Corynebacterium pseudodiphtheriticum as a pathogen in bacterial co-infection in COVID-19 patients with mechanical ventilation

Assessment of the prognosis, frequency, and isolated bacteria in ventilator-associated pneumonia among patients with severe coronavirus disease 2019 pneumonia: A single-center retrospective observational study

INTRODUCTION

Acute respiratory distress syndrome (ARDS) due to severe coronavirus disease 2019 (COVID-19) pneumonia is associated with a high incidence of ventilator-associated pneumonia (VAP). We aimed to evaluate the epidemiology of VAP associated with severe COVID-19 pneumonia.

METHODS

This retrospective observational study recruited patients with COVID-19-associated ARDS admitted to our center from April 1, 2020, to September 30, 2021. The primary outcome was the survival-to-discharge rate. The secondary outcomes were the VAP rate, time to VAP, length of ICU stay, length of ventilator support, and isolated bacteria.

RESULTS

Sixty-eight patients were included in this study; 23 developed VAP. The survival-to-discharge rate was 60.9 % in the VAP group and 84.4 % in the non-VAP group. The median time to VAP onset was 16 days. The median duration of ventilator support and of ICU stay were higher in the VAP group than in the non-VAP group. The VAP rate was 33.8 %. The most common isolated species was Stenotrophomonas maltophilia. On admission, carbapenems were used in a maximum number of cases (75 %). Furthermore, the median body mass index (BMI) was lower and the median sequential organ failure assessment (SOFA) score on admission was higher in the VAP group than in the non-VAP group.

CONCLUSIONS

The survival-to-discharge rate in VAP patients was low. Moreover, VAP patients tended to have long ICU stays, low BMI, and high SOFA scores on admission. Unusually, S. maltophilia was the most common isolated bacteria, which may be related to the frequent use of carbapenems.

COVID-19 and brain-heart-lung microbial fingerprints in Italian cadavers

Introduction: The fact that SARS-CoV-2, the coronavirus that caused COVID-19, can translocate within days of infection to the brain and heart and that the virus can survive for months is well established. However, studies have not investigated the crosstalk between the brain, heart, and lungs regarding microbiota that simultaneously co-inhabit these organs during COVID-19 illness and subsequent death. Given the significant overlap of cause of death from or with SARS-CoV-2, we investigated the possibility of a microbial fingerprint regarding COVID-19 death. Methods: In the current study, the 16S rRNA V4 region was amplified and sequenced from 20 COVID-19-positive and 20 non-COVID-19 cases. Nonparametric statistics were used to determine the resulting microbiota profile and its association with cadaver characteristics. When comparing non-COVID-19 infected tissues versus those infected by COVID-19, there is statistical differences (p < 0.05) between organs from the infected group only. Results: When comparing the three organs, microbial richness was significantly higher in non-COVID-19-infected tissues than infected. Unifrac distance metrics showed more variance between control and COVID-19 groups in weighted analysis than unweighted; both were statistically different. Unweighted Bray-Curtis principal coordinate analyses revealed a near distinct two-community structure: one for the control and the other for the infected group. Both unweighted and weighted Bray-Curtis showed statistical differences. Deblur analyses demonstrated Firmicutes in all organs from both groups. Discussion: Data obtained from these studies facilitated the defining of microbiome signatures in COVID-19 decedents that could be identified as taxonomic biomarkers effective for predicting the occurrence, the co-infections involved in its dysbiosis, and the evolution of the virus.

The Respiratory Commensal Bacterium Corynebacterium pseudodiphtheriticum as a Mucosal Adjuvant for Nasal Vaccines

Previously, we demonstrated that nasally administered Corynebacterium pseudodiphteriticum 090104 (Cp) or its bacterium-like particles (BLPs) increase the resistance of mice against bacterial and viral respiratory pathogens by modulating the innate immunity. In this work, we evaluated the ability of Cp and BLPs to stimulate alveolar macrophages, and to enhance the humoral immune response induced by a commercial vaccine against Streptococcus pneumoniae. In the first set of experiments, Cp or the BLPs were incubated with primary cultures of murine alveolar macrophages and the phagocytic activity, and the production of cytokines was evaluated. The results revealed that Cp and BLPs were efficiently phagocyted by respiratory macrophages and that both treatments triggered the production of TNF-α, IFN-γ, IL-6, and IL-1β. In the second set of experiments, 3-week-old Swiss mice were intranasally immunized at days 0, 14, and 28 with the pneumococcal vaccine Prevenar®13 (PCV), Cp + PCV, or BLPs + PCV. On day 33, samples of bronco-alveolar lavages (BAL) and serum were collected for the study of specific antibodies. In addition, immunized mice were challenged with S. pneumoniae serotypes 6B or 19F on day 33 and sacrificed on day 35 (day 2 post-infection) to evaluate the resistance to the infection. Both Cp + PCV and BLPs + PCV groups had higher specific serum IgG and BAL IgA antibodies than the PCV control mice. In addition, the mice that were immunized with Cp + PCV or BLPs + PCV had lower lung and blood pneumococcal cell counts as well as lower levels of BAL albumin and LDH, indicating a reduced lung damage compared to the control mice. Improved levels of anti-pneumococcal antibodies were also detected in the serum and BAL samples after the challenges with the pathogens. The results demonstrated that C. pseudodiphteriticum 090104 and its bacterium-like particles are capable of stimulating the respiratory innate immune system serving as adjuvants to potentiate the adaptive humoral immune response. Our study is a step forward in the positioning of this respiratory commensal bacterium as a promising mucosal adjuvant for vaccine formulations aimed at combating respiratory infectious diseases.

Massive sequencing of the V3-V4 hypervariable region of bronchoalveolar lavage from patients with COVID-19 and VAP reveals the collapse of the pulmonary microbiota

Background. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic is a predisposing factor for the development of healthcare-associated infections, of which ventilator-associated pneumonia (VAP) is one.Hypothesis. VAP is caused by ESKAPE bacteria and other pathogens not detected by microbiological culture.Aim. To elucidate the bacterial pathogens of severe coronavirus disease 2019 (COVID-19) and VAP patients by massive sequencing and to predict their degree of relationship with the age and sex of the patients.Methods. Analysis of ribosomal libraries of the V3-V4 hypervariable region obtained by Illumina sequencing of bronchoalveolar lavages from COVID-19 and VAP (first wave) patients from Hospital Juárez de México.Results. Acinetobacter and Pseudomonas were the main bacterial genera in the bronchoalveolar lavages (BALs) analysed. Other members of the ESKAPE group, such as Enterococcus and Klebsiella, were also identified. Taxonomic composition per patient showed that non-ESKAPE genera were present with significant relative abundances, such as Prevotella, Stenotrophomas, Enterococcus, Mycoplasma, Serratia and Corynebacterium. Kruskal-Wallis analysis proved that VAP acquisition is an adverse event that is not influenced by the sex and age of COVID-19 patients.Discussion. Metagenomic findings in COVID-19/VAP patients highlight the importance of implementing comprehensive microbiological diagnostics by including alternative tools for the detection of the causal agents of healthcare-associated infections (HAIs).Conclusions. Timely identification of bacteria 'not sought' in diagnostic bacteriology laboratories will allow specific and targeted treatments. Implications for the restricted diagnosis of VAP causative agents in COVID-19 patients and the presence of pathogens not detected by classical microbiology are analysed and discussed.

Staphylococcus epidermidis Controls Opportunistic Pathogens in the Nose, Could It Help to Regulate SARS-CoV-2 (COVID-19) Infection?

Staphylococcus epidermidis is more abundant in the anterior nares than internal parts of the nose, but its relative abundance changes along with age; it is more abundant in adolescents than in children and adults. Various studies have shown that S. epidermidis is the guardian of the nasal cavity because it prevents the colonization and infection of respiratory pathogens (bacteria and viruses) through the secretion of antimicrobial molecules and inhibitors of biofilm formation, occupying the space of the membrane mucosa and through the stimulation of the host’s innate and adaptive immunity. There is a strong relationship between the low number of S. epidermidis in the nasal cavity and the increased risk of serious respiratory infections. The direct application of S. epidermidis into the nasal cavity could be an effective therapeutic strategy to prevent respiratory infections and to restore nasal cavity homeostasis. This review shows the mechanisms that S. epidermidis uses to eliminate respiratory pathogens from the nasal cavity, also S. epidermidis is proposed to be used as a probiotic to prevent the development of COVID-19 because S. epidermidis induces the production of interferon type I and III and decreases the expression of the entry receptors of SARS-CoV-2 (ACE2 and TMPRSS2) in the nasal epithelial cells.

Etiological significance of Corynebacterium spp. in the development of diseases of the respiratory tract

Corynebacterium spp. It is associated with inflammatory diseases of the respiratory tract (tracheitis, pharyngitis, rhinosinusitis, bronchitis, pneumonia, etc.). C. pseudodiphtheriticum can be the causative agent of bacterial coinfection in patients with a new coronavirus infection (COVID-19). The aim is to determine the pathogenic properties and resistance to antimicrobial drugs of Corynebacterium spp. strains to establish their etiological significance in the development of inflammatory diseases of the respiratory tract. Strains of Corynebacterium spp. isolated from patients with inflammatory diseases of the respiratory tract (43 pcs.) and practically healthy individuals (29 pcs.). Isolates were identified by mass spectrometric method (MALDI-TOF MS), their cytopathic effect in CHO-K1 cell culture, hemolytic, urease activity, antimicrobial drug resistance were determined. Strains of Corynebacterium spp. isolated from patients in the amount of 105 CFU/ml or more, practically healthy - 104 CFU/ml or less. Isolates of Corynebacterium spp. patients had a more pronounced cytopathic effect (83.7±11.1%) and were more often resistant to antimicrobial drugs than those isolated from practically healthy. To establish the etiological significance of Corynebacterium spp. isolates. in the development of inflammatory diseases of the respiratory tract, it is advisable to determine their amount in biological material (105 CFU/ml or more), the cytopathic effect on CHO-K1 cell culture, as well as the presence of multiple resistance to antimicrobial drugs. Differences in the characteristics of Corynebacterium spp. isolates. from patients with respiratory tract pathology and practically healthy individuals are associated with the strain, not the species, of corynebacteria.