The role of surveillance cultures in guiding ventilator-associated pneumonia therapy:

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.

Bronchoalveolar lavage of ventilator-associated pneumonia patients for antibiotic resistance and susceptibility test

Background and Aims

Ventilator-associated pneumonia is highly prevalent nosocomial infection among patients under mechanical ventilation. Bronchoalveolar lavage (BAL) is effective in identifying the type of pathogen involved and determine the course of antibiotic. The aim of this study was to evaluate the prevalence of different pathogens involved in ventilator-associated pneumonia (VAP) and associated antibiotic resistance and sensitivity pattern.

Methods

In this descriptive cross-sectional study, patients admitted to the intensive care unit under mechanical ventilation at Shahid Madani Educational and Medical Center in Karaj during 2018 and 2020 were included. BAL samples were obtained from the patients. Demographic data, duration of hospitalization, duration of mechanical ventilation, and antibiotic susceptibility and resistance tests were recorded for all the patients.

Results

Among 335 patients included in the study, 215 (64.2%) were males. The mean age of the patients was 55.06 ± 14.90 years. The most common pathogens reported were Acinetobacter baumannii (40%), Pseudomonas aeruginosa (21.2%), and Staphylococcus aureus (13.4%). The mean age of the patients, gender, duration of mechanical ventilation, and duration of hospitalization were not associated with the type of pathogen, P > .05, respectively.

Conclusion

BAL of these patients indicated that various pathogens are responsible for VAP, and can vary from patient to patient. Antibiotic resistance and susceptibility pattern of these pathogens vary and therefore is important in determining the course of the treatment.

Economic and Epidemiological Impact of an Improvement Plan for the Decrease of Ventilator-Associated Pneumonia in a Tertiary Hospital in Mexico

INTRODUCTION

The objective of this work is to measure the economic and epidemiological impact of the implementation of a comprehensive quality improvement plan (CQIP) for the prevention and reduction of ventilator-associated pneumonia (VAP) in the adult intensive care unit in a Mexican hospital.

MATERIALS AND METHODS

A cross-sectional, ambispective, comparative, analytical, observational study was conducted with epidemiological data on cases of health care-associated infections and with information from the Hospital Epidemiological Surveillance Unit from August 2017 to July 2018.

RESULTS

Before to the implementation of the CQIP, there were a total of 26 VAPs, with a rate of 32.2 per 1000 ventilator-days. After the implementation of CQIP, there were 14 VAPs, with a rate of 23.4 per 1000 ventilator-days, with a 46.2% decrease in incidence (P = 0.02). Before the installation of the interventions, the expense was $4,471,073.80, with an average cost per case of $171,964.38. The total cost per bed-day in the adult intensive care unit was $331,280.00, and for hospitalization, the cost was $192,038.00; for the use of antimicrobials, an expense of $749,689.20 was calculated, and for the use of mechanical ventilation, the cost was $2,974,275.60. The percentage of decrease in the cost of VAP after CQIP implementation was 46.5%.

CONCLUSIONS

The implementation of CQIP based on the risk evaluation factors of VAP resulted in their decrease, which is reflected in a patient safety and quality care improvement.

Bacteria in the respiratory tract-how to treat? Or do not treat?

BACKGROUND

Acute and chronic respiratory tract infections are a common cause of inappropriate antimicrobial prescription. Antimicrobial therapy leads to the development of resistance and the emergence of opportunistic pathogens that substitute the indigenous microbiota.

METHODS

This review explores the major challenges and lines of research to adequately establish the clinical role of bacteria and the indications for antimicrobial treatment, and reviews novel therapeutic approaches.

RESULTS

In patients with chronic pulmonary diseases and structural disturbances of the bronchial tree or the lung parenchyma, clinical and radiographic signs and symptoms are almost constantly present, including a basal inflammatory response. Bacterial adaptative changes and differential phenotypes are described, depending on the clinical role and niche occupied. The respiratory tract has areas that are potentially inaccessible to antimicrobials. Novel therapeutic approaches include new ways of administering antimicrobials that may allow intracellular delivery or delivery across biofilms, targeting the functions essential for infection, such as regulatory systems, or the virulence factors required to cause host damage and disease. Alternatives to antibiotics and antimicrobial adjuvants are under development.

CONCLUSIONS

Prudent treatment, novel targets, and improved drug delivery systems will contribute to reduce the emergence of antimicrobial resistance in lower respiratory tract infections.

Relation between presence of extended-spectrum β-lactamase-producing Enterobacteriaceae in systematic rectal swabs and respiratory tract specimens in ICU patients

BACKGROUND

The choice of empirical antimicrobial therapy for pneumonia in intensive care unit (ICU) is a challenge, since pneumonia is often related to multidrug-resistant pathogens, particularly extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E). To prevent the overuse of broad-spectrum antimicrobial therapy, the main objective of this study was to test the performance of digestive colonization surveillance as a predictor of ESBL-E presence or absence in respiratory samples performed in ICU and to evaluate the impact of time sampling (≤5 days or >5 days) on such prediction.

DESIGN

Multicentric retrospective observational study, including every patient with a respiratory tract specimen positive culture and a previous rectal ESBL-E screening performed within 7 days before the respiratory sample, between January 2012 and December 2014. Results were analyzed in two groups: respiratory samples obtained during the first 5 days of ICU stay (early group) and respiratory samples obtained after 5 days (late group).

INTERVENTIONS

none.

RESULTS

Among 2498 respiratory tract samples analyzed corresponding to 1503 patients, 1557 (62.3%) were performed early (≤5 days) and 941 (37.7%) later (>5 days). Positivity rates for ESBL-E were 15.0 and 36.8% for rectal swabs in the early and late groups, respectively. Sensitivity, specificity, positive (PPV) and negative (NPV) predictive values and likelihood ratios were calculated for ESBL-E digestive colonization as a predictor of ESBL-E presence in respiratory samples. PPVs of ESBL-E digestive colonization were 14.5% (95% CI [12.8; 16.3]) and 34.4% (95% CI [31.4; 37.4]), for the early and late groups, respectively, whereas NPVs were 99.2% (95% CI [98.7; 99.6]) and 93.4% (95% CI [91.9; 95.0]), respectively.

CONCLUSIONS

Systematic surveillance of ESBL-E digestive colonization may be useful to limit the use of carbapenems when pneumonia is suspected in ICU. When rectal swabs are negative, the risk of having ESBL-E in respiratory samples is very low even after 5 days of ICU stay.

Antibody-free detection of infectious bacteria using quantum dots-based barcode assay

Staphylococcus aureus, methicillin-resistant Staphylococcus aureus and Klebsiella pneumoniae are the most representative bacteria causing infectious diseases. Due to the increased application of antibiotics, the bacterial resistance is growing causing severe complications. Therefore, a sensitive determination of these pathogens is crucial for effective treatment. The aim of this study was to design an effective method for multiplex detection of Staphylococcus aureus, methicillin-resistant Staphylococcus aureus and Klebsiella pneumoniae taking advantage from properties of magnetic particles as well as fluorescent nanoparticles (quantum dots). The method was able to detect as low concentrations of bacteria as 10² CFU/mL using the bacteria-specific genes (fnbA, mecA and wcaG).

Rapid quantification of Staphylococcus aureus from endotracheal aspirates of ventilated patients: a proof-of-concept study

Major concern for intubated patients is ventilator-associated pneumonia (VAP). Early detection of VAP and its causative microorganism(s) is a key challenge for clinicians. Diagnosis is based on clinical, radiological, and microbiological elements, the latter being provided 24-48h after sampling. According to practices, clinicians can sample endotracheal aspirates (ETAs) so as to check for patient colonization or perform ETA in case of VAP suspicion. In this proof-of-concept study, we report the evaluation of a semiautomated molecular method to rapidly quantify Staphylococcus aureus, one of the most involved microorganisms in VAP, directly from raw ETA samples. After evaluation using artificial ETA samples, our method was applied on 40 clinical ETA samples. All S. aureus-positive samples were successfully detected and quantified. Our method can provide an efficient sample preparation protocol for all raw ETA samples, combined with an accurate quantification of the bacterial load, in less than 3h 30min.