Background/Objectives: Methicillin-resistant Staphylococcus aureus (MRSA) remains a major cause of both community-onset and hospital-acquired infections, yet longitudinal data from Latin American hospitals spanning the COVID-19 pandemic are scarce. We characterized temporal trends, seasonality, and the impact of the COVID-19 pandemic on MRSA prevalence and incidence density among clinical S. aureus isolates at a tertiary-care hospital in western Mexico over 9.5 years. Methods: We analyzed 6625 non-duplicate clinical S. aureus isolates (6609 with valid resistance data) from June 2016 to December 2025. Temporal trends were assessed using Mann–Kendall tests, Theil–Sen estimation, and binomial generalized linear models. Seasonality was evaluated through STL decomposition, generalized additive models, and Fourier analysis. An interrupted time series (ITS) model with GLS-AR(1) and Newey–West corrections compared three COVID-19 phases: pre-pandemic (2016–2020), high viral circulation (2020–2022), and post-peak stabilization (2022–2025). Exposure-adjusted incidence densities (per 1000 patient-days) were analyzed in parallel. Results: MRSA prevalence declined from 28.1% pre-pandemic to 14.0% post-peak (Mann–Kendall z = −9.03, p < 0.001; OR = 0.85 per year, 95% CI: 0.829–0.871). MRSA incidence density decreased by 50%, from 1.27 to 0.63 per 1000 patient-days, while aggregate S. aureus incidence density remained stable (z = −0.17, p = 0.868). The ITS joint Wald test confirmed a significant cumulative shift in MRSA trajectory post-pandemic (p = 0.019 counts; p = 0.012 incidence density), with a significant post-peak level drop (p = 0.008). S. aureus exhibited moderate seasonality peaking in May–July (GAM edf = 7.26, p < 0.001), whereas MRSA showed only marginal seasonal variation. Conclusions: MRSA declined markedly across the study period, with the steepest reduction following the Omicron peak. The decline persisted after adjustment for pandemic-related fluctuations in hospital volume, supporting periodic reassessment of empiric anti-MRSA prescribing policies in similar settings.

Background: Pneumocystis jirovecii pneumonia (PJP) in non-HIV immunocompromised adults carries 30%–60% mortality. Adjunctive corticosteroids are standard in HIV-PJP but remain contested in non-HIV PJP. Objectives: To determine whether adjunctive corticosteroids reduce mortality and invasive mechanical ventilation (IMV) in non-HIV PJP, and whether effect estimates differ between randomized and observational study designs. Design: Systematic review and meta-analysis. Data sources and methods: Six databases and two trial registers were searched from inception to February 7, 2026. Randomized and observational studies comparing adjunctive corticosteroids versus no corticosteroids or placebo in non-HIV adults with PJP were eligible. Random-effects meta-analyses (restricted maximum likelihood) of two co-primary outcomes included subgroup, sensitivity, E -value, and Grading of Recommendations Assessment analyses. Results: Twenty-eight studies were included (one randomized controlled trial (RCT), 27 observational; ∼ 5300 patients): 22 contributed corticosteroid-versus-no-corticosteroid comparisons and six contributed dose-comparison data only. Evidence was discordant by design (interaction p = 0 . 006 ): the RCT showed lower IMV (hazard ratio (HR) 0.36, 95% CI 0.14–0.90) and lower 90-day mortality (HR 0.59, 0.37–0.93); regression-adjusted observational studies suggested harm (odds ratio (OR) 1.56, 1.10–2.22); propensity-based estimates were null-compatible. Pre-specified mortality pools were non-significant short-term (OR 1.22, 0.88–1.70) and intermediate-term (OR 1.39, 0.85–2.29). Secondary infections ( k = 4 ): OR 1.04 (0.63–1.72); RCT 0.59 (0.32–1.06). E -values for RCT effects (3.44 IMV; 2.24 mortality) exceeded the 1.81 E -value of the adjusted observational mortality pool. Certainty was very low for pooled mortality and moderate for RCT outcomes. Conclusion: Reliable inference rests on the single RCT rather than the pooled observational estimate, which is discordant by design and most consistent with confounding by indication. In the RCT, corticosteroids did not significantly reduce 28-day mortality but lowered IMV and 90-day mortality and sped respiratory recovery, without clear excess secondary infections (low certainty). Corticosteroids may be considered for severe respiratory failure using the PIC (ClinicalTrials.gov NCT02944045) protocol; adequately powered confirmatory trials are needed. Trial registration : PROSPERO CRD420261304396.

Measles has re-emerged as a public health concern despite effective vaccination. This study describes the clinical and epidemiological characteristics associated with hospital admission among confirmed measles cases attended at a tertiary referral hospital in Jalisco, Mexico, during the 2025-2026 outbreak. We conducted an observational, hospital-based cohort study of confirmed measles cases attended from November 2025 to May 2026. Congenital measles cases and records with missing hospitalization status were excluded. Data were obtained from clinical records and surveillance systems. Univariable logistic regression and two multivariable models were fitted: an epidemiological model excluding respiratory severity markers and a clinical presentation model including oxygen saturation and respiratory rate. Among 609 confirmed cases, 186/609 patients (30.5%) were hospitalized. Most were pediatric patients (460/609 [75.5%]), and 489/609 (80.3%) were eligible but unvaccinated. Among hospitalized patients, pneumonia was the most frequent complication (51/186 [27.4%]), and 107/186 (57.5%) required supplemental oxygen. In the epidemiological model, each additional day from symptom onset to medical care was associated with hospitalization (adjusted odds ratio [aOR] 1.14 per day; 95% confidence interval [CI] 1.04-1.25), lower oxygen saturation (aOR 3.51 per 5-percentage-point decrease; 95% CI 2.53-4.98), and higher respiratory rate (aOR 1.27 per 5 breaths/min increase; 95% CI 1.05-1.54). Hospital admission was common and was mainly characterized by delayed care and objective respiratory compromise.

Background/Objectives: Avoidable mortality—deaths before age 75 from preventable or treatable causes—is a key indicator of health system performance. In Mexico, nearly two-thirds of municipalities lack hospital beds, yet no study has examined the municipal-level association between healthcare infrastructure and avoidable mortality. This study assessed whether healthcare desert status is independently associated with avoidable mortality after adjusting for social deprivation. Methods: This ecological study analyzed 1891 Mexican municipalities (population ≥ 1000) over 2015–2024. Avoidable deaths were classified per OECD/Eurostat criteria (January 2022 revision). Healthcare desert status was defined by municipal hospital bed availability from 2019 facility data. Negative binomial mixed-effects regression estimated incidence-rate ratios (IRRs) adjusted for social deprivation, age structure, and state-level heterogeneity. Interrupted time-series analysis quantified pandemic disruption. Results: Of 4,960,244 deaths under 75 years, 81.2% were avoidable. Of 1891 municipalities, 1187 (62.8%) lacked hospital beds (healthcare deserts). Desert municipalities had 42.5% higher avoidable mortality (IRR = 1.425; 95% CI: 1.370–1.482; pre-pandemic 2015–2019), which attenuated to 1.353 after age-structure adjustment. Each standard-deviation increase in hospital beds (1 SD ≈ 2.2 beds per 1000) was associated with 7.9% lower mortality (IRR = 0.921). Avoidable mortality exhibited strong spatial clustering (Moran’s I = 0.382) in southern Mexico. By 2024, the desert–adequate mortality gap had widened by approximately five fold (from $\sim$12 to 69 per 100,000 population). Conclusions: Healthcare deserts are independently associated with substantially higher avoidable mortality in Mexico. The COVID-19 pandemic durably amplified pre-existing disparities associated with healthcare infrastructure deficits. Targeted hospital expansion in underserved municipalities is urgently needed, alongside investment in social determinants of health.

Background/Objectives: Whether the COVID-19 pandemic uniformly increased antimicrobial resistance (AMR) is contested, and aggregate analyses may mask organism-specific patterns. The objective of the study was to characterize changes in the level and slope of monthly multidrug-resistant (MDR), possible extensively drug-resistant (pXDR), possible pandrug-resistant (pPDR), vancomycin-resistant enterococci (VRE), and methicillin-resistant Staphylococcus aureus (MRSA) positivity at a Mexican tertiary-care hospital, and to assess heterogeneity by organism, antimicrobial class, specimen type, and hospital service. Methods: Retrospective interrupted time-series of deduplicated bacterial isolates (October 2017 to January 2026), analyzed by segmented regression across pre-pandemic, pandemic, and post-peak phases. Results: Cohort-wide MDR positivity had been declining before 2020 and rose abruptly at pandemic onset (level shift +6.81 percentage points, p = 0.0092) with a simultaneous slope reversal, reaching 24.27 percentage points above the extrapolated pre-pandemic trend by February 2022 (95% CI 14.26–34.28, p < 0.0001). The decline resumed after the pandemic peak, but the two slope changes did not offset one another (joint p = 0.0064). pXDR and pPDR moved in the same direction (+8.93, p = 0.0233; +15.40, p = 0.0113). VRE showed no significant departure, whereas MRSA declined in every phase yet departed significantly from its extrapolated trajectory (+23.68, p = 0.0040). Among species, Escherichia coli showed the largest departure from its counterfactual (+48.82 percentage points, p < 0.0001) and Klebsiella pneumoniae had the largest abrupt level rise (+14.46 percentage points, p = 0.0055), while S. aureus declined in every phase despite an abrupt rise in level at pandemic onset. At the class level, carbapenem and third-/fourth-generation cephalosporin non-susceptibility rose at pandemic onset and returned to baseline afterwards (19.1% to 28.0% to 18.7%, and 51.7% to 59.4% to 52.5%; all q < 0.001), whereas fluoroquinolone non-susceptibility rose and did not revert, climbing further in E. coli (61.5% to 65.2% to 72.7%, q = 0.0012) and plateauing at an elevated level in K. pneumoniae (37.6% to 46.5% to 49.3%, q = 0.1919 post-peak). Conclusions: Resistance trajectories across pandemic-related phases were divergent and, for the Gram-negative organisms, incompletely reversed, with the highest burden of advanced resistance in high-intensity settings. Organism-resolved surveillance and sustained stewardship are needed.