Longitudinal Evaluation of Gut Bacteriomes and Viromes after Fecal Microbiota Transplantation for Eradication of Carbapenem-Resistant Enterobacteriaceae.

Understanding the role of fecal microbiota transplantation (FMT) in the decolonization of multidrug-resistant organisms (MDRO) is critical. Specifically, little is known about virome changes in MDRO-infected subjects treated with FMT. Using shotgun metagenomic sequencing, we characterized longitudinal dynamics of the gut virome and bacteriome in three recipients who successfully decolonized carbapenem-resistant Enterobacteriaceae (CRE), including Klebsiella spp. and Escherichia coli, after FMT. We observed large shifts of the fecal bacterial microbiota resembling a donor-like community after transfer of a fecal microbiota dominated by the genus Ruminococcus. We found a substantial expansion of Klebsiella phages after FMT with a concordant decrease of Klebsiella spp. and striking increase of Escherichia phages in CRE E. coli carriers after FMT. We also observed the CRE elimination and similar evolution of Klebsiella phage in mice, which may play a role in the collapse of the Klebsiella population after FMT. In summary, our pilot study documented bacteriome and virome alterations after FMT which mediate many of the effects of FMT on the gut microbiome community. IMPORTANCE Fecal microbiota transplantation (FMT) is an effective treatment for multidrug-resistant organisms; however, introducing a complex mixture of microbes also has unknown consequences for landscape features of gut microbiome. We sought to understand bacteriome and virome alterations in patients undergoing FMT to treat infection with carbapenem-resistant Enterobacteriaceae. This finding indicates that transkingdom interactions between the virome and bacteriome communities may have evolved in part to support efficient FMT for treating CRE.

Development of an Ordinal Scale Treatment Endpoint for Adults Hospitalized With Influenza.

BACKGROUND: An obstacle in influenza therapeutics development is the lack of clinical endpoints, especially in hospitalized patients. A single time-point binary outcome measure is limited by patients' diverse clinical trajectories and low event rates. METHODS: A 6-point ordinal scale with ascending clinical status severity (scoring: discharged; subacute care; acute care without/with respiratory failure; intensive care unit [ICU]; death) was proposed to study outcomes of adults hospitalized with influenza. Individual patient data from 2 active surveillance cohorts' datasets (2015/2016-2017/2018; Edmonton, Hong Kong) was used for evaluation. The impact of neuraminidase inhibitor (NAI) treatment on longitudinal ordinal outcome changes over 30 days was analyzed using mixed-effects ordinal logistic regression and group-based trajectory models. RESULTS: Patient (n = 1226) baseline characteristics included age (mean 68.0 years), virus-type (A 78.1%, B 21.9%), respiratory failure (57.2%), ICU admittance (14.4%), and NAI treatment within 5 days of illness (69.2%). Outcomes at 30 days included discharged (75.2%), subacute care (13.7%), acute care (4.5%), and death (6.6%). Two main clinical trajectories were identified, predictive by baseline scoring (mean ±â€…SD, 4.3 ±â€…0.6 vs 3.5 ±â€…0.6, P < .001). Improved outcomes with NAI treatment within 5 days were indicated by significantly lower clinical status scores over time (unadjusted odds ratio [OR], 0.53; 95% confidence interval [CI], .41-.69; P < .001; adjusted OR, 0.62; 95% CI, .50-.77; P < .001, for baseline score, age, and within-patient correlations). In subanalysis, influenza vaccination was also associated with lower scores (adjusted OR, 0.67; 95% CI, .50-.90; P = .007). Analyses of binary endpoints showed insignificant results. CONCLUSIONS: The ordinal outcome scale is a potentially useful clinical endpoint for influenza therapeutic trials, which could account for the diverse clinical trajectories of hospitalized patients, warranting further development.

Adherence to Treatment Guideline Improves Patient Outcomes in a Prospective Cohort of Adults Hospitalized for Community-Acquired Pneumonia.

BACKGROUND: Understanding local epidemiology and etiologies of community-acquired pneumonia in hospitalized patients is crucial for determining the appropriateness of treatment guidelines. We aim to determine the etiologies, severity, and outcomes in adults hospitalized for community-acquired pneumonia and to study the impact of empirical antibiotic therapy on patient outcomes. METHODS: We performed a prospective observational cohort study involving adults hospitalized for community-acquired pneumonia in Hong Kong. Sputum, nasopharyngeal aspirate, blood, and urine were collected for bacterial culture, molecular tests for detection of viruses and atypical pathogens, and antigen tests. Multivariable logistic regression model and Cox proportional hazard models were performed to determine independent factors associated with prolonged hospitalization and mortality. RESULTS: From February 2017 to July 2018, 258 patients were enrolled. The median age was 73 (interquartile range, 61-80) years, 66% were male, 57% had underlying chronic illnesses, 13% had CURB-65 score ≥3, and 10% had higher 1-year mortality. Pathogens were identified in 45% of patients; 20% had viral, 15% had bacterial, and 9% had polymicrobial pneumonia. Streptococcus pneumoniae (12%), influenza virus (12%), and Mycoplasma pneumoniae (1.2%) were the most common bacterial, viral, and atypical pathogens, respectively. Nonadherence to local empirical antibiotic treatment guidelines (primarily recommending beta-lactam and doxycycline) was observed in 25% and was independently associated with prolonged hospitalization (≥7 days) and higher mortality, after adjustment for age, underlying chronic illness, and disease severity. CONCLUSIONS: Adherence to treatment guidelines was associated with shorter hospitalization and improved survival. We provided evidence for the use of doxycycline for coverage of atypical pathogens in nonsevere pneumonia.

Antiviral Therapy for Hepatitis B Prevents Liver Injury in Patients With Tuberculosis and Hepatitis B Coinfection.

BACKGROUND: Chronic hepatitis B virus (HBV) infection increases the risk of liver injury in patients who undergo antituberculosis treatment. It is uncertain whether antiviral treatment for HBV at the time of tuberculosis diagnosis would reduce the risk of liver injury. METHODS: We performed a population-level, retrospective, cohort study that involved all patients with tuberculosis-HBV coinfection treated in public hospitals in Hong Kong over a 16-year period. Patients who received antiviral treatment at the time of tuberculosis diagnosis were considered "patients on antiviral therapy." A multivariable Cox proportional hazards model was used to determine the adjusted hazard ratio of hospitalization due to drug-induced liver injury within 1 year in patients on antiviral therapy, adjusting for the propensity score. RESULTS: Of 3698 patients with tuberculosis-HBV coinfection, 488 (13.2%) were patients on antiviral therapy. Of the remaining 3210 patients, 446 (13.9%) started antiviral therapy within 1 year of tuberculosis diagnosis. Adjusting for the propensity score, patients on antiviral therapy had a lower risk of hospitalization due to drug-induced liver injury compared with those not on treatment (adjusted hazard ratio, 0.44; 95% confidence interval .26-.72). Compared with patients who started antiviral therapy within 1 year of tuberculosis diagnosis, patients on antiviral therapy also had a lower risk of hospitalization due to drug-induced liver injury and a lower risk of liver-related mortality. CONCLUSIONS: We show that antiviral treatment for HBV given at the time of tuberculosis diagnosis reduced the risk of liver injury in tuberculosis-HBV coinfected patients.

Disease Burden, Characteristics, and Outcomes of Methicillin-Resistant Staphylococcus aureus Bloodstream Infection in Hong Kong.

We aimed to describe disease burden, characteristics, and outcomes of methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI) in Hong Kong. A retrospective, observational study was conducted in 26 Hong Kong public hospitals between January 2010 and December 2012. The primary outcome measures were 30-day mortality rate and infection-related hospital cost. Of 1133 patients reviewed, 727 (64.17%) were male, 1075 (94.88%) had health care-associated community-onset and 44 (3.88%) had hospital-onset MRSA infection. The mean age of patients was 76 (SD = 15) years, including 172 (15.18%) aged 20 to 59 years and 961 (84.8%) aged ≥60 years. The annual incidence rates in age groups of 20 to 59 years and ≥60 years were 0.96 to 1.148 per 100 000 and 22.7 to 24.8 per 100 000, respectively. The 30-day mortality was 367 (32.39%). Older patients (>79 years), chronic lung disease, and prior hospitalization were associated with increased mortality. The mean cost was US$10 565 (SD = 11 649; US$1 = HK$7.8). MRSA BSI was a significant burden in Hong Kong.

IFITM3, TLR3, and CD55 Gene SNPs and Cumulative Genetic Risks for Severe Outcomes in Chinese Patients With H7N9/H1N1pdm09 Influenza.

Background: We examined associations between single-nucleotide polymorphisms (SNPs) of IFITM3, TLR3, and CD55 genes and influenza clinical outcomes in Chinese. Methods: A multicenter study was conducted on 275 adult cases of avian (H7N9) and pandemic (H1N1pdm09) influenza. Host DNA was extracted from diagnostic respiratory samples; IFITM3 rs12252, TLR3 rs5743313, CD55 rs2564978, and TLR4 rs4986790/4986791 were targeted for genotyping (Sanger sequencing). The primary outcome analyzed was death. Results: IFITM3 and TLR3 SNPs were in Hardy-Weinberg equilibrium; their allele frequencies (IFITM3/C-allele 0.56, TLR3/C-allele 0.88) were comparable to 1000 Genomes Han Chinese data. We found over-representation of homozygous IFITM3 CC (54.5% vs 33.2%; P = .02) and TLR3 CC (93.3% vs 76.9%; P = .04) genotypes among fatal cases. Recessive genetic models showed their significant independent associations with higher death risks (adjusted hazard ratio [aHR] 2.78, 95% confidence interval [CI] 1.29-6.02, and aHR 4.85, 95% CI 1.11-21.06, respectively). Cumulative effects were found (aHR 3.53, 95% CI 1.64-7.59 per risk genotype; aHR 9.99, 95% CI 1.27-78.59 with both). Results were consistent for each influenza subtype and other severity indicators. The CD55 TT genotype was linked to severity. TLR4 was nonpolymorphic. Conclusions: Host genetic factors may influence clinical outcomes of avian and pandemic influenza infections. Such findings have important implications on disease burden and patient care in at-risk populations.

Brief Report: Progression of Atherosclerosis in HIV-Infected Individuals-Prospective Data From an Asian Cohort.

BACKGROUND: The magnitude and risk factors of progression of atherosclerosis in Asian HIV-infected individuals were unknown. This study aimed to evaluate: (1) the rate of progression of atherosclerosis in HIV-infected individuals, and (2) metabolic and inflammatory parameters that may predict atherosclerosis progression in HIV-infected individuals in an Asian cohort. SETTING: A prospective, longitudinal study was performed among adults attending an HIV Metabolic clinic in Hong Kong. METHODS: Carotid intima media thickness (cIMT) was measured at baseline and 24 months. Body composition, metabolic, and inflammatory biomarkers [including homeostasis model assessment of insulin resistance, LDL (low-density lipoprotein) cholesterol particle size, high-sensitive C reactive protein, adiponectin] associated with cIMT change were analyzed; their predictive performances were estimated using receiver operating characteristic analyses. RESULTS: Sixty-one HIV-infected individuals (mean ± SD age 49.8 ± 11.4 years, 89% men, 97% Chinese, diabetes 39%, hypertension 30%, and dyslipidemia 85%) were recruited. Annual rate of change of cIMT was +0.0075 (0.0000-0.0163) mm/yr, and 19% developed new plaque at 24 months. Two patients died during the study period, 1 because of sudden cardiac death. Using receiver operating characteristic analyses, combination of lower limb fat percentage, LDL cholesterol subclass pattern B, and lower adiponectin level, but not Framingham score, predicted greater cIMT progression in HIV-infected individuals. CONCLUSIONS: Asian HIV-infected individuals had atherosclerosis progression. Limb fat percentage, LDL cholesterol particle size, and adiponectin level may identify at-risk Asian HIV-infected individuals for early intervention.

Anti-inflammatory effects of adjunctive macrolide treatment in adults hospitalized with influenza: A randomized controlled trial.

INTRODUCTION: - Macrolides can ameliorate inflammation in respiratory diseases, providing clinical benefits. Data in influenza is lacking. METHOD: - A randomized, open-label, multicenter trial among adults hospitalized for laboratory-confirmed influenza was conducted. Study treatments of oseltamivir and azithromycin (500 mg/day), or oseltamivir alone, both for 5 days, were allocated at 1:1 ratio. The primary outcome was plasma cytokine/chemokine concentration change over time (Day 0-10); secondary outcomes were viral load and symptom score changes. Generalized Estimating Equation (GEE) models were used to analyze longitudinal data. RESULTS: - Fifty patients were randomized to the oseltamivir-azithromycin or oseltamivir groups, with comparable baseline characteristics (age, 57 ± 18 years; A/H3N2, 70%), complications (72%), and viral load. Pro-inflammatory cytokines IL-6 (GEE: ß -0.037, 95%CI-0.067,-0.007, P = 0.016; reduction from baseline -83.4% vs -59.5%), CXCL8/IL-8 (ß -0.018, 95%CI-0.037,0.000, P = 0.056; -80.5% vs -58.0%), IL-17 (ß -0.064, 95%CI-0.117,-0.012, P = 0.015; -74.0% vs -34.3%), CXCL9/MIG (ß -0.010, 95%CI-0.020,0.000, P = 0.043; -71.3% vs -56.0%), sTNFR-1, IL-18, and CRP declined faster in the oseltamivir-azithromycin group. There was a trend toward faster symptom resolution (ß -0.463, 95%CI-1.297,0.371). Viral RNA decline (P = 0.777) and culture-negativity rates were unaffected. Additional ex vivo studies confirmed reduced induction of IL-6 (P = 0.017) and CXCL8/IL-8 (P = 0.005) with azithromycin. CONCLUSION: - We found significant anti-inflammatory effects with adjunctive macrolide treatment in adults with severe influenza infections. Virus control was unimpaired. Clinical benefits of a macrolide-containing regimen deserve further study. [ClinicalTrials.gov NCT01779570].

Economic outcomes of influenza in hospitalized elderly with and without ICU admission.

BACKGROUND: To describe direct medical costs of influenza in hospitalized elderly, with and without intensive care unit (ICU) admission, during the 2014-2015 season in Hong Kong. METHODS: A retrospective study was conducted in 110 inpatients aged ≥65 years with laboratory-confirmed influenza treated by antiviral therapy during season 2014-2015 in a tertiary hospital. Resource utilization of influenza-related diagnostic and laboratory tests, medications for influenza treatment, usage of general medical ward and ICU during the influenza-related length of hospital stay (IR-LOS) were collected. RESULTS: There were 18 (16.4%) and 92 (83.4%) cases with and without ICU admission, respectively. The difference in influenza-related mortality rates between patients with (11.1%) and without ICU admission (2.2%) was not statistically significant (P=0.064). Patients with ICU admission reported longer IR-LOS (12.7 ±6.0 days versus 5.5 ±2.7 days; P<0.001) and higher direct costs (36,588 USD ±21,482 versus 5,773 USD ±2,017; P<0.001; 1 USD=7.8 HKD). Male gender (OR=14.50; 95% CI 1.68, 125.07) and respiratory complications (OR=9.61; 95% CI 1.90, 48.50) were positive predictors of ICU admission. Age ≥70 years (OR=0.09; 95% CI 0.02, 0.46) and antiviral therapy initiation within 7 days (OR=0.05; 95% CI 0.003, 0.79) were negative predictors of ICU admission. Influenza B was a positive predictor of high-cost hospitalization in non-ICU survivors (OR=7.33; 95% CI 1.24, 43.29). No predictor of mortality was identified. CONCLUSIONS: Hospitalization cost in elderly for seasonal influenza was substantial in Hong Kong. The cost in patients with ICU admission was significantly higher than those without ICU care. Respiratory complications and male gender predicted ICU admission. Influenza B infection predicted high-cost hospitalization in non-ICU survivors.

High morbidity and mortality of Clostridium difficile infection and its associations with ribotype 002 in Hong Kong.

OBJECTIVES: We aim to study the disease burden, risk factors and severity of Clostridium difficile infection (CDI) in Hong Kong. METHODS: We conducted a prospective, case-control study in three acute-care hospitals in Hong Kong. Adult inpatients who developed CDI diarrhoea confirmed by PCR (n = 139) were compared with the non-CDI controls (n = 114). Ribotyping of isolates and antimicrobial susceptibility testing were performed. RESULTS: The estimated crude annual incidence of CDI was 23-33/100,000 population, and 133-207/100,000 population among those aged ≥65 years. The mean age of CDI patients was 71.5. Nursing home care, recent hospitalization, antibiotics exposure (adjusted OR 3.0, 95% CI 1.3-7.1) and proton-pump inhibitors use (adjusted OR 2.2, 95% CI 1.2-3.9) were risk factors. Severe CDI occurred in 41.7%. Overall mortality was 16.5% (among severe CDI, 26.5%). The commonest ribotypes were 002 (22.8%), 014 (14.1%), 012 and 046; ribotype 027 was absent. Ribotype 002 was associated with fluoroquinolone resistance and higher mortality (47.6% vs. 12.7%; adjusted HR 2.8, 95% CI 1.1-7.0). CONCLUSIONS: Our findings show high morbidity and mortality of CDI in the older adults, and identify ribotype 002 as a possible virulent strain causing serious infections in this cohort.

High Viral Load and Respiratory Failure in Adults Hospitalized for Respiratory Syncytial Virus Infections.

A prospective study among adults hospitalized for polymerase chain reaction-confirmed respiratory syncytial virus infections (n = 123) showed frequent occurrence of lower respiratory-tract complications causing respiratory insufficiency (52.8%), requirement for assisted ventilation (16.3%), and intensive care unit admission/death (12.2%). High viral RNA concentration was detected at time of hospitalization, including in patients who presented later than 2 days of illness (day 1-2, 7.29 ± 1.47; day 3-4, 7.28 ± 1.41; day 5-8, 6.66 ± 1.87 log10 copies/mL). RNA concentration was independently associated with risk of complications and respiratory insufficiency (adjusted odds ratio 1.40 per log10 copies/mL increase, 95% confidence interval, 1.03-1.90; P = .034). Our data indicate the need and provide a basis for clinical research on antiviral therapy in this population.

High mortality in adults hospitalized for active tuberculosis in a low HIV prevalence setting.

BACKGROUND: This study aims to evaluate the outcomes of adults hospitalized for tuberculosis in a higher-income region with low HIV prevalence. METHODS: A retrospective cohort study was conducted on all adults hospitalized for pulmonary and/or extrapulmonary tuberculosis in an acute-care hospital in Hong Kong during a two-year period. Microscopy and solid-medium culture were routinely performed. The diagnosis of tuberculosis was made by: (1) positive culture of M. tuberculosis, (2) positive M. tuberculosis PCR result, (3) histology findings of tuberculosis infection, and/or (4) typical clinico-radiological manifestations of tuberculosis which resolved after anti-TB treatment, in the absence of alternative diagnoses. Time to treatment ('early', started during initial admission; 'late', subsequent periods), reasons for delay, and short- and long-term survival were analyzed. RESULTS: Altogether 349 patients were studied [median(IQR) age 62(48-77) years; non-HIV immunocompromised conditions 36.7%; HIV/AIDS 2.0%]. 57.9%, 16.3%, and 25.8% had pulmonary, extrapulmonary, and pulmonary-extrapulmonary tuberculosis respectively. 58.2% was smear-negative; 0.6% multidrug-resistant. 43.4% developed hypoxemia. Crude 90-day and 1-year all-cause mortality was 13.8% and 24.1% respectively. 57.6% and 35.8% received 'early' and 'late' treatment respectively, latter mostly culture-guided [median(IQR) intervals, 5(3-9) vs. 43(25-61) days]. Diagnosis was unknown before death in 6.6%. Smear-negativity, malignancy, chronic lung diseases, and prior exposure to fluoroquinolones (adjusted-OR 10.6, 95%CI 1.3-85.2) delayed diagnosis of tuberculosis. Failure to receive 'early' treatment independently predicted higher mortality (Cox-model, adjusted-HR 1.8, 95%CI 1.1-3.0). CONCLUSIONS: Mortality of hospitalized tuberculosis patients is high. Newer approaches incorporating methods for rapid diagnosis and initiation of anti-tuberculous treatment are urgently required to improve outcomes.

Role of human Toll-like receptors in naturally occurring influenza A infections.

BACKGROUND: We investigated the roles of Toll-like receptors (TLRs) in naturally occurring influenza. METHODS: A prospective, case - control study was conducted. Adults hospitalized with virologically confirmed influenza A infections (onset <48 hours, before treatment) were compared with age-/gender-matched controls. TLRs (2, 3, 4, 7, 8, 9) expression in monocytes and dendritic cells (DCs - total, myeloid, plasmacytoid) was quantitated using flow cytometry. Gene expression of RLRs (RIG-1, MDA-5) was evaluated using real-time PCR. Concomitant signaling molecules expression, plasma cytokine/chemokine concentrations, and respiratory tract viral loads were measured. PBMCs were cultured and stimulated ex vivo with TLR-specific ligands for cytokine responses. RESULTS: Forty two patients with influenza (24 A/H3N2, 18 A/H1N1pdm09) and 20 controls were studied. Patients' mean age was 68 ± 16 years; 81% had respiratory/cardiovascular complications. There were increased cellular expressions of TLR9, TLR8, TLR3, and TLR7 during influenza; TLR2 and TLR4 were suppressed. Results were similar for both virus strains. Higher TLR expression levels at presentation significantly correlated with lower viral loads (Spearman's rho: -0.46 to -0.69 for TLR9, TLR8, and TLR3; P-values <0.05). Multivariate regression models (adjusted for age, comorbidity, disease severity, time from onset) confirmed their independent associations. Increased signaling molecules (phospho-MAPKs, IκB) and inflammatory cytokines (IL-6, sTNFR-1, CCL2/MCP-1; CXCL10/IP-10, IFN-γ) correlated with increased TLR expression. RLRs were upregulated simultaneously. PBMCs of patients with influenza showed significant, dynamic changes in their cytokine responses upon TLR stimulation, compared with controls. CONCLUSIONS: Our results suggest that TLRs play an important role in early, innate viral inhibition in naturally occurring influenza. Inflammatory cytokine responses are concomitantly induced. These findings support investigation of TLR targeting as a novel intervention approach for prophylaxis against influenza.

Comparisons of oseltamivir-resistant (H275Y) and concurrent oseltamivir-susceptible seasonal influenza A(H1N1) virus infections in hospitalized adults, 2008-2009.

In an observational cohort study, we found that adults hospitalized for oseltamivir-resistant (H275Y) seasonal H1N1 influenza (n = 46) were older than those infected with oseltamivir-susceptible strains (n = 31) [74(IQR 59-83) versus 64(IQR 48-76) years; P = 0·045], and most had major comorbidities (78% versus 65%). Disease severity and clinical outcomes were comparable between the two groups: radiographic pneumonia 40-42%, supplemental oxygen use 47-48%, critical illness 11-13%, median duration of hospitalization 5-6 days, death rate 6-9%. Failure to receive effective antiviral therapy was associated with progression to critical illness (23% versus 0%, P = 0·016) and death (20% versus 0%, P = 0·033) in hospitalized patients with seasonal H1N1 influenza.

Seasonal influenza A virus in feces of hospitalized adults.

In a cohort of hospitalized adults with seasonal influenza A in Hong Kong, viral RNA was frequently (47%) detected in stool specimens. Viable virus was rarely isolated. Viral RNA positivity had little correlation with gastrointestinal symptoms and outcomes. In vitro studies suggested low potential for seasonal influenza viruses to cause direct intestinal infections.

Cytokine response patterns in severe pandemic 2009 H1N1 and seasonal influenza among hospitalized adults.

BACKGROUND: Studying cytokine/chemokine responses in severe influenza infections caused by different virus subtypes may improve understanding on pathogenesis. METHODS: Adults hospitalized for laboratory-confirmed seasonal and pandemic 2009 A/H1N1 (pH1N1) influenza were studied. Plasma concentrations of 13 cytokines/chemokines were measured at presentation and then serially, using cytometric-bead-array with flow-cytometry and ELISA. PBMCs from influenza patients were studied for cytokine/chemokine expression using ex-vivo culture (Whole Blood Assay,±PHA/LPS stimulation). Clinical variables were prospectively recorded and analyzed. RESULTS: 63 pH1N1 and 53 seasonal influenza patients were studied. pH1N1 patients were younger (mean±S.D. 42.8±19.2 vs 70.5±16.7 years), and fewer had comorbidities. Respiratory/cardiovascular complications were common in both groups (71.4% vs 81.1%), although severe pneumonia with hypoxemia (54.0% vs 28.3%) and ICU admissions (25.4% vs 1.9%) were more frequent with pH1N1. Hyperactivation of the proinflammatory cytokines IL-6, CXCL8/IL-8, CCL2/MCP-1 and sTNFR-1 was found in pH1N1 pneumonia (2-15 times normal) and in complicated seasonal influenza, but not in milder pH1N1 infections. The adaptive-immunity (Th1/Th17)-related CXCL10/IP-10, CXCL9/MIG and IL-17A however, were markedly suppressed in severe pH1N1 pneumonia (2-27 times lower than seasonal influenza; P-values<0.01). This pattern was further confirmed with serial measurements. Hypercytokinemia tended to be sustained in pH1N1 pneumonia, associated with a slower viral clearance [PCR-negativity: day 3-4, 55% vs 85%; day 6-7, 67% vs 100%]. Elevated proinflammatory cytokines, particularly IL-6, predicted ICU admission (adjusted OR 12.6, 95%CI 2.6-61.5, per log(10)unit increase; P = 0.002), and correlated with fever, tachypnoea, deoxygenation, and length-of-stay (Spearman's rho, P-values<0.01) in influenza infections. PBMCs in seasonal influenza patients were activated and expressed cytokines ex vivo (e.g. IL-6, CXCL8/IL-8, CCL2/MCP-1, CXCL10/IP-10, CXCL9/MIG); their 'responsiveness' to stimuli was shown to change dynamically during the illness course. CONCLUSIONS: A hyperactivated proinflammatory, but suppressed adaptive-immunity (Th1/Th17)-related cytokine response pattern was found in severe pH1N1 pneumonia, different from seasonal influenza. Cytokine/immune-dysregulation may be important in its pathogenesis.

Complications and outcomes of pandemic 2009 Influenza A (H1N1) virus infection in hospitalized adults: how do they differ from those in seasonal influenza?

BACKGROUND: It is unclear whether pandemic 2009 influenza A (pH1N1) infection caused more significant disease among hospitalized adults than seasonal influenza. METHODS: A prospective, observational study was conducted in adults hospitalized with polymerase chain reaction-confirmed pH1N1 infection in 2 acute-care general hospitals from June 2009 to May 2010 (n = 382). Complications and outcomes were described and compared with those in a seasonal influenza cohort (2007-2008, same hospitals; n = 754). RESULTS: Hospitalized patients with pH1N1 influenza were younger than those with seasonal influenza (mean age ± standard deviation, 47 ± 20 vs 70 ± 19 years) and fewer had comorbid conditions (48% vs 64%). The rate of positive immunofluorescence assay results was low (54% vs 84%), and antiviral use was frequent (96% vs 52%). Most patients in both cohorts developed complicated illnesses (67.8% vs 77.1%), but patients with pH1N1 influenza had higher rates of extrapulmonary complications (23% vs 16%; P = .004) and intensive care unit admission and/or death (patient age <35 years, 2.3% vs 0%; 35-65 years, 12.4% vs 3.2%; >65 years, 13.5% vs 8.5%; adjusted odds ratio [OR] 2.13; 95% confidence interval [CI], 1.25-3.62; P = .005). Patients who received antiviral treatment within 96 h after onset had better survival (log-rank test, P < .001). However, without timely treatment, the mortality risk was higher with pH1N1 infection (9.0% vs 5.8% for seasonal influenza; adjusted OR, 6.85; 95% CI, 1.64-28.65; P = .008]. Bacterial superinfection worsened outcomes. CONCLUSIONS: Adults hospitalized for pH1N1 influenza had significant complications and mortality despite being younger than patients with seasonal influenza. Antiviral treatment within 96 h may improve survival.