A comparison of pulmonary exacerbations with single and multiple organisms in patients with cystic fibrosis and chronic Burkholderia cepacia infection

Species distribution and antimicrobial susceptibility of Burkholderia cepacia complex isolates in clinical infections: Experience from a tertiary care hospital, Southern India

PURPOSE

Burkholderia cepacia complex (Bcc) is a diverse group of environmental bacteria associated with opportunistic infections. The identification of Bcc using conventional methods poses challenges. Bcc infections are difficult to treat due to intrinsic antibiotic resistance. The study aimed to investigate the species distribution and antimicrobial susceptibility of clinical Bcc isolates.

METHODS

A total of 153 Bcc isolates obtained from clinical samples were analysed. Species identification was carried out using automated methods, including MALDI-TOF MS and VITEK2. Antimicrobial susceptibility testing was performed using the disc diffusion method.

RESULTS

Burkholderia cenocepacia (70.5%) emerged as the most prevalent species, followed by Burkholderia contaminans (9.8%) and Burkholderia cepacia (7.2%). Ventilator-associated pneumonia (38.6%) was the most common infection, followed by sepsis (28.1%). Co-existence of Bcc with other pathogens in many cases suggested potential co-infection scenarios. Antimicrobial susceptibility revealed that ceftazidime, co-trimoxazole and meropenem were the most effective drugs, while levofloxacin proved to be the least effective. Moderate susceptibility was noted to minocycline, with 4.6% of isolates exhibiting multi-drug resistance.

CONCLUSION

This study provides valuable insights into the prevalence, clinical associations, and antibiotic susceptibility of Bcc in India. It highlights the importance of Bcc as a nosocomial pathogen, especially in vulnerable patient populations. The findings contribute to understanding Bcc infections, their distribution, and emphasize the necessity for accurate identification methods in clinical settings.

Outcomes and endpoints reported in studies of pulmonary exacerbations in people with cystic fibrosis: A systematic review

BACKGROUND

There is no consensus about which outcomes should be evaluated in studies of pulmonary exacerbations in people with cystic fibrosis (CF). Outcomes used for evaluation should be meaningful; that is, they should capture how people feel, function or survive and be acknowledged as important to people with CF, or should be reliable surrogates of those outcomes. We aimed to summarise the outcomes and corresponding endpoints which have been reported in studies of pulmonary exacerbations, and to identify those which are most likely to be meaningful.

METHODS

A PROSPERO registered systematic review (CRD42020151785) was conducted in Medline, Embase and Cochrane from inception until July 2020. Registered trials were also included.

RESULTS

144 studies met the inclusion criteria. A wide range of outcomes and corresponding endpoints were reported. Death, QoL and many patient-reported outcomes are likely to be meaningful as they directly capture how people feel, function or survive. Forced expiratory volume in 1-second [FEV₁] is a validated surrogate of risk of death and reduced QoL. The extent of structural lung disease has also been correlated with lung function, pulmonary exacerbations and risk of death. Since no evidence of a correlation between airway microbiology or biomarkers with clinically meaningful outcomes was found, the value of these as surrogates was unclear.

CONCLUSIONS

Death, QoL, patient-reported outcomes, FEV₁, and structural lung changes were identified as outcomes that are most likely to be meaningful. Development of a core outcome set in collaboration with stakeholders including people with CF is recommended.

A Pipeline for Screening Small Molecules with Growth Inhibitory Activity against Burkholderia cenocepacia

Infections with the bacteria Burkholderia cepacia complex (Bcc) are very difficult to eradicate in cystic fibrosis patients due the intrinsic resistance of Bcc to most available antibiotics and the emergence of multiple antibiotic resistant strains during antibiotic treatment. In this work, we used a whole-cell based assay to screen a diverse collection of small molecules for growth inhibitors of a relevant strain of Bcc, B. cenocepacia K56-2. The primary screen used bacterial growth in 96-well plate format and identified 206 primary actives among 30,259 compounds. From 100 compounds with no previous record of antibacterial activity secondary screening and data mining selected a total of Bce bioactives that were further analyzed. An experimental pipeline, evaluating in vitro antibacterial and antibiofilm activity, toxicity and in vivo antibacterial activity using C. elegans was used for prioritizing compounds with better chances to be further investigated as potential Bcc antibacterial drugs. This high throughput screen, along with the in vitro and in vivo analysis highlights the utility of this experimental method to quickly identify bioactives as a starting point of antibacterial drug discovery.

Clinical and in vitro evidence for the antimicrobial therapy in Burkholderia cepacia complex infections

Treatment of infections caused by Burkholderia cepacia complex (Bcc) in cystic fibrosis (CF) patients poses a complex problem. Bcc is multidrug-resistant due to innate and acquired mechanisms of resistance. As CF patients receive multiple courses of antibiotics, susceptibility patterns of strains from CF patients may differ from those noted in strains from non-CF patients. Thus, there was a need for assessing in vitro and clinical data to guide antimicrobial therapy in these patients. A systematic search of literature, followed by extraction and analysis of available information from human and in vitro studies was done. The results of the analysis are used to address various aspects like use of antimicrobials for pulmonary and non-pulmonary infections, use of combination versus monotherapy, early eradication, duration of therapy, route of administration, management of biofilms, development of resistance during therapy, pharmacokinetics-pharmacodynamics correlations, therapy in post-transplant patients and newer drugs in Bcc-infected CF patients.

The emerging relationship between the airway microbiota and chronic respiratory disease: clinical implications

Until recently, relationships between evidence of colonization or infection by specific microbial species and the development, persistence or exacerbation of pulmonary disease have informed our opinions of airway microbiology. However, recent applications of culture-independent tools for microbiome profiling have revealed a more diverse microbiota than previously recognized in the airways of patients with chronic pulmonary disease. New evidence indicates that the composition of airway microbiota differs in states of health and disease and with severity of symptoms and that the microbiota, as a collective entity, may contribute to pathophysiologic processes associated with chronic airway disease. Here, we review the evolution of airway microbiology studies of chronic pulmonary disease, focusing on asthma, chronic obstructive pulmonary disease and cystic fibrosis. Building on evidence derived from traditional microbiological approaches and more recent culture-independent microbiome studies, we discuss the implications of recent findings on potential microbial determinants of respiratory health or disease.

Effects of the microbial secondary metabolites pyrrolnitrin, phenazine and patulin on INS-1 rat pancreatic β-cells

The effects on pancreatic β-cell viability and function of three microbial secondary metabolites pyrrolnitrin, phenazine and patulin were investigated, using the rat clonal pancreatic β-cell line, INS-1. Cells were exposed to 10-fold serial dilutions (range 0-10 μg mL(-1)) of the purified compounds for 2, 24 and 72 h. After 2 h exposure, only patulin (10 μg mL(-1)) was cytotoxic. All compounds showed significant cytotoxicity after 24 h. None of the compounds altered insulin secretion with 2 and 20 mM glucose after 2 h. However, after 24 h treatment, phenazine and pyrrolnitrin (10 and 100 ng mL(-1)) potentiated insulin production and glucose-stimulated insulin secretion, whereas patulin had no effect. Exposure (24 h) to either phenazine (100 ng mL(-1)) or pyrrolnitrin (10 ng mL(-1)) caused similar increases in the Ca(2+) content of INS-1 cells. The outward membrane current was inhibited after 24 h exposure to either phenazine (100 ng mL(-1)) or pyrrolnitrin (10 or 100 ng mL(-1)). This study presents novel data suggesting that high concentrations of pyrrolnitrin and phenazine are cytotoxic to pancreatic β-cells and thus possibly diabetogenic, whereas at lower concentrations these agents are nontoxic and may be insulinotropic. The possible role of such agents in the development of cystic fibrosis-related diabetes is discussed.