Quantitative culture of endotracheal aspirate and BAL fluid samples in the management of patients with ventilator-associated pneumonia: a randomized clinical trial

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.

Systematic review of the impact of appropriate versus inappropriate initial antibiotic therapy on outcomes of patients with severe bacterial infections

We investigated the impact of appropriate versus inappropriate initial antimicrobial therapy on the clinical outcomes of patients with severe bacterial infections as part of a systematic review and meta-analyses assessing the impact of delay in appropriate antimicrobial therapy. Literature searches of MEDLINE and Embase, conducted on 24 July 2018, identified studies published after 2007 reporting the impact of delay in appropriate antibiotic therapy for hospitalised adult patients with bacterial infections. Results were statistically pooled for outcomes including mortality, hospital length of stay (LOS) and treatment failure. Subgroup analyses were explored by site of infection where data permitted. Inclusion criteria were met by 145 studies, of which 114 reported data on the impact of appropriate versus inappropriate initial therapy. In the pooled analysis, rates of mortality were significantly in favour of appropriate therapy [odds ratio (OR) = 0.44, 95% CI 0.38-0.50]. Across eight studies, LOS was shorter with appropriate therapy compared with inappropriate therapy [mean difference (MD) -2.54 days (95% CI -5.30 to 0.23)], but not significantly so. The incidence of treatment failure was significantly lower in patients who received appropriate therapy compared with patients who received inappropriate therapy (six studies: OR = 0.33, 95% CI 0.16-0.66) as was mean hospital costs (four studies: MD -7.38 thousand US$ or Euros, 95% CI -14.14 to -0.62). Initiation of appropriate versus inappropriate antibiotics can reduce mortality, reduce treatment failure and decrease LOS, highlighting the importance of broad‑spectrum empirical therapy and rapid diagnostics for early identification of the causative pathogen. [Study registration: PROSPERO: CRD42018104669].

Perioperative risk factors for postoperative pneumonia after major oral cancer surgery: A retrospective analysis of 331 cases

Objective

Postoperative pneumonia (POP) is common and results in prolonged hospital stays, higher costs, increased morbidity and mortality. However, data on the incidence and risk factors of POP after oral and maxillofacial surgery are rare. This study aims to identify perioperative risk factors for POP after major oral cancer (OC) surgery.

Methods

Perioperative data and patient records of 331 consecutive subjects were analyzed in the period of April 2014 to March 2016. We individually traced each OC patient for a period to discharge from the hospital or 45 days after surgery, whichever occur later.

Results

The incidence of POP after major OC surgery with free flap construction or major OC surgery was 11.6% or 4.5%, respectively. Patient-related risk factors for POP were male sex, T stage, N stage, clinical stage and preoperative serum albumin level. Among the investigated procedure-related variables, incision grade, mandibulectomy, free flap reconstruction, tracheotomy, intraoperative blood loss, and the length of the operation were shown to be associated with the development of POP. Postoperative hospital stay was also significantly related to increased incidence of POP. Using a multivariable logistic regression model, we identified male sex, preoperative serum albumin level, operation time and postoperative hospital stay as independent risk factors for POP.

Conclusion

Several perioperative risk factors can be identified that are associated with POP. At-risk oral cancer patients should be subjected to intensified postoperative pulmonary care.

Diagnostic Value of Endotracheal Aspirates Sonication on Ventilator-Associated Pneumonia Microbiologic Diagnosis

Microorganisms are able to form biofilms within respiratory secretions. Methods to disaggregate such biofilms before utilizing standard, rapid, or high throughput diagnostic technologies may aid in pathogen detection during ventilator associated pneumonia (VAP) diagnosis. Our aim was to determine if sonication of endotracheal aspirates (ETA) would increase the sensitivity of qualitative, semi-quantitative, and quantitative bacterial cultures in an animal model of pneumonia caused by Pseudomonas aeruginosa or by methicillin resistant Staphylococcus aureus (MRSA). Material and methods: P. aeruginosa or MRSA was instilled into the lungs or the oropharynx of pigs in order to induce severe VAP. Time point assessments for qualitative and quantitative bacterial cultures of ETA and bronchoalveolar lavage (BAL) samples were performed at 24, 48, and 72 h after bacterial instillation. In addition, at 72 h (autopsy), lung tissue was harvested to perform quantitative bacterial cultures. Each ETA sample was microbiologically processed with and without applying sonication for 5 min at 40 KHz before bacterial cultures. Sensitivity and specificity were determined using BAL as a gold-standard. Correlation with BAL and lung bacterial burden was also determined before and after sonication. Assessment of biofilm clusters and planktonic bacteria was performed through both optical microscopy utilizing Gram staining and Confocal Laser Scanning Microscopy utilizing the LIVE/DEAD^®BacLight kit. Results: 33 pigs were included, 27 and 6 from P. aeruginosa and MRSA pneumonia models, respectively. Overall, we obtained 85 ETA, 69 (81.2%) from P. aeruginosa and 16 (18.8%) from MRSA challenged pigs. Qualitative cultures did not significantly change after sonication, whereas quantitative ETA cultures did significantly increase bacterial counting. Indeed, sonication consistently increased bacterial burden in ETAs at 24, 48, and 72 h after bacterial challenge. Sonication also improved sensitivity of ETA quantitative cultures and maintained specificity at levels previously reported and accepted for VAP diagnosis. Conclusion: The use of sonication in ETA respiratory samples needs to be clinically validated since sonication could potentially improve pathogen detection before standard, rapid, or high throughput diagnostic methods used in routine microbial diagnostics.

New diagnostic methods for pneumonia in the ICU

PURPOSE OF REVIEW

Pneumonia leading to severe sepsis and critical illness including respiratory failure remains a common and therapeutically challenging diagnosis. Current clinical approaches to surveillance, early detection, and conventional culture-based microbiology are inadequate for optimal targeted antibiotic treatment and stewardship. Efforts to enhance diagnosis of community-acquired and health care-acquired pneumonia, including ventilator-associated pneumonia (VAP), are the focus of recent studies reviewed here.

RECENT FINDINGS

Newer surveillance definitions are sensitive for pneumonia in the ICU including VAP but consistently underdetect patients that are clinically shown to have bacterial VAP based on clinical diagnostic criteria and response to antibiotic treatment. Routinely measured plasma biomarkers, including procalcitonin and C-reactive protein, lack sufficient precision and predictive accuracy to inform diagnosis. Novel rapid microbiological diagnostics, including nucleic-acid amplification, mass spectrometry, and fluorescence microscopy-based technologies are promising approaches for the future. Exhaled breath biomarkers, including measurement of volatile organic compounds, represent a future approach.

SUMMARY

The integration of novel diagnostics for rapid microbial identification, resistance phenotyping, and antibiotic sensitivity testing into usual care practice could significantly transform the care of patients and potentially inform significantly improved targeted antimicrobial selection, de-escalation, and stewardship.

Quality of the aetiological diagnosis of ventilator-associated pneumonia in Spain in the opinion of intensive care specialists and microbiologists

INTRODUCTION

Current guidelines for the microbiological diagnosis of ventilator-associated pneumonia (VAP) are imprecise. Based on data provided by intensive care specialists (ICS) and microbiologists, this study defines the clinical practices and microbiological techniques currently used for an aetiological diagnosis of VAP and pinpoints deficiencies.

METHODS

Eighty hospitals in the national health network with intensive care and microbiology departments were sent two questionnaires, one for each department, in order to collect data on VAP diagnosis for the previous year.

RESULTS

Out of the 80 hospitals, 35 (43.8%) hospitals participated. These included 673 ICU beds, 32,020 ICU admissions, 173,820 ICU days stay, and generated 27,048 lower respiratory tract specimens in the year. A third of the hospitals (35%) had a microbiology department available 24/7. Most samples (83%) were tracheal aspirates. Gram stain results were immediately reported in around half (47%) of the hospitals. Quantification was made in 75% of hospitals. Molecular techniques and direct susceptibility testing were performed in 12% and one institution, respectively. Mean turnaround time for a microbiological report was 1.7 (SD; 0.7), and 2.2 (SD; 0.6) days for a negative and positive result, respectively. Telephone/in-person information was offered by 65% of the hospitals. Most (89%) ICS considered microbiological information as very useful. No written procedures were available in half the ICUs.

CONCLUSIONS

Both ICS and microbiologists agreed that present guidelines for the diagnosis of VAP could be much improved, and that a new set of consensus guidelines is urgently required. A need for guidelines to be more effectively implemented was also identified in order to improve outcomes in patients with VAP.

The value of antibody-coated bacteria in tracheal aspirates for the diagnosis of ventilator-associated pneumonia: a case-control study

Objective:

Ventilator-associated pneumonia (VAP) is the leading type of hospital-acquired infection in ICU patients. The diagnosis of VAP is challenging, mostly due to limitations of the diagnostic methods available. The aim of this study was to determine whether antibody-coated bacteria (ACB) evaluation can improve the specificity of endotracheal aspirate (EA) culture in VAP diagnosis.

Methods:

We conducted a diagnostic case-control study, enrolling 45 patients undergoing mechanical ventilation. Samples of EA were obtained from patients with and without VAP (cases and controls, respectively), and we assessed the number of bacteria coated with FITC-conjugated monoclonal antibodies (IgA, IgM, or IgG) or an FITC-conjugated polyvalent antibody. Using immunofluorescence microscopy, we determined the proportion of ACB among a fixed number of 80 bacteria.

Results:

The median proportions of ACB were significantly higher among the cases (n = 22) than among the controls (n = 23)-IgA (60.6% vs. 22.5%), IgM (42.5% vs. 12.5%), IgG (50.6% vs. 17.5%), and polyvalent (75.6% vs. 33.8%)-p < 0.001 for all. The accuracy of the best cut-off points for VAP diagnosis regarding monoclonal and polyvalent ACBs was greater than 95.0% and 93.3%, respectively.

Conclusions:

The numbers of ACB in EA samples were higher among cases than among controls. Our findings indicate that evaluating ACB in EA is a promising tool to improve the specificity of VAP diagnosis. The technique could be cost-effective and therefore useful in low-resource settings, with the advantages of minimizing false-positive results and avoiding overtreatment.

Interpretation for practice guidelines for prevention, diagnosis, and treatment of ventilator-associated pneumonia in burn patients by american burn association

“American Burn Association Practice Guidelines for Prevention, Diagnosis, and Treatment of Ventilator-Associated Pneumonia in Burn Patients” was published to provide recommendation for the prevention, diagnosis, and treatment of ventilator-associated pneumonia in burn patients. This article makes interpretations and conclusions for prevention, diagnosis and treatment from this guideline in the combination of domestic burn patients.