Ventilator-associated pneumonia: problems with diagnosis and therapy

Dental and ENT Evaluation Before Liver Transplantation

The assessment of dental and ear, nose and throat (ENT) conditions holds significant importance in the pre-transplantation evaluation for individuals undergoing liver transplantation. This evaluation aims to address concerns related to dental and ENT issues both before and after liver transplantation. These concerns include the risk of sepsis, the impact of post-transplantation immunosuppression, the detection of existing malignancies, including oral potentially malignant disorders (OPMDs), and identifying any contraindications to the transplantation procedure. However, it is worth noting that there exists a notable absence of clear guidelines and protocols in the existing literature regarding this practice. Moreover, recent studies have presented conflicting results, and concerns have arisen regarding the cost-effectiveness of these evaluations. It is crucial to perform these investigations judiciously to avoid unnecessary testing burdens and delays in placing patients on waiting lists, particularly when considering live donor liver transplantation (LDLT) evaluations. A comprehensive examination of the oral and ENT regions, in conjunction with relevant laboratory tests, can play a pivotal role in identifying and managing oral and ENT diseases before the liver transplantation procedure. Timely recognition and treatment of potential issues are essential for minimizing perioperative morbidity and mortality. There is an evident need for prospective trials and studies to further explore and establish guidelines in the critical area of dental and ENT evaluation in liver transplantation recipients. Such research efforts would contribute significantly to enhancing our understanding and management of oral and ENT conditions in the pre-transplantation setting, ultimately improving patient care and outcomes.

Microbiome Profiling Demonstrates Concordance of Endotracheal Tube Aspirates With Direct Lower Airway Sampling in Intubated Patients

BACKGROUND

Endotracheal aspirates (ETAs) are widely used for microbiologic studies of the respiratory tract in intubated patients. However, they involve sampling through an established endotracheal tube using suction catheters, both of which can acquire biofilms that may confound results.

RESEARCH QUESTION

Does standard clinical ETA in intubated patients accurately reflect the authentic lower airway bacterial microbiome?

STUDY DESIGN AND METHODS

Comprehensive quantitative bacterial profiling using 16S rRNA V1-V2 gene sequencing was applied to compare bacterial populations captured by standard clinical ETA vs contemporaneous gold standard samples acquired directly from the lower airways through a freshly placed sterile tracheostomy tube. The study included 13 patients undergoing percutaneous tracheostomy following prolonged (median, 15 days) intubation. Metrics of bacterial composition, diversity, and relative quantification were applied to samples.

RESULTS

Pre-tracheostomy ETAs closely resembled the gold standard immediate post-tracheostomy airway microbiomes in bacterial composition and community features of diversity and quantification. Endotracheal tube and suction catheter biofilms also resembled cognate ETA and fresh tracheostomy communities.

INTERPRETATION

Unbiased molecular profiling shows that standard clinical ETA sampling has good concordance with the authentic lower airway microbiome in intubated patients.

The endotracheal tube microbiome associated with Pseudomonas aeruginosa or Staphylococcus epidermidis

Ventilator-associated pneumonia (VAP) is one of the commonest hospital-acquired infections associated with high mortality. VAP pathogenesis is closely linked to organisms colonizing the endotracheal tube (ETT) such as Staphylococcus epidermidis and Pseudomonas aeruginosa, the former a common commensal with pathogenic potential and the latter a known VAP pathogen. However, recent gut microbiome studies show that pathogens rarely function alone. Hence, we determined the ETT microbial consortium co-colonizing with S. epidermidis or P. aeruginosa to understand its importance in the development of VAP and for patient prognosis. Using bacterial 16S rRNA and fungal ITS-II sequencing on ETT biomass showing presence of P. aeruginosa and/or S. epidermidis on culture, we found that presence of P. aeruginosa correlated inversely with patient survival and with bacterial species diversity. A decision tree, using 16S rRNA and patient parameters, to predict patient survival was generated. Patients with a relative abundance of Pseudomonadaceae <4.6% and of Staphylococcaceae <70.8% had the highest chance of survival. When Pseudomonadaceae were >4.6%, age of patient <66.5 years was the most important predictor of patient survival. These data indicate that the composition of the ETT microbiome correlates with patient prognosis, and presence of P. aeruginosa is an important predictor of patient outcome.

Biofilm-dependent airway infections: a role for ambroxol?

Biofilms are a key factor in the development of both acute and chronic airway infections. Their relevance is well established in ventilator associated pneumonia, one of the most severe complications in critically ill patients, and in cystic fibrosis, the most common lethal genetic disease in Caucasians. Accumulating evidence suggests that biofilms could have also a role in chronic obstructive pulmonary disease and their involvement in bronchiectasis has been proposed as well. When they grow in biofilms, microorganisms become multidrug-resistant. Therefore the treatment of biofilm-dependent airway infections is problematic. Indeed, it still largely based on measures aiming to prevent the formation of biofilms or remove them once that they are formed. Here we review recent evidence suggesting that the mucokinetic drug ambroxol has specific anti-biofilm properties. We also discuss how additional pharmacological properties of this drug could be beneficial in biofilm-dependent airway infections. Specifically, we review the evidence showing that: 1-ambroxol exerts anti-inflammatory effects by inhibiting at multiple levels the activity of neutrophils, and 2-it improves mucociliary clearance by interfering with the activity of airway epithelium ion channels and transporters including sodium/bicarbonate and sodium/potassium/chloride cotransporters, cystic fibrosis transmembrane conductance regulator and aquaporins. As a whole, the data that we review here suggest that ambroxol could be helpful in biofilm-dependent airway infections. However, considering the limited clinical evidence available up to date, further clinical studies are required to support the use of ambroxol in these diseases.

Chlorhexidine for the prevention of ventilator associated pneumonia in critically ill adults

Nosocomial pneumonia is common in critically ill patients and is associated with high mortality rates. The development of pneumonia in the intensive care unit (ICU) has been associated with bacterial colonisation within the oral cavity and translocation into the respiratory tract. Over recent years, several strategies have been employed and recommended for preventing ventilator associated pneumonia in the ICU. Chlorhexidine, a topical antiseptic, is a promising agent in preventing nosocomial pneumonia because of its wide antimicrobial spectrum of activity, ease of administration, minimal concerns of contributing to bacterial resistance and relatively benign side effect profile. To evaluate the safety and efficacy of chlorhexidine in preventing nosocomial pneumonia in critically ill patients, we conducted a literature search by using PubMed, EMBASE, CINAHL, Web of Science, and MEDLINE databases; Google Scholar, and the Cochrane Central Register of Controlled Trials (1966– February 2013) for relevant studies. Overall, seven clinical trials were identified. These studies showed mixed results and the majority failed to demonstrate a significant reduction in the incidence of nosocomial pneumonia with the use of chlorhexidine. However, the cardiothoracic surgery ICU patient population may benefit from its use. Further studies are warranted to clearly define the role of chlorhexidine in preventing nosocomial pneumonia.