Severe Ventilator-associated Pneumonia Research Articles

Effect of acetylcysteine solution combined with fiberoptic bronchoscopy alveolar lavage in elderly patients with severe ventilator-associated pneumonia


 
 
 
 Purpose: To explore the effect of acetylcysteine solution combined with fiberoptic bronchoscopy alveolar lavage in elderly patients with severe ventilator-associated pneumonia (VAP).
 Methods: A total of 120 elderly patients with severe VAP admitted to Department of Critical Care Medicine, the First Affiliated Hospital of Xinjiang Medical University in the past two years were selected for this study. They were randomized into groups A and B. Group B underwent fiberoptic bronchoscopy alveolar lavage for 7 days, group A received acetylcysteine solution plus. Clinical pulmonary infection score (CPIS), respiratory mechanics changes, blood gas levels, inflammatory factor levels, antibiotic use time and mechanical ventilation time were compared.
 Results: Compared to group B, group A witnessed a lower CPIS, an evidently superior dynamic lung compliance (Cdyn), and worse for other respiratory mechanics indices (p < 0.001). After treatment, the partial pressure of blood oxygen (PaO2) and oxygenation index (PaO2/FiO2) saw a surge; the partial pressure of carbon dioxide (PaCO2) tapered off, and the levels of inflammatory factors witnessed a slump in group A than compared with those for group B (p < 0.001). A shorter antibiotic use time and mechanical ventilation time was observed in group A compared with group B (p < 0.001).
 Conclusion: Acetylcysteine solution combined with fiberoptic bronchoscopy alveolar lavage yields a promising outcome in notably ameliorating CPIS, respiratory mechanics indicators and blood gas levels, driving down the level of inflammatory factors and diminishing treatment time in elderly patients with severe VAP.
 
 
 

Modified sequential sac ligation and staged closure technique for the management of giant omphalocele

PurposeThis study aimed to describe sac ligation and sequential closure for the management of giant omphalocele (GO) and analyze its outcomes. MethodsThe medical records of 13 neonates with GO treated at a tertiary general hospital between July 2012 and April 2020 were reviewed. Sac ligation and progressive external compression were performed on most cases immediately after birth. Staged closure with or without a prosthetic patch was conducted after a period of sac suspension. ResultsSac ligation-traction-compression was performed on 12 cases, of which 10 underwent staged closure, one with delayed closure. One patient with coexistent esophageal atresia was deemed ineligible for surgery. Among those who had undergone staged closure, 9 survived; however, one neonate who complicated with bilateral diaphragmatic eventration and severe ventilator-associated pneumonia died from multiple-organ failure. Pentalogy of Cantrell was excluded. One patient in whom primary closure was performed after birth died aged 29 h. Pneumonia was the most common infection among patients (5/13), with three having ventilator-associated pneumonia. The median durations of mechanical ventilation and hospital stay were 22.2 days (range, 1–151) and 44.2 days (range, 2–152), respectively, and 25.6 days and 46.4 days, respectively, among patients with staged closure. Among five infants who required oxygen support for more than 28 days, four had pulmonary hypoplasia. ConclusionsAside from abdominal wall defects, other major comorbidities and pulmonary hypoplasia influence the prognosis of GO. Sac ligation and staged closure is a effective choice for GO.Type of Study: Retrospective StudyLevel of Evidence: Level IV

Clinical effect of nebulized acetylcysteine inhalation combined with bronchoscopy in the treatment of elderly patients with severe ventilator-associated pneumonia

Objective: To explore the clinical effect of nebulized acetylcysteine inhalation combined with bronchoscopy in treating elderly patients with severe ventilator-associated pneumonia (VAP). Methods: From January 2016 to December 2017, 80 elderly patients with severe VAP who were hospitalized in Zhejiang Hospital were divided into acetylcysteine+ bronchoscopy group [24 males and 16 females, aged (78±7) years] and bronchoscopy group [26 males and 14 females, aged (80±7) years]using random number table for a prospective cohort study. Patients in bronchoscopy group were treated with bronchoscopy in addition to conventional supportive care of symptoms. Patients in acetylcysteine+ bronchoscopy group received nebulized acetylcysteine inhalation therapy on the basis of the treatment given to patients in bronchoscopy group. Patients in both groups received treatment continuously for 7 days. The simplified clinical pulmonary infection score (CPIS) in both groups was assessed before and after treatment. Venous blood of 10 mL was collected before and after treatment to detect leukocyte count, serum C-reactive protein, and procalcitonin. Arterial blood of 1 mL was collected before and after treatment to detect partial arterial oxygen pressure (PaO(2)), partial arterial carbon dioxide pressure (PaCO(2)), oxygenation index. The inhalation platform pressure (Pplat), dynamic lung compliance (Cdyn), airway resistance, work of breathing, time of antibiotic use, and time of mechanical ventilation of patients in two groups were recorded before and after treatment. Data were statistically analyzed with chi-square test and t test. Results: (1) The simplified CPIS, leukocyte count, serum C-reactive protein, and procalcitonin of patients in acetylcysteine+ bronchoscopy group were significantly lower than those in bronchoscopy group after treatment (t=2.32, 2.15, 6.08, 7.12, P<0.05 or P<0.01). The simplified CPIS, leukocyte count, serum C-reactive protein, and procalcitonin of patients in acetylcysteine+ bronchoscopy group and bronchoscopy group after treatment were significantly lower than those before treatment (t=13.76, 13.60, 12.70, 8.32, 11.44, 14.28, 9.48, 9.50, P<0.01). (2) Compared with bronchoscopy group, patients in acetylcysteine+ bronchoscopy group had significantly higher PaO(2) and oxygenation index (t=4.14, 2.55, P<0.05 or P<0.01) but significantly lower PaCO(2) (t=4.36, P<0.01) after treatment. The PaO(2) and oxygenation index of patients in acetylcysteine+ bronchoscopy group after treatment were significantly higher than those before treatment (t=10.90, 43.72, P<0.01). The PaO(2) and oxygenation index of patients in bronchoscopy group after treatment were also significantly higher than those before treatment (t=6.55, 43.03, P<0.01). The PaCO(2) of patients in both groups after treatment were significantly lower than those before treatment (t=21.54, 21.92, P<0.01). (3) The Cdyn of patients in acetylcysteine+ bronchoscopy group after treatment was significantly higher than that in bronchoscopy group (t=5.41, P<0.01), and Pplat, airway resistance, and work of breathing were significantly lower than those in bronchoscopy group (t=2.18, 5.46, 2.49, P<0.05 or P<0.01). The Cdyn of patients in both groups after treatment were significantly higher than those before treatment (t=16.10, 10.90, P<0.01), and Pplat, airway resistance, and work of breathing were significantly lower than those before treatment (t=21.18, 11.13, 9.32, 15.50, 5.17, 5.97, P<0.01). (4)The time of mechanical ventilation and antibiotic usage of patients in acetylcysteine+ bronchoscopy group were (6.9±1.9)and (8.7±2.8) d, respectively, which were significantly shorter than (10.1±2.2) and (11.6±3.5) d in bronchoscopy group (t=6.85, 4.09, P<0.01). Conclusions: Nebulized acetylcysteine inhalation combined with bronchoscopy can significantly control the degree of lung infection in elderly patients with severe VAP, improve patients' respiratory mechanics parameter and blood gas analysis indicator, and shorten the time for mechanical ventilation and antibiotic usage.

Clinical, microbiological research of the effectiveness of inhalation use of quaternary ammonium antiseptic in the prevention and treatment of infectious respiratory complications in critically ill patients

Introduction: The aim is to study the microbiological and clinical efficacy of decamethoxinebased quaternary ammonium antiseptic inhalations in the complex management of respiratory infectious complications in critically ill children.&#x0D; Methods: The use of inhalation of antiseptic medicinal decamethoxine (DCM) was studied in patients with ventilator-associated pneumonia (VAP) (n=30), of ages 12-18 years. All patients received standard intensive care according to the guidelines. Inhalations of 5 mL DCM (0.02%) antiseptic per inhalation TID for 7 days in combination with systemic antibiotic therapy were used in the study group (n=15). Clinical microbiological studies and assessment of Toll-like receptor (e.g. TLR-4) serum levels were performed in patients.&#x0D; Results: The use of DCM inhalations along with systemic antibiotic therapy improved parameters of dynamic compliance by 3.4-fold and decreased lung resistance by 2.4-fold in patients after 48-72 hours of mechanical ventilation. The microbial spectrum of patients at the beginning of VAP was represented by gram-positive (S. aureus — 28.6%, S. pyogenes — 10.2%) and gramnegative (P. aeruginosa — 16.3%; A. baumannii — 12.24%; K. pneumoniae — 10.2%) pathogens. The pathogens were isolated in the monoculture (20.4%) and in microbial associations (79.6%). A significant decrease by 3 orders of magnitude (log (2.640.43) CFU/mL) in the microbial count in tracheobronchial secretions was determined after 7 days of additional use of DCM inhalations when compared to the initial levels of microbial colonization (p&lt;0.001). The microbial spectrum of the respiratory tract was predominantly represented by S. aureus (27.78%), A. baumannii (11.11%) and E. cloacae (5.56%) in monoculture (61.11%), whereas the microbial count was 4 orders of magnitude higher in the comparison group, versus that of the study group (p&lt;0.001), and was represented by microbial associations (93.33%). A strong correlation was found between the reduction of the gram-negative pathogen count and the decrease of TLR-4 serum levels (r-Pearson=0.893), that almost reached baseline levels after DCM inhalations, while TLR-4 levels remained 2 times higher than baseline levels after the use of systemic antimicrobial therapy alone (p&lt;0.001).&#x0D; Conclusion: The use of DCM inhalations in combination with systemic antibiotic therapy provides for an effective reduction of pathogen count in the respiratory tract, leading to the early (48-72h) improvement in lung ventilation and TLR-4 serum levels, and subsequent significant improvement of treatment efficacy in severe VAP patients.

Reinventing the wheel: Impact of prolonged antibiotic exposure on multidrug-resistant ventilator-associated pneumonia in trauma patients.

Multidrug-resistant (MDR) strains of both Acinetobacter baumannii (AB) and Pseudomonas aeruginosa (PA) as causative ventilator-associated pneumonia (VAP) pathogens are becoming increasingly common. Still, the risk factors associated with this increased resistance have yet to be elucidated. The purpose of this study was to examine the changing sensitivity patterns of these pathogens over time and determine which risk factors predict MDR in trauma patients with VAP. Patients with either AB or PA VAP over 10 years were stratified by pathogen sensitivity (sensitive [SEN] and MDR), age, severity of shock, and injury severity. Prophylactic and empiric antibiotic days, risk factors for severe VAP, and mortality were compared. Multivariable logistic regression was performed to determine which risk factors were independent predictors of MDR. Three hundred ninety-seven patients were identified with AB or PA VAP. There were 173 episodes of AB (91 SEN and 82 MDR) and 224 episodes of PA (170 SEN and 54 MDR). The incidence of MDR VAP did not change over the study (p = 0.633). Groups were clinically similar with the exception of 24-hour transfusions (14 vs. 19 units, p = 0.009) and extremity Abbreviated Injury Scale (AIS) score (1 vs. 3, p < 0.001), both significantly increased in the MDR group. Antibiotic exposure as well as multiple episodes of inadequate empiric antibiotic therapy (mIEAT) (63% vs. 81%, p < 0.001) were significantly increased in the MDR group. Multivariable logistic regression identified prophylactic antibiotic days (odds ratio, 23.1; 95% confidence interval, 16.7-28, p < 0.001) and mIEAT (odds ratio, 18.1; 95% confidence interval, 12.2-26.1, p = 0.001) as independent predictors of MDR after adjusting for severity of shock, injury severity, severity of VAP, and antibiotic exposure. Prolonged exposure to unnecessary antibiotics remains one of the strongest predictors for the development of antibiotic resistance. Multivariable logistic regression identified prophylactic antibiotic days and mIEAT an independent risk factors for MDR VAP. Thus, limiting prophylactic antibiotic days is the only potentially modifiable risk factor for the development of MDR VAP in trauma patients. Level IV Therapeutic; level III Prognostic.

Combined Rifampin and Sulbactam Therapy for Multidrug-Resistant Acinetobacter Baumannii Ventilator-Associated Pneumonia in Pediatric Patients.

Background:With essentially no drug available to control the infection caused by the extensively drug-resistant Acinetobacter baumannii (XDR-Ab) in infants and young children, this study explored the clinical outcomes of pediatric patients with drug-resistant XDR-Ab who were treated with rifampicin in combination with sulbactam sodium.Methods:The data for clinical outcomes, microbiological responses, and side effects were collected and evaluated for 12 critically ill infants and young children diagnosed with ventilator-associated pneumonia caused by XDR-Ab following surgical treatment for congenital heart disease in a pediatric cardiac intensive care unit. This study was approved by local institutional review board (IRB).Results:Two patients died from the complex underlining diseases. The other 10 patients were weaned off the mechanical ventilation successfully within 4–15 days after the start of treatment with rifampicin combined with sulbactam sodium and discharged home. Three cases experienced adverse side effects, including severe rash and elevated aminotransferase level.Conclusion:The combination of rifampicin and sulbactam sodium appeared to be an effective and safe therapy for severe ventilator-associated pneumonia caused by XDR-Ab in infants and young children. Side effects such as skin rashes and elevated aminotransferase levels can be reversed once rifampicin is discontinued in time. (Funded by the Department of Cardiovascular Surgery, The Second Xiangya Hospital, Central South University, Chang­sha, China; the Departments of Anesthesiology and Pain Medicine of University of California Davis Health; and the National Institutes of Health.)

Verona integron-encoded metallo-β-lactamase-producing Klebsiella pneumoniae sepsis in an extremely premature infant

Abstract During the course of an outbreak due to Verona integron-encoded Metallo-β-lactamase (VIM)-producing Klebsiella pneumonia (KP) in the neonatal intensive care unit (NICU) of Maggiore Hospital in Bologna (Italy), an 8-day-old extremely low birth weight (ELBW) infant developed a severe ventilator-associated pneumonia (VAP) with concomitant bacteraemia. Although the microorganism was susceptible only to colistin and tigecycline, the patient was successfully treated with a combination of antibiotics including high-dosage, prolonged infusion of meropenem (MEM) and intravenous plus aerosolised gentamicin (GEN). This report highlights that, even when the microorganism is considered non-susceptible to MEM and GEN, the combination of these two agents could have a significant survival benefit.

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

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

What We Learned From the EU-VAP/CAP Study for Severe Pneumonia

EU-VAP/CAP is the largest observational, multicenter, international study conducted in Europe, focusing on severe pneumonia in the intensive care unit. It provided important insights into the different aspects of diagnostics and management of severe community-acquired pneumonia (CAP) and nosocomial pneumonia. Incidence, specificities of early-onset and late-onset settings, microbiologic etiology, antimicrobial prescription, and outcomes were analyzed, with a closer look at ventilator-associated pneumonia (VAP). Distinct populations showing specific risk factors, and outcomes were set (trauma VAP, elderly VAP, chronic obstructive pulmonary disease VAP), stressing VAP variety and complexity. This review assesses EU-VAP/CAP findings that opened perspectives on future research: the role of antibiotic choice in reducing severe CAP mortality, the study of a very early-onset VAP subset, the high frequency of potential resistant microorganisms in VAPs without known risk factor for resistance, the importance of describing specific VAP subpopulations (trauma, elderly, chronic obstructive pulmonary disease), and the insufficiency of nurse-to-patient ratio index to assess the nursing impact on VAP occurrence. The EU-VAP/CAP study comprehensively helped portray the picture of severe pneumonia across Europe and clarify the main themes that need to be scrutinized in the near future to reduce the heavy burden of severe CAP and VAP.

Influence of auxiliary treatment of bronchoscopy alveolar lavage on respiratory mechanics index and infection control effect in patients with severe ventilator associated pneumonia

Objective To observe influence of auxiliary treatment of bronchoscopy alveolar lavage on respiratory mechanics index and infection control effect in patients with severe ventilator associated pneumonia (VAP). Methods 84 cases of severe VAP patients were randomly divided into the observation group(n=42 cases)and control group(n=42 cases), control group was given antibiotics and conventional sputum suction lavage treatment, the observation group was given bronchoscopy alveolar lavage and antibiotics. Clinical pulmonary infection score(CPIS)and serum calcitonin level(PTC)were recorded in the two groups before and after treatment. Respiratory mechanics indexes such as the dynamic compliance(Cdyn), the airway peak pressure (PIP), work of breathing(WOB)and airway resistance(Raw)were measured in the two groups before and after bronchoscopy alveolar lavage, and the clinical efficacy of two groups were compared. Results CPIS of the observation group(6.37±1.31),(5.42±1.13),(3.52±0.53)was significantly lower than that of the control group(7.72±1.56),(7.14±1.33),(5.13±0.94)(t=4.295,6.387,5.821,all P<0.05)after 3,5,7 d treatment.PTC of the observation group((4.71±0.85)μg/L,(2.65±0.61)μg/L, (0.62±0.23)μg/L)were significantly lower than those of the control group(5.10±0.92)μg/L,(3.96±0.72)μg/L,(1.31±0.43)μg/L(t=4.295,6.387,5.821,all P<0.05)after 3,5,7 d treatment. Cdyn of the observation group after 1 and 4 h bronchoscopy alveolar lavage(35.39±6.39),(35.59± 5.83)were high those of the control group(26.82±4.63),(25.64±4.28)(t=7.038,-10.462,all P<0.05); WOB(10.08±0.45),(8.10±0.38),PIP(21.28±2.76),(15.29±1.67)and Raw(10.08±0.45),(8.10±0.38) in the observation group after 1and 4h bronchoscopy alveolar lavage were lower those in the control group WOB(0.63±0.17),(0.49±0.12),Raw(13.49±0.50),(11.42±0.42),PIP(27.38±3.10),(23.44±2.60)(1h: t=9.681,3.937,32.853,all P<0.05;4h:t=12.231,6.064,6.313,all P<0.05). Total effective rate of the observation group was obviously higher than that of the control group after treatment(93.3%vs.77.8%,chisquare=5.486,P<0.05). Conclusion Auxiliary treatment of bronchoscopy alveolar lavage has clinical curative effect in patients with severe VAP, the method can effectively decreased PTC level of VAP patients, to acquire lung infection control, and improve the respiratory mechanics parameters. Key words: Pneumonia, Ventilator dependence; Bronchoscopy Alveoler lavage; Respiratory mechanics

Gender disparity in ventilator-associated pneumonia following trauma: identifying risk factors for mortality.

Gender alone offers no survival advantage in humans following trauma. However, male gender does predict increased morbidity, specifically ventilator-associated pneumonia (VAP). Previous work has shown that despite lower incidence of VAP, females with VAP have increased mortality. The purposes of this study were to evaluate the impact of VAP and gender on outcome and to determine which characteristics of severe VAP predict mortality in trauma patients. Patients with VAP (≥10 colony-forming units per milliliter in bronchoalveolar lavage) over 8 years were stratified by gender, age, severity of shock, and injury severity. Severe VAP factors were defined as multiple-episode, polymicrobial, multidrug-resistant, nosocomial VAP diagnosed within 7 days of admission (eNVAP), and multiple inadequate empiric antibiotic therapy episodes. Mortality and severe VAP factors were compared using χ analysis. Multivariable logistic regression (MLR) was performed to determine which VAP factors were independent predictors of mortality. A total of 854 patients were identified, 676 men (79%) and 178 women (21%). Despite a higher incidence of VAP among males (3.8% vs. 2.6%, p = 0.001), mortality was higher in females (24% vs. 15%, p = .009). All characteristics of severe VAP were increased in females except multiple episodes (p = 0.15). MLR identified eNVAP as an independent predictor of mortality in females with severe VAP after adjusting for age, Glasgow Coma Scale (GCS) score, Injury Severity Score (ISS), admission base excess, and 24-hour transfusions (odds ratio, 9.97; p = 0.001). That females develop less VAP but experience increased mortality confirms previous studies. Characteristics of severe VAP are increased in females and may contribute to this observed mortality difference. MLR identified eNVAP as an independent predictor of mortality in females with severe VAP following trauma. Epidemiologic/prognostic study, level III.

Multidrug-resistant Acinetobacter lwoffii infection in neonatal intensive care units

Multidrug-resistant Acinetobacter lwoffii infection in neonatal intensive care units Narongsak Nakwan1,2, Jeerawan Wannaro2, Narongwit Nakwan31Neonatal Intensive Care Unit, 2Department of Pediatrics, 3Department of Medicine, Hat Yai Medical Education Center, Hat Yai Hospital, Songkhla, ThailandAim: To describe the clinical, bacteriological features, and outcome of Acinetobacter lwoffii infection in the neonatal population.Method: We retrospectively reviewed the medical records of four neonatal cases of A. lwoffii infection admitted to the Hat Yai Hospital, January 2005 to December 2009.Results: Four cases (one in 2007, and three in 2008) were identified as having A. lwoffii infection. Of the four cases, three presented with late-onset infection (after 72 hours of age), while 1 presented with early-onset (within the first 72 hours of age). All cases were inserted with umbilical catheters, required positive pressure mechanical ventilation, and had been treated previously with antibiotic drugs at time of diagnosis. Antimicrobial susceptibility testing of seven isolates (three in blood, three in sputum, and one in cerebrospinal fluid) was performed using the disk diffusion method. The most tested isolates were susceptible to netilmicin, imipenem, cefoperazone/sulbactam, while most were simultaneously generally resistant to amikacin, gentamicin, ceftazidime, ceftriaxone, cefepime, ciprofloxacin, and clindamicin. The treatment of A. lwoffii infection in the four cases varied. Only one case was successfully treated with imipenem, while three cases died from severe ventilator-associated pneumonia, and severe sepsis.Conclusion: This study increases awareness of A. lwoffii infection in the neonatal population, particularly in premature infants with several risk factors for nosocomial infection, including central intravascular catheters and prolonged mechanical ventilation.Keywords: Acinetobacter lwoffii, Acinetobacter infection, newborn infant

Severe ventilator-associated pneumonia caused by methicillin-resistant Staphylococcus aureus and other pathogens: report of a case successfully managed by serial surveillance cultures of endotracheal aspirates

Severe ventilator-associated pneumonia (VAP) caused by methicillin-resistant Staphylococcus aureus (MRSA) developed in a patient with acute respiratory distress syndrome. After tracheostomy, the patient was treated with antibiotic therapy guided by serial surveillance cultures of endotracheal aspirates. According to the result of the culture, the suitable antibiotic targeting the pathogen (e.g., MRSA, Pseudomonas aeruginosa, Klebsiella oxytoca) that had grown most predominantly in the culture was used until clinical resolution of VAP, leading to avoidance of overusing broad-spectrum antibiotics and ultimately a favorable outcome. During vancomycin (VCM) therapy for MRSA VAP, MRSA bacteremia occurred even though the trough value of VCM was sufficiently high. After the change from VCM to linezolid (LZD), the VAP improved promptly, indicating that LZD is superior to VCM in the treatment of MRSA pneumonia.

Autoinducer production and quorum-sensing dependent phenotypes of Pseudomonas aeruginosa vary according to isolation site during colonization of intubated patients

BackgroundPseudomonas aeruginosa frequently colonizes and is responsible for severe ventilator-associated pneumonia in intubated patients. A quorum-sensing (QS) circuit, depending on the production of the two QS-signaling molecules (autoinducers, AIs) 3-oxo-C12-HSL and C4-HSL, regulates the production by P. aeruginosa of several virulence factors and is required for biofilm formation. Therefore QS-inhibition has been suggested as a new target for preventive and/or therapeutic strategies. However the precise role of QS during colonization and subsequent infections of intubated patients remains unclear.ResultsWe wondered whether QS is active during colonization of intubated patients, and whether P. aeruginosa isolates growing inside the biofilm covering the intubation devices and those resident in the lungs of colonized patients differ in their QS-dependent phenotypes. We collected the intubation devices of eight patients colonized by P. aeruginosa. We detected 3-oxo-C12-HSL on eight, and C4-HSL on six of these devices. In three of these patients we also obtained P. aeruginosa isolates from tracheal aspirates at the time of extubation (n = 18), as well as isolates from the intubation devices (n = 25). We genotyped these isolates, quantified their AIs production, and determined three QS-dependent phenotypes (adherence capacity, biofilm and elastase production). The production of 3-oxo-C12-HSL was consistently increased for isolates from the intubation devices, whereas the production of C4-HSL was significantly higher for isolates from tracheal aspirates. Isolates from tracheal aspirates produced significantly higher amounts of elastase but less biofilm, and had a marginally reduced adhesion capacity than isolates from the intubation devices. Levels of 3-oxo-C12-HSL and elastase production correlated statistically for tracheal intubation isolates, whereas levels of 3-oxo-C12-HSL production and adhesion ability, as well as biofilm production, correlated weakly amongst intubation device isolates.ConclusionOur findings demonstrate that autoinducers are produced during the colonization of intubated patients by P. aeruginosa. The microenvironment, in which P. aeruginosa grows, may select for bacteria with different capacities to produce autoinducers and certain QS-dependent phenotypes. QS-inhibition might therefore affect differently isolates growing inside the biofilm covering intubation devices and those resident in the lungs.