Search Results (3,204)

Angiostrongyliasis, the primary cause of eosinophilic meningitis, represents an emerging disease caused by Angiostrongylus cantonensis larvae, inadvertently transmitted to humans. The diagnosis of human angiostrongyliasis relies on epidemiological features, clinical symptoms, medical history, and laboratory findings, notably hyper eosinophilia in blood and cerebrospinal fluid. Consequently, accurate diagnosis is challenging and prone to confusion with other parasitic diseases. The quest for an early, rapid, and specific diagnostic test for angiostrongyliasis persists, driven by the imperative for enhanced test specificity. This study focused on mapping IgM epitopes on galectin-1 (Gal-1) and galectin-2 (Gal-2) proteins derived from A. cantonensis. The specificity of the epitopes was assessed using database homology analysis. After selecting specific epitopes, researchers chemically synthesized 12 individual multi-antigen peptides (MAPs4) and one chimeric polypeptide that is 65 amino acids long. The effectiveness of these synthesized peptides was subsequently evaluated using enzyme-linked immunoassay (ELISA). A total of twelve unique IgM epitopes were discovered; five were linked to Gal-1, while seven were linked to Gal-2. An ELISA-peptide method confirmed the twelve epitopes, and then the chimeric polypeptide was employed as an antigen to coat ELISA plates. This setup was evaluated with patients’ sera to diagnose strongyloidiasis in vitro. This study provides a comprehensive representation of the IgM epitopes of Gal-1 and Gal-2 from A. cantonensis. ELISA data utilizing the chimeric polypeptide demonstrate that the selected sequences hold promise for the development of a specific immunological assay tailored for the acute diagnosis of angiostrongyliasis infections. Full article

Fruit tree leaves are an abundant agro-waste material with promising yet underexplored biological potential. This study compared the biological activity of aqueous extracts obtained from apple (Malus domestica), apricot (Prunus armeniaca), and cherry (Prunus cerasus) leaves and their kombucha-fermented counterparts in the context of cosmetic and dermatological applications. Phytochemical composition before and after fermentation was analyzed chromatographically. Antioxidant activity was evaluated using DPPH, ABTS, and FRAP assays, while intracellular reactive oxygen species (ROS) levels in keratinocytes and fibroblasts were assessed using the H₂DCFDA probe. Cytotoxicity was determined by Alamar Blue and Neutral Red assays. Antimicrobial activity against seven bacterial strains was investigated using minimum inhibitory concentration and disc diffusion methods. Anti-inflammatory activity was evaluated in LPS-stimulated THP-1 cells by measuring TNF-α, IL-1β, and IL-6 levels using ELISA. The influence of the samples on collagenase, elastase, and hyaluronidase activity was also analyzed. Fermentation increased the content of selected phenolic compounds and enhanced antioxidant, antimicrobial, anti-inflammatory, and anti-ageing properties. Ferments more effectively reduced oxidative stress in skin cells and showed no cytotoxicity within the tested concentration range. These findings indicate that kombucha fermentation may support the valorization of fruit tree leaf agro-waste as multifunctional ingredients for skincare formulations. Full article

Background/Objectives: Tumors of the salivary glands represent a rare and heterogeneous group of tumors, the diagnosis and treatment of which present significant clinical challenges. One of the key processes affecting the progression of these tumors is angiogenesis, in which vascular endothelial growth factor (VEGF) and its receptors play a fundamental role. The aim of the present study was to assess differences in VEGF levels in salivary gland tumor tissue compared with normal salivary gland tissue. Methods: Salivary gland tissue samples were obtained by surgical resection. Thirteen patients were included in the study, nine with malignant lesions and four patients with normal salivary gland tissue as controls. After tissue homogenization, VEGF concentration was analyzed by a chemiluminescent ELISA (Human VEGF QuantiGlo ELISA Kit, QVE00B; R&D Systems, Minneapolis, MN, USA). Results: VEGF concentrations in salivary gland tumor tissue homogenate supernatants showed a higher central tendency than controls, but the between-group difference did not reach statistical significance (Mann–Whitney U test, p = 0.199; Welch’s t-test as sensitivity analysis, p = 0.102). Conclusions: VEGF quantification in salivary gland tissue homogenate supernatants was feasible and showed substantial inter-individual variability with partial overlap between tumors and controls. Although tumors showed higher central tendency, the differences were not statistically significant in this small cohort; therefore, the findings are hypothesis-generating and do not support diagnostic or prognostic claims. Full article

Breast cancer (BC) is associated with metabolic factors that may influence circulating lipids and apolipoproteins. We performed a cross-sectional observational study including 198 women with infiltrating ductal breast carcinoma and 78 cancer-free controls. In the analyzed data, the breast cancer cohort included 39 premenopausal and 44 postmenopausal women without neoadjuvant chemotherapy (NACT), and 35 premenopausal and 54 postmenopausal women exposed to NACT; controls included 63 premenopausal and 52 postmenopausal women. Serum ApoA1 and ApoB were measured by ELISA, and HDL and LDL cholesterol were measured by enzymatic methods. Analyses included two-way ANOVA, Tukey post hoc testing, false-discovery-rate correction, and multivariable linear models adjusted for age and BMI, with HC3 robust sensitivity analyses. In cancer patients, HDL was lower in women exposed to NACT (adjusted β= −8.16, 95% CI −12.61 to −3.71), and ApoA1 differed by menopausal status. Subtype-aware analyses in the available subset did not show independent molecular subtype effects after multiplicity correction. These findings support cross-sectional associations between menopausal status, treatment exposure, and lipid/apolipoprotein profiles, but do not establish causality or prognostic value. Prospective longitudinal studies are required. Full article

Background/Objectives: Adipokines are candidate biomarkers in critical illness due to their roles in immunity and metabolism, both profoundly altered in sepsis. Omentin-1, vaspin, and chemerin have been studied in selected septic cohorts, but not concurrently in a heterogeneous ICU population including both septic and non-septic patients. Methods: Prospective observational cohort of 200 consecutive ICU patients with 28-day follow-up. Biomarkers were measured by ELISA within 24 h of admission. Analyses included Mann–Whitney U tests, Spearman correlations, ROC curves, and logistic regression with APACHE II and SOFA as comparators. Results: Vaspin was significantly higher in septic versus non-septic patients (406.4 [190.0–799.6] vs. 275.8 [101.8–559.8] pg/mL; p = 0.009). Omentin-1 was elevated in 28-day non-survivors (34.4 [22.5–56.1] vs. 25.1 [15.0–48.4] ng/mL; p = 0.037; AUROC 0.599), but lost significance after APACHE II adjustment (p = 0.295). Chemerin trended lower in non-survivors (p = 0.099); in septic patients, it correlated inversely with SOFA (r = −0.43) and lactate (r = −0.40), both p < 0.001. IL-6 and IL-10 were higher in non-survivors; IL-10 predicted 28-day mortality (AUROC 0.783), comparable to APACHE II (0.785). Conclusions: Vaspin distinguishes sepsis in mixed ICU populations. Omentin-1 shows a severity-driven association with mortality that does not survive APACHE II adjustment (AUROC 0.599, poor standalone discrimination), while chemerin inversely tracks hypoperfusion markers in septic patients, suggesting a potential counter-regulatory role requiring mechanistic confirmation. Individually, these adipokines do not add prognostic value beyond established severity scores, but their biological orthogonality to classical cytokines warrants exploration in multi-marker panel studies. Full article

Background/Objectives: Arboviruses including dengue virus (DENV), Zika virus (ZIKV), chikungunya virus (CHIKV), yellow fever virus (YFV), and West Nile virus (WNV) co-circulate across the Americas, generating overlapping febrile syndromes that challenge etiological diagnosis based solely on clinical criteria. Cartridge-based multiplex molecular platforms offer potential for decentralized testing in hyperendemic settings, yet independent real-world evaluations of their clinical and analytical performance remain limited. Methods: A retrospective two-phase analytical study was conducted. Phase 1 assessed clinical diagnostic accuracy for dengue using 163 de-identified serum samples classified using a composite reference standard consisting of Panbio NS1 ELISA reactivity (≥11 Panbio units) combined with compatible clinical and epidemiological data, operationalized in accordance with the PAHO 2023 laboratory confirmation algorithm for dengue; RT-qPCR was not routinely available for all archived samples, and reported sensitivity should therefore be interpreted as a conservative lower-bound estimate; Phase 2 evaluated analytical sensitivity across all eight panel targets using characterized arboviral reference strains in serial dilution experiments, with reference RT-qPCR assays as the comparator; this phase was incorporated to characterize detection thresholds for targets not represented by clinical specimens. Results: In Phase 1, the M10 demonstrated sensitivity of 96.0% (96/100), specificity of 100% (63/63), overall accuracy of 97.5%, and near-perfect agreement with the reference standard (Cohen’s κ = 0.95). DENV-3 was the predominant serotype (74/96; 77.1%), followed by DENV-1 (16.7%) and DENV-4 (6.3%); DENV-2 was not detected. In Phase 2, operational LoDs (defined as the lowest concentration yielding a detectable Ct in all triplicate reactions for the RT-qPCR, and from a single cartridge per dilution point for the STANDARD M10) were equivalent or superior to reference RT-qPCR for six targets (DENV-1, DENV-3, DENV-4, ZIKV, WNV, YFV; range 1–5 PFU/mL), while DENV-2 and CHIKV showed 20-fold higher operational LoDs (20 PFU/mL vs. 1 PFU/mL for the reference RT-qPCR); formal LoD₉₅ estimates were not determined. Conclusions: The STANDARD M10 Arbovirus Panel shows high clinical accuracy for dengue and adequate analytical sensitivity for most targets, supporting its use as a complementary decentralized molecular tool. Reduced sensitivity for DENV-2 and CHIKV and the absence of formal LoD₉₅ estimates remain key limitations to be addressed in future validation studies. Full article

Background: Chronic hepatitis B virus (HBV) infection remains a major global health challenge and a leading cause of liver cirrhosis and hepatocellular carcinoma. Interleukin-6 (IL-6), a key pro-inflammatory cytokine, plays an important role in immune regulation and hepatic inflammation. However, its relationship with HBV viral load and disease severity remains incompletely understood. Methods: A hospital-based cross-sectional study was conducted among 293 HBsAg-positive patients. Serum IL-6 levels were measured using ELISA, and HBV DNA was quantified using real-time quantitative PCR. Patients were stratified according to viral load. Statistical analyses included non-parametric tests, Spearman correlation, principal component analysis (PCA), and multiple linear regression. Results: The median age was 45 years (IQR: 34–57), among which 54.6% were male. The median HBV DNA was 3.37 log₁₀ IU/mL (IQR: 2.45–3.75), and IL-6 concentration was 2.38 log₁₀ pg/mL (IQR: 2.21–2.49). IL-6 levels increased significantly across viral load categories (p < 0.001) and were higher in HBeAg-positive patients (p = 0.002), with no significant differences across age, sex, or cirrhosis. IL-6 levels correlated with HBV DNA (r = 0.40, p < 0.001). PCA identified distinct viral-inflammatory and biochemical axes. Regression analysis confirmed HBV DNA as the significant independent predictor (β = 0.461, p < 0.001; adjusted R² = 0.206). Conclusion: IL-6 was closely associated with HBV DNA levels, while the association with conventional biochemical markers of hepatocellular injury was significantly less in this cohort, suggesting that IL-6 may serve as an adjunct biomarker of disease activity in patients with chronic hepatitis B. Full article

Congenital heart defects represent prevalent malformations requiring complex surgical interventions. Outcomes are influenced by clinical severity, inflammatory response, and complexity of care, highlighting the need for improved risk stratification tools. Objectives: To describe the behavior and distribution of perioperative sTREM-1 concentrations in a pediatric cohort undergoing cardiac surgery, exploratorily stratified by RACHS-1 and TISS-28 severity scores. Methods: A translational cross-sectional study was conducted with 32 children (aged 0–14 years) undergoing surgical correction for congenital heart disease at a Brazilian public referral hospital (2021–2022). Exclusion criteria included genetic syndromes, active infections, or previous cardiac surgeries. Clinical severity was assessed using RACHS-1 (mortality risk) and TISS-28 (care complexity) scores. Serum sTREM-1 levels were measured via ELISA preoperatively and postoperatively. Statistical analysis involved the Shapiro–Wilk normality test, descriptive statistics expressed as medians and interquartile ranges, and Spearman’s rank correlation coefficient to evaluate the relationship between sTREM-1 levels and severity scores, with significance set at p < 0.05. Results: The cohort consisted predominantly of males (56.25%), term infants (93.75%), with 50% presenting cyanosis. RACHS-1 category 3 was most common (34.37%), while TISS-28 category 2 predominated (40.62%). Most patients were discharged (93.75%). Preoperative sTREM-1 levels showed no significant correlation with RACHS-1 (r_s = 0.265; p = 0.143) or TISS-28 scores (r_s = 0.227; p = 0.212). Conversely, postoperative sTREM-1 concentrations significantly and positively correlated with both RACHS-1 (r_s = 0.356; p = 0.045) and TISS-28 categories (r_s = 0.394; p = 0.026), reflecting higher biomarker levels in more severe clinical scenarios. Conclusions: Postoperative sTREM-1 levels correlated significantly with surgical risk and clinical severity, showing higher median concentrations in more severe RACHS-1 and TISS-28 categories. Conversely, no preoperative correlation was observed, suggesting sTREM-1 primarily reflects postoperative inflammatory responses and surgical complexity. Full article

Background/Objectives: Intraspecific aggression and cannibalism severely reduce survival in aquaculture of the Japanese swimming crab, Portunus trituberculatus. Starvation can induce stress-related behavioral changes and alter aggressive behavior in animals, but its behavioral and neurochemical effects in crustaceans remain poorly understood. This study aimed to characterize starvation-associated behavioral changes in P. trituberculatus and to examine their associations with hemolymph serotonin (5-HT) levels, 5-HT1, 5-HT2, and DA1 expression, and aggressive behavior. Methods: Male P. trituberculatus (16 ± 1 g) were randomly assigned to starvation durations of 0–12 days. Starvation-associated behavioral responses were assessed with an underwater light–dark maze and open-field test, and video-recorded behavioral trajectories were analyzed. Hemolymph 5-HT was measured by ELISA. Aggressive behavior was recorded after pairing crabs showing different starvation-associated behavioral states. Expression of 5-HT1, 5-HT2, and DA1 genes in multiple tissues was detected by RT-qPCR. Results: Starvation for 3–6 days significantly reduced time spent in the light arm and center zone, together with decreased hemolymph 5-HT levels. At 7–8 days, time spent in these zones increased and 5-HT levels increased, whereas these behavioral indices decreased again after 9 days. Starvation-associated behavioral changes were associated with reduced attack frequency and attack duration. Moreover, crabs showing starvation-associated behavioral changes showed altered expression of 5-HT1, 5-HT2, and DA1 genes in muscle and eyestalk after aggressive encounters. Full article

Background: Brain-derived neurotrophic factor (BDNF) is crucial in the nociception and mechanisms underlying chronic and neuropathic pain. The evaluation of circulating BDNF in patients with multimodal analgesia has not been reported previously. We hypothesized that opioid-based multi-analgesia induces changes in BDNF values and that BDNF correlates with pain intensity in neuropathic pain. Methods: Adult patients who met low back pain (LBP) criteria and received multimodal opioid-based therapy were included. The control group included patients with LBP who did not receive any pharmacotherapy. Plasma measurements obtained with the ELISA test were analyzed. The study was registered at Clinical Trials.gov (NCT 04227223). Results: Patients with multimodal opioid-based analgesia had significantly higher BDNF values compared to the monotherapy: 3.6 ng/mL vs. 2.7 ng/mL, p = 0.01. No statistical differences were observed compared to the non-pharmacologically treated group: 3.6 ng/mL vs. 5.0 ng/mL, p = 0.75. The median BDNF values were lowest in the mild-pain group, and significant differences were observed between the severe and moderate-pain groups (p = 0.006) and the mild-pain group (p = 0.0001). BDNF was significantly higher in the neuropathic-pain group compared to the group of patients without neuropathic pain (p = 0.0005). A significant correlation was demonstrated between the BDNF and numerical rating pain score (NRS) in the neuropathic-pain component (rho = 0.6, p = 0.001). Conclusions: Multimodal opioid-based analgesia decreases plasma BDNF concentrations less than opioid monotherapy, which offers an opportunity to limit opioid-induced adverse effects. BDNF influences pain intensity and predicts neuropathic pain in multimodal opioid-based analgesia. Full article

Post-exercise release of cardiac biomarkers reflects physiological adaptations of the myocardium to exercise; however, data on their kinetics after exhaustive exercise under hypoxia remain scarce. We determined the kinetics of cardiac biomarker changes following a single bout of exercise to volitional exhaustion under normoxia and moderate normobaric hypoxia (2000 m and 3000 m a.s.l.) in trained (n = 12; VO_2max 64.2 ± 2.9 mL·kg⁻¹·min⁻¹) and untrained (n = 12; VO_2max 44.1 ± 7.4 mL·kg⁻¹·min⁻¹) men. Participants performed a graded exercise test (GXT) followed by a constant-workload exercise test (CXT) at the lactate threshold under three conditions (FiO₂ = 20.9%, 16.5%, 14.4%). Venous blood was sampled at rest, immediately post-exercise, and at 2, 6, and 24 h of recovery for determination of cardiac troponin T (cTnT) and I (cTnI), myoglobin (Mb), creatine kinase MB isoform (CK-MB), heart-type fatty acid-binding protein (H-FABP), ischemia-modified albumin (IMA), and N-terminal pro-B-type natriuretic peptide (NT-proBNP) by ELISA. Exhaustive exercise induced significant elevations in all biomarkers, peaking at 2–6 h post-exercise and largely returning to resting values by 24 h. Moderate normobaric hypoxia did not augment the cardiac biomarker response; rather, it attenuated the increases in Mb, NT-proBNP, and IMA, likely due to earlier peripheral fatigue and lower absolute mechanical work. The inhibitory effect of hypoxia on cTnI release was observed exclusively in trained men, suggesting an interaction between training-related cardiac adaptations and the hypoxic stimulus. These findings support the safety of high-intensity exercise at simulated altitudes of 2000–3000 m a.s.l. Full article

Background: Parvovirus B19 (B19V) has a well-established tropism for erythroid progenitor cells and is a recognized cause of anemia in immunocompromised individuals. Patients with end-stage renal disease (ESRD) receiving maintenance hemodialysis are predisposed to anemia due to multiple mechanisms and are frequently exposed to healthcare settings, raising concern that prior B19V infection may contribute to anemia severity or resistance to erythropoiesis-stimulating agents (ESAs). However, data regarding the clinical relevance of B19V seroprevalence in hemodialysis patients remain limited. Methods: We conducted a single-center, observational cross-sectional study including 131 adult patients on maintenance hemodialysis and 50 healthy controls. Parvovirus B19 IgG serostatus was assessed by enzyme-linked immunosorbent assay (ELISA) and used exclusively as a marker of prior (past) exposure rather than active infection; our aim was to determine whether IgG-defined prior exposure leaves a measurable long-term imprint on erythropoiesis. None of the participants had clinical features suggestive of acute parvovirus infection or an unexplained aplastic episode at enrollment. Demographic data, comorbidities, dialysis characteristics, ESA use, and laboratory parameters (hemoglobin, hematocrit, mean corpuscular volume, inflammatory markers, and albumin) were collected. Between-group and within-cohort comparisons used non-parametric tests, and multivariable logistic and linear regression models were used to adjust for age, sex, and other relevant covariates. Results: Parvovirus B19 IgG seropositivity was common in both groups (64.9% of hemodialysis patients vs. 48% of controls; crude odds ratio [OR] 2.00, 95% confidence interval [CI] 1.03–3.88, p = 0.043). However, hemodialysis patients were substantially older and more often male; after adjustment for age and sex, dialysis status was no longer independently associated with seropositivity (adjusted OR 1.4, 95% CI 0.8–2.3, p = 0.20), and within the hemodialysis cohort seropositivity was not associated with age or sex. Hemodialysis patients exhibited significantly lower hemoglobin and hematocrit and higher inflammatory markers than controls, consistent with ESRD-related anemia. Within the hemodialysis cohort, B19 IgG-positive and IgG-negative patients did not differ in hemoglobin, hematocrit, mean corpuscular volume, C-reactive protein, albumin, or ESA use, and IgG serostatus remained unrelated to hemoglobin in a multivariable model adjusting for age, sex, inflammation, nutrition, dialysis vintage, and ESA use (adjusted β = −0.20 g/dL, 95% CI −0.68 to 0.28, p = 0.42). Past Parvovirus B19 exposure was therefore not associated with anemia severity or treatment requirements. Conclusions: In this cohort of stable maintenance hemodialysis patients, prior Parvovirus B19 exposure, as indicated by IgG seropositivity, was not associated with increased anemia severity, inflammation, or ESA use, and the higher crude seroprevalence in dialysis patients was attributable to their older age rather than to dialysis itself. Because IgG reflects past exposure only and IgM and viral DNA were not assessed, these findings apply strictly to past (IgG-defined) exposure and cannot address active or persistent B19V infection. They suggest that routine Parvovirus B19 IgG screening in asymptomatic hemodialysis patients is unlikely to be useful for anemia management, whereas active or persistent infection—detectable only by molecular testing—remains the more plausible contributor to unexplained or refractory anemia and merits study in selected patients. Full article

Background. Newborn ruminants are born agammaglobulinemic, and colostrum quality (IgG concentration) is often insufficient, especially in heifers, leading to high morbidity and mortality from diarrheal infections. Objective. To develop and evaluate colostrum enrichment with specific egg yolk immunoglobulins (IgY) for the prevention of diarrhea in newborn calves. Methods. Hens were hyperimmunized with an inactivated vaccine against rotavirus, coronavirus, and E. coli. Yolk melange was prepared. Total and specific IgY were measured by chromatography and ELISA. Trials were conducted in three farms with high diarrhea incidence: experimental calves (n = 25) received 100 mL of melange (5 yolks) with the first two colostrum feedings; controls (n = 25) received native colostrum. Results. One yolk contained up to 100 mg of polyclonal IgY, with 8% specific antibodies. Diarrhea occurred in 12% of experimental calves (mild, no drugs) vs. 76% in controls (24% required antibiotics/rehydration). Testing in two other farms (n = 42, n = 38) reduced incidence 5.2–6.8-fold compared to the previous period. Conclusions. Enriching colostrum with specific IgY from hyperimmunized hens is highly effective and affordable for preventing diarrheal infections in newborn calves, especially in herds with poor colostrum quality in heifers. Full article

Background: Glucose transporter 1 (GLUT1) is frequently upregulated in solid tumors and may reflect metabolic adaptation of malignant tissues. However, evidence regarding GLUT1 protein levels in salivary gland tumors remains limited. Methods: In this pilot study, GLUT1 protein concentrations were quantified in tissue homogenate supernatants from salivary gland tumors (n = 9) and non-malignant salivary gland tissue obtained from surgical margins (controls; n = 4) using a commercial ELISA kit (BlueGene Biotech; E01G0020) according to the manufacturer’s instructions. Supernatants were stored at −80 °C until analysis. Group comparisons were performed using a non-parametric Mann–Whitney U test. Results: GLUT1 levels showed substantial inter-individual variability. The tumor group exhibited higher values than controls [median (IQR): 15.53 (12.44–26.38) vs. 10.14 (7.40–13.26); mean ± SD: 19.26 ± 11.49 vs. 10.33 ± 4.39 (ng/mL)], although the between-group difference did not reach statistical significance (Mann–Whitney U = 27, two-sided p = 0.199). Conclusions: These preliminary data suggest heterogeneity of GLUT1 levels in salivary gland tumor tissue homogenates and numerically higher concentrations compared with non-malignant margin tissue. These findings should be interpreted as preliminary and hypothesis-generating. Larger, clinically annotated cohorts with orthogonal validation are required before any diagnostic, prognostic, or clinical relevance of GLUT1 can be considered. Full article

Background and Objectives: Classical cardiovascular risk factors account for only a fraction of acute coronary syndromes (ACSs), and chronic Chlamydia pneumoniae infection has been proposed as a contributor to atherogenesis through persistent inflammation and endothelial dysfunction. We tested whether C. pneumoniae infection is independently associated with ACS by quantifying seroprevalence, inflammatory markers, and their relationship with conventional cardiovascular risk factors. Materials and Methods: In a prospective case–control design, we enrolled 47 patients with ACSs (29 with acute myocardial infarction and 18 with unstable angina) and 53 age- and locality-matched controls at Alexandria University Hospital. The clinical evaluation comprised electrocardiography, echocardiography, lipid profile, and high-sensitivity C-reactive protein (CRP). C. pneumoniae-specific IgG and IgM were measured by ELISA, with positive samples confirmed by microimmunofluorescence. Logistic regression models were adjusted for age, sex, hypertension, diabetes, dyslipidemia, and smoking. Results: IgM was undetectable in all 100 participants, excluding acute infection. IgG seropositivity was higher in cases than in controls (83.0% vs. 60.4%; OR: 3.20; 95% CI: 1.23–8.30; p = 0.017) and remained suggestive after multivariable adjustment (adjusted OR: 4.59; 95% CI: 1.33–18.28; p = 0.021), although the estimate is imprecise and does not meet our prespecified multivariate threshold of p < 0.01. Within the ACS cohort, IgG seropositivity was not significantly associated with CRP elevation (Fisher’s exact p = 1.000). CRP elevation was near-universal in cases (93.6%) and absent in controls (0%; p < 0.001). Conclusions: Chronic C. pneumoniae infection was associated with ACS in unadjusted analysis, with a suggestive but underpowered signal after multivariable adjustment, although the observational design precludes causal inference, and reverse causality cannot be excluded. Prospective studies using direct pathogen detection are required to determine whether the association reflects a contributory mechanism or shared susceptibility. Full article