A hypervirulent Acinetobacter baumannii strain has robust anti-phagocytosis ability.

BACKGROUND: Acinetobacter baumannii (A. baumannii) is associated with both hospital-acquired infections (HAP) and community-acquired pneumonia (CAP). In this study, we present a novel CAP-associated A. baumannii (CAP-AB) strain causing severe pneumonia in an afore healthy male patient without underlying conditions. Subsequently, we investigated the pathogenicity and immunogenicity of this CAP-AB strain using a mice pneumonia model. RESULTS: A 58-year-old male patient with no underlying conditions experienced worsening symptoms of a productive cough, sputum, and fever that developed acutely, in just 24 h. The diagnosis was severe community-acquired pneumonia (CAP) and type-1 respiratory failure. An A. baumannii strain was isolated from his sputum and blood cultures. To gain a deeper understanding of the rapid progression of its pathology, we utilized the CAP-associated A. baumannii strain YC128, a previously obtained hospital-acquired pneumonia A. baumannii (HAP-AB) strain YC156, and a highly virulent A. baumannii control strain LAC-4 to construct a mouse pneumonia model, and subsequently compared the mortality rate of the three groups. Following inoculation with 107 CFU of A. baumannii, the mortality rate for the YC128, LAC-4, and YC156 groups was 60% (6/10), 30% (3/10), and 0%, respectively. The bacterial burden within the pulmonary, liver, and spleen tissues of mice in the YC128 group was significantly higher than that of the YC156 group, and slightly higher than that of the LAC-4 group. Pathological analysis of lung tissue using HE-staining revealed that the inflammatory pathological changes in mice from the YC128 group were significantly more severe than those in the YC156 group. Additionally, CT scan images displayed more pronounced inflammation in the lungs of mice from the YC128 group compared to the YC156 group. Local levels of cytokines/chemokines such as IL-1ß, IL-6, TNF-α, and CXCL1 were assessed via RT-qPCR in lung tissues. In comparison with the YC156 strain, the highly virulent YC128 strain induced the expression of proinflammatory cytokines more rapidly and severely. Furthermore, we examined the in vitro anti-phagocytosis ability of YC128 and YC156 strains against mice peritoneal macrophages, revealing that the highly virulent YC128 isolate displayed greater resistance to macrophage uptake in contrast to YC156. Results from Whole Genome Sequencing (WGS) indicated that YC128 harbored a complete type VI secretion system (T6SS) gene cluster, while YC156 lacked the majority of genes within the T6SS gene cluster. The other virulence-related genes exhibited minimal differences between YC128 and YC156. Drawing from previous studies, we postulated that the T6SS is linked to the hypervirulence and robust anti-phagocytic ability of YC128. CONCLUSIONS: This article reports on the isolation of a novel hypervirulent CAP-AB strain, YC128, from a severe CAP patient. The results demonstrate that this CAP-AB strain, YC128, is capable of inducing fatal pneumonia and extrapulmonary dissemination in a mouse pneumonia model. Moreover, this highly virulent CAP-AB strain exhibits significantly stronger anti-phagocytic abilities compared to the HAP-AB YC156 strain. Genome sequencing comparisons reveal that the heightened hypervirulence and enhanced anti-phagocytosis abilities observed in YC128 may be attributed to the presence of the T6SS.

Etiology of bacterial pneumonia and multi-drug resistance pattern among pneumonia suspected patients in Ethiopia: a systematic review and meta-analysis.

BACKGROUND: Bacterial pneumonia can affect all age groups, but people with weakened immune systems, young children, and the elderly are at a higher risk. Streptococcus pneumoniae, Klebsiella pneumoniae, Haemophilus influenzae, and Pseudomonas aeruginosa are the most common causative agents of pneumonia, and they have developed high MDR in recent decades in Ethiopia. This systematic review and meta-analysis aimed to determine the pooled prevalence of bacterial pneumonia and multidrug resistance in Ethiopia. METHODS: The articles were searched extensively in the electronic databases and grey literature using entry terms or phrases. Studies meeting the eligibility criteria were extracted in MS Excel and exported for statistical analysis into STATA version 14 software. The pooled prevalence of bacterial pneumonia and multidrug resistance were calculated using a random-effects model. Heterogeneity was assessed by using the I2 value. Publication bias was assessed using a funnel plot and Egger's test. A sensitivity analysis was done to assess the impact of a single study on the pooled effect size. RESULT: Of the 651 studies identified, 87 were eligible for qualitative analysis, of which 11 were included in the meta-analysis consisting of 1154 isolates. The individual studies reported prevalence of bacterial pneumonia ranging from 6.19 to 46.3%. In this systematic review and metanalysis, the pooled prevalence of bacterial pneumonia in Ethiopia was 37.17% (95% CI 25.72-46.62), with substantial heterogeneity (I2 = 98.4%, p < 0.001) across the studies. The pooled prevalence of multidrug resistance in bacteria isolated from patients with pneumonia in Ethiopia was 67.73% (95% CI: 57.05-78.40). The most commonly isolated bacteria was Klebsiella pneumoniae, with pooled prevalence of 21.97% (95% CI 16.11-27.83), followed by Streptococcus pneumoniae, with pooled prevalence of 17.02% (95% CI 9.19-24.86), respectively. CONCLUSION: The pooled prevalence of bacterial isolates from bacterial pneumonia and their multidrug resistance were high among Ethiopian population. The initial empirical treatment of these patients remains challenging because of the strikingly high prevalence of antimicrobial resistance.

Lung ultrasound and procalcitonin, improving antibiotic management and avoiding radiation exposure in pediatric critical patients with bacterial pneumonia: a randomized clinical trial.

BACKGROUND: Pneumonia is a major public health problem with an impact on morbidity and mortality. Its management still represents a challenge. The aim was to determine whether a new diagnostic algorithm combining lung ultrasound (LUS) and procalcitonin (PCT) improved pneumonia management regarding antibiotic use, radiation exposure, and associated costs, in critically ill pediatric patients with suspected bacterial pneumonia (BP). METHODS: Randomized, blinded, comparative effectiveness clinical trial. Children < 18y with suspected BP admitted to the PICU from September 2017 to December 2019, were included. PCT was determined at admission. Patients were randomized into the experimental group (EG) and control group (CG) if LUS or chest X-ray (CXR) were done as the first image test, respectively. Patients were classified: 1.LUS/CXR not suggestive of BP and PCT < 1 ng/mL, no antibiotics were recommended; 2.LUS/CXR suggestive of BP, regardless of the PCT value, antibiotics were recommended; 3.LUS/CXR not suggestive of BP and PCT > 1 ng/mL, antibiotics were recommended. RESULTS: 194 children were enrolled, 113 (58.2%) females, median age of 134 (IQR 39-554) days. 96 randomized into EG and 98 into CG. 1. In 75/194 patients the image test was not suggestive of BP with PCT < 1 ng/ml; 29/52 in the EG and 11/23 in the CG did not receive antibiotics. 2. In 101 patients, the image was suggestive of BP; 34/34 in the EG and 57/67 in the CG received antibiotics. Statistically significant differences between groups were observed when PCT resulted < 1 ng/ml (p = 0.01). 3. In 18 patients the image test was not suggestive of BP but PCT resulted > 1 ng/ml, all of them received antibiotics. A total of 0.035 mSv radiation/patient was eluded. A reduction of 77% CXR/patient was observed. LUS did not significantly increase costs. CONCLUSIONS: Combination of LUS and PCT showed no risk of mistreating BP, avoided radiation and did not increase costs. The algorithm could be a reliable tool for improving pneumonia management. CLINICAL TRIAL REGISTRATION: NCT04217980.

Cost-effectiveness analysis of CTZ/TAZ for the treatment of ventilated hospital-acquired bacterial pneumonia and ventilator-associated bacterial pneumonia in Japan.

BACKGROUND: Resistant bacterial infections, particularly those caused by gram-negative pathogens, are associated with high mortality and economic burdens. Ceftolozane/tazobactam demonstrated efficacy comparable to meropenem in patients with ventilated hospital-acquired bacterial pneumonia in the ASPECT-NP study. One cost-effectiveness analysis in the United States revealed that ceftolozane/tazobactam was cost effective, but no Japanese studies have been conducted. Therefore, the objective of this study was to assess the cost-effectiveness of ceftolozane/tazobactam compared to meropenem for patients with ventilated hospital-acquired bacterial pneumonia/ventilator-associated bacterial pneumonia from a health care payer perspective. METHODS: A hybrid decision-tree Markov decision-analytic model with a 5-year time horizon were developed to estimate costs and quality-adjusted life-years and to calculate the incremental cost-effectiveness ratio associated with ceftolozane/tazobactam and meropenem in the treatment of patients with ventilated hospital-acquired bacterial pneumonia/ventilator-associated bacterial pneumonia. Clinical outcomes were based on the ASPECT-NP study, costs were based on the national fee schedule of 2022, and utilities were based on published data. One-way sensitivity analysis and probabilistic sensitivity analysis were also conducted to assess the robustness of our modeled estimates. RESULTS: According to our base-case analysis, compared with meropenem, ceftolozane/tazobactam increased the total costs by 424,731.22 yen (£2,626.96) and increased the quality-adjusted life-years by 0.17, resulting in an incremental cost-effectiveness ratio of 2,548,738 yen (£15,763.94) per quality-adjusted life-year gained for ceftolozane/tazobactam compared with meropenem. One-way sensitivity analysis showed that although the incremental cost-effectiveness ratio remained below 5,000,000 yen (£30,925) for most of the parameters, the incremental net monetary benefit may have been less than 0 depending on the treatment efficacy outcome, especially the cure rate and mortality rate for MEPM and mortality rate for CTZ/TAZ. 53.4% of the PSA simulations demonstrated that CTZ/TAZ was more cost-effective than MEPM was. CONCLUSION: Although incremental cost-effectiveness ratio was below ï¿¥5,000,000 in base-case analysis, whether ceftolozane/tazobactam is a cost-effective alternative to meropenem for ventilated hospital-acquired bacterial pneumonia/ventilator-associated bacterial pneumonia in Japan remains uncertain. Future research should examine the unobserved heterogeneity across patient subgroups and decision-making settings, to characterise decision uncertainty and its consequences so as to assess whether additional research is required.

Enhancing pediatric pneumonia diagnosis through masked autoencoders.

Pneumonia, an inflammatory lung condition primarily triggered by bacteria, viruses, or fungi, presents distinctive challenges in pediatric cases due to the unique characteristics of the respiratory system and the potential for rapid deterioration. Timely diagnosis is crucial, particularly in children under 5, who have immature immune systems, making them more susceptible to pneumonia. While chest X-rays are indispensable for diagnosis, challenges arise from subtle radiographic findings, varied clinical presentations, and the subjectivity of interpretations, especially in pediatric cases. Deep learning, particularly transfer learning, has shown promise in improving pneumonia diagnosis by leveraging large labeled datasets. However, the scarcity of labeled data for pediatric chest X-rays presents a hurdle in effective model training. To address this challenge, we explore the potential of self-supervised learning, focusing on the Masked Autoencoder (MAE). By pretraining the MAE model on adult chest X-ray images and fine-tuning the pretrained model on a pediatric pneumonia chest X-ray dataset, we aim to overcome data scarcity issues and enhance diagnostic accuracy for pediatric pneumonia. The proposed approach demonstrated competitive performance an AUC of 0.996 and an accuracy of 95.89% in distinguishing between normal and pneumonia. Additionally, the approach exhibited high AUC values (normal: 0.997, bacterial pneumonia: 0.983, viral pneumonia: 0.956) and an accuracy of 93.86% in classifying normal, bacterial pneumonia, and viral pneumonia. This study also investigated the impact of different masking ratios during pretraining and explored the labeled data efficiency of the MAE model, presenting enhanced diagnostic capabilities for pediatric pneumonia.

Early predictors of bacterial pneumonia infection in children with congenital heart disease after cardiopulmonary bypass: a single-centre retrospective study.

OBJECTIVES: The objective of this study was to evaluate the early predictors of bacterial pneumonia infection in children with congenital heart disease (CHD) after cardiopulmonary bypass (CPB). DESIGN: Retrospective study. SETTING: A freestanding tertiary paediatric hospital in China. PARTICIPANTS: Patients admitted to the hospital due to CHD who underwent open-heart surgery. OUTCOME MEASURES: We retrospectively reviewed and analysed data from 1622 patients with CHD after CPB from June 2018 to December 2020 at the Children's Hospital of Nanjing Medical University. Enrolled patients were assigned to an infection group or a non-infection group according to the presence of postoperative bacterial pneumonia infection, and the differences in clinical indicators were compared. Potential predictors were analysed by multivariate logistic regression analysis and area under the curve (AUC) analysis. RESULTS: Among the 376 patients (23.2%) in the infection group, the three most common bacteria were Streptococcus pneumoniae in 67 patients (17.8%), Escherichia coli in 63 patients (16.8%) and Haemophilus influenzae in 53 patients (14.1%). The infection group exhibited a lower weight (8.0 (6.0-11.5) kg vs 11.0 (7.5-14.5) kg, p<0.001). In the infection group, procalcitonin (PCT) (ng/mL: 4.72 (1.38-9.52) vs 1.28 (0.47-3.74), p<0.001) and C reactive protein (CRP) (mg/L: 21.0 (12.1-32.0) vs 17.0 (10.0-27.0), p<0.001) levels were significantly greater than those in the non-infection group. Binary logistic regression analysis revealed that weight, PCT and CRP were independent risk factors for pulmonary bacterial infection after CPB. The AUCs of weight, PCT, CRP and PCT+CRP for predicting pulmonary bacterial infection after CPB were 0.632 (95% CI 0.600 to 0.664), 0.697 (95% CI 0.667 to 0.727), 0.586 (95% CI 0.554 to 0.618) and 0.694 (95% CI 0.664 to 0.724), respectively, and the cut-off values were ≤10.25 kg, ≥4.25 ng/mL, ≥6.50 mg/L and ≥0.20, respectively. The sensitivities were 69.7%, 54.0%, 93.9% and 70.2%, and the specificities were 53.5%, 77.7%, 19.4% and 59.1%, respectively. CONCLUSIONS: In our study, weight, PCT and CRP were found to be independent predictors of pulmonary bacterial infection after CPB. Moreover, PCT was the most specific predictor, and CRP was the most sensitive independent predictor that might be beneficial for the early diagnosis of pulmonary bacterial infection after CPB in patients with CHD.

Characterization and Determinants of Long-Term Immune Recovery Under Suppressive Antiretroviral Therapy.

OBJECTIVE: We developed a robust characterization of immune recovery trajectories in people living with HIV on antiretroviral treatment (ART) and relate our findings to epidemiological risk factors and bacterial pneumonia. METHODS: Using data from the Swiss HIV Cohort Study and the Zurich Primary HIV Infection Cohort Study (n = 5907), we analyzed the long-term trajectories of CD4 cell and CD8 cell counts and their ratio in people living with HIV on ART for at least 8 years by fitting nonlinear mixed-effects models. The determinants of long-term immune recovery were investigated using generalized additive models. In addition, prediction accuracy of the modeled trajectories and their impact on the fit of a model for bacterial pneumonia was assessed. RESULTS: Overall, our population showed good immune recovery (median plateau [interquartile range]-CD4: 718 [555-900] cells/µL, CD8: 709 [547-893] cells/µL, CD4/CD8: 1.01 [0.76-1.37]). The following factors were predictive of recovery: age, sex, nadir/zenith value, pre-ART HIV-1 viral load, hepatitis C, ethnicity, acquisition risk, and timing of ART initiation. The fitted models proved to be an accurate and efficient way of predicting future CD4 and CD8 cell recovery dynamics: Compared with carrying forward the last observation, mean squared errors of the fitted values were lower by 1.3%-18.3% across outcomes. When modeling future episodes of bacterial pneumonia, using predictors derived from the recovery dynamics improved most model fits. CONCLUSION: We described and validated a method to characterize individual immune recovery trajectories of people living with HIV on suppressive ART. These trajectories accurately predict long-term immune recovery and the occurrence of bacterial pneumonia.

Evaluation of the effect of therapeutic durations on small ruminant bacterial pneumonia.

BACKGROUND: Sheep and goat production in Ethiopia is hindered by numerous substandard production systems and various diseases. Respiratory disease complexes (RDC) pose a significant threat to the productivity of these animals. Pneumonia is a common manifestation of respiratory disease complexes and often necessitates a prolonged course of antibiotic treatment. This study aimed to optimize and propose the ideal duration of therapy for pneumonia in sheep and goats. METHODS: The study was conducted from February to June 2021 at the Veterinary Teaching Hospital of the College of Veterinary Medicine and Agriculture, Addis Ababa University. The study recruited 54 sheep and goats presented to the hospital for treatment with a confirmed RDC as determined based on clinical signs and bacteriological methods. The animals were randomly allocated to 5 groups each group receiving 10% oxytetracycline (Phenxyl, Phenix, Belgum) intramuscularly for a duration of 3, 4, 5, 6 and 7 consecutive days. The treatment outcomes were assessed by recording vital signs (body temperature, respiratory rate, heart rate, coughing, and nasal discharges), performing lung ultrasonography (L-USG) as well as collection of nasal swabs for bacterial isolation and molecular identification before and after completion of the treatment. An ordered logistic regression model with random effects was employed to determine the optimal therapeutic duration, taking into account the cumulative scores of the outcome variables across the different groups. RESULTS: Among the 54 sheep and goats treated with 10% oxytetracycline, a total of 74.07% (95% CI, 60.35-85.04) achieved complete recovery, as confirmed through clinical, ultrasound, and bacteriological methods. In Group 1 (G1), out of 12 sheep and goats, 8 (83.0%) recovered completely; in Group 2 (G2), out of 11 animals, 9 (82.0%) recovered completely; in Group 3 (G3), out of 11 animals, 10 (93.0%) recovered completely; in Group 4 (G4), out of 9 animals, 9 (100.0%) recovered completely; and in Group 5 (G5), out of 11 animals, 10 (91.0%) recovered completely. Bacteriological examination of nasal swabs indicated involvement of M. hemolytica in 27 (50.00%) and P. multocida in 13 (24.07%) of pneumonic animals. Detection of specific marker genes confirmed only five of the presumptive M. hemolytica isolates, whilst no isolates tested positive for P. multocida. Post-treatment samples collected from recovered animals did not yield any M. hemolytica nor P. multocida. Based on results from clinical signs, L-USG, and bacterial infection variables, the group of sheep and goats treated for seven consecutive days (G5) showed the highest recovery score compared to the other groups, and there was a statistically significant difference (coefficient (ß) = - 2.296, p = 0.021) in variable score between G5 and G1. These findings suggest that the administration of 10% oxytetracycline for a full course of seven consecutive days resulted in symptomatic and clinical recovery rates from respiratory disease in sheep and goats.

Radiographic findings of adenoviral pneumonia in children.

OBJECTIVE: Adenovirus pneumonia is a common cause of community-acquired pneumonia in children and can mimic bacterial pneumonia, but there are few publications on its radiographic features. This study has evaluated the chest radiography findings of community-acquired adenovirus pneumonia in children. The frequency of radiological findings mimicking bacterial pneumonia was investigated. The clinical features of patients with adenovirus pneumonia possessing radiological findings mimicking bacterial pneumonia were also evaluated. MATERIALS AND METHODS: The chest radiographs of patients diagnosed with adenovirus pneumonia were retrospectively reviewed. The chest radiographs were interpreted independently by a pediatric infectious disease specialist and a pediatric radiologist. Chest radiography findings mimicking bacterial pneumonia (bacterial-like) were specified as consolidation +/- pleural effusion. Other findings on chest radiography or a completely normal chest X-ray were specified as findings that were compatible with "typical viral pneumonia". RESULTS: A total of 1407 patients were positive for adenovirus with respiratory multiplex PCR. The 219 patients who met the study criteria were included in the study. Chest radiographs were normal in 58 (26.5 %) patients. The chest radiograph findings mimicked bacterial pneumonia in 41 (18.7 %) patients. CONCLUSION: Adenovirus pneumonia occurs predominantly in children aged five years and younger, as with other viral pneumonias. The radiographic findings in adenovirus pneumonia are predominantly those seen in viral pneumonia. Increasing age and positivity for only adenovirus without other viruses on respiratory multiplex PCR were associated with the chest radiograph being more likely to be "bacterial-like". Adenovirus may lead to lobar/segmental consolidation at a rate that is not very rare.

In vitro modelling of bacterial pneumonia: a comparative analysis of widely applied complex cell culture models.

Bacterial pneumonia greatly contributes to the disease burden and mortality of lower respiratory tract infections among all age groups and risk profiles. Therefore, laboratory modelling of bacterial pneumonia remains important for elucidating the complex host-pathogen interactions and to determine drug efficacy and toxicity. In vitro cell culture enables for the creation of high-throughput, specific disease models in a tightly controlled environment. Advanced human cell culture models specifically, can bridge the research gap between the classical two-dimensional cell models and animal models. This review provides an overview of the current status of the development of complex cellular in vitro models to study bacterial pneumonia infections, with a focus on air-liquid interface models, spheroid, organoid, and lung-on-a-chip models. For the wide scale, comparative literature search, we selected six clinically highly relevant bacteria (Pseudomonas aeruginosa, Mycoplasma pneumoniae, Haemophilus influenzae, Mycobacterium tuberculosis, Streptococcus pneumoniae, and Staphylococcus aureus). We reviewed the cell lines that are commonly used, as well as trends and discrepancies in the methodology, ranging from cell infection parameters to assay read-outs. We also highlighted the importance of model validation and data transparency in guiding the research field towards more complex infection models.

PulmoNet: a novel deep learning based pulmonary diseases detection model.

Pulmonary diseases are various pathological conditions that affect respiratory tissues and organs, making the exchange of gas challenging for animals inhaling and exhaling. It varies from gentle and self-limiting such as the common cold and catarrh, to life-threatening ones, such as viral pneumonia (VP), bacterial pneumonia (BP), and tuberculosis, as well as a severe acute respiratory syndrome, such as the coronavirus 2019 (COVID-19). The cost of diagnosis and treatment of pulmonary infections is on the high side, most especially in developing countries, and since radiography images (X-ray and computed tomography (CT) scan images) have proven beneficial in detecting various pulmonary infections, many machine learning (ML) models and image processing procedures have been utilized to identify these infections. The need for timely and accurate detection can be lifesaving, especially during a pandemic. This paper, therefore, suggested a deep convolutional neural network (DCNN) founded image detection model, optimized with image augmentation technique, to detect three (3) different pulmonary diseases (COVID-19, bacterial pneumonia, and viral pneumonia). The dataset containing four (4) different classes (healthy (10,325), COVID-19 (3,749), BP (883), and VP (1,478)) was utilized as training/testing data for the suggested model. The model's performance indicates high potential in detecting the three (3) classes of pulmonary diseases. The model recorded average detection accuracy of 94%, 95.4%, 99.4%, and 98.30%, and training/detection time of about 60/50 s. This result indicates the proficiency of the suggested approach when likened to the traditional texture descriptors technique of pulmonary disease recognition utilizing X-ray and CT scan images. This study introduces an innovative deep convolutional neural network model to enhance the detection of pulmonary diseases like COVID-19 and pneumonia using radiography. This model, notable for its accuracy and efficiency, promises significant advancements in medical diagnostics, particularly beneficial in developing countries due to its potential to surpass traditional diagnostic methods.

Tau and Aß42 in lavage fluid of pneumonia patients are associated with end-organ dysfunction: A prospective exploratory study.

BACKGROUND: Bacterial pneumonia and sepsis are both common causes of end-organ dysfunction, especially in immunocompromised and critically ill patients. Pre-clinical data demonstrate that bacterial pneumonia and sepsis elicit the production of cytotoxic tau and amyloids from pulmonary endothelial cells, which cause lung and brain injury in naïve animal subjects, independent of the primary infection. The contribution of infection-elicited cytotoxic tau and amyloids to end-organ dysfunction has not been examined in the clinical setting. We hypothesized that cytotoxic tau and amyloids are present in the bronchoalveolar lavage fluid of critically ill patients with bacterial pneumonia and that these tau/amyloids are associated with end-organ dysfunction. METHODS: Bacterial culture-positive and culture-negative mechanically ventilated patients were recruited into a prospective, exploratory observational study. Levels of tau and Aß42 in, and cytotoxicity of, the bronchoalveolar lavage fluid were measured. Cytotoxic tau and amyloid concentrations were examined in comparison with patient clinical characteristics, including measures of end-organ dysfunction. RESULTS: Tau and Aß42 were increased in culture-positive patients (n = 49) compared to culture-negative patients (n = 50), independent of the causative bacterial organism. The mean age of patients was 52.1 ± 16.72 years old in the culture-positive group and 52.78 ± 18.18 years old in the culture-negative group. Males comprised 65.3% of the culture-positive group and 56% of the culture-negative group. Caucasian culture-positive patients had increased tau, boiled tau, and Aß42 compared to both Caucasian and minority culture-negative patients. The increase in cytotoxins was most evident in males of all ages, and their presence was associated with end-organ dysfunction. CONCLUSIONS: Bacterial infection promotes the generation of cytotoxic tau and Aß42 within the lung, and these cytotoxins contribute to end-organ dysfunction among critically ill patients. This work illuminates an unappreciated mechanism of injury in critical illness.

Socio-demographic and comorbid risk factors for poor prognosis in patients hospitalized with community-acquired bacterial pneumonia in southeastern US.

BACKGROUND: How socio-demographic characteristics and comorbidities affect bacterial community-acquired pneumonia (CAP) prognosis during/after hospitalization is important in disease management. OBJECTIVES: To identify predictors of medical intensive care unit (MICU) admission, length of hospital stay (LOS), in-hospital mortality, and bacterial CAP readmission in patients hospitalized with bacterial CAP. METHODS: ICD-9/10 codes were used to query electronic medical records to identify a cohort of patients hospitalized for bacterial CAP at a tertiary hospital in Southeastern US between 01/01/2013-12/31/2019. Adjusted accelerated failure time and modified Poisson regression models were used to examine predictors of MICU admission, LOS, in-hospital mortality, and 1-year readmission. RESULTS: There were 1956 adults hospitalized with bacterial CAP. Median (interquartile range) LOS was 11 days (6-23), and there were 26 % (513) MICU admission, 14 % (266) in-hospital mortality, and 6 % (117) 1-year readmission with recurrent CAP. MICU admission was associated with heart failure (RR 1.38; 95 % CI 1.17-1.62) and obesity (RR 1.26; 95 % CI 1.04-1.52). Longer LOS was associated with heart failure (adjusted time ratio[TR] 1.27;95 %CI 1.12-1.43), stroke (TR 1.90;95 %CI 1.54,2.35), type 2 diabetes (TR 1.20;95 %CI 1.07-1.36), obesity (TR 1.50;95 %CI 1.31-1.72), Black race (TR 1.17;95 %CI 1.04-1.31), and males (TR 1.24;95 %CI 1.10-1.39). In-hospital mortality was associated with stroke (RR 1.45;95 %CI 1.03-2.04) and age ≥65 years (RR 1.34;95 %CI 1.06-1.68). 1-year readmission was associated with COPD (RR 1.55;95 %CI 1.05-2.27) and underweight BMI (RR 1.74;95 %CI 1.04-2.90). CONCLUSIONS: Comorbidities and socio-demographic characteristics have varying impacts on bacterial CAP in-hospital prognosis and readmission. More studies are warranted to confirm these findings to develop comprehensive care plans and inform public health interventions.

Using a targeted metabolomics approach to explore differences in ARDS associated with COVID-19 compared to ARDS caused by H1N1 influenza and bacterial pneumonia.

RATIONALE: Acute respiratory distress syndrome (ARDS) is a life-threatening critical care syndrome commonly associated with infections such as COVID-19, influenza, and bacterial pneumonia. Ongoing research aims to improve our understanding of ARDS, including its molecular mechanisms, individualized treatment options, and potential interventions to reduce inflammation and promote lung repair. OBJECTIVE: To map and compare metabolic phenotypes of different infectious causes of ARDS to better understand the metabolic pathways involved in the underlying pathogenesis. METHODS: We analyzed metabolic phenotypes of 3 ARDS cohorts caused by COVID-19, H1N1 influenza, and bacterial pneumonia compared to non-ARDS COVID-19-infected patients and ICU-ventilated controls. Targeted metabolomics was performed on plasma samples from a total of 150 patients using quantitative LC-MS/MS and DI-MS/MS analytical platforms. RESULTS: Distinct metabolic phenotypes were detected between different infectious causes of ARDS. There were metabolomics differences between ARDSs associated with COVID-19 and H1N1, which include metabolic pathways involving taurine and hypotaurine, pyruvate, TCA cycle metabolites, lysine, and glycerophospholipids. ARDSs associated with bacterial pneumonia and COVID-19 differed in the metabolism of D-glutamine and D-glutamate, arginine, proline, histidine, and pyruvate. The metabolic profile of COVID-19 ARDS (C19/A) patients admitted to the ICU differed from COVID-19 pneumonia (C19/P) patients who were not admitted to the ICU in metabolisms of phenylalanine, tryptophan, lysine, and tyrosine. Metabolomics analysis revealed significant differences between C19/A, H1N1/A, and PNA/A vs ICU-ventilated controls, reflecting potentially different disease mechanisms. CONCLUSION: Different metabolic phenotypes characterize ARDS associated with different viral and bacterial infections.

Plasma levels of neurogenic inflammation related neuropeptides in pediatric patients with community-acquired pneumonia and their potential diagnostic value in distinguishing viral and bacterial pneumonia.

Neurogenic inflammation is involved in the development and progression of respiratory inflammatory diseases. However, its role in community-acquired pneumonia (CAP) remains unclear. We therefore aimed to investigate plasma levels of neurogenic inflammation-related neuropeptides, calcitonin gene-related peptide (CGRP), substance P (SP), vasoactive intestinal peptide (VIP) and neuropeptide Y (NPY), and procalcitonin (PCT) in pediatric patients with CAP and to assess their diagnostic value in viral and bacterial/mixed pneumonia. A total of 124 pediatric patients with CAP (1 month-18 years old) and 56 healthy children of similar ages were prospectively enrolled. The patients were classified as viral (n = 99) and bacterial/mixed (n = 25) pneumonia. Plasma levels of the peptides were quantified by ELISA. ROC analysis was performed to evaluate possible diagnostic value of the peptides. While plasma levels of CGRP, VIP and PCT were significantly higher in patients with CAP than in the control group, respectively, NPY levels were significantly lower. Moreover, plasma levels of all neuropeptides and PCT were significantly higher in bacterial pneumonia patients compared to viral pneumonia patients. ROC analysis revealed that CGRP, SP and NPY had a diagnostic value in distinguishing viral and bacterial/mixed pneumonia. CONCLUSIONS: Our findings suggest that these neuropeptides may be implicated in pediatric CAP. CGRP, SP and NPY together may be a promising candidate in distinguishing viral and bacterial/mixed pneumonia, however, for this, further studies are needed. WHAT IS KNOWN: • Neurogenic inflammation contributes to the development and progression of respiratory inflammatory diseases such as chronic obstructive pulmonary disease and bronchial asthma. WHAT IS NEW: • Plasma levels of neurogenic inflammation related neuropeptides calcitonin gene-related peptide, substance P, vasoactive intestinal peptide and neuropeptide Y are changed in pediatric community-acquired pneumonia. Calcitonin gene-related peptide, substance P and neuropeptide Y are promising candidates in distinguishing viral and bacterial/mixed pneumonia.

Achromobacter pneumonia in a patient with advanced COPD, a diagnostic challenge.

Bacterial pneumonia causes significant morbidity and mortality especially in elderly and immunocompromised hosts. Achromobacter xylosoxidans denitrificans pneumonia is very rarely reported. However, the reported cases have been in patients who are either immunocompromised or have bronchiectasis. We hereby present a unique case of Achromobacter xylosoxidans denitrificans pneumonia in an immunocompetent patient with advanced chronic obstructive pulmonary disease (COPD). Our patient is a Caucasian male admitted with shortness of breath, fever and cough. Chest X-ray demonstrated right-sided infiltrates and he was treated with intravenous ceftriaxone and azithromycin. He was discharged home on oral amoxicillin-clavulanate 875-125 mg two times per day for a total of 7 days. Patient returned to emergency room after 5 weeks with persistent symptoms and chest X-ray revealed persistent right-sided infiltrate and sputum culture showed Achromobacter xylosoxidans denitrificans. The patient was started on oral levofloxacin 750 mg one time per day for 2 weeks with resolution of symptoms.

Influenza and Viral Pneumonia.

Influenza and other respiratory viruses are commonly identified in patients with community-acquired pneumonia, hospital-acquired pneumonia, and in immunocompromised patients with pneumonia. Clinically, it is difficult to differentiate viral from bacterial pneumonia. Similarly, the radiological findings of viral infection are in general nonspecific. The advent of polymerase chain reaction testing has enormously facilitated the identification of respiratory viruses, which has important implications for infection control measures and treatment. Currently, treatment options for patients with viral infection are limited but there is ongoing research on the development and clinical testing of new treatment regimens and strategies.

Target attainment of intravenous lefamulin for treatment of acute bacterial skin and skin structure infections.

OBJECTIVES: Lefamulin is a pleuromutilin antibiotic approved for the treatment of community-acquired bacterial pneumonia (CABP). Its spectrum of activity, good penetration into soft tissues and low rates of cross-resistance also make lefamulin a potentially valuable option for treatment of acute bacterial skin and skin structure infections (ABSSSIs). A Phase 2 trial of lefamulin for ABSSSI indicated similar efficacy of 100 and 150 mg q12h IV dosing regimens. In the present study, the potential of lefamulin for this indication was further evaluated from a translational pharmacokinetic/pharmacodynamic perspective. METHODS: PTA was determined for various dosages using Monte Carlo simulations of a population pharmacokinetic model of lefamulin in ABSSSI patients and preclinical exposure targets associated with bacteriostasis and a 1-log reduction in bacterial count. Overall target attainment against MSSA and MRSA was calculated using lefamulin MIC distributions. RESULTS: Overall attainment of the bacteriostasis target was 94% against MSSA and 84% against MRSA for the IV dosage approved for CABP (150 mg q12h). Using the same target, for the 100 mg q12h regimen, overall target attainment dropped to 68% against MSSA and 50% against MRSA. Using the 1-log reduction target, overall target attainment for both regimens was <40%. CONCLUSIONS: Lefamulin at the currently approved IV dosage covers most Staphylococcus aureus isolates when targeting drug exposure associated with bacteriostasis, suggesting potential of lefamulin for the treatment of ABSSSIs. Lefamulin may not be appropriate in ABSSSI when rapid bactericidal activity is warranted.

Insights into the role of the respiratory tract microbiome in defense against bacterial pneumonia.

The respiratory tract microbiome (RTM) is a microbial ecosystem inhabiting different niches throughout the airway. A critical role for the RTM in dictating lung infection outcomes is underlined by recent efforts to identify community members benefiting respiratory tract health. Obligate anaerobes common in the oropharynx and lung such as Prevotella and Veillonella are associated with improved pneumonia outcomes and activate several immune defense pathways in the lower airway. Colonizers of the nasal cavity, including Corynebacterium and Dolosigranulum, directly impact the growth and virulence of lung pathogens, aligning with robust clinical correlations between their upper airway abundance and reduced respiratory tract infection risk. Here, we highlight recent work identifying respiratory tract bacteria that promote airway health and resilience against disease, with a focus on lung infections and the underlying mechanisms driving RTM-protective benefits.

Community-acquired bacterial pneumonia in children: an update on antibiotic duration and immunization strategies.

PURPOSE OF REVIEW: This review is structured to update clinicians on the epidemiology, antibiotic treatment, and prevention of pediatric bacterial pneumonia. The review provides information regarding the current research on antibiotic management for bacterial pneumonia and the newest immunization recommendations to prevent pneumococcal pneumonia and other respiratory infections. RECENT FINDINGS: The recommended length of antibiotic therapy for bacterial pneumonia has been discrepant between low-income and high-income countries. Recently, randomized controlled trials conducted in high-income countries provided evidence to support a short antibiotic course (3-5 days) for uncomplicated bacterial pneumonia in otherwise healthy children. The negative impact of inaccurate penicillin allergy labels in children with pneumonia has emphasized the importance of prompt allergy de-labeling. Newer pneumococcal vaccines are recommended for children and are expected to have a significant impact on bacterial pneumonia rates. SUMMARY: Pediatric bacterial pneumonia is an important contributor to childhood morbidity and mortality. A short antibiotic course seems to be sufficient for the outpatient management of uncomplicated bacterial pneumonia; however, more studies are required in the inpatient setting. Future studies will inform the impact of recently introduced pneumococcal and respiratory syncytial virus vaccines on the epidemiology of bacterial pneumonia.