Changing pharyngeal bacterial flora of hospitalized patients. Emergence of gram-negative bacilli

[Nosocomial pneumonia]

Nosocomial pneumonia is defined as pneumonia occurring ≥ 48 h after hospital admission in a patient without severe immunosuppression. It can occur in spontaneously breathing patients or with noninvasive ventilation (NIV) and mechanically ventilated patients. In patients with suspected ventilator-associated pneumonia (VAP) (semi)quantitative cultures of tracheobronchial aspirates or bronchoalveolar lavage fluid should be perfomed. The initial empirical antimicrobial treatment is determined by the risk for multidrug-resistant pathogens (MDRP). The advantage of combination treatment increases with the prevalence of MDRPs. The antibiotic treatment should be adapted when the microbiological results are available. After 72 h a standardized re-evaluation including the response to treatment and also checking of the suspected diagnosis of pneumonia in a structured form is mandatory. Treatment failure can occur as a primary or secondary failure and in the case of primary progression necessitates another comprehensive diagnostic work-up before any further antibiotic treatment.

Molecular Genetic Analysis of Perioperative Colonization by Infection-Related Microorganisms in Patients Receiving Intraoral Microvascular Grafts

Background/Objectives: In oral and maxillofacial surgery, the reconstruction of defects often involves the transfer of skin tissue into the oral cavity utilizing microvascular grafts. This study investigates postoperative changes in microbial colonization following intraoral microvascular transplantation, as well as potential influencing factors. Methods: In 37 patients undergoing intraoral reconstructions, pre- and postoperative swabs were taken from the donor and recipient regions to quantify the seven selected marker bacteria using TaqMan PCRs. Patient-specific factors and clinical data were also recorded. Results: The infection-associated Acinetobacter baumannii tended to decrease postoperatively, while the infectious pathogens Pseudomonas aeruginosa, Enterococcus faecalis and the family of Enterobacteriaceae showed a postoperative increase without being directly associated with a clinical infection. Streptococcus mitis showed a significant postoperative decrease on buccal mucosa and increase on the graft surface (oral dysbiosis) and was significantly reduced or displaced by other bacteria (e.g., Mycoplasma salivarium, positive selection) when treated with ampicillin/sulbactam. Conclusions: The cutaneous microbiome of the graft adapts to the local intraoral environment. Postoperative shifts in oral bacterial colonization and an increase in infection-relevant bacteria were observed. These perioperative changes in colonization are also influenced by the administration of ampicillin/sulbactam. Consequently, single doses of antibiotics appear to be more beneficial compared to longer-term preventive use.

Selective decontamination of the digestive tract: concept and application

Selective digestive decontamination (SDD) is a prophylactic strategy aimed at preventing or eradicating bacterial overgrowth in the intestinal flora that precedes the development of most infections in the Intensive Care Unit. SDD prevents serious infections, reduces mortality, is cost-effective, has no adverse effects, and its short- or long-term use is not associated with any significant increase in antimicrobial resistance. SDD is one of the most widely evaluated interventions in critically ill patients, yet its use is not widespread. The present article offers a narrative review of the most relevant evidence and an update of the pathophysiological concepts of infection control supporting the use of SDD.

Effectiveness of supervised implementation of an oral health care protocol on ventilator-associated pneumonia patients in intensive care units: a double-blind multicenter randomized controlled trial

Background

The available scientific evidence suggests a significant association between oral bacteria and the incidence of ventilator-associated pneumonia (VAP).

Aims

The aim of this study was to determine the effectiveness of an oral health protocol in the prevention of ventilator-associated pneumonia.

Methods

In this multi-center RCT, conducted in the intensive care units of neurological patients in three general teaching hospitals of two provinces located in the west of the Iran, a consecutive sample of 200 intubated patients were initially recruited. Patients were randomly allocated to the intervention (received oral health care based on evidence-based oral health protocol) or control (routine oral health care) groups. Both groups received their prescribed treatment regimen for seven consecutive days. The percentage of VAP diagnoses as main outcome assessed using clinical pulmonary infection score (CPIS).

Findings

The rate of VAP in the intervention and control groups was 5% and 64%, respectively. The intervention reduced the risk of VAP by 97% and this difference was statistically significant (P <0.001). The chance of VAP occurrence in patients with lower levels of consciousness in univariate and multivariate analysis was significantly higher (OR: 2.38; 95%CI: 1.11-5.26) P <0.05).

Conclusion

The results of our study suggest that the use of a dynamic supervised oral health care guideline is more effective than the routinely used protocols in the intensive care units of hospitals.

Oral colonization by gram-negative bacilli in patients with hematologic malignancies and solid tumors compared with healthy controls

BACKGROUND

Colonization of the oropharynx with gram-negative bacilli (GNB) is considered a negative prognostic factor in immunocompromised individuals. Hemato-oncologic patients represent a high-risk group due to their immunodeficiencies and associated treatments. This study aimed to determine the rates of oral colonization by GNB, associated factors, and clinical outcomes in patients with hematologic malignancies and solid tumors compared with healthy subjects.

METHODS

We conducted a comparative study of hemato-oncologic patients and healthy subjects from August to October 2022. Swabs were taken from the oral cavity; specimens with GNB were identified and tested for antimicrobial susceptibility.

RESULTS

We included 206 participants (103 hemato-oncologic patients and 103 healthy subjects). Hemato-oncologic patients had higher rates of oral colonization by GNB (34% vs. 17%, P = 0.007) and GNB resistant to third-generation cephalosporins (11.6% vs. 0%, P < 0.001) compared to healthy subjects. Klebsiella spp. was the predominant genus in both groups. The factor associated with oral colonization by GNB was a Charlson index ≥ 3, while ≥ 3 dental visits per year were a protective factor. Regarding colonization by resistant GNB in oncology patients, antibiotic therapy and a Charlson index ≥ 5 were identified as associated factors, while better physical functionality (ECOG ≤ 2) was associated with less colonization. Hemato-oncologic patients colonized with GNB had more 30-day infectious complications (30.5% vs. 2.9%, P = 0.0001) than non-colonized patients.

CONCLUSION

Oral colonization by GNB and resistant GNB are prevalent in cancer patients, especially those with higher scores on the severity scales. Infectious complications occurred more frequently in colonized patients. There is a knowledge gap about dental hygiene practices in hemato-oncologic patients colonized by GNB. Our results suggest that patients' hygienic-dietary habits, especially frequent dental visits, are a protective factor against colonization.

[Bacterial gut microbiota-key player in sepsis]

The gut microbiota is comprised of over 1200 different bacteria and forms a symbiotic community with the human organism, the holobiont. It plays an important role in the maintenance of homeostasis, e.g., of the immune system and essential metabolic processes. Disturbances in the balance of this reciprocal relationship are called dysbiosis and, in the field of sepsis, are associated with incidence of disease, extent of the systemic inflammatory response, severity of organ dysfunction, and mortality. In addition to providing guiding principles in the fascinating relationship between "human and microbe," this article summarizes recent findings regarding the role of the bacterial gut microbiota in sepsis, which is one a very relevant in intensive care medicine.

The Microbial Etiology of Community-Acquired Pneumonia in Adults: from Classical Bacteriology to Host Transcriptional Signatures

All modern advances notwithstanding, pneumonia remains a common infection with substantial morbidity and mortality. Understanding of the etiology of pneumonia continues to evolve as new techniques enable identification of already known organisms and as new organisms emerge. We now review the etiology of pneumonia (at present often called "community-acquired pneumonia") beginning with classic bacteriologic techniques, which identified Streptococcus pneumoniae as the overwhelmingly common cause, to more modern bacteriologic studies, which emphasize Haemophilus influenzae, Staphylococcus aureus, Moraxella catarrhalis, Enterobacteriaceae, Pseudomonas, and normal respiratory flora. Urine antigen detection is useful in identifying Legionella and pneumococcus. The low yield of bacteria in recent studies is due to the failure to obtain valid sputum samples before antibiotics are administered. The use of high-quality sputum specimens enables identification of recognized ("typical") bacterial pathogens as well as a role for commensal bacteria ("normal respiratory flora"). Nucleic acid amplification technology for viruses has revolutionized diagnosis, showing the importance of viral pneumonia leading to hospitalization with or without coinfecting bacterial organisms. Quantitative PCR study of sputum is in its early stages of application, but regular detection of high counts of bacterial DNA from organisms that are not seen on Gram stain or grown in quantitative culture presents a therapeutic dilemma. This finding may reflect the host microbiome of the respiratory tract, in which case treatment may not need to be given for them. Finally, host transcriptional signatures might enable clinicians to distinguish between viral and bacterial pneumonia, an important practical consideration.

Hospital-Acquired Pneumonia

Pneumonia acquired during hospitalization is called nosocomial pneumonia (NP). Nosocomial pneumonia is divided into two types. Hospital-acquired pneumonia (HAP) refers to hospital-acquired pneumonia, whereas ventilator-associated pneumonia (VAP) refers to ventilator-associated pneumonia. Most clinical literature stresses VAP’s importance and associated mortality and morbidity, whereas HAP is not given enough attention even while being the most common cause of NP. HAP, like VAP, carries a high mortality and morbidity. HAP is the commonest cause of mortality from hospital-acquired infections. HAP is a common determinant for intensive care unit (ICU) admits with respiratory failure. Recent research has identified definite risk factors responsible for HAP. If these are prevented or modified, the HAP incidence can be significantly decreased with improved clinical outcomes and lesser utilization of the health care resources. The prevention approach will need multiple strategies to address the issues. Precise epidemiological data on HAP is deficient due to limitations of the commonly used diagnostic measures. The diagnostic modalities available in HAP are less invasive than VAP. Recent infectious disease society guidelines have stressed the importance of HAP by removing healthcare-associated pneumonia as a diagnosis. Specific differences exist between HAP and VAP, which are gleaned over in this chapter.

An Analysis of the Infections and Determination of Empiric Antibiotic Therapy in Cats and Dogs with Cancer-Associated Infections

Cancer patients commonly develop infectious complications over the course of the disease. One thousand patients receiving treatment for an oncologic disease at a single veterinary teaching hospital were retrospectively reviewed for concurrent infections. A total of 153 confirmed bacterial infections were identified, 82 of which were abscesses or wounds, 13 of which were respiratory infections, 3 of which were ear infections, and 55 of which were urinary tract infections. It was observed that the majority of the infections were caused by bacteria that are normally associated with that specific site location. Escherichia coli was the most common pathogen linked to infections in general, but Staphylococcus pseudintermedius was a frequently identified pathogen associated with wound infections. The susceptibility to diverse antimicrobials varied with the site of infection. Eleven cases (7.1%) were caused by opportunistic infections of the site, and E. coli and Pseudomonas aeruginosa were the pathogens isolated. Those bacteria were resistant to many antibiotics but showed susceptibility to aminoglycosides, imipenem, quinolones, and polymyxin B. In conclusion, veterinary patients with cancer or those under treatment for tumors develop infections by commonly encountered bacteria in the different sites of the body, with a susceptibility to antibiotics that is not out of line from what is expected. A small subset of cases developed opportunistic infections, with microbes that were more resistant to many classes of antibiotics.

Association between the point-rating system used for oral health and the prevalence of Gram-negative bacilli in hematological inpatients: A retrospective cohort study

Gram-negative bacteremia is a major cause of death among hematology inpatients who require heavy-dose chemotherapy and hematopoietic stem cell transplantation. Gram-negative bacillus (GNB) is more likely to be detected when the oral health is poor. However, there is a dearth of studies on the relationship between oral assessment and prevalence of GNB in hematology inpatients.This retrospective study aimed to evaluate the relationship between the original point-rating system for oral health examinations (point-oral exam) and the prevalence of GNB in hematology inpatients at the hematology ward of the Yamanashi University Hospital. GNB was detected by cultivating samples from the sputum and blood of each patient.A total of 129 subjects underwent a medical checkup and point-oral exam. The sputum and blood culture results of 55 patients were included in this study. The total points of patients positive for GNB (n = 25, 45.5%) were significantly higher than those who were negative for GNB (total score: median, 25th, 75th, percentile; 6 [4, 7] vs 2 [1, 4]; P = .00016). Based on the receiver operating characteristic analysis, a cutoff score of 5 proved to be most useful to detect GNB.An oral evaluation with a cutoff value of 5 or higher in the point-oral exam might indicate the need for a more thorough oral management to prevent the development of systemic infections from GNB.

The Association Between Endotracheal Tube Size and Aspiration (During Flexible Endoscopic Evaluation of Swallowing) in Acute Respiratory Failure Survivors

OBJECTIVES

To determine whether a modifiable risk factor, endotracheal tube size, is associated with the diagnosis of postextubation aspiration in survivors of acute respiratory failure.

DESIGN

Prospective cohort study.

SETTING

ICUs at four academic tertiary care medical centers.

PATIENTS

Two hundred ten patients who were at least 18 years old, admitted to an ICU, and mechanically ventilated with an endotracheal tube for longer than 48 hours were enrolled.

INTERVENTIONS

Within 72 hours of extubation, all patients received a flexible endoscopic evaluation of swallowing examination that entailed administration of ice, thin liquid, thick liquid, puree, and cracker boluses. Patient demographics, treatment variables, and hospital outcomes were abstracted from the patient's medical records. Endotracheal tube size was independently selected by the patient's treating physicians.

MEASUREMENTS AND MAIN RESULTS

For each flexible endoscopic evaluation of swallowing examination, laryngeal pathology was evaluated, and for each bolus, a Penetration Aspiration Scale score was assigned. Aspiration (Penetration Aspiration Scale score ≥ 6) was further categorized into nonsilent aspiration (Penetration Aspiration Scale score = 6 or 7) and silent aspiration (Penetration Aspiration Scale score = 8). One third of patients (n = 68) aspirated (Penetration Aspiration Scale score ≥ 6) on at least one bolus, 13.6% (n = 29) exhibited silent aspiration, and 23.8% (n = 50) exhibited nonsilent aspiration. In a multivariable analysis, endotracheal tube size (≤ 7.5 vs ≥ 8.0) was significantly associated with patients exhibiting any aspiration (Penetration Aspiration Scale score ≥ 6) (p = 0.016; odds ratio = 2.17; 95% CI 1.14-4.13) and with risk of developing laryngeal granulation tissue (p = 0.02).

CONCLUSIONS

Larger endotracheal tube size was associated with increased risk of aspiration and laryngeal granulation tissue. Using smaller endotracheal tubes may reduce the risk of postextubation aspiration.

The Surviving Sepsis Campaign: Basic/Translational Science Research Priorities

Objectives:

Expound upon priorities for basic/translational science identified in a recent paper by a group of experts assigned by the Society of Critical Care Medicine and the European Society of Intensive Care Medicine.

Data Sources:

Original paper, search of the literature.

Study Selection:

By several members of the original task force with specific expertise in basic/translational science.

Data Extraction:

None.

Data Synthesis:

None.

Conclusions:

In the first of a series of follow-up reports to the original paper, several members of the original task force with specific expertise provided a more in-depth analysis of the five identified priorities directly related to basic/translational science. This analysis expounds on what is known about the question and what was identified as priorities for ongoing research. It is hoped that this analysis will aid the development of future research initiatives.

Decreased Intestinal Microbiome Diversity in Pediatric Sepsis: A Conceptual Framework for Intestinal Dysbiosis to Influence Immunometabolic Function

Supplemental Digital Content is available in the text.

Objectives:

The intestinal microbiome can modulate immune function through production of microbial-derived short-chain fatty acids. We explored whether intestinal dysbiosis in children with sepsis leads to changes in microbial-derived short-chain fatty acids in plasma and stool that are associated with immunometabolic dysfunction in peripheral blood mononuclear cells.

Design:

Prospective observational pilot study.

Setting:

Single academic PICU.

Patients:

Forty-three children with sepsis/septic shock and 44 healthy controls.

Measurements and Main Results:

Stool and plasma samples were serially collected for sepsis patients; stool was collected once for controls. The intestinal microbiome was assessed using 16S ribosomal RNA sequencing and alpha- and beta-diversity were determined. We measured short-chain fatty acids using liquid chromatography, peripheral blood mononuclear cell mitochondrial respiration using high-resolution respirometry, and immune function using ex vivo lipopolysaccharide-stimulated whole blood tumor necrosis factor-α. Sepsis patients exhibited reduced microbial diversity compared with healthy controls, with lower alpha- and beta-diversity. Reduced microbial diversity among sepsis patients (mainly from lower abundance of commensal obligate anaerobes) was associated with increased acetic and propionic acid and decreased butyric, isobutyric, and caproic acid. Decreased levels of plasma butyric acid were further associated with lower peripheral blood mononuclear cell mitochondrial respiration, which in turn, was associated with lower lipopolysaccharide-stimulated tumor necrosis factor-α. However, neither intestinal dysbiosis nor specific patterns of short-chain fatty acids were associated with lipopolysaccharide-stimulated tumor necrosis factor-α.

Conclusions:

Intestinal dysbiosis was associated with altered short-chain fatty acid metabolites in children with sepsis, but these findings were not linked directly to mitochondrial or immunologic changes. More detailed mechanistic studies are needed to test the role of microbial-derived short-chain fatty acids in the progression of sepsis.

The microbiota in pneumonia: From protection to predisposition

Mucosal surfaces of the upper respiratory tract and gut are physiologically colonized with their own collection of microbes, the microbiota. The normal upper respiratory tract and gut microbiota protects against pneumonia by impeding colonization by potentially pathogenic bacteria and by regulating immune responses. However, antimicrobial therapy and critical care procedures perturb the microbiota, thus compromising its function and predisposing to lung infections (pneumonia). Interindividual variations and age-related alterations in the microbiota also affect vulnerability to pneumonia. We discuss how the healthy microbiota protects against pneumonia and how host factors and medical interventions alter the microbiota, thus influencing susceptibility to pneumonia.

Disturbance in the oropharyngeal microbiota in relation to antibiotic and proton pump inhibitor medication and length of hospital stay

The aim of this study was to investigate the appearance of a disturbed oropharyngeal microbiota during hospitalization and explore the patient characteristics that maybe associated with such a disturbance. Oropharyngeal swabs were collected from 134 patients at hospital admission and every 3-4 days thereafter. The samples were cultivated to determine the presence of a disturbed microbiota, which, in turn, was subcategorized into respiratory tract pathogens, gut microbiota and yeast species. Demographics, medical history data and hospitalization events were compared. The percentage of disturbed oropharyngeal microbiota increased significantly with length of stay (LOS). Receiving antibiotic treatment during the hospitalization tended to be associated with a disturbed microbiota (OR 2.75 [0.99-7.60]). Proton pump inhibitor (PPI) medication and receiving antibiotics before hospitalization were associated with the development of a disturbed oropharyngeal microbiota with colonization of gut pathogens (OR 3.49 [1.19-10.2] and OR 4.52 [1.13-18.1], respectively), while acute hospital admission was associated with a lower risk of colonization of gut pathogens (OR: 0.23 [0.074-0.72]). The risk of developing a disturbed oropharyngeal microbiota increased with LOS in hospitalized patients. PPI medication and receiving antibiotics before hospitalization were independent risk factors for developing oropharyngeal colonization of gut pathogens.

Efficacy of Lactiplantibacillus plantarum 299 and 299v against nosocomial oropharyngeal pathogens in vitro and as an oral prophylactic treatment in a randomized, controlled clinical trial

Background

Disturbance in the oropharyngeal microbiota is common in hospitalized patients and contributes to the development of nosocomial pneumonia. Lactiplantibacillus plantarum 299 and 299v (Lp299 and Lp299v) are probiotic bacteria with beneficial effects on the human microbiome.

Aim

To investigate how Lp299 and Lp299v affect the growth of nosocomial oropharyngeal pathogens in vitro and to evaluate the efficacy in vivo when these probiotics are administered prophylactically in hospitalized patients.

Methods

The in vitro effect of Lp299 and Lp299v on nosocomial respiratory tract pathogens was evaluated using two methods, the co‐culture and agar overlay. In the clinical study, patients were randomized to orally receive either probiotics or placebo twice daily during their hospital stay. Oropharyngeal swabs were analyzed at inclusion and every fourth day throughout hospitalization.

Findings

All tested pathogens were completely inhibited by both Lp299 and Lp299v using the agar‐overlay method. In the co‐culture experiment, Lp299 and Lp299v significantly (p < 0.05) reduced the growth of all pathogens except for Enterococcus faecalis co‐incubated with Lp299. In the clinical study, daily oral treatment with Lp299 and Lp299v did not influence the development of disturbed oropharyngeal microbiota or nosocomial infection. Proton pump inhibitors, antibiotics, and steroid treatment were identified as risk factors for developing disturbed oropharyngeal microbiota.

Conclusions

Lp299 and Lp299v inhibited pathogen growth in vitro but did not affect the oropharyngeal microbiota in vivo. The ClinicalTrials.gov Identifier for this study is NCT02303301.

Gut Microbiota Modulation: Implications for Infection Control and Antimicrobial Stewardship

The human microbiome comprises a complex ecosystem of microbial communities that exist within the human body, the largest and most diverse of which are found within the human intestine. It has been increasingly implicated in human health and diseases, demonstrably playing a critical role in influencing host immune response, protection against pathogen overgrowth, biosynthesis, and metabolism. As our understanding of the links between the gut microbiota with host immunity and infectious diseases deepens, there is a greater need to incorporate methods of modulating it as a means of therapy or infection prevention in daily clinical practice. Traditional antimicrobial stewardship principles have been evaluated to assess their impact on the gut microbiota diversity and the consequent repercussions, taking into consideration antibiotic pharmacokinetic and pharmacodynamic properties. Novel strategies of selective digestive decontamination and fecal microbiota transplantation to regulate the gut microbiota have also been tested in different conditions with variable results. This review seeks to provide an overview of the available literature on the modulation of the gut microbiota and its implications for infection control and antimicrobial stewardship. With increased understanding, gut microbiota profiling through metataxonomic analysis may provide further insight into modulating microbial communities in the context of infection prevention and control.

The Social Distancing Imposed To Contain COVID-19 Can Affect Our Microbiome: a Double-Edged Sword in Human Health

Hygienic measures imposed to control the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and contain COVID-19 have proven effective in controlling the pandemic. In this article, we argue that these measures could impact the human microbiome in two different and disparate ways, acting as a double-edged sword in human health. New lines of research have shown that the diversity of human intestinal and oropharyngeal microbiomes can shape pulmonary viral infection progression. Here, we suggest that the disruption in microbial sharing, as it is associated with dysbiosis (loss of bacterial diversity associated with an imbalance of the microbiota with deleterious consequences for the host), may worsen the prognosis of COVID-19 disease.

Hygienic measures imposed to control the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and contain COVID-19 have proven effective in controlling the pandemic. In this article, we argue that these measures could impact the human microbiome in two different and disparate ways, acting as a double-edged sword in human health. New lines of research have shown that the diversity of human intestinal and oropharyngeal microbiomes can shape pulmonary viral infection progression. Here, we suggest that the disruption in microbial sharing, as it is associated with dysbiosis (loss of bacterial diversity associated with an imbalance of the microbiota with deleterious consequences for the host), may worsen the prognosis of COVID-19 disease. In addition, social detachment can also decrease the rate of transmission of antibiotic-resistant bacteria. Therefore, it seems crucial to perform new studies combining the pandemic control of COVID-19 with the diversity of the human microbiome.

The surviving sepsis campaign: basic/translational science research priorities

Objectives

Expound upon priorities for basic/translational science identified in a recent paper by a group of experts assigned by the Society of Critical Care Medicine and the European Society of Intensive Care Medicine.

Data sources

Original paper, search of the literature.

Study selection

This study is selected by several members of the original task force with specific expertise in basic/translational science. Data extraction and data synthesis are not available.

Conclusions

In the first of a series of follow-up reports to the original paper, several members of the original task force with specific expertise provided a more in-depth analysis of the five identified priorities directly related to basic/translational science. This analysis expounds on what is known about the question and what was identified as priorities for ongoing research. It is hoped that this analysis will aid the development of future research initiatives.

Biofilm formation on three different endotracheal tubes: a prospective clinical trial

BACKGROUND

Biofilm formation on endotracheal tubes (ETTs) is an early and frequent event in mechanically ventilated patients. The biofilm is believed to act as a reservoir for infecting microorganisms and thereby contribute to development and relapses of ventilator-associated pneumonia (VAP). Once a biofilm has formed on an ETT surface, it is difficult to eradicate. This clinical study aimed to compare biofilm formation on three widely used ETTs with different surface properties and to explore factors potentially predictive of biofilm formation.

METHODS

We compared the grade of biofilm formation on ETTs made of uncoated polyvinyl chloride (PVC), silicone-coated PVC, and PVC coated with noble metals after > 24 h of mechanical ventilation in critically ill patients. The comparison was based on scanning electron microscopy of ETT surfaces, biofilm grading, surveillance and biofilm cultures, and occurrence of VAP.

RESULTS

High-grade (score ≥ 7) biofilm formation on the ETTs was associated with development of VAP (OR 4.17 [95% CI 1.14-15.3], p = 0.031). Compared to uncoated PVC ETTs, the silicone-coated and noble-metal-coated PVC ETTs were independently associated with reduced high-grade biofilm formation (OR 0.18 [95% CI 0.06-0.59], p = 0.005, and OR 0.34 [95% CI 0.13-0.93], p = 0.036, respectively). No significant difference was observed between silicon-coated ETTs and noble-metal-coated ETTs (OR 0.54 [95% CI 0.17-1.65], p = 0.278). In 60% of the oropharyngeal cultures and 58% of the endotracheal cultures collected at intubation, the same microorganism was found in the ETT biofilm at extubation. In patients who developed VAP, the causative microbe remained in the biofilm in 56% of cases, despite appropriate antibiotic therapy. High-grade biofilm formation on ETTs was not predicted by either colonization with common VAP pathogens in surveillance cultures or duration of invasive ventilation.

CONCLUSION

High-grade biofilm formation on ETTs was associated with development of VAP. Compared to the uncoated PVC ETTs, the silicone-coated and noble-metal-coated PVC ETTs were independently associated with reduced high-grade biofilm formation. Further research on methods to prevent, monitor, and manage biofilm occurrence is needed.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02284438 . Retrospectively registered on 21 October 2014.

Microbiome: what intensivists should know

The standard conditions of critical illness (including sepsis, acute respiratory distress syndrome, and multiorgan failure) cause enormous global mortality and a growing economic burden. Increasing evidence suggests that critical illness may be associated with loss of commensal microbes and overgrowth of potentially pathogenic and inflammatory bacteria. This state could be associated with poor outcomes. Therefore, microbiota-targeted interventions are potentially attractive novel treatment options. Although the precise mechanisms of microbiome-directed treatments such as prebiotics, probiotics, and fecal microbiota transplantation remain to be determined, they can be utilized in the Intensive Care Unit (ICU) setting. The current review aims to offer intensivists an evidenced-based approach on what we currently know about the role of the microbiome in critical illness and how the microbiome could be targeted in the clinical practice to improve ICU-related outcomes.

Metabolomics and the Microbiome as Biomarkers in Sepsis

Metabolomics is an emerging field of research interest in sepsis. Metabolomics provides new ways of exploring the diagnosis, mechanism, and prognosis of sepsis. Advancements in technologies have enabled significant improvements in identifying novel biomarkers associated with the disease progress of sepsis. The use of metabolomics in the critically ill may provide new approaches to enable precision medicine. Furthermore, the dynamic interactions of the host and its microbiome can lead to further progression of sepsis. Understanding these interactions and the changes in the host's genomics and the microbiome can provide novel preventive and therapeutic strategies against sepsis.

Oral colonisation by antimicrobial-resistant Gram-negative bacteria among long-term care facility residents: prevalence, risk factors, and molecular epidemiology

Background

For residents of long-term care facilities (LTCFs), antimicrobial-resistant bacteria (ARB) are a risk factor, yet their oral colonisation, potentially leading to aspiration pneumonia, remains unclear. This study was undertaken to survey the prevalence, phenotypic characteristics, and molecular epidemiology of antimicrobial-resistant Gram-negative bacteria in the oral cavity of LTCF residents, and to analyse the risk factors for such carriers.

Methods

This study involved 98 residents of a LTCF in Hiroshima City, Japan, aged between 55 and 101 years. Oropharyngeal swabs were collected and plated on screening media for ESBL-producing and carbapenem-resistant bacteria; isolates were identified and tested for antibiotic susceptibility; biofilm formation was tested in vitro; identification of epidemic clones were pre-determined by PCR; resistance genes, sequence types, and whole-genome comparison of strains were conducted using draft genome sequences. Demographic data and clinical characterisations were collected and risk factors analysed.

Results

Fifty-four strains from 38% of the residents grew on screening media and comprised predominantly of Acinetobacter spp. (35%), Enterobacteriaceae spp. (22%), and Pseudomonas spp. (19%). All Escherichia coli isolates carried CTX-M-9 group and belonged to the phylogroup B2, O25:H4 ST131 fimH30 lineage. Six Acinetobacter baumannii isolates presented identical molecular characteristics and revealed more biofilm production than the others, strongly suggesting their clonal lineage. One Acinetobacter ursingii isolate displayed extensive resistance to various ß-lactams due to multiple acquired resistance genes. One Pseudomonas aeruginosa isolate showed exceptional resistance to all ß-lactams including carbapenems, aminoglycosides, and a new quinolone, showing a multidrug-resistant Pseudomonas aeruginosa (MDRP) phenotype and remarkable biofilm formation. Genome sequence analysis revealed this isolate was the bla_IMP-1-positive clone ST235 in Japan. Strokes (cerebral infarction or cerebral haemorrhage) and percutaneous endoscopic gastrostomy tubes were recognised as risk factors for oral colonisation by ARB in the LTCF residents.

Conclusions

ARB, as defined by growth on screening agar plates, which carried mobile resistance genes or elements or conferred high biofilm formation, were already prevalent in the oral cavity of LTCF residents. Health-care workers involved in oral care should be aware of antimicrobial resistance and pay special attention to transmission prevention and infection control measures to diminish ARB or mobile resistance elements dissemination in LTCFs.

Risk Factors, Causes, and Costs of Hospital Readmission After Head and Neck Cancer Surgery Reconstruction

Importance

Thirty-day hospital readmissions have substantial direct costs and are increasingly used as a measure of quality care. However, data regarding the risk factors and reasons for readmissions in head and neck cancer surgery reconstruction are lacking.

Objective

To describe the rate, risk factors, and causes of 30-day readmission in patients with head and neck cancer following free or pedicled flap reconstruction.

Design, Setting, and Participants

This retrospective, population-based cohort study analyzed medical records from the Nationwide Readmissions Database of 9487 patients undergoing pedicled or free flap reconstruction of head and neck oncologic defects between January 1, 2010, and December 31, 2014. Data analysis was performed in October 2017.

Exposures

Pedicled or free flap reconstruction of an oncologic head and neck defect.

Main Outcomes and Measures

The primary outcome was 30-day all-cause readmissions. Secondary outcomes included risk factors, causes, and costs of readmission. Multivariate regression analyses were conducted to determine factors independently associated with 30-day readmissions.

Results

Among 9487 patients included in the study (6798 male; 71.7%), the median age was 63 years (interquartile range, 55-71 years), and the 30-day readmission rate was 19.4% (n = 1839), with a mean cost per readmission of $15 916 (standard error of the mean, $785). The most common indication for readmission was wound complication (26.5%, n = 487). On multivariate regression, significant risk factors for 30-day readmission were median household income in the lowest quartile (vs highest quartile: odds ratio [OR], 1.58; 95% CI, 1.18-2.11), congestive heart failure (OR, 1.68; 95% CI, 1.14-2.47), liver disease (OR, 2.02; 95% CI, 1.22- 3.33), total laryngectomy (OR, 1.40; 95% CI, 1.12-1.75), pharyngectomy (OR, 1.47; 95% CI, 1.08-2.01), blood transfusion (OR, 1.30; 95% CI, 1.04-1.64), discharge to home with home health care (vs routine: OR, 1.32; 95% CI, 1.04-1.67), and discharge to a nursing facility (vs routine: OR, 1.77; 95% CI, 1.30-2.40).

Conclusions and Relevance

Using the Nationwide Readmissions Database, we demonstrate that approximately 1 in 5 patients undergoing head and neck cancer surgery reconstruction is readmitted within 30 days of surgery. Readmissions are most commonly associated with wound complications. Socioeconomic status, complex ablative procedures, and patient comorbidities are independent risk factors for readmission. These findings may be useful to clinicians in developing perioperative interventions aimed to reduce hospital readmissions and improve quality of patient care.

Should We Fiddle with Gut Microbiome in Critically Ill?

The gut that we took for granted in the critically ill, as just a conduit for food passage has over the decade or so shown us that it is an active endocrine and exocrine organ with over 40 trillion microorganisms living commensally within it. This cosmos of microorganisms that is called the gut microbiome comprises roughly 1,000 different species and put together is more DNA than the entire human genome. Under normal circumstances, in a healthy individual multiple elements of the gut viz intestinal epithelium, gut barrier function, the microbiomes, all put together offer protection against infection and this is crucial in maintenance of health. Any change to the norm, be it in the form of surgical interventions, the introduction of medications, or the pathophysiological effects of systemic disease leads to a 360° alteration in this finely construed ecosystem leading to devastating effects that go beyond the boundaries of the gut itself. Intestinal epithelium helps to absorb nutrients as well as acts as the coordinator of mucosal immunity (first line of immune defense). During ill health, gut epithelial apoptosis occurs, alterations happen in the tight epithelial junctions leading to loss of gut barrier function and loss of the mucosal immunity leading to mucosal damage and hyperpermeability. Lastly, the microbiome is transformed into a pathobiome, with resultant increase in pathogenic bacteria and induction of virulence in commensal gut bacteria. Multiple organ damage starts to set in, caused by toxins leaving the intestine via both portal blood flow and mesenteric lymph. This review article traces the gut microbiomic ecology in health and sickness, modern tools that are used to manipulate gut microbiome in the search for the prevention and treatment of critical illness and will explore if appropriate manipulation of gut microbiome can influence or modulate the course of critical illness.

How to cite this article: Venkatachalam B, Abraham BK. Should We Fiddle with Gut Microbiome in Critically Ill? Indian J Crit Care Med 2020;24(Suppl 4):S211–S214.

Bacterial colonization of Montgomery salivary bypass tubes after hypopharyngeal reconstruction in head and neck cancer patients

Background

Hypopharyngeal reconstruction after salvage pharyngolaryngectomy results in high postoperative morbidity. The use of salivary bypass tubes can reduce pharyngocutaneous fistula (PCF) formation. The influence of bacterial colonization has not been described in literature.

Methods

Bacterial swipes from 26 consecutive patients reconstructed after laryngopharyngectomy in combination with Montgomery salivary bypass tubes (MSBT) were analyzed in regards to PCF formation.

Results

PCF occurred in 2 untreated primary and in 9 salvage laryngopharyngectomies, respectively. Bacterial colonization showed high rates of gram-negative pathogens and drug resistance to standard Ampicillin treatment. Type of bacteria was not associated with fistula formation. Antibiotic resistance was found in 6 out 11 patients (54%) with PCF.

Conclusions

We identified high rates of antibiotic-resistant Gram-negative pathogens on MSBT. Although not statistically significant, PCF were found more frequently in drug-resistant patients. Bacterial colonization of hypopharyngeal reconstructions should therefore be taken into account for perioperative prophylaxis.

Selective decontamination of the digestive tract (SDD) in critically ill patients: a narrative review

Selective decontamination of the digestive tract (SDD) is an infection prevention measure for intensive care unit (ICU) patients that was proposed more than 30 years ago, and that is currently considered standard of care in the Netherlands, but only used sporadically in ICUs in other countries. In this narrative review, we first describe the rationale of the individual components of SDD and then review the evidence base for patient-centered outcomes, where we distinguish ICUs with low prevalence of antibiotic resistance from ICUs with moderate–high prevalence of resistance. In settings with low prevalence of antibiotic resistance, SDD has been associated with improved patient outcome in three cluster-randomized studies. These benefits were not confirmed in a large international cluster-randomized study in settings with moderate-to-high prevalence of antibiotic resistance. There is no evidence that SDD increases antibiotic resistance. We end with future directions for research.

Oropharyngeal Bacterial Colonization after Chlorhexidine Mouthwash in Mechanically Ventilated Critically Ill Patients

WHAT WE ALREADY KNOW ABOUT THIS TOPIC

WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Oropharyngeal care with chlorhexidine to prevent ventilator-associated pneumonia is currently questioned, and exhaustive microbiologic data assessing its efficacy are lacking. The authors therefore aimed to study the effect of chlorhexidine mouthwash on oropharyngeal bacterial growth, to determine chlorhexidine susceptibility of these bacteria, and to measure chlorhexidine salivary concentration after an oropharyngeal care.

METHODS

This observational, prospective, single-center study enrolled 30 critically ill patients under mechanical ventilation for over 48 h. Oropharyngeal contamination was assessed by swabbing the gingivobuccal sulcus immediately before applying 0.12% chlorhexidine with soaked swabs, and subsequently at 15, 60, 120, 240, and 360 min after. Bacterial growth and identification were performed, and chlorhexidine minimal inhibitory concentration of recovered pathogens was determined. Saliva was collected in 10 patients, at every timepoint, with an additional timepoint after 30 min, to measure chlorhexidine concentration.

RESULTS

Two hundred fifty bacterial samples were analyzed and identified 48 pathogens including Streptococci (27.1%) and Enterobacteriaceae (20.8%). Oropharyngeal contamination before chlorhexidine mouthwash ranged from 10 to 10 colony-forming units (CFU)/ml in the 30 patients (median contamination level: 2.5·10 CFU/ml), and remained between 8·10 (lowest) and 3·10 CFU/ml (highest count) after chlorhexidine exposure. These bacterial counts did not decrease overtime after chlorhexidine mouthwash (each minute increase in time resulted in a multiplication of bacterial count by a coefficient of 1.001, P = 0.83). Viridans group streptococci isolates had the lowest chlorhexidine minimal inhibitory concentration (4 [4 to 8] mg/l); Enterobacteriaceae isolates had the highest ones (32 [16 to 32] mg/l). Chlorhexidine salivary concentration rapidly decreased, reaching 7.6 [1.8 to 31] mg/l as early as 60 min after mouthwash.

CONCLUSIONS

Chlorhexidine oropharyngeal care does not seem to reduce bacterial oropharyngeal colonization in critically ill ventilated patients. Variable chlorhexidine minimal inhibitory concentrations along with low chlorhexidine salivary concentrations after mouthwash could explain this ineffectiveness, and thus question the use of chlorhexidine for ventilator-associated pneumonia prevention.

Prevention of hospital-acquired pneumonia

PURPOSE OF REVIEW

Hospital-acquired pneumonia (HAP) is the leading cause of death from hospital-acquired infection. Little work has been done on strategies for prevention of HAP. This review aims to describe potential HAP prevention strategies and the evidence supporting them. Oral care and aspiration precautions may attenuate some risk for HAP. Oral and digestive decontamination with antibiotics may be effective but could increase risk for resistant organisms. Other preventive measures, including isolation practices, remain theoretical or experimental.

RECENT FINDINGS

Hospital-acquired pneumonia occurs because of pharyngeal colonization with pathogenic organisms and subsequent aspiration of these pathogens.

SUMMARY

Most potential HAP prevention strategies remain unproven.

Manipulation of the microbiome in critical illness-probiotics as a preventive measure against ventilator-associated pneumonia

Objective

To describe the possible modes of action of probiotics and provide a systematic review of the current evidence on the efficacy of probiotics to prevent ventilator-associated pneumonia (VAP) in critically ill patients.

Methods

We conducted an unrestricted search of the English language medical literature. For each individual study, the relative risk of VAP was calculated using the reported primary outcome data.

Results

The search identified a total of 72 articles. Eight articles enrolling a total of 1229 patients fulfilled the inclusion and exclusion criteria. In four trials, the investigators were blinded for the intervention, and two trials used an intention-to-treat analysis. Loss to follow-up with regard to the primary endpoint ranged from 0 to 14% in the intervention groups and from 0 to 16% in the control groups. The incidence of VAP expressed as the percentage of studied patients was reported in seven trials. The incidence of VAP ranged from 4 to 36% in the intervention groups and from 13 to 50% in the control groups. The relative risk for VAP ranged between 0.30 and 1.41. Three trials showed a significant difference in favor of probiotic therapy between the intervention and the control groups.

Conclusions

The incidence of VAP tended to be lower in patients treated with probiotics in most trials identified by the systematic search. Due to the heterogeneity of the studies and the low quality of evidence, it remains difficult to draw firm conclusions. The efficacy of preventive probiotics should be studied in more detail in future trials. Application of probiotics for the prevention of VAP seems to be safe with only few side effects reported in the selected trials.

Electronic supplementary material

The online version of this article (10.1186/s40635-019-0238-1) contains supplementary material, which is available to authorized users.

Health Care-Associated Pneumonia: Is It Still a Useful Concept?

"Health care-associated pneumonia (HCAP) was introduced into guidelines because of concerns about the increasing prevalence of drug-resistant pathogens (DRPs) not covered by standard empirical therapy. We now know that DRPs are very localized phenomena with low rates in most sites. Although HCAP risk factors are associated with a higher mortality, this is driven by comorbidities rather than the pathogens. Empirical coverage of DRPs has generally not resulted in better patient outcomes. A far more nuanced approach must be taken for patients with risk factors for DRPs taking into account the local cause and severity of disease.

Genetic diversity of human head lice and molecular detection of associated bacterial pathogens in Democratic Republic of Congo

BACKGROUND

Head louse, Pediculus humanus capitis, is an obligatory blood-sucking ectoparasite, distributed worldwide. Phylogenetically, it occurs in five divergent mitochondrial clades (A-E); each exhibiting a particular geographical distribution. Recent studies suggest that, as in the case of body louse, head louse could be a disease vector. We aimed to study the genetic diversity of head lice collected in the Democratic Republic of the Congo (DR Congo) and to screen for louse-borne pathogens in these lice.

METHODS

A total of 181 head lice were collected from 27 individuals at the Monkole Hospital Center located in Kinshasa. All head lice were genotyped and screened for the presence of louse-borne bacteria using molecular methods. We searched for Bartonella quintana, Borrelia recurrentis, Rickettsia prowazekii, Anaplasma spp., Yersinia pestis, Coxiella burnetii and Acinetobacter spp.

RESULTS

Among these head lice, 67.4% (122/181) belonged to clade A and 24.3% (44/181) belonged to clade D. Additionally, for the first time in this area, we found clade E in 8.3% (15/181) of tested lice, from two infested individuals. Dual infestation with clades A and D was observed for 44.4% individuals. Thirty-three of the 181 head lice were infected only by different bacterial species of the genus Acinetobacter. Overall, 16 out of 27 individuals were infested (59.3%). Six Acinetobacter species were detected including Acinetobacter baumannii (8.3%), Acinetobacter johnsonii (1.7%), Acinetobacter soli (1.7%), Acinetobacter pittii (1.7%), Acinetobacter guillouiae (1.1%), as well as a new potential species named "Candidatus Acinetobacter pediculi".

CONCLUSIONS

To our knowledge, this study reports for the first time, the presence of clade E head lice in DR Congo. This study is also the first to report the presence of Acinetobacter species DNAs in human head lice in DR Congo.

Critical illness and the role of the microbiome

The number of microbes living within the intestinal lumen is similar to the number of all cells of human origin in the host. Although historically little attention has been paid to the massive microbial community residing inside each of us, the last few years have witnessed an explosion of information related to the role of the microbiome in the maintenance of health and in the pathogenesis of disease. Here, we review data suggesting that the microbiome is converted into a pathobiome in critical illness and potential strategies for targeting the microbiome for therapeutic gain in the intensive care unit.

Oropharyngeal colonization: epidemiology, treatment and ventilator-associated pneumonia prevention

Oropharyngeal (OP) colonization and ventilator-associated pneumonia (VAP) mechanisms are tightly linked. A significant within-population variation in OP colonization has been described, with its composition being dependent from patients' severity. For instance, healthy subjects have a very low rate in Gram-negative bacteria (GNB) colonization, while its rate rises in comorbid patients, reaching high proportions in ICU patients. Various factors can be put forward to explain the modifications of hospital acquired OP. ICU patients might suffer from underlying diseases; the gastric reflux induced by the presence of nasogastric tubes and the patients' position influences OP colonization; salivary composition might influence OP content, as it modulates bacterial adhesion and induces reversible bacterial changes enhancing bacterial binding. The transition from OP colonization to VAP has been shown in numerous studies, with the digestive tract acting as a filter, or as a reservoir. Some therapies have been investigated to modulate OP colonization, in order to reduce the risk for VAP. Among those, mammalian antimicrobial peptides have been shown effective in reducing GNB colonization in healthy subjects, but failed in preventing VAP in ICU patients. The widely used chlorhexidine was tested in numerous trials. Data on its efficacy are conflicting, and meta-analyses yield discordant results. Above all, several drawbacks have aroused: a poor tolerance of concentrated solutions; an increased risk of death in the less severe patients; and a reduced susceptibility towards chlorhexidine of number of VAP pathogens. Proanthocyanidins, used to prevent Escherichia coli adhesion to the urothelium, have been tested in mice model of pneumonia with interesting results. Some complementary data are needed before moving to clinical research. Future research paths should include a reappraisal of OP colonization; finding better formulations for chlorhexidine; define the best populations to target oral decontamination and developing other strategies to prevent and treat OP colonization.

Rapid gastrointestinal loss of Clostridial Clusters IV and XIVa in the ICU associates with an expansion of gut pathogens

Commensal gastrointestinal bacteria resist the expansion of pathogens and are lost during critical illness, facilitating pathogen colonization and infection. We performed a prospective, ICU-based study to determine risk factors for loss of gut colonization resistance during the initial period of critical illness. Rectal swabs were taken from adult ICU patients within 4 hours of admission and 72 hours later, and analyzed using 16S rRNA gene sequencing and selective culture for vancomycin-resistant Enterococcus (VRE). Microbiome data was visualized using principal coordinate analyses (PCoA) and assessed using a linear discriminant analysis algorithm and logistic regression modeling. 93 ICU patients were analyzed. At 72 hours following ICU admission, there was a significant decrease in the proportion of Clostridial Clusters IV/XIVa, taxa that produce short chain fatty acids (SCFAs). At the same time, there was a significant expansion in Enterococcus. Decreases in Cluster IV/XIVa Clostridia were associated with loss of gut microbiome colonization resistance (reduced diversity and community stability over time). In multivariable analysis, both decreased Cluster IV/XIVa Clostridia and increased Enterococcus after 72 hours were associated with receipt of antibiotics. Cluster IV/XIVa Clostridia, although a small fraction of the overall gastrointestinal microbiome, drove distinct clustering on PCoA. During initial treatment for critical illness, there was a loss of Cluster IV/XIVa Clostridia within the distal gut microbiome which associated with an expansion of VRE and with a loss of gut microbiome colonization resistance. Receipt of broad-spectrum antibiotics was associated with these changes.

Proton pump inhibitor medication is associated with colonisation of gut flora in the oropharynx

BACKGROUND

The normal body exists in mutualistic balance with a large range of microbiota. The primary goal of this study was to establish whether there is an imbalance in the oropharyngeal flora early after hospital or ICU admittance, and whether flora differs between control, ward and critically ill patients. The secondary goal was to explore whether there are patient characteristics that can be associated with a disturbed oropharyngeal flora.

METHODS

Oropharyngeal cultures were obtained from three different study groups: (1) controls from the community, (2) ward patients and (3) critically ill patients, the two latter within 24 h after admittance.

RESULTS

Cultures were obtained from 487 individuals: 77 controls, 193 ward patients and 217 critically ill patients. Abnormal pharyngeal flora was more frequent in critically ill and ward patients compared with controls (62.2% and 10.4% vs. 1.3%, P < 0.001 and P = 0.010, respectively). Colonisation of gut flora in the oropharynx was more frequent in critically ill patients compared with ward patients or controls (26.3% vs. 4.7% and 1.3%, P < 0.001 and P < 0.001, respectively). Proton pump inhibitor medication was the strongest independent factor associated with the presence of gut flora in the oropharynx in both ward and critically ill patients (P = 0.030 and P = 0.044, respectively).

CONCLUSION

This study indicates that abnormal oropharyngeal flora is an early and frequent event in hospitalised patients and more so in the critically ill, compared to controls. Proton pump inhibitor medication is associated with colonisation of gut flora in the oropharynx.

Pathogen colonization of the gastrointestinal microbiome at intensive care unit admission and risk for subsequent death or infection

PURPOSE

Loss of colonization resistance within the gastrointestinal microbiome facilitates the expansion of pathogens and has been associated with death and infection in select populations. We tested whether gut microbiome features at the time of intensive care unit (ICU) admission predict death or infection.

METHODS

This was a prospective cohort study of medical ICU adults. Rectal surveillance swabs were performed at admission, selectively cultured for vancomycin-resistant Enterococcus (VRE), and assessed using 16S rRNA gene sequencing. Patients were followed for 30 days for death or culture-proven bacterial infection.

RESULTS

Of 301 patients, 123 (41%) developed culture-proven infections and 76 (25%) died. Fecal biodiversity (Shannon index) did not differ based on death or infection (p = 0.49). The presence of specific pathogens at ICU admission was associated with subsequent infection with the same organism for Escherichia coli, Pseudomonas spp., Klebsiella spp., and Clostridium difficile, and VRE at admission was associated with subsequent Enterococcus infection. In a multivariable model adjusting for severity of illness, VRE colonization and Enterococcus domination (≥ 30% 16S reads) were both associated with death or all-cause infection (aHR 1.46, 95% CI 1.06-2.00 and aHR 1.47, 95% CI 1.00-2.19, respectively); among patients without VRE colonization, Enterococcus domination was associated with excess risk of death or infection (aHR 2.13, 95% CI 1.06-4.29).

CONCLUSIONS

Enterococcus status at ICU admission was associated with risk for death or all-cause infection, and rectal carriage of common ICU pathogens predicted specific infections. The gastrointestinal microbiome may have a role in risk stratification and early diagnosis of ICU infections.

Allergic and Nonallergic Rhinitis. Classification and Pathogenesis: Part II. Nonallergic Rhinitis

Part I of this review classified and defined the causes of chronic rhinitis, describing in detail the etiology and pathophysiology of allergic rhinitis. Part II focuses on the nonallergic (non-IgE) causes of chronic rhinitis, concentrating on their clinical presentations, differential characteristics, and known or speculative pathophysiology. A comprehensive understanding of the allergic and nonallergic conditions associated with symptomatic rhinitis should aid the clinician in the appropriate diagnosis and treatment of patients with chronic rhinitis.

Dysbiosis Across Multiple Body Sites in Critically Ill Adult Surgical Patients

The microbiota of critically ill patients likely undergoes dramatic changes but has not been rigorously studied with a culture-independent high-throughput approach. The aim of this study was to characterize spatial and temporal variation in the microbiota of critically ill patients. Trauma and acute surgery patients admitted to the intensive care unit (ICU) were sampled at five body sites (stool, tongue, skin, trachea, urine) every 3 to 4 days. A mean of 10.8 samples was collected from 32 patients with a mean sampling period of 8.8 days. Bacterial 16S rRNA sequences were amplified and sequenced for microbiota analyses. Results were compared to data from unhospitalized adult participants in the American Gut and Human Microbiome Projects. Relative to healthy adults, alpha diversity was decreased in ICU gut and skin samples at all time points. Diversity in tongue swabs decreased over time. Beta diversity measures indicated differences in community membership between critically ill and healthy adults at each body site. Taxonomic alterations in the ICU included depletion of important commensal bacteria such as Faecalibacterium in GI samples and Corynebacterium in skin swabs and enrichment with pathogens such as Enterococcus, Mycoplasma, and Staphylococcus. A high proportion of ICU sample sets contained pathogens present simultaneously at three body sites indicating widespread colonization. In several cases, clinically relevant airway infections were preceded by the appearance of the causative pathogen in tracheal microbiome profiles. These results demonstrate that the microbiome of critically ill patients undergoes a loss of diversity, loss of site specificity, and a shift toward dominant pathogens. These changes may provide opportunities to precisely modulate the microbiome and thereby improve patient outcomes.

Comparison of the Microbiota of Older Adults Living in Nursing Homes and the Community

Our objective for this study was to characterize the microbial communities of the anterior nares (nose), posterior pharynx (throat), and skin of the femoral and subclavian areas in older adults from nursing homes and the community. Older adults (≥65 years) without antibiotic use for the past 3 months were recruited from nursing homes (NH; n = 16) and from the community (CB; n = 51). Specimens were taken from nose, throat, and skin sites for culture and bacterial profiling using 16S rRNA gene sequencing. We found that pathogenic Gram-negative rod (GNR) colonization on the femoral skin was higher in NH participants than CB participants; otherwise, there were no differences in GNR colonization at other body sites or in Staphylococcus aureus colonization at any body site. Bacterial community profiling demonstrated that the operational taxonomic unit compositions of the different body sites were similar between NH and CB participants, but the analysis identified differences in relative abundance levels. Streptococcus spp. were more abundant and Prevotella spp. were less abundant in the throats of NH participants than in throats of CB participants. Proteus, Escherichia coli, and Enterococcus were more abundant in NH participants on the femoral skin. We found a pattern of decreased abundance of specific Proteobacteria in NH participants at the anterior nares and at both skin sites. We concluded that bacterial communities were largely similar in diversity and composition within body sites between older adults without recent antibiotic use from NH compared to those from the community. Our findings support the rationale for improved hygiene in NH residents to reduce the transmission risk of antibiotic-resistant bacteria, such as Enterococcus spp. or Enterobacteriaceae. IMPORTANCE The nose, throat, and skin over the subclavian and femoral veins are the body sites which harbor the bacteria which most commonly cause health care-associated infection. We assessed the effect of nursing home residence on the microbiota of these body sites in older adults. We found that the microbiota composition of the different body sites was similar between nursing home and community participants, but we identified differences in relative abundance levels. We found remarkable similarities in the bacterial communities of different body sites in older adults who lived in nursing homes compared to those in the community among people who had not been on antibiotics for the past 3 months. We also found that the femoral skin microbiota had evidence of stool contamination in the nursing home residents, providing a rationale for improved skin hygiene. Taken together, it appears that the health care environment does not alter the microbiota to the extent that antibiotics do.

Characterizing non-linear effects of hospitalisation duration on antimicrobial resistance in respiratory isolates: an analysis of a prospective nationwide surveillance system

OBJECTIVES

Our objective was to systematically study the influence of length of hospital stay on bacterial resistance in relevant respiratory tract isolates.

METHODS

Using prospective epidemiological data from the National Swiss Antibiotic Resistance Surveillance System, susceptibility testing results for respiratory isolates retrospectively retrieved from patients hospitalised between 2008 and 2014 were compiled. Generalized additive models were used to illustrate resistance rates relative to hospitalisation duration and to adjust for co-variables.

RESULTS

In all, 19 622 isolates of six relevant and predominant species were included. Resistance patterns for the predominant species showed a species-specific and antibiotic-resistance-specific profile in function of hospitalisation duration. The oxacillin resistance profile in Staphylococcus aureus isolates was constantly increasing (monophasic). The pattern of resistance to cefepime in Pseudomonas aeruginosa was biphasic with a decreasing resistance rate for the first 5 days of hospitalisation and an increase for days 6-30. A different biphasic pattern occurred in Escherichia coli regarding amoxicillin-clavulanic acid resistance: odds/day increased for the first 7 days of hospitalisation and then remained stable for days 8-30. In the adjusted models epidemiological characteristics such as age, ward type, hospital type and linguistic region were identified as relevant co-variables for the resistance rates. The contribution of these confounders was specific to the individual species/antibiotic resistance models.

CONCLUSIONS

Resistance rates do not follow a dichotomic pattern (early versus late nosocomial) as suggested by current hospital-acquired pneumonia treatment guidelines. Duration of hospitalisation rather appears to have a more complex and non-linear relationship with bacterial resistance in hospital-acquired pneumonia, also depending on host and environmental factors.

The Influence of pH Elevation on the Incidence of Nosocomial Pneumonia

Nosocomial pneumonia, one of the most common hos pital-acquired infectious diseases, is associated with sub stantial morbidity and mortality, approaching 50% in selected patients. Patients with alterations in their tracheobronchial tree or natural host-defense mecha nisms are at increased risk of developing pneumonia. Organisms gain access to the normally sterile tracheo bronchial tree primarily by aspiration of colonized oro pharyngeal gastric secretions. Risk factors for bacterial colonization and the development of nosocomial pneu monia include increased age, elevated pH of gastric con tents, postoperative state, nutritional status, severe underlying disease (for example, chronic obstructive pulmonary disease), administration of corticosteroids or other immunosuppressive therapy, and intubation or mechanical ventilation. High gastric volume may also increase the chance of aspiration of secretions in some high-risk patients.

Ventilator-Associated Pneumonia: A Review

Ventilator-associated pneumonia is the most frequent intensive care unit (ICU)-related infection in patients requiring mechanical ventilation. In contrast to other ICU-related infections, which have a low mortality rate, the mortality rate for ventilator-associated pneumonia ranges from 20% to 50%. These clinically significant infections prolong duration of mechanical ventilation and ICU length of stay, underscoring the financial burden these infections impose on the health care system. The causes of ventilator-associated pneumonia are varied and differ across different patient populations and different types of ICUs. This varied presentation underscores the need for the intensivist treating the patient with ventilator-associated pneumonia to have a clear knowledge of the ambient microbiologic flora in their ICU. Prevention of this disease process is of paramount importance and requires a multifaceted approach. Once a diagnosis of ventilator-associated pneumonia is suspected, early broad-spectrum antibiotic administration decreases morbidity and mortality and should be based on knowledge of the sensitivities of common infecting organisms in the ICU. De-escalation of therapy, once final culture results are available, is necessary to minimize development of resistant pathogens. Duration of therapy should be based on the patient’s clinical response, and every effort should be made to minimize duration of therapy, thus further minimizing the risk of resistance.

Head and neck intensity modulated radiation therapy leads to an increase of opportunistic oral pathogens

OBJECTIVES

The introduction of intensity modulated radiation therapy (IMRT) has led to new possibilities in the treatment of head and neck cancer (HNC). Limited information is available on how this more advanced radiation technique affects the oral microflora. In a prospective study we assessed the effects of various advanced treatments for HNC on the oral microflora, as well as the effects of elimination of oral foci of infection.

MATERIALS AND METHODS

All consecutive dentate patients >18years, diagnosed with a primary oral or oropharynx carcinoma and seen for a pre-treatment dental screening (May 2011-May 2013) were included. Patients were grouped by oncologic treatment: surgery (SURG), IMRT (IMRT) or IMRT+chemotherapy (CHIMRT). Dental screening data, demographic data, subgingival biofilm samples, oral lavages and whole saliva samples were obtained to microbiologically analyze the effects of cancer treatments (1-year follow-up).

RESULTS

This study included 82 patients (29 SURG, 26 IMRT and 27 CHIMRT). The trends in changes in prevalence and proportions of microorganisms were comparable in the IMRT and CHIMRT group. However, relative to the SURG group, increased prevalence of enteric rods, staphylococci and Candida species was observed in the IMRT and CHIMRT groups. In these groups, elimination of oral foci decreased the frequency of detection of pathogens such as Porphyromonas gingivalis, Tannerella forsythia and Streptococcus mutans.

CONCLUSION

Different treatments in HNC patients result in different changes in the oral microflora. Opportunistic pathogens such as staphylococci, enteric rods and Candida sp. tend to increase in prevalence after IMRT with or without chemotherapy, but not after surgical intervention.

Antibiotic-Resistant Acinetobacter baumannii Increasing Success Remains a Challenge as a Nosocomial Pathogen

Antibiotic-resistant infectious bacteria currently imply a high risk and therefore constitute a strong challenge when treating patients in hospital settings. Characterization of these species and of particular strains is a priority for the establishment of diagnostic tests and preventive procedures. The relevance of Acinetobacter baumannii as a problematic microorganism in inpatient facilities, particularly intensive care units, has increased over time. This review aims to draw attention to (i) the historical emergence of carbapenem-resistant Acinetobacter baumannii, (ii) the current status of surveillance needs in Latin America, and (iii) recent data suggesting that A. baumannii continues to spread and evolve in hospital settings. First, we present synopsis of the series of events leading to the discovery and precise identification of this microorganism in hospital settings. Then key events in the acquisition of antibiotic-resistant genes by this microorganism are summarized, highlighting the race between new antibiotic generation and emergence of A. baumannii resistant strains. Here we review the historical development of this species as an infectious threat, the current state of its distribution, and antibiotic resistance characteristics, and we discuss future prospects for its control.