Bacteriology of aspiration pneumonia in patients with acute coma

Accuracy of the Infectious Diseases Society of America and British Thoracic Society Criteria for Acute Pneumonia in Differentiating Chemical and Bacterial Complications of Aspiration in Comatose Ventilated Patients Following Drug Poisoning

Drug poisoning frequently leads to admission to intensive care units, often resulting in aspiration, a potentially life-threatening condition if not properly managed. Aspiration can manifest as either bacterial aspiration pneumonia (BAP) or aspiration pneumonitis (AP), which are challenging to distinguish potentially leading to overprescription of antibiotics and the emergence of multidrug-resistant bacteria. This study aims to assess the accuracy of the Infectious Diseases Society of America (IDSA) and British Thoracic Society (BTS) criteria in differentiating BAP from AP in comatose ventilated patients following drug poisoning. This cross-sectional study included 95 patients admitted for drug poisoning at the Lille University Hospital intensive care department, between 2013 and 2017, requiring mechanical ventilation and receiving antibiotics for aspiration. Patients were categorized as having bacterial complications if tracheal sampling yielded positive culture results, and if they were otherwise considered to have chemical complications. The sensitivity, specificity, positive predictive value, and negative predictive value of IDSA and BTS criteria in identifying patients with bacterial complications were evaluated. Among the patients, 34 (36%) experienced BAP. The IDSA criteria demonstrated a sensitivity of 62% and specificity of 33%, while the BTS criteria showed a sensitivity of 50% and specificity of 38%. Both the IDSA and BTS criteria exhibited poor sensitivity and specificity in identifying microbiologically confirmed pneumonia in comatose ventilated patients following drug poisoning.

The upper and lower respiratory tract microbiome in severe aspiration pneumonia

Uncertainty persists whether anaerobic bacteria represent important pathogens in aspiration pneumonia. In a nested case-control study of mechanically ventilated patients classified as macro-aspiration pneumonia (MAsP, n = 56), non-macro-aspiration pneumonia (NonMAsP, n = 91), and uninfected controls (n = 11), we profiled upper (URT) and lower respiratory tract (LRT) microbiota with bacterial 16S rRNA gene sequencing, measured plasma host-response biomarkers, analyzed bacterial communities by diversity and oxygen requirements, and performed unsupervised clustering with Dirichlet Multinomial Models (DMM). MAsP and NonMAsP patients had indistinguishable microbiota profiles by alpha diversity and oxygen requirements with similar host-response profiles and 60-day survival. Unsupervised DMM clusters revealed distinct bacterial clusters in the URT and LRT, with low-diversity clusters enriched for facultative anaerobes and typical pathogens, associated with higher plasma levels of SPD and sCD14 and worse 60-day survival. The predictive inter-patient variability in these bacterial profiles highlights the importance of microbiome study in patient sub-phenotyping and precision medicine approaches for severe pneumonia.

Development and validation of a novel poisoning agitation-sedation score for predicting the need for endotracheal intubation and mechanical ventilation in acutely poisoned patients with disturbed consciousness

BACKGROUND

Accurate assessment of disturbed consciousness level (DCL) is crucial for predicting acutely poisoned patients' outcomes.

AIM

Development of a novel Poisoning Agitation-Sedation Score (PASS) to predict the need for endotracheal intubation (ETI) and mechanical ventilation (MV) in acutely poisoned patients with DCL. Validation of the proposed score on a new set of acutely poisoned patients with DCL.

METHODS

This study was conducted on 187 acutely poisoned patients with DCL admitted to hospital from June 2020 to November 2021 (Derivation cohort). Patients' demographics, toxicological data, neurological examination, calculation of the Glasgow Coma Scale (GCS), Full Outline of Unresponsiveness (FOUR) score, Richmond Agitation-Sedation Scale (RASS), and outcomes were gathered for developing a new score. The proposed score was externally validated on 100 acutely poisoned patients with DCL (Validation cohort).

RESULTS

The PASS assessing sedation consists of FOUR (reflexes and respiration) and GCS (motor) and provides a significantly excellent predictive power (AUC = 0.975) at a cutoff ≤9 with 100% sensitivity and 92.11% specificity for predicting the need for ETI and MV in sedated patients. Additionally, adding RASS (agitation) to the previous model exhibits significantly good predictive power (AUC = 0.893), 90.32% sensitivity, and 73.68% specificity at a cutoff ≤14 for predicting the need for ETI and MV in disturbed consciousness patients with agitation.

CONCLUSION

The proposed PASS could be an excellent, valid and feasible tool to predict the need for ETI and MV in acutely poisoned disturbed consciousness patients with or without agitation.

Bacterial Aspiration Pneumonia in Generalized Convulsive Status Epilepticus: Incidence, Associated Factors and Outcome

Suspicion of bacterial aspiration pneumonia (BAP) is frequent during generalized convulsive status epilepticus (GCSE). Early identification of BAP is required in order to avoid useless antibiotic therapy. In this retrospective monocentric study, we aimed to determine the incidence of aspiration syndrome and BAP in GCSE requiring mechanical ventilation (MV) and factors associated with the occurrence of BAP. Patients were older than 18 years and had GCSE requiring MV. To distinguish BAP from pneumonitis, tracheal aspirate and quantitative microbiological criterion were used. Out of 226 consecutive patients, 103 patients (46%) had an aspiration syndrome, including 54 (52%) with a BAP. Staphylococcus aureus represented 33% of bacterial strains. No relevant baseline characteristics differed, including serum levels of CRP, PCT, and albumin. The median duration of treatment for BAP was 7 days (5-7). Patients with BAP did not have a longer duration of MV (p = 0.18) and ICU stay (p = 0.18) than those with pneumonitis. At 3 months, 24 patients (44%) with BAP and 10 (27%) with pneumonitis had a poor functional outcome (p = 0.06). In conclusion, among patients with GCSE, half of the patients had an aspiration syndrome and one-quarter suffered from BAP. Clinical characteristics and biomarkers were not useful for differentiating BAP from pneumonitis. These results highlight the need for a method to rapidly differentiate BAP from pneumonitis, such as polymerase-chain-reaction-based techniques.

[Management of Adult Community-Acquired Pneumonia and Prevention - Update 2021 - Guideline of the German Respiratory Society (DGP), the Paul-Ehrlich-Society for Chemotherapy (PEG), the German Society for Infectious Diseases (DGI), the German Society of Medical Intensive Care and Emergency Medicine (DGIIN), the German Viological Society (DGV), the Competence Network CAPNETZ, the German College of General Practitioneers and Family Physicians (DEGAM), the German Society for Geriatric Medicine (DGG), the German Palliative Society (DGP), the Austrian Society of Pneumology Society (ÖGP), the Austrian Society for Infectious and Tropical Diseases (ÖGIT), the Swiss Respiratory Society (SGP) and the Swiss Society for Infectious Diseases Society (SSI)]

The present guideline provides a new and updated concept of the management of adult patients with community-acquired pneumonia. It replaces the previous guideline dating from 2016.The guideline was worked out and agreed on following the standards of methodology of a S3-guideline. This includes a systematic literature search and grading, a structured discussion of recommendations supported by the literature as well as the declaration and assessment of potential conflicts of interests.The guideline has a focus on specific clinical circumstances, an update on severity assessment, and includes recommendations for an individualized selection of antimicrobial treatment.The recommendations aim at the same time at a structured assessment of risk for adverse outcome as well as an early determination of treatment goals in order to reduce mortality in patients with curative treatment goal and to provide palliation for patients with treatment restrictions.

Aspiration Risk Factors, Microbiology, and Empiric Antibiotics for Patients Hospitalized With Community-Acquired Pneumonia

BACKGROUND

Aspiration community-acquired pneumonia (ACAP) and community-acquired pneumonia (CAP) in patients with aspiration risk factors (AspRFs) are infections associated with anaerobes, but limited evidence suggests their pathogenic role.

RESEARCH QUESTION

What are the aspiration risk factors, microbiology patterns, and empiric anti-anaerobic use in patients hospitalized with CAP?

STUDY DESIGN AND METHODS

This is a secondary analysis of GLIMP, an international, multicenter, point-prevalence study of adults hospitalized with CAP. Patients were stratified into three groups: (1) ACAP, (2) CAP/AspRF+ (CAP with AspRF), and (3) CAP/AspRF- (CAP without AspRF). Data on demographics, comorbidities, microbiological results, and anti-anaerobic antibiotics were analyzed in all groups. Patients were further stratified in severe and nonsevere CAP groups.

RESULTS

We enrolled 2,606 patients with CAP, of which 193 (7.4%) had ACAP. Risk factors independently associated with ACAP were male, bedridden, underweight, a nursing home resident, and having a history of stroke, dementia, mental illness, and enteral tube feeding. Among non-ACAP patients, 1,709 (70.8%) had CAP/AspRF+ and 704 (29.2%) had CAP/AspRF-. Microbiology patterns including anaerobes were similar between CAP/AspRF-, CAP/AspRF+ and ACAP (0.0% vs 1.03% vs 1.64%). Patients with severe ACAP had higher rates of total gram-negative bacteria (64.3% vs 44.3% vs 33.3%, P = .021) and lower rates of total gram-positive bacteria (7.1% vs 38.1% vs 50.0%, P < .001) when compared with patients with severe CAP/AspRF+ and severe CAP/AspRF-, respectively. Most patients (>50% in all groups) independent of AspRFs or ACAP received specific or broad-spectrum anti-anaerobic coverage antibiotics.

INTERPRETATION

Hospitalized patients with ACAP or CAP/AspRF+ had similar anaerobic flora compared with patients without aspiration risk factors. Gram-negative bacteria were more prevalent in patients with severe ACAP. Despite having similar microbiological flora between groups, a large proportion of CAP patients received anti-anaerobic antibiotic coverage.

Comparison of the in Vivo Activities of Garenoxacin and Levofloxacin in a Murine Model of Pneumonia by Mixed-Infection with Streptococcus pneumoniae and Parvimonas micra

Community-acquired pneumonia (CAP) can involve mixed-species bacterial infection. However, few studies have investigated antimicrobial efficacy in the treatment of mixed species infections. This study aimed to compare the in vivo antimicrobial activity of garenoxacin (GRNX) and levofloxacin (LVFX) against Streptococcus pneumoniae and Parvimonas micra in a murine model of mixed species bacterial pneumonia. S. pneumoniae D-6888 and P. micra No. 242 were used in this study. Antimicrobial activity toward each isolate was calculated as the change in bacterial count in the lungs (Δlog₁₀ CFU/mL) of mice after 24 h of treatment compared with the count in pretreated animals (0 h). The MICs of GRNX and LVFX against S. pneumoniae D-6888 were 0.06 and 0.5 mg/L and the MICs against P. micra No. 242 were 0.03 and 0.12 mg/L, respectively. In a murine pneumonia mixed-infection model, GRNX showed significantly higher in vivo antimicrobial activity against S. pneumoniae than LVFX (GRNX; －2.02 ± 0.99 log₁₀ CFU/mL vs. LVFX; －0.97 ± 0.61 log₁₀ CFU/mL, p = 0.0188). GRNX displayed about 2-fold more potent activity against P. micra than LVFX (GRNX; －1.12 ± 0.56 log₁₀ CFU/mL vs. LVFX; －0.61 ± 0.43 log₁₀ CFU/mL, p = 0.1029). These results suggest that GRNX is preferable for the treatment of mixed species bacterial CAP.

Antimicrobial activity of solithromycin and levofloxacin against a murine pneumonia mixed-infection model caused by Streptococcus pneumoniae and anaerobic bacteria

INTRODUCTION

Solithromycin is a novel fluoroketolide developed to treat pneumonia. But, few studies evaluating its antimicrobial activity against S. pneumoniae in a mixed-infection model with anaerobes are available, while community-acquired pneumonia can involve mixed-infection of Streptococcus pneumoniae and anaerobic bacteria. This study evaluated the antimicrobial activity of solithromycin against macrolide-resistant S. pneumoniae and anaerobic bacteria with a murine pneumonia mixed-infection model.

MATERIAL AND METHODS

We evaluated antimicrobial activity of solithromycin (10 and 20 mg/kg) and levofloxacin (126 mg/kg) against S. pneumoniae with a three-point mutation in penicillin-binding protein and an ermB gene, and Parvimonas micra. Antimicrobial efficacy was calculated for each isolate as the change in bacterial count (Δlog₁₀ CFU/mL) obtained in the treated mice after 24 h compared with the count in the starting control animals.

RESULTS

The solithromycin and levofloxacin minimum inhibitory concentrations (MICs) for S. pneumoniae were 0.03 and 0.5 μg/mL, respectively. The solithromycin and levofloxacin MICs for P. micra were 0.015 and 0.12 μg/mL, respectively. In a mixed-infection model, solithromycin showed significantly higher antimicrobial activity against S. pneumoniae than levofloxacin (solithromycin 20 mg/kg; -2.87 ± 1.33 log₁₀ CFU/mL vs. levofloxacin; -1.35 ± 0.37 log₁₀ CFU/mL, p = 0.0397). Similarly, solithromycin showed significantly higher antimicrobial activity against P. micra than levofloxacin (solithromycin 20 mg/kg; -2.78 ± 0.98 log₁₀ CFU/mL vs. levofloxacin; -1.57 ± 0.47 log₁₀ CFU/mL, p = 0.0400).

DISCUSSION

Solithromycin showed higher antimicrobial activities against macrolide-resistant S. pneumoniae and P. micra than levofloxacin, even though they were coexisted in murine lung tissue. Our results suggest that solithromycin could be effective for pneumonia patients due to S. pneumoniae to reduce bacterial density in lung tissue.

Incidence and Consequences of Near-Drowning-Related Pneumonia-A Descriptive Series from Martinique, French West Indies

Drowning represents one major cause of accidental death. Near-drowning patients are exposed to aspiration that may result in pneumonia with life-threatening consequences. We designed this descriptive study to investigate the frequency, nature, and consequences of post-drowning pneumonia. One hundred and forty-four near-drowning patients (33 children and 111 adults) admitted during four years to the University Hospital of Martinique, French Indies, were included. Patients presented pre-hospital cardiac arrest (41%) and exhibited acute respiratory failure (54%), cardiovascular failure (27%), and lactic acidosis (75%) on admission. Empirical antibiotics, as decided by the physicians in charge, were administered in 85 patients (59%). Post-drowning early onset bacterial pneumonia was diagnosed as “possible” in 13 patients (9%) and “confirmed” in 22 patients (15%). Tracheal aspiration revealed the presence of polymorphous pharyngeal flora (59%) or one predominant bacteria species (41%) including Enterobacter aerogenes, Enterobacter cloacae, Staphylococcus aureus, Pseudomonas aeruginosa, Aeromonas hydrophilia, and Morganella morgani. Despite adequate supportive care, drowning resulted in 45 fatalities (31%). Early onset bacterial aspiration pneumonia (either possible or confirmed) did not significantly influence the risk of death. In conclusion, near-drowning–related bacterial aspiration pneumonia seems rare and does not influence the mortality rate. There is still a need for practice standardization to improve diagnosis of post-drowning pneumonia and near-drowning patient management.

Detection of cfxA2, cfxA3, and cfxA6 genes in beta-lactamase producing oral anaerobes

Purpose

The aim of this study was to identify β-lactamase-producing oral anaerobic bacteria and screen them for the presence of cfxA and BlaTEM genes that are responsible for β-lactamase production and resistance to β-lactam antibiotics.

Material and Methods

Periodontal pocket debris samples were collected from 48 patients with chronic periodontitis and anaerobically cultured on blood agar plates with and without β-lactam antibiotics. Presumptive β-lactamase-producing isolates were evaluated for definite β-lactamase production using the nitrocefin slide method and identified using the API Rapid 32A system. Antimicrobial susceptibility was performed using disc diffusion and microbroth dilution tests as described by CLSI Methods. Isolates were screened for the presence of the β-lactamase-TEM (BlaTEM) and β-lactamase-cfxA genes using Polymerase Chain Reaction (PCR). Amplified PCR products were sequenced and the cfxA gene was characterized using Genbank databases.

Results

Seventy five percent of patients carried two species of β-lactamase-producing anaerobic bacteria that comprised 9.4% of the total number of cultivable bacteria. Fifty one percent of β-lactamase-producing strains mainly Prevotella, Porphyromonas, and Bacteroides carried the cfxA gene, whereas none of them carried blaTEM. Further characterization of the cfxA gene showed that 76.7% of these strains carried the cfxA2 gene, 14% carried cfxA3, and 9.3% carried cfxA6. The cfxA6 gene was present in three Prevotella spp. and in one Porphyromonas spp. Strains containing cfxA genes (56%) were resistant to the β-lactam antibiotics.

Conclusion

This study indicates that there is a high prevalence of the cfxA gene in β-lactamase-producing anaerobic oral bacteria, which may lead to drug resistance and treatment failure.