Prevalence and outcome of severe chronic obstructive pulmonary disease exacerbations caused by multidrug-resistant bacteria:

Epidemiology and outcomes of multidrug-resistant bacterial infection in non-cystic fibrosis bronchiectasis

PURPOSE

Multidrug-resistant (MDR) bacteria impose a considerable health-care burden and are associated with bronchiectasis exacerbation. This study investigated the clinical outcomes of adult patients with bronchiectasis following MDR bacterial infection.

METHODS

From the Chang Gung Research Database, we identified patients with bronchiectasis and MDR bacterial infection from 2008 to 2017. The control group comprised patients with bronchiectasis who did not have MDR bacterial infection and were propensity-score matched at a 1:2 ratio. The main outcomes were in-hospital and 3-year mortality.

RESULTS

In total, 554 patients with both bronchiectasis and MDR bacterial infection were identified. The types of MDR bacteria that most commonly affected the patients were MDR- Acinetobacter baumannii (38.6%) and methicillin-resistant Staphylococcus aureus (18.4%), Extended-spectrum-beta-lactamases (ESBL)- Klebsiella pneumoniae (17.8%), MDR-Pseudomonas (14.8%), and ESBL-E. coli (7.5%). Compared with the control group, the MDR group exhibited lower body mass index scores, higher rate of chronic bacterial colonization, a higher rate of previous exacerbations, and an increased use of antibiotics. Furthermore, the MDR group exhibited a higher rate of respiratory failure during hospitalization (MDR vs. control, 41.3% vs. 12.4%; p < 0.001). The MDR and control groups exhibited in-hospital mortality rates of 26.7% and 7.6%, respectively (p < 0.001); 3-year respiratory failure rates of 33.5% and 13.5%, respectively (p < 0.001); and 3-year mortality rates of 73.3% and 41.5%, respectively (p < 0.001). After adjustments were made for confounding factors, the infection with MDR and MDR bacteria species were determined to be independent risk factors affecting in-hospital and 3-year mortality.

CONCLUSIONS

MDR bacteria were discovered in patients with more severe bronchiectasis and were independently associated with an increased risk of in-hospital and 3-year mortality. Given our findings, we recommend that clinicians identify patients at risk of MDR bacterial infection and follow the principle of antimicrobial stewardship to prevent the emergence of resistant bacteria among patients with bronchiectasis.

Early antibiotic therapy is associated with a lower probability of successful liberation from mechanical ventilation in patients with severe acute exacerbation of chronic obstructive pulmonary disease

Background

While antibiotic therapy is advocated to improve outcomes in acute exacerbation of chronic obstructive pulmonary disease (AECOPD) whenever mechanical ventilation is required, the evidence relies on small studies carried out before the era of widespread antibiotic resistance. Furthermore, the impact of systematic antibiotic therapy on successful weaning from mechanical ventilation was never investigated accounting for the competitive risk of death. The aim of the study was to assess whether early antibiotic therapy (eABT) increases successful mechanical ventilation weaning probability as compared to no eABT, in patients with AECOPD without pneumoniae, using multivariate competitive risk regression.

Methods

Retrospective analysis of patients admitted in 2 intensive care units (ICU) from 2012 to 2020 for AECOPD without pneumonia and requiring mechanical ventilation. eABT was defined as any anti-bacterial chemotherapy introduced during the first 24 h after ICU admission. The primary outcomes were the adjusted subdistribution hazard ratio (SHR) of the probability of being successfully weaned from mechanical ventilation (i.e. non-invasive and invasive ventilation) according to eABT status and accounting for the competitive risk of death.

Results

Three hundred and ninety-one patients were included, of whom 66% received eABT. eABT was associated with a lower probability of successful liberation from mechanical ventilation when accounting for the competing risk of death in multivariate analyses (SHR 0.71 [95% confidence interval, 0.57–0.89], p < 0.01), after adjustment with covariates of disease severity. This association was present in all subgroups except in patients under invasive mechanical ventilation on ICU day-1, in patients with ICU day-1 worst PaCO₂ > 74 torr (median value) and in patients with a documented bacterial bronchitis at ICU admission. Ventilator-free days at day 28, ICU-free days at day 28 and invasive mechanical ventilation-free days at day 28, were significantly lower in the eABT group, while there was no significant difference in mortality at day 28 between patients who received eABT and those who did not.

Conclusions

eABT was independently associated with a lower probability of being successfully weaned from mechanical ventilation, suggesting that the clinician decision to overrule systematic administration of eABT was not associated with a detectable harm in AECOPD ICU patients without pneumonia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-022-01060-2.

Multiple Compounds Secreted by Pseudomonas aeruginosa Increase the Tolerance of Staphylococcus aureus to the Antimicrobial Metals Copper and Silver

Alternative antimicrobials, such as metals, are one of the methods currently used to help mitigate antibiotic resistance. Metal-based antimicrobials such as copper and silver are used currently both to prevent and to treat infections. Although the efficacy of these antimicrobials has been determined in single-species culture, bacteria rarely exist in a single-species group in the environment. Both Pseudomonas aeruginosa and Staphylococcus aureus are often found associated with each other in severe chronic infections displaying increased virulence and antibiotic tolerance. In this study, we determined that multiple compounds secreted by P. aeruginosa are able to increase the tolerance of S. aureus to both copper and silver. This work demonstrates the expansive chemical communication occurring in polymicrobial infections between bacteria.

Metal-based antimicrobials have been used for thousands of years to treat and prevent bacterial infections. Currently, both silver and copper are used in health care and industry to prevent and treat the spread of harmful bacteria. However, like most antimicrobial agents, their efficacy against polymicrobial infections has not been fully elucidated. Coinfection with Pseudomonas aeruginosa and Staphylococcus aureus and the resulting interactions have been implicated in higher virulence, antibiotic resistance, and increased chronic infections. Here, the influence of secreted compounds from P. aeruginosa on metal antimicrobial tolerance in S. aureus was examined. This study determined that multiple compounds from P. aeruginosa increase the tolerance of S. aureus to copper and/or silver when cultured in simulated wound fluid. The presence of these secreted compounds from P. aeruginosa during exposure of S. aureus to copper or silver increased the MIC from 500 μM to 2,000 μM for copper and 16 to 63 μM for silver. The contribution of specific compounds to S. aureus tolerance was determined using gene deletion and disruption mutants, and metabolite analysis. Compounds identified as potential contributors were then individually added to S. aureus during metal exposure. Copper tolerance in S. aureus was found to be increased by amino acids and dihydroaeruginoate (Dha) secreted by P. aeruginosa. The silver tolerance provided to S. aureus was influenced only by two amino acids, serine and threonine, as well as the Pseudomonas quinolone signal (PQS) molecules from P. aeruginosa.

IMPORTANCE Alternative antimicrobials, such as metals, are one of the methods currently used to help mitigate antibiotic resistance. Metal-based antimicrobials such as copper and silver are used currently both to prevent and to treat infections. Although the efficacy of these antimicrobials has been determined in single-species culture, bacteria rarely exist in a single-species group in the environment. Both Pseudomonas aeruginosa and Staphylococcus aureus are often found associated with each other in severe chronic infections displaying increased virulence and antibiotic tolerance. In this study, we determined that multiple compounds secreted by P. aeruginosa are able to increase the tolerance of S. aureus to both copper and silver. This work demonstrates the expansive chemical communication occurring in polymicrobial infections between bacteria.

Risk Factors of Multidrug-Resistant Bacteria in Lower Respiratory Tract Infections: A Systematic Review and Meta-Analysis

Background

Multidrug-resistant (MDR) bacteria are the main cause of lower respiratory tract infections (LRTIs) with high mortality. The purpose of this study is to identify the risk factors associated with MDR by performing a systematic review and meta-analysis.

Methods

PubMed, EMBASE (via Ovid), and Cochrane Library were systematically searched for studies on the risk factors for MDR bacteria in LRTIs as of November 30, 2019. Literature screening, data abstraction, and quality assessment of the eligible studies were performed independently by two researchers.

Results

A total of 3,607 articles were retrieved, of which 21 articles representing 20 cohort studies published in English were included after title/abstract and full-text screening. Among the 21 articles involving 7,650 patients and 1,360 MDR organisms, ten reported the risk factors for MDR Gram-positive bacteria (GPB) and Gram-negative bacteria (GNB), ten for MDR GNB, and one for MDR GPB. The meta-analysis results suggested that prior antibiotic treatment, inappropriate antibiotic therapy, chronic lung disease, chronic liver disease and cerebral disease, prior MDR and PA infection/colonization, recent hospitalization, longer hospitalization stay, endotracheal tracheostomy and mechanical ventilation, tube feeding, nursing home residence, and higher disease severity score were independent risk factors for MDR bacteria.

Conclusions

This review identified fourteen clinical factors that might increase the risk of MDR bacteria in patients with LRTIs. Clinicians could take into account these factors when selecting antibiotics for patients and determine whether coverage for MDR bacteria is required. More well-designed studies are needed to confirm the various risk factors for MDR bacteria in the future.

Stenotrophomonas maltophilia Infection in a Patient with Acute Exacerbation of Chronic Obstructive Pulmonary Disease (COPD): A Colonizer or True Infection?

BACKGROUND This article describes a finding of sputum culture positive for Stenotrophomonas maltophilia in an elderly woman with past medical history of chronic obstructive pulmonary disease (COPD) and hypertension, presenting with acute hypoxemic hypercapnic respiratory failure secondary to COPD exacerbation from bronchitis/bronchopneumonia. CASE REPORT Computed tomography (CT) of the chest showed secretions in the lower lobe bronchi and small scattered clustered nodules consistent with bronchitis/mild bronchopneumonia without evidence of pulmonary embolism. A sputum culture was positive for Stenotrophomonas maltophilia. She was treated with trimethoprim/sulfamethoxazole for 10 days. She recovered and was subsequently discharged from the hospital. CONCLUSIONS Stenotrophomonas maltophilia, previously known as a colonizer, is now being recognized as a true respiratory infection, especially in immunocompromised patients and those with chronic diseases like COPD presenting with signs and symptoms of infection. Therefore, early identification and prompt treatment of Stenotrophomonas maltophilia infection is important for a favorable outcome.

Differences in microbial etiology between hospital-acquired pneumonia and ventilator-associated pneumonia: a single-center retrospective study in Guang Zhou

Purpose: Nosocomial pneumonia is a common nosocomial infection that includes hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia(VAP). It is an important cause of morbidity and mortality in hospitalized patients. This study aimed to evaluate the differences in microbial etiology and outcomes between HAP and VAP, particularly in related risk factors of multidrug-resistant organism (MDRO) causing HAP and VAP.

Patients and methods: This single-center retrospective, observational study included patients with HAP/VAP. Clinical and epidemiological data of nosocomial pneumonia confirmed by microbial etiology that occurred in the Third Affiliated Hospital of Sun Yat-sen University, China, from January 2014 to December 2017 were obtained.

Results: A total of 313 HAP cases and 106 VAP cases were included. The leading pathogens of HAP and VAP were similar, including Acinetobacter baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Antimicrobial susceptibility of the pathogens was low, and P. aeruginosa in VAP was less susceptible. In the multivariate logistic regression analysis, the risk factors associated with MDRO-HAP were chronic obstructive pulmonary disease, antibiotic therapy in the preceding 90 days, and prior endotracheal tracheostomy. The risk factor of MDRO-VAP was ≥5 days of hospitalization. The 30-day mortality rates of HAP and VAP were 18.5% and 42.5%.

Conclusion: The leading pathogens were similar in both HAP and VAP, and antimicrobial susceptibility of the pathogens was low. The risk factors associated with MDRO infection in HAP and VAP have significant variability; hence, attention should be paid to improve prognosis. VAP was associated with poorer outcomes compared with HAP.

Face mask sampling reveals antimicrobial resistance genes in exhaled aerosols from patients with chronic obstructive pulmonary disease and healthy volunteers

Introduction

The degree to which bacteria in the human respiratory tract are aerosolised by individuals is not established. Building on our experience sampling bacteria exhaled by individuals with pulmonary tuberculosis using face masks, we hypothesised that patients with conditions frequently treated with antimicrobials, such as chronic obstructive pulmonary disease (COPD), might exhale significant numbers of bacteria carrying antimicrobial resistance (AMR) genes and that this may constitute a previously undefined risk for the transmission of AMR.

Methods

Fifteen-minute mask samples were taken from 13 patients with COPD (five paired with contemporaneous sputum samples) and 10 healthy controls. DNA was extracted from cell pellets derived from gelatine filters mounted within the mask. Quantitative PCR analyses directed to the AMR encoding genes: blaTEM (β-lactamase), ErmB (target methylation), mefA (macrolide efflux pump) and tetM (tetracycline ribosomal protection protein) and six additional targets were investigated. Positive signals above control samples were obtained for all the listed genes; however, background signals from the gelatine precluded analysis of the additional targets.

Results

9 patients with COPD (69%), aerosolised cells containing, in order of prevalence, mefA, tetM, ErmB and blaTEM, while three healthy controls (30%) gave weak positive signals including all targets except blaTEM. Maximum estimated copy numbers of AMR genes aerosolised per minute were mefA: 3010, tetM: 486, ErmB: 92 and blaTEM: 24. The profile of positive signals found in sputum was not concordant with that in aerosol in multiple instances.

Discussion

We identified aerosolised AMR genes in patients repeatedly exposed to antimicrobials and in healthy volunteers at lower frequencies and levels. The discrepancies between paired samples add weight to the view that sputum content does not define aerosol content. Mask sampling is a simple approach yielding samples from all subjects and information distinct from sputum analysis. Our results raise the possibility that patient-generated aerosols may be a significant means of AMR dissemination that should be assessed further and that consideration be given to related control measures.

[Bacteriology of acute exacerbations of chronic obstructive pulmonary disease in Tunisia]

INTRODUCTION

The role of bacteria, including atypical organisms, in acute exacerbations of chronic obstructive pulmonary disease (AECOPD) has been assessed in various ways in Tunisia.

METHODS

This was a descriptive and analytical study of patients with a mean age of 68.3±10.5 years hospitalized for AECOPD. Bacteriological examination included a cytological sputum exam and serology for atypical organisms including Mycoplasma pneumoniae, Coxiella burnetii, Chlamydophila pneumoniae and Legionella pneumophila using standard techniques.

RESULTS

Of the 240 patients enrolled, 175 sputum cultures (73%) were considered significant. Twenty-nine cultures were positive (16.5%) and 31 microorganisms were isolated of which the most frequent were P. aeruginosa (25.8%), K. pneumoniae (16.2%), H. influenzae (13%) and S. pneumoniae (9.7%). The prevalence of C. pneumoniae, M. pneumoniae and C. burnetii was 8.4%, 9% and 6.6%, respectively. No L. pneumophila infection was found. The Anthonisen criteria were associated with a positive culture (P=0.04). Almost half (40.9%) of the isolates were resistant to conventional first line antibiotics (43.7% to amoxicillin-clavulanic acid).

CONCLUSIONS

Awareness of the low positivity of quantitative sputum bacteriology and the large percentage of resistant strains with a predominance of exclusively multi-resistant Pseudomonas should help in the management of patients with AECOPD.

Viral Etiology of Chronic Obstructive Pulmonary Disease Exacerbations during the A/H1N1pdm09 Pandemic and Postpandemic Period

Viral infections are one of the main causes of acute exacerbations of chronic obstructive pulmonary disease (AE-COPD). Emergence of A/H1N1pdm influenza virus in the 2009 pandemic changed the viral etiology of exacerbations that were reported before the pandemic. The aim of this study was to describe the etiology of respiratory viruses in 195 Spanish patients affected by AE-COPD from the pandemic until the 2011-12 influenza epidemic. During the study period (2009–2012), respiratory viruses were identified in 48.7% of samples, and the proportion of viral detections in AE-COPD was higher in patients aged 30–64 years than ≥65 years. Influenza A viruses were the pathogens most often detected during the pandemic and the following two influenza epidemics in contradistinction to human rhino/enteroviruses that were the main viruses causing AE-COPD before the pandemic. The probability of influenza virus detection was 2.78-fold higher in patients who are 30–64 years old than those ≥65. Most respiratory samples were obtained during the pandemic, but the influenza detection rate was higher during the 2011-12 epidemic. There is a need for more accurate AE-COPD diagnosis, emphasizing the role of respiratory viruses. Furthermore, diagnosis requires increased attention to patient age and the characteristics of each influenza epidemic.

New drug therapies for COPD

Clinical trials with new drugs for chronic obstructive pulmonary disease (COPD) have been performed. Viruses exacerbate COPD and bacteria may play a part in severe COPD; therefore, antibiotic and antiviral approaches have a sound rationale. Antiinflammatory approaches have been studied. Advances in understanding the molecular basis of other processes have resulted in novel drugs to target reactive oxidant species, mucus, proteases, fibrosis, cachexia, and muscle wasting, and accelerated aging. Studies with monoclonal antibodies have been disappointing, highlighting the tendency for infections and malignancies during treatment. Promising future directions are lung regeneration with retinoids and stem cells.

Bibliography. Current world literature

This bibliography is compiled by clinicians from the journals listed at the end of this publication. It is based on literature entered into our database between 1 November 2007 and 31 October 2008 (articles are generally added to the database about two and a half months after publication). In addition, the bibliography contains every paper annotated by reviewers; these references were obtained from a variety of bibliographic databases and published between the beginning of the review period and the time of going to press. The bibliography has been grouped into topics that relate to the reviews in this issue.

New drugs for exacerbations of chronic obstructive pulmonary disease

Tobacco smoking is the dominant risk factor for chronic obstructive pulmonary disease (COPD), but viral and bacterial infections are the major causes of exacerbations in later stages of disease. Reactive oxygen species (ROS), pathogen-associated molecular patterns (PAMPs), and damage-associated molecular patterns (DAMPs) activate families of pattern recognition receptors (PRRs) that include the toll-like receptors (TLRs). This understanding has led to the hypothesis that COPD is an archetypal disease of innate immunity. COPD is characterised by abnormal response to injury, with altered barrier function of the respiratory tract, an acute phase reaction, and excessive activation of macrophages, neutrophils, and fibroblasts in the lung. The activated non-specific immune system then mediates the processes of inflammation and repair, fibrosis, and proteolysis. COPD is also associated with corticosteroid resistance, abnormal macrophage and T-cell populations in the airway, autoinflammation and autoimmunity, aberrant fibrosis, accelerated ageing, systemic and concomitant disease, and defective regeneration. Such concepts have been used to generate a range of molecular targets, and clinical trials are taking place to identify effective drugs for the prevention and treatment of COPD exacerbations.

Treatment of acute bacterial exacerbations of chronic bronchitis

BACKGROUND

Controversies persist regarding the optimal management of patients with acute exacerbations of chronic bronchitis (AECB).

OBJECTIVE

To evaluate the available evidence on relevant issues, namely the need for administering antimicrobials in patients with AECB, the identification of the subgroup of patients with AECB needing antibiotics, the antimicrobial regimen of choice and its optimal duration, the existence of new agents, and the value of non-antimicrobial regimens for AECB.

METHODS

Data from various sources of evidence, including recent relevant meta-analyses, were appraised.

CONCLUSION

Administration of antimicrobial agents, combined with bronchodilators and systemic corticosteroids, is warranted in approximately half of AECBs (i.e., in bacterial exacerbations) to achieve a survival benefit. Simple clinical parameters, mainly sputum purulence, and biomarkers, such as procalcitonin, are useful in identifying patients requiring antibiotics. Advanced antibiotics (quinolones, macrolides, or amoxicillin/clavulanic acid) are more effective than 'old' antibiotics in AECB; regimens of short duration (for 5 days) are preferred. There is no difference between several classes of advanced antibiotics regarding their short-term effectiveness; however, quinolones are associated with better long-term outcomes than macrolides. Newer quinolones and new formulations of macrolides enrich clinicians' armamentarium against AECB.

A postmortem analysis of major causes of early death in patients hospitalized with COPD exacerbation

BACKGROUND

Mortality from COPD is increasing worldwide, but detailed causes of death are rarely assessed, particularly in low-income countries.

METHODS

In a retrospective study, we reviewed the autopsy reports and medical records of deceased patients admitted to the hospital for severe exacerbation of COPD, from January 2005 to December 2007, at the Institute for Pulmonary Diseases of Vojvodina, Serbia.

RESULTS

Forty-three patients with a hospital admission diagnosis of COPD exacerbation underwent autopsy; all had died within 24 h of admission to the hospital. Twenty-three patients (54%) had a long COPD history (> 10 years), and 19 patients (44%) had more than one hospitalization in the last year of life. The median age at death was 70 years (interquartile range, 65 to 75 years), and male sex was predominant (n = 31; 72%). The main (primary) causes of death were reported as cardiac failure (n = 16; 37.2%), pneumonia (n = 12; 27.9%), and pulmonary thromboembolism (PTE) (n = 9; 20.9%). Respiratory failure due to a progression of COPD was the primary cause of death in six patients (14%). Most patients had more then one comorbid disease (n = 33; 77%), and the most frequent comorbid disease was chronic heart failure (n = 25; 58%).

CONCLUSIONS

Autopsy results suggest that common contributing causes of early death in patients hospitalized with severe COPD exacerbation are concomitant complications, as follows: cardiac failure, pneumonia, and PTE. Quality improvement interventions should focus on recognizing and treating these conditions at the time of hospital admission.