Infectious Diseases — New This Week — July 29

A stewardship-heavy two weeks. The anti-anaerobic antibiotics sub-study of the BALANCE trial provides the strongest evidence yet linking unnecessary anaerobic coverage to 41% higher 90-day mortality in BSI patients — duration-dependent, with metagenomics confirming gut anaerobe depletion and Enterococcus faecium enrichment. A companion Anaerobic Activity Index quantifies what “anti-anaerobic” actually means on a 0–100 scale (meropenem 59, pip-tazo 52, ceftriaxone 36, cefepime 24), operationalizing the 2026 SSC recommendation to avoid empiric anaerobic coverage. On the OFID side, the CDC’s 2023 antimicrobial use prevalence survey shows 1 in 2 US inpatients still receives antimicrobials despite near-universal ASPs — the class shift from fluoroquinolones (9.2% → 2.8%) to 3rd/4th-gen cephalosporins (12.3% → 18.6%) is striking. And from the INFECT cohort, gas on imaging does NOT distinguish clostridial from polymicrobial NSTI — correcting a persistent clinical heuristic.

Clinical Infectious Diseases

Major studies & stewardship

CIDStewardship · BALANCE sub-studyHigh yield · ID

Anti-Anaerobic Antibiotics, Mortality, and the Gut Microbiome: A Sub-Study of the BALANCE Trial

In BSI patients without an anaerobic indication, are anti-anaerobic antibiotics associated with higher mortality?

Population2851 BSI patients from the BALANCE RCT without an indication for anaerobic coverage. ExposureAnti-anaerobic antibiotics (74% received them — mainly piperacillin-tazobactam 64%, meropenem 30%). OutcomeIPTW-adjusted 90-day mortality: OR 1.41 (95% CI 1.03–1.92). Duration-dependent: ≥4 days OR 1.82 (1.13–2.94). Strongest in less severely ill (SOFA <4: OR 1.89). Metagenomic sequencing confirmed gut anaerobe depletion and E. faecium enrichment. What this changesSupports the 2026 SSC guideline recommendation to avoid empiric anaerobic coverage when no anaerobic risk factors are present. The strongest evidence yet for this principle.

Clinical takeaway. Three of every four BSI patients without an anaerobic indication still received anti-anaerobic antibiotics. That unnecessary exposure was associated with 41% higher mortality — and the signal was strongest in patients with intact immune defenses (SOFA <4), exactly where you would expect microbiome disruption to matter most. The editorial (ciag461) notes an important nuance: ceftriaxone itself depletes obligate anaerobes, so the real spectrum is “more vs less” anaerobic coverage, not binary presence/absence. Default to cefepime or ceftriaxone over pip-tazo/meropenem when no anaerobic source is identified.

Anki: carded — CID::Major_Study + Subject::Infectious_Disease

CIDStewardship · Tool developmentHigh yield · ID

Development and Application of an Anaerobic Activity Index

Can anaerobic antibiotic exposure be scored on a continuous scale rather than a binary label — and does the score predict clinical outcomes?

What it isA 0–100 Anaerobic Activity Index (AAI) for 21 antibiotics, based on in vitro susceptibility against 7 anaerobic bacterial groups from a systematic review of 88 papers. Key scoresMeropenem 59, ertapenem 58, tigecycline 57, linezolid 53, pip-tazo 52, metronidazole 49, ceftriaxone 36, cefepime 24, aztreonam 4. ValidationApplied to a burn ICU cohort (n = 509): highest 7-day AAI quartile had aOR 2.90 (1.65–5.08) for the 90-day composite (death, HAI, pathogen isolation). The binary anti-anaerobic classification was NOT associated with the primary outcome. What this changesMoves beyond the simplistic “anti-anaerobic yes/no” dichotomy. Operationalizes the 2026 SSC recommendation with a quantitative metric. Immediately useful as a reference table.

Clinical takeaway. The AAI table itself is the clinical deliverable — print it and tape it inside the stewardship binder. The validation is single-center (burn ICU), but the scoring tool is generalizable. Two surprises: linezolid scored 53 (5th highest), challenging the assumption that it is purely aerobic; and metronidazole scored only 49 despite being the prototypical “anaerobic” drug, because it has no activity against several microaerophilic and aerotolerant anaerobes. The editorial (ciag471) worries that too many parallel scores (AAI, mASI, DASC, DOT) may fragment stewardship metrics and advocates for a unified consensus score.

Anki: carded — CID::Major_Study + Subject::Infectious_Disease

Notable

CIDVaccines · Target trial emulationNotable · ID

Nirsevimab and Antibiotic Use in Children: Target Trial Emulation

Does nirsevimab reduce antibiotic prescribing as an indirect stewardship benefit?

Key findingAmong 15,341 infants across 32 CHOP practices, nirsevimab reduced antibiotic prescribing by 14.4% for outpatient ARTIs, 40.3% for bronchiolitis, and 69.4% for RSV-related hospitalizations. Fellow implicationDemonstrates a meaningful stewardship co-benefit of RSV prophylaxis that strengthens the case for universal infant immunization. Target trial emulation is a rigorous causal inference design. Useful advocacy data for stewardship programs, though the finding is observational and does not change prescribing directly.

CIDDFO · ViewpointNotable · ID

The Clean Margin in Diabetic Foot Osteomyelitis: Conceptual Appeal, Practical Uncertainty

Is the 2023 IDSA/IWGDF recommendation to tailor antibiotic duration by resection margin status ready for routine use?

Key argumentThe concept is ill-defined: surgical impression, histopathology, and microbiology of margins represent fundamentally different perspectives that are often discordant, yet the guidelines treat them as interchangeable. The recommendation rests heavily on a single pilot trial (n = 93). Preliminary Yale data (131 surgeries) showed 88% concordance, but standardized definitions are needed. Fellow implicationDirectly relevant to daily ID consult work on DFO. Argues for caution when applying the guideline recommendation — ask the surgeon which definition of “clean margin” they used, and recognize the evidence is thinner than it appears.

CIDVaccines · Bayesian re-analysisNotable · ID

Bayesian Re-Analysis of the GALFLU Trial: High-Dose vs Standard-Dose Influenza Vaccine

Does a Bayesian lens clarify the equivocal GALFLU frequentist result for HD-IIV in adults ≥65?

Key finding133,882 adults aged 65–79. Across non-informative, evidence-based, and sceptical priors, HD-IIV showed >80% probability of >10% rVE against influenza-or-pneumonia hospitalization (posterior median rVE 17–24%). Even with the sceptical prior, probability of any benefit was >83% for all outcomes. All-cause mortality showed 8.6–12.8% rVE. Fellow implicationStrengthens the already-compelling case for high-dose influenza vaccine in older adults. The Bayesian framework adds interpretive clarity to the equivocal frequentist result but this is incremental evidence. Sanofi-funded.

CIDResistance · Global surveillanceNotable · ID

Molecular Epidemiology of ExPEC BSI Worldwide (2011–2023)

What is the global molecular landscape of E. coli bloodstream infections?

Key finding10,098 isolates from 26 countries. O25 was the dominant serotype overall (18.7%) and among MDR isolates (36.6%). MDR rates varied enormously: India 83%, Mexico 77%, China 69% vs Sweden 11%, NZ 12%. Carbapenem resistance remained low (1.1%). O25-ST131 confirmed as the global dominant MDR clone. Fellow implicationLargest global ExPEC BSI molecular epidemiology study to date. Useful reference for geographic resistance patterns and the ExPEC vaccine pipeline context (J&J-funded). Does not immediately change clinical management.

Also new in CID. Vaccine misinformation — an international expert panel critically appraises the Lamerato et al non-peer-reviewed analysis claiming vaccinated children have 2.5× higher chronic illness rates. Five fatal flaws identified: uncontrolled confounding, surveillance bias, exposure misclassification, unequal follow-up (970 vs 461 days), and outcome multiplicity. The entire signal is explained by diagnostic-opportunity bias (~7 vs ~2 visits/year). Excellent teaching resource for patient conversations (ciag403). HIV/multimorbidity — in the AFRICOS cohort (3028 PWH, sub-Saharan Africa), continued multimorbidity was associated with higher hospitalization risk (aHR 1.27); malaria accounted for 87% of systemic infection admissions. Expected direction of effect in a limited-generalizability setting (ciag353).

Open Forum Infectious Diseases

Major studies & stewardship

OFIDStewardship · CDC prevalence surveyHigh yield · ID

Antimicrobial Use in U.S. Hospitals: Comparison of 2015 and 2023 Prevalence Surveys

After a decade of antimicrobial stewardship expansion, has overall antimicrobial use in US hospitals changed?

Key findingCDC EIP survey of 13,653 patients in 218 US hospitals. Overall AU prevalence 49.7% in 2023, unchanged from 49.1% in 2015. ASP presence increased 79.4% → 98.6%. Fluoroquinolone use plummeted: 9.2% → 2.8% (P < .001). 3rd/4th-gen cephalosporin use increased 12.3% → 18.6% (P < .001). Surgical prophylaxis exceeded 24 hours in 24.9% of cases despite guidelines. Fellow implicationThe definitive baseline for US hospital antimicrobial use. Despite near-universal ASPs, 1 in 2 inpatients still receives an antimicrobial. The fluoroquinolone-to-cephalosporin class shift is a measurable stewardship success, but the persistent surgical prophylaxis duration problem remains a concrete target.

Clinical takeaway. This is the number to cite in any stewardship presentation: 49.7%. Despite ASPs being nearly universal, overall use has not budged. What HAS changed is the class mix — the FQ decline from 9.2% to 2.8% is a genuine success story (likely driven by FDA black box warnings + C. difficile awareness). The compensatory rise in 3rd/4th-gen cephalosporins and the stubborn 25% rate of prolonged surgical prophylaxis tell us where to focus next.

OFIDBacterial · Prospective cohortHigh yield · ID

Clinical Features of Clostridial Necrotizing Soft-Tissue Infections: The INFECT Cohort

Does gas on imaging distinguish clostridial from polymicrobial necrotizing soft-tissue infection?

Key finding10 clostridial NSTIs among 409 NSTI cases (Scandinavia). Gas on radiology did NOT distinguish clostridial from polymicrobial NSTI (57% vs 60%). Clostridial phenotype: extremity involvement (P < .001), immunodeficiency (40%, P = .019), penetrating trauma (30%, P = .010), severe pain (78%, P = .044). C. perfringens and C. septicum were equally represented. MortalityOverall 30-day mortality 20%. Mixed clostridial/polymicrobial NSTIs had the highest mortality: 4/7 (57%). Monomicrobial clostridial NSTI mortality was 0/3 in this cohort. What this changesCorrects a persistent clinical heuristic: gas ≠ Clostridial. The clinical triad (extremity + immunodeficiency + severe pain) is a better discriminator than imaging gas.

Clinical takeaway. The reflexive “gas = gas gangrene = Clostridium” mental model is wrong: polymicrobial NSTIs produce gas just as often. The better clinical signal for clostridial etiology is the combination of extremity location, immunodeficiency, and disproportionate pain. The most dangerous subgroup is mixed clostridial/polymicrobial (57% mortality), which argues for broad empiric coverage (not just high-dose penicillin + clindamycin) until cultures return.

Anki: carded — OFID::Major_Study + Subject::Infectious_Disease

OFIDBacterial · FoodNet surveillanceHigh yield · ID

Invasive Listeriosis in the United States: FoodNet Surveillance, 2008–2023

Has the incidence of sporadic invasive listeriosis changed over 16 years, and which populations bear the highest burden?

Key finding1938 sporadic cases (2008–2023) across 10 FoodNet sites. Incidence stable at 0.25/100,000 PY (2020–2023) despite aging population — implying ~16% decrease in exposure since 2008. Pregnant women had 64-fold higher risk. Hispanic, non-Hispanic Asian, and non-Hispanic Black populations had higher incidence. Demographic projections predict increasing absolute incidence through 2040. Fellow implicationThe definitive US national Listeria surveillance dataset. Key counseling numbers: 64-fold pregnancy risk, stable incidence despite food-safety improvements offset by an aging population. Racial/ethnic disparities are actionable for targeted counseling in ID and OB-ID consult work.

Clinical takeaway. Despite 16 years of food-safety interventions, invasive listeriosis incidence has not declined — food-safety gains are cancelled out by population aging and immunosuppression. The 64-fold risk in pregnancy and the racial/ethnic disparities are the high-yield counseling points. This study also reminds us that projections through 2040 predict rising absolute numbers, making Listeria food-safety counseling increasingly important for immunocompromised patients.

Notable

OFIDBacterial · Retrospective cohortNotable · ID

AKI Risk in Salmonella vs Campylobacter Enteritis

Is Salmonella enteritis more nephrotoxic than Campylobacter?

Key finding232 hospitalized patients. AKI: Salmonella 70.9% vs Campylobacter 26.6% (adjusted OR 3.19, 95% CI 1.23–8.30). 42% of Salmonella patients developed AKI stages 2–3. 17% who recovered from AKI before discharge later developed AKD/CKD. Fellow implicationClinically relevant for managing hospitalized gastroenteritis: monitor renal function closely in Salmonella enteritis, and consider outpatient renal follow-up. Small single-center study (evidence-strength caveat).

OFIDVaccines/STI · VE studyNotable · ID

4CMenB Vaccine Effectiveness Against Meningococcal Carriage and Gonorrhea in Northern Territory Australia

Does the meningococcal B vaccine provide cross-protection against gonorrhea in a real-world setting?

Key finding30,650 NT Australia adolescents. VE against gonorrhea 38.4% (95% CI 18.6–53.4%) with 2 doses, higher in females (45.9%). First VE study in Aboriginal/Torres Strait Islander population. Meningococcal carriage increased from 4.0% to 6.2% despite vaccination. Fellow implicationAdds real-world VE data to the growing evidence for 4CMenB cross-protection against gonorrhea. Important for vaccine policy but not directly practice-changing yet. The paradoxical carriage increase warrants monitoring.

OFIDBacterial · Cross-sectionalNotable · ID

Streptococcus pneumoniae Carriage in Older Adults in Denmark, 2019–2022

How common is pneumococcal carriage in older adults, and do IPD serotypes match carriage serotypes?

Key finding1764 adults ≥65. Carriage prevalence 9.8% (mostly detected by molecular methods, not culture). Non-PCV13 types dominated both carriage and IPD. Young grandchildren increased carriage odds (aOR 1.8). Serotypes 3 and 8 (28% of IPD) were absent from carriage, suggesting high invasive potential. PPV23 did not affect carriage. Fellow implicationSupports the case for higher-valency conjugate vaccines in older adults. The serotype 3 and 8 carriage–IPD discordance is a useful teaching point about invasive vs commensal potential. Grandchild contact = modifiable risk factor for counseling.

Also new in OFID. HIV care continuum — a Missouri multistate Markov model found 29.3% of newly linked PWH disengaged within 1 year; younger age and Black race were risk factors; viral suppression was 93% in retained vs 81.6% in reengaged patients (ofag414). Ending the HIV epidemic — CEPAC microsimulation projects that current trajectory reduces MSM transmissions only 32% by 2035; the 90% EHE target requires combined high-level testing/linkage/engagement/PrEP; engagement in care is the single most influential lever (ofag386). HCV in immigrants — CANUHC cohort from 17 Canadian sites showed immigrants achieved 100% SVR vs 98.6% Canadian-born, but mean delay from immigration to assessment was 24.9 years (ofag461). SARS-CoV-2 nAb waning — 25 HCWs post-XBB.1.5 vaccination showed 36–62% nAb decline by 6 months; titers against JN.1 sublineage variants fell to very low levels; immune imprinting noted (ofag446). Mycology education — training 149 Nigerian clinicians on serious fungal diseases tripled mycology sample submissions and first identified CrAg-positive and galactomannan-positive patients at centers with no prior fungal serology (ofag442). ED infection classification — modified CDC/NHSN criteria for ED use showed very good interobserver agreement (kappa 0.87 infection diagnosis, 0.89 pathogens, 0.80 sepsis) in 1062 patients (ofag466). Measles in Uganda — 57.9% of suspected cases in children <18 months were confirmed; 41% occurred before the MCV1-eligible age, supporting earlier vaccination in high-burden settings (ofag459). SARS-CoV-2 data harmonization — CRWDi infrastructure harmonized test data from 4 labs across 5.2 million patients, cataloging 27 NAAT names and 59 result code variants (ofag454). Giardia & WASH — secondary analysis of the WASH Benefits Bangladesh trial showed WSH interventions reduced Giardia infection by ~20% consistently across both dry and monsoon seasons in 2273 children (ofag430). RSV vaccine — the live intranasal D46/cp/ΔM2-2 candidate was overattenuated in RSV-seronegative children (only 50% seroconverted); LID/ΔM2-2/1030s identified as the lead candidate going forward (ofag388).

Anki cards generated this run — high-yield filter applied. 3 cards minted (hard ceiling 25; four-gate bar governs). 23 articles summarized for awareness only. All cards tagged with journal prefix + Subject::Infectious_Disease. See 2026-08-07_ID-anki-cards.tsv.

Original paraphrase — all figures from the archived full text. No publisher content redistributed. Each article linked via DOI to the publisher page.

Generated by the CID/OFID biweekly digest routine · August 7, 2026