Clinical, laboratory and radiologic characteristics of 2009 pandemic influenza A/H1N1 pneumonia: primary influenza pneumonia versus concomitant/secondary bacterial pneumonia

Please cite this paper as: Song et al. (2011). Clinical, laboratory and radiologic characteristics of 2009 pandemic influenza A/H1N1 pneumonia: primary influenza pneumonia versus concomitant/secondary bacterial pneumonia. Influenza and Other Respiratory Viruses 5(6), e535–e543. Background Although influenza virus usually involves the upper respiratory tract, pneumonia was seen more frequently with the 2009 pandemic influenza A/H1N1 than with seasonal influenza. Methods From September 1, 2009, to January 31, 2010, a specialized clinic for patients (aged ≥15 years) with ILI was operated in Korea University Guro Hospital. RT‐PCR assay was performed to diagnose 2009 pandemic influenza A/H1N1. A retrospective case–case–control study was performed to determine the predictive factors for influenza pneumonia and to discriminate concomitant/secondary bacterial pneumonia from primary influenza pneumonia during the 2009–2010 pandemic. Results During the study period, the proportions of fatal cases and pneumonia development were 0·12% and 1·59%, respectively. Patients with pneumonic influenza were less likely to have nasal symptoms and extra‐pulmonary symptoms (myalgia, headache, and diarrhea) compared to patients with non‐pneumonic influenza. Crackle was audible in just about half of the patients with pneumonic influenza (38·5% of patients with primary influenza pneumonia and 53·3% of patients with concomitant/secondary bacterial pneumonia). Procalcitonin, C‐reactive protein (CRP), and lactate dehydrogenase were markedly increased in patients with influenza pneumonia. Furthermore, procalcitonin (cutoff value 0·35 ng/ml, sensitivity 81·8%, and specificity 66·7%) and CRP (cutoff value 86·5 mg/IU, sensitivity 81·8%, and specificity 59·3%) were discriminative between patients with concomitant/secondary bacterial pneumonia and patients with primary influenza pneumonia. Conclusions Considering the subtle manifestations of 2009 pandemic influenza A/H1N1 pneumonia in the early stage, high clinical suspicion is required to detect this condition. Both procalcitonin and CRP would be helpful to differentiate primary influenza pneumonia from concomitant/secondary bacterial pneumonia.     

Cytokine response in pediatric patients with pandemic influenza H1N1 2009 virus infection and pneumonia: comparison with pediatric pneumonia without H1N1 2009 infection

Objectives

We investigated serum cytokine levels in pediatric patients with pandemic influenza H1N1 2009 virus (H1N1) infection‐pneumonia and in pediatric patients with pneumonia but without H1N1 infection, and examined correlations between cytokine levels and clinical/laboratory findings.

Methods

Fifty‐seven cases of infection by H1N1 were confirmed by RT‐PCR and enrolled. Of these 57 cases, 26 had a severe H1N1 infection (group 1), and 31 had a mild H1N1 infection (group 2). Sera from 18 cases with pneumonia without H1N1 infection (group 3) were used as controls. The serum levels of 10 cytokines were determined by multiplex assay.

Results

The serum levels of IFN‐α, IL‐6, and IP‐10 were significantly higher in H1N1 infected cases than in group 3, and levels of IL‐6 and IP‐10 were significantly higher in group 1 than in group 2. The level of IL‐10 was significantly higher in groups 1 and 3 than in group 2. However, levels of IFN‐γ and IL‐17 were not significantly different between the three groups. IL‐1β, IL‐4, and MIP‐1α were not detectable in most patients. IP‐10 and IL‐6 levels were found to show negative correlations with lymphocyte count and oxygen saturation.

Conclusions

We found higher levels of cytokines (IFN‐α, IL‐6, IP‐10) of innate immunity than those of acquired immunity in pediatric H1N1 infection. Of the cytokines found to be increased in cases with H1N1 infection, IP‐10 and IL‐6 were found to be correlated with disease severity (lymphopenia and hypoxia). IP‐10 and IL‐6 may be important markers in pediatric H1N1 infection. Pediatr Pulmonol. 2011; 46: 1233–1239. © 2011 Wiley Periodicals, Inc.

     

甲型H1N1流感合并肺炎患者临床和影像学表现分析

目的探讨甲型H1N1流感合并肺炎临床和影像学表现。方法分析本院2009年9～2010年3月临床确诊24例甲型H1N1流感合并肺炎患者临床和影像学资料。结果 18例胸片均表现为肺纹理增多,6例表现为单肺斑片状影。CT显示6例单侧肺部炎性渗出影,12例双侧肺部炎性渗出影,4例弥漫性棉絮状病变;2例实质间质混合渗出。12例甲型H1N1流感合并肺炎患者出院1个月做CT检查,7例完全恢复正常;3例斑片状密度增高影2月后复查CT完全吸收;2例纤维条索影。结论影像学表现对于确定病变范围、病程发展变化和治疗后动态观察具有非常重要的参考价值。     

Influenza-associated bacterial pathogens in patients with 2009 influenza A (H1N1) infection: impact of community-associated methicillin-resistant Staphylococcus aureus in Queensland, Australia

Background: Secondary bacterial pneumonia due to community onset methicillin‐resistant Staphylococcus aureus (MRSA) has become a highly publicised cause of influenza‐associated death. There is a risk that case reports of fatal outcomes with post‐influenza MRSA pneumonia may unduly influence antibiotic prescribing. Aims: The aim of this study was to demonstrate the incidence of community‐onset MRSA pneumonia in 2009 H1N1 influenza patients. Methods: The microbiology records of patients positive for influenza A (H1N1) in 2009 were reviewed for positive blood or respiratory tract cultures and urinary pneumococcal antigen results within a Queensland database. Patients with such positive results within 48 h of hospital admission and a positive H1N1 influenza result in the prior 6 weeks were included. Results: In 2009, 4491 laboratory‐confirmed pandemic influenza A (H1N1) infections were detected. Fifty patients (1.1% of the H1N1 cohort) who were hospitalised with H1N1 and who had a bacterial respiratory tract pathogen were identified. Streptococcus pneumoniae (16 patients; 32%), Staphylococcus aureus (13 patients; 26%) and Haemophilus influenzae (9 patients; 18%) were the most commonly cultured organisms. Of the cohort of 4491 patients, MRSA was detected in only two patients, both of whom were admitted to intensive care units and survived after prolonged admissions. Conclusions: Influenza‐associated community‐onset MRSA pneumonia was infrequently identified in the 2009 H1N1 season in Queensland, despite community‐onset MRSA skin and soft tissue infections being very common. Although post‐influenza MRSA pneumonia is of great concern, its influence on empiric‐prescribing guidelines should take into account its incidence relative to other secondary bacterial pathogens.     

H1N1 swine origin influenza infection in the United States and Europe in 2009 may be similar to H1N1 seasonal influenza infection in two Australian states in 2007 and 2008

Background The population‐based impact of infection with swine origin influenza A (H1N1) virus infection was not clear in the early days of the epidemic towards the end of May 2009. Australia had seven confirmed cases by 22 May 2009. We aimed to compare available data on swine origin influenza A (H1N1) virus infection overseas with seasonal influenza A (H1N1) virus infection in Australia to assist with forward planning. Methods Data on infection with seasonal influenza A (H1N1) virus in patients recruited through sentinel general practices in Victoria and Western Australia in 2007 and 2008 were compared with early publications on infection with swine origin influenza A (H1N1) virus in the United States and Europe. Results Influenza A (H1N1) virus infection was predominantly a disease of younger people, regardless of whether the virus was of swine or human origin. The median age of infection with swine origin virus was 20 years in the United States and 22 years in Spain, while the median age of infection with human origin virus was 18 years in Western Australia and 23 years in Victoria. Conclusions The median age of infection with influenza A (H1N1) virus was around 20 ± 3 years, independent of the origin of the H1N1 virus but a higher proportion of swine origin influenza infections occurred in people aged 10–18 years. This is at least partially explained by biased sampling among surveillance patients, although it may also reflect a different infection pattern.     

Immunization with 1976 swine H1N1- or 2009 pandemic H1N1-inactivated vaccines protects mice from a lethal 1918 influenza infection

Please cite this paper as: Easterbrook et al. (2011) Immunization with 1976 swine H1N1‐ or 2009 pandemic H1N1‐inactivated vaccines protects mice from a lethal 1918 influenza infection. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750‐2659.2010.00191.x. Background Zoonotic infections with H1N1 influenza viruses that evolved initially from the 1918 virus (1918) and adapted to swine threatened a pandemic in 1976 (1976 swH1N1) and a novel reassortant H1N1 virus caused a pandemic in 2009–2010 (2009 pH1N1). Epidemiological and laboratory animal studies show that protection from severe 2009 pH1N1 infection is conferred by vaccination or prior infection with 1976 swH1N1 or 1918. Objectives Our aim was to demonstrate cross‐protection by immunization with 2009 pH1N1 or 1976 swH1N1 vaccines following a lethal challenge with 1918. Further, the mechanisms of cross‐protective antibody responses were evaluated. Methods Mice were immunized with 1976 swH1N1, 2009 pH1N1, 2009 seasonal trivalent, or 1918 vaccines and challenged with 1918. Cross‐reactive antibody responses were assessed and protection monitored by survival, weight loss, and pathology in mice. Results and Conclusions Vaccination with the 1976 swH1N1 or 2009 pH1N1 vaccines protected mice from a lethal challenge with 1918, and these mice lost no weight and had significantly reduced viral load and pathology in the lungs. Protection was likely due to cross‐reactive antibodies detected by microneutralization assay. Our data suggest that the general population may be protected from a future 1918‐like pandemic because of prior infection or immunization with 1976 swH1N1 or 2009 pH1N1. Also, influenza protection studies generally focus on cross‐reactive hemagglutination‐inhibiting antibodies; while hemagglutinin is the primary surface antigen, this fails to account for other influenza viral antigens. Neutralizing antibody may be a better correlate of human protection against pathogenic influenza strains and should be considered for vaccine efficacy.     

Influenza A/H1N1 2009 pneumonia in kidney transplant recipients: characteristics and outcomes following high‐dose oseltamivir exposure

S.P. Watcharananan, T. Suwatanapongched, P. Wacharawanichkul, W. Chantratitaya, V. Mavichak, S.B. Mossad. Influenza A/H1N1 2009 pneumonia in kidney transplant recipients: characteristics and outcomes following high‐dose oseltamivir exposure.
Transpl Infect Dis 2010: 12: 127–131. All rights reserved Abstract: We report 2 cases of severe pneumonia due to the novel pandemic influenza A/H1N1 2009 in kidney transplant recipients. Our patients initially experienced influenza‐like illness that rapidly progressed to severe pneumonia within 48 h. The patients became hypoxic and required non‐invasive ventilation. The novel influenza A/H1N1 2009 was identified from their nasal swabs. These cases were treated successfully with a relatively high dose of oseltamivir, adjusted for their renal function. Clinical improvement was documented only after a week of antiviral therapy. Despite early antiviral treatment, we showed that morbidity following novel pandemic influenza A/H1N1 2009 infection is high among kidney transplant recipients.     

降钙素原、C反应蛋白在细菌性肺炎诊断价值研究

目的 研究降钙素原(PCT)、C反应蛋白(CRP)在细菌性肺炎临床诊断价值.方法 比较病毒、细菌、支原体引起的肺炎患者PCT、CRP血清浓度的变化情况及不同严重程度细菌性肺炎患者PCT、CRP的血清水平.结果 三组CRP、PCT、WBC、NEUT经方差分析比较,差异有统计学意义(P＜0.05).CRP以细菌组升高幅度最大,支原体组次之;PCT以细菌组升高幅度最大,病毒组与支原体组升高不明显;细菌组中病情不同严重程度组别CRP、PCT、WBC经方差分析比较,差异有统计学意义(P＜0.05),CRP、PCT、WBC随病情严重程度依次升高.结论 PCT、CRP在细菌性肺炎的病原诊断、病情评估、预后判断上有重要临床应用价值.     

Clinical characteristics and outcomes of hospitalized patients with 2009 H1N1 influenza in a large acute care tertiary hospital, Singapore

This study describes the clinical characteristics and outcomes of hospitalized patients with 2009 H1N1 influenza in a large, acute care, tertiary hospital in Singapore. Of the 265 hospitalized patients with laboratory-confirmed 2009 influenza A (H1N1) during the height of the H1N1 flu pandemic, 13% (35) suffered severe outcomes including a mortality rate of 4.5% (12). Severe outcomes were associated with patients aged 40 years or more, underlying comorbidities, and complicated by pneumonia.     

降钙素原、C反应蛋白对下呼吸道感染的临床意义分析

目的 研究降钙素原（PCT）与C反应蛋白（CRP）联合检测在在下呼吸道感染病原诊断及病情评估的临床应用价值.方法 以50例下呼吸道感染患者为研究对象,比较不同病因及不同病情严重程度支气管肺炎患者CRP、PCT检测情况.结果 细菌组、病毒组、支原体组CRP两两比较均存在统计学差异（P＜0.05）,PCT细菌组与其他两组比较均存在统计学差异（P＜0.05）,细菌组CRP、PCT呈正相关（r=0.724,P＜0.05）,病毒组、支原体组CRP、PCT无相关性;细菌性组中随病情严重程度加深,CRP、PCT血清水平进行性增高.结论 CRP、PCT对下呼吸道感染病原体的早期诊断、病情评判及预后评估有重要的临床应用价值.     

2009年甲型H1N1流感患者临床特点的研究

目的调查2009年甲型H1N1流感患者的临床特点。方法通过调查2009年11月至2010年2月符合流感疑似病例收治入院的136例患者,明确2009甲型H1N1流感组,季节性甲型流感组和非流感组的人口学情况,肺炎发生的差异,危重症发生的差异,以及实验室检测参数的差异,筛选出需要住院的流感疑似患者发生肺炎的危险因素。结果 2009甲型H1N1流感发病年龄更年轻（36±17岁）;孕妇的构成比（42.2%）高于其他组;发生肺炎的构成比（51.11%）高于其他组;病死1例。D-二聚体、AST、LDH异常增加的构成比明显大于其他发热患者。结论甲型H1N1流感的易感人群是年轻人和孕妇。甲型H1N1流感是发生肺炎的危险因素,容易并发肺炎和呼吸衰竭,及引起血凝系统、骨骼肌、心肌的损害。     

儿童危重型H1N1流感肺炎伴胸腔积液的临床特征及淋巴细胞亚型特征

目的 分析危重症H1 N1流感患儿合并胸腔积液的临床特征及自身免疫功能的变化.方法 采用回顾性分析方法,收集2017年1月至2020年3月确诊为重症甲流的126例患儿的临床资料.根据有无胸腔积液分为胸腔积液阳性组(n=54)和胸腔积液阴性组(n=72);比较两组间基本临床资料,炎性指标和免疫功能.结果 胸腔积液阳性组与...     

63例重症甲型H1N1流感病例的临床特点及救治体会

目的分析成人重症甲型HlNl流感患者的流行病学及临床特征。方法分析63例重症甲型H1N1流感患者的临床表现,比较其流行病学信息及临床特征。结果 63例患者中59例患者病情好转出院,4例死亡。临床表现以显著的低氧血症为主要特征,患者有明显的全身症状,多器官功能障碍及免疫功能低下多见,易合并继发细菌或真菌感染。但经过积极抗病毒、抗感染、改善全身症状及支持治疗后,大部分患者病情改善。结论重症甲型H1N1流感病例病程进展快、低氧血症难以纠正、肺部病变范围广、合并感染严重,因此,早发现、尽早开始全身的综合救治是治疗成功的关键。     

The role of initial radiologic and clinical manifestations in predicting the prognosis for pneumonia caused by H1N1 influenza virus

Objective

The aim of this study is to investigate the prognostic values of initial radiologic findings and preexisting medical conditions in pneumonia caused by H1N1 influenza virus that were obtained during the novel swine-origin influenza A (H1N1) virus (S-OIV) pandemic spread.

Methods

Thirty-nine patients hospitalized due to H1N1 infection between September and December 2009 were retrospectively evaluated regarding the radiologic and clinical aspects. The thoracic computed tomography (CT) findings of all patients were assessed and accompanying conditions that may raise the morbidity were stated. The patients were divided into two groups as those who needed the intensive care unit administration and those treated with brief hospitalization; initial radiologic findings and preexisting medical situations of patients were compared among both groups respectively in terms of their prognostic value.

Results

In 39 patients with H1N1 infection (21 males and 18 females; mean age of 53.9±14 in range between 19 and 99 years); the necessity of intensive care was significantly higher in patients with solely chronic obstructive pulmonary disease (COPD) (P=0.008, Odds ratio: 27) or co-existence of COPD and malignity (Odds ratio: 13); however, no statistically significant difference between two groups was observed regarding the radiologic facts or other combinations of accompanying medical conditions in terms of any effects to the prognosis.

Conclusions

In the H1N1 (S-OIV) pandemic, we observed that merely the contribution to the diagnostic process; the radiologic features have no significance as being prognostic indicator. Additionally; the superposition of H1N1 infection in patients with either COPD or COPD by malignity was stated to be a potential risk factor in terms of increased morbidity.     

Serum procalcitonin concentrations in bacterial pneumonia in children: a negative result in primary healthcare settings

A microbe-specific diagnosis in community-acquired pneumonia (CAP) is difficult in children, and studies on nonspecific chest radiographic and host response markers have been inconsistent. Serum procalcitonin (PCT) is a newly recognized, promising marker for differentiating between bacterial and viral infections. Serum PCT was measured by a luminometric assay in 190 children with CAP diagnosed in the primary healthcare setting during a population-based study in a geographically defined population. The pneumococcal, mycoplasma, chlamydia, and viral etiology of infections was studied by an extensive serologic test panel. The median PCT concentrations were 0.47, 0.46, and 0.35 ng/mL in children aged <5 years, 5-9 years, and >/=10 years (P = 0.004). An elevated PCT >1.0 ng/mL was seen in 12.1% and >2.0 ng/mL in only 2.1% of the children. No association was seen between severity (inpatient vs. outpatient care) and etiology of CAP (evidence for pneumococcal, mycoplasma, or chlamydia, vs. viral infection). We conclude that serum PCT measurements have no role in the diagnosis of bacterial CAP in children in primary healthcare settings.     

Hematopoietic stem cell transplantation from a related donor infected with influenza H1N1 2009

S.H. Lee, H. Cheuh, K.H. Yoo, Y.J. Kim, K.W. Sung, H.H. Koo, D.H. Kim, S.J. Kim, K. Kim, J.H. Jang, C.W. Jung. Hematopoietic stem cell transplantation from a related donor infected with influenza H1N1 2009.
Transpl Infect Dis 2011: 13: 548–550. All rights reserved