included data standardisation (n = 13), IT capacity (n = 10), data linkage (n = 7), system integration (n = 7) and data protection (n = 6). Few countries had access to structured EHR data on patient symptoms (n = 1), infection origin (n = 2) and catheter-related variables (n = 5). Most countries had not yet implemented data validation processes (n = 12) nor decided on standardised vocabularies for most variables. All countries aimed to automate EHR-BSI surveillance.CONCLUSIONAutomation of BSI surveillance is critically relevant for the development of surveillance systems and to support infection and control measures (IPC) for HAIs. Implementation of automated EHR-based BSI surveillance varied between countries; a generic protocol and a network of experts have established a way forward. Future efforts should focus on harmonisation, data quality, and leveraging EHR-BSI data to strengthen HAI surveillance and to improve IPC.