Initial bacterial colonization in patients admitted to a respiratory intensive care unit: bacteriological pattern and risk factors

Stethoscopes or Maybe "Bacterioscopes" - Is hand Hygiene Solely Capable of Preventing Hospital-Associated Infections?

The stethoscope remains an indispensable diagnostic tool for medical students. Improper stethoscope hygiene may cause bacterial infections, including hospital-associated infections (HAIs), which challenge the Polish medical system. The study's main objective was to evaluate the hygiene habits declared by medical students. Moreover, microbiological control with the characteristics of potentially pathogenic microorganisms was performed. The study included 66 medical students from the Faculty of Medicine at the Jagiellonian University Medical College in Cracow, Poland. The participants filled in an anonymous questionnaire. Stethoscope contamination was assessed through isolation, identification, testing of antibiotic resistance, and clonality of the isolates bacterial pathogens. The survey showed that only 30.3% of students cleaned their stethoscopes after each patient, and 1.5% never did this. Of the 66 stethoscopes tested, 100% were positive for bacterial growth. Staphylococcus spp. was the most frequently isolated contaminant (50.5%). The questionnaire results demonstrated the necessity of the validated procedures for cleaning the stethoscopes. Stethoscopes used by medical students are contaminated with numerous bacterial species, including multidrug-resistant organisms. The clonal structure of the MRSA and MRSE populations acquired from stethoscopes has been demonstrated. Our results confirm the possibility that these medical devices mediate the spread of hazardous pathogens in the hospital environment. Practical exercises are essential to forming the correct hygiene habits involving stethoscopes, which enable practicing and checking the correctness of the established skills.

Effect of 0.12% Chlorhexidine Use for Oral Care on Ventilator-Associated Respiratory Infections: A Randomized Controlled Trial

BACKGROUND

Evidence suggests that the effect of 0.12% chlorhexidine (CHX) use for oral care on the development of ventilator-associated pneumonia (VAP) and ventilator-associated tracheobronchitis (VAT) is lacking. Evidence-based approaches to the prevention of VAP and VAT are of paramount importance for improving patients' outcomes.

OBJECTIVES

This study aimed to (1) compare the effect of 0.12% CHX use for oral care on preventing VAP and VAT with the placebo group, as well as (2) compare its effect on oral health and prevention of oral microbial colonization with the placebo group.

METHODS

Prospective, single-blinded, randomized controlled trial performed in 2 intensive care units at a hospital. The sample comprised 57 mechanically ventilated adults randomly allocated to the 0.12% CHX group and the placebo group. Barnason's oral assessment guide was used to evaluate the oral health of both groups before oral care during the first 24 hr of tracheal intubation (Day 0) and at Day 2 and Day 3. Oropharyngeal secretion, endotracheal tube aspirate, and nonbronchoscopic bronchoalveolar lavage samples were collected on Day 0 and Day 3.

RESULTS

The rate of VAT development was not statistically different between the groups (p = .318). However, a significant difference existed in the rate of VAP development (p = .043). The frequency of oropharyngeal colonization significantly decreased in the 0.12% CHX group compared with the placebo group at Day 3 (p = .001).

CONCLUSION

The use of 0.12% CHX for oral care could be effective for VAP prevention and reducing microbial colonization in mechanically ventilated patients.

Is ventilated hospital-acquired pneumonia a worse entity than ventilator-associated pneumonia?

Introduction

Nosocomial pneumonia develops after ≥48 h of hospitalisation and is classified as ventilator-associated pneumonia (VAP) and hospital-acquired pneumonia (HAP); the latter may require mechanical ventilation (V-HAP) or not (NV-HAP).

Main findings

VAP and HAP affect a significant proportion of hospitalised patients and are characterised by poor clinical outcomes. Among them, V-HAP has the greatest 28-day mortality rate followed by VAP and NV-HAP (27.8% versus 18% versus 14.5%, respectively). However, no differences in terms of pathophysiology, underlying microbiological pathways and subsequent therapy have been identified. International guidelines suggest specific flow charts to help clinicians in the therapeutic management of such diseases; however, there are no specific recommendations beyond VAP and HAP classification. HAP subtypes are scarcely considered as different entities and the lack of data from the clinical scenario limits any final conclusion. Hopefully, recent understanding of the pathophysiology of such diseases, as well as the discovery of new therapies, will improve the outcome associated with such pulmonary infections.

Conclusion

Nosocomial pneumonia is a multifaced disease with features of pivotal interest in critical care medicine. Due to the worrisome data on mortality of patients with nosocomial pneumonia, further prospective studies focused on this topic are urgently needed.

Due to the different mortality of each subtype of nosocomial pneumonia, including ventilator-associated pneumonia and hospital-acquired pneumonia requiring mechanical ventilation, new prospective studies are urgently neededhttps://bit.ly/3fFoZ6U

STRESS ULCER PROPHYLAXIS AS A RISK FACTOR FOR TRACHEAL COLONIZATION AND HOSPITAL-ACQUIRED PNEUMONIA IN INTENSIVE CARE PATIENTS: IMPACT ON LATENCY TIME FOR PNEUMONIA

Stress ulcer prophylaxis is associated with bacterial colonization of respiratory tract. The aims of our study were to determine risk factors for trachea colonization (TC), colonization of pharynx (CP) or stomach (CD) and hospital-acquired pneumonia (HAP), and divide the factors into those with high risk and low risk. The study population (ventilated intensive care unit (ICU) patients eligible to receive stress ulcer prophylaxis) was randomized to receive one of three different treatment protocols: ranitidine, sucralfate, and no stress ulcer prophylaxis (control group). Clinical data relative to pre-specified risk factors for TC or HAP were recorded, as follows: APACHE II score (second risk factor), duration of intubation or tracheotomy (third risk factor), duration of mechanical ventilation (fourth risk factor) and duration of hospitalization in the ICU (fifth risk factor). Gastric pH was recorded and microbiological data regarding stomach, pharynx and trachea were collected on the 1^st, 2^nd, 3^rd and 5^th day. Fifty-eight out of 81 patients developed HAP (including ventilator-associated pneumonia), which occurred later in patients with gastric content pH <4 or those that were tracheotomized. Stress ulcer prophylaxis was not associated with HAP; however, it was proved as a risk factor for TC. TC was detected in tracheotomized patients and was caused by gram-negative pathogens. CP was associated with TC, since the majority of patients had CP before TC. A combination of risk factors (APACHE II >18, age >65, mechanical ventilation and sedation) caused a higher incidence of HAP and lower incidence of TC. HAP was more frequent in patients staying in the ICU for >10 days and those with cardiovascular disease as the underlying disorder. Sedation and previous antibiotic therapy correlated with longer latent period (LAT), while higher values of gastric content pH were related to shorter LAT. The longest LAT was found in patients colonized with Acinetobacter spp. Risk factors that accelerated the occurrence of HAP were found to have caused previous colonization. A combination of risk factors increased the likelihood of TC and HAP, and shortened LAT between TC and HAP.

Ventilator-associated pneumonia: The central role of transcolonization

Ventilator-associated pneumonia remain frequent and serious diseases since they are associated with considerable crude mortality. Pathophysiology is centered on modifications of regional bacterial flora, especially tracheobronchial tree and oropharyngeal sphere. Bacterial migration from an anatomical area to another seems to be the main explanation of these alterations which are called "transcolonization". The association of transcolonization and lack of tightness of the endotracheal tube cuff provides a direct pathway for bacteria from the upper to the subglottic airways, eventually leading to ventilator-associated pneumonia. Although modification of bacterial flora has been largely studied, the mechanism which underlays the ability of the implantation, growing and interactions with the local microbiome that leads to the observed transcolonization remains to be more clearly deciphered. The aim of our review is to emphasize the cornerstone importance of the "transcolonization" as a nosological entity playing a central role in ventilator-associated pneumonia.

Are tracheal surveillance cultures useful in the intensive care unit?

Endotracheal aspirate (ETA) surveillance cultures have been used to predict the microorganisms responsible for ventilator associated pneumonia (VAP) in intensive care unit (ICU) patients for 3 decades. However, although more than a dozen studies have been performed, the usefulness and the safety of this strategy are still debated. Tracheobronchial bacterial colonization often precedes the occurrence of VAP, and it has been postulated that the microbes present in the tracheal secretions a few days before VAP might be the same as those retrieved in the lower respiratory tract. A large number of studies, with heterogeneous designs and variable results, have questioned the possibility of predicting, by regular ETA cultures after the 48^th hour of mechanical ventilation (MV), the microbiology of VAP and therefore of determining the adequate antibiotic therapy to limit the over-prescription of broad spectrum molecules when following guidelines. Although it has shown some promising results, the strategy has not achieved unanimity because of some discordant data. The aim of this review is to provide an updated overview of the literature available in the field and to attempt to determine the strengths and weaknesses of antibiotic stewardship based on ETA surveillance cultures in VAP, particularly in the global context of drug resistant microorganism emergence and the crucial necessity of broad spectrum molecule preservation.

Prognostic Risk Factors in Ventilator-Associated Pneumonia

BACKGROUND Ventilator-associated pneumonia (VAP) is a nosocomial infection commonly seen in patients in intensive care units (ICU). This study aimed to analyze factors affecting prognosis of patients diagnosed with VAP. MATERIAL AND METHODS Critically ill patients with VAP were retrospectively evaluated between June 2002 and June 2011 in the ICU. VAP diagnosis was made according to 2005 ATS/IDSA (Infectious Diseases Society of America/American Thoracic Society) criteria. First pneumonia attacks of patients were analyzed. RESULTS When early- and late-onset pneumonia causes were compared according to ICU and hospital admittance, resistant bacteria were found to be more common in pneumonias classified as early-onset according to ICU admittance. APACHE II score of >21 (p=0.016), SOFA score of >6 (p<0.001) on admission to ICU and SOFA score of >6 (p<0.001) on day of diagnosis are risk factors affecting mortality. Additionally, low PaO2/FIO2 ratio at onset of VAP had a negative effect on prognosis (p<0.001). SOFA score of >6 on the day of VAP diagnosis was an independent risk factor for mortality [(p<0.001; OR (95%CI): 1.4 (1.2-1.6)]. CONCLUSIONS Resistant bacteria might be present in early-onset VAP. Especially, taking LOS into consideration may better estimate the presence of resistant bacteria. Acinetobacter baumannii, Pseudomonas aeruginosa, and methicillin-resistant Staphylococcus aureus (MRSA) were the most frequent causative microorganisms for VAP. SOFA score might be more valuable than APACHE II score. Frequently surveilling SOFA scores may improve predictive performance over time.

Haemophilus parainfluenzae as a marker of the upper respiratory tract microbiota changes under the influence of preoperative prophylaxis with or without postoperative treatment in patients with lung cancer

Background

Haemophili are representative microbiota of the upper respiratory tract. The aim of this study was to assess the effects of perioperative antimicrobial prophylaxis and/or postoperative treatment on Haemophilus parainfluenzae prevalence, and antimicrobial sensitivity in short-term hospitalized patients with lung cancer who underwent surgery.

Results

Samples were collected from 30 short-term hospitalized patients with lung cancer and from 65 healthy people. The nasal and throat specimens were taken twice from each patient: before (EI, Examination I), on the fourth/fifth day (EII, Examination II) after surgery, and once from healthy people. The isolates identification and antimicrobial susceptibility were detected by routine diagnostic methods. H. parainfluenzae was found in throat specimens of 42/65 (64.6 %) healthy people, while in 19/30 (63.3 %) lung cancer patients in EI (p = 0.6203) and in 13/30 (43.3 %) ones in EII (p = 0.0106). Neither the disease itself nor short-term hospitalization with perioperative prophylaxis alone affected H. parainfluenzae prevalence in EII, while perioperative prophylaxis with postoperative treatment significantly decreased its colonization in EII. The differences in the number of patients colonized by Candida spp. in EI and in EII were observed (p = 0.0082).Totally, 23/58 (39.7 %) of H. parainfluenzae isolates were resistant mainly to beta-lactams; among 11 ampicillin-resistant isolates only 3 were beta-lactamase positive.

Conclusions

The antimicrobial perioperative prophylaxis together with postoperative treatment may disturb the composition of the airways microbiota represented by H. parainfluenzae, in addition to selecting the resistant strains of bacteria and promoting yeasts colonization in lung cancer patients undergoing surgery.

Risk factors for tracheobronchial acquisition of resistant Gram-negative bacterial pathogens in mechanically ventilated ICU patients

The aim of this study was to identify risk factors for tracheobronchial acquisition with the most common resistant Gram-negative bacteria in the intensive care unit (ICU) during the first week after intubation and mechanical ventilation. Tracheobronchial and oropharyngeal cultures were obtained at admission, after 48 hours, and after 7 days of mechanical ventilation. Patient characteristics, interventions, and antibiotic usage were recorded. Among 71 eligible patients with two negative bronchial cultures for resistant Gram-negative bacteria (at admission and within 48 hours), 41 (58%) acquired bronchial resistant Gram-negative bacteria by day 7. Acquisition strongly correlated with presence of the same pathogens in the oropharynx: Acinetobacter baumannii [odds ratio (OR) = 20·2, 95% confidence interval (CI): 5·5-73·6], Klebsiella pneumoniae (OR = 8·0, 95% CI: 1·9-33·6), and Pseudomonas aeruginosa (OR = 27, 95%: CI 2·7-273). Bronchial acquisition with resistant K. pneumoniae also was associated with chronic liver disease (OR = 3·9, 95% CI: 1·0-15·3), treatment with aminoglycosides (OR = 4·9, 95% CI: 1·4-18·2), tigecycline (OR = 4·9, 95% CI: 1·4-18·2), and linezolid (OR = 3·9, 95% CI: 1·1-15·0). In multivariate analysis, treatment with tigecycline and chronic liver disease were independently associated with bronchial resistant K. pneumoniae acquisition. Our results show a high incidence of tracheobronchial acquisition with resistant Gram-negative microorganisms in the bronchial tree of newly intubated patients. Oropharynx colonization with the same pathogens and specific antibiotics use were independent risk factors.

Is a strategy based on routine endotracheal cultures the best way to prescribe antibiotics in ventilator-associated pneumonia?

OBJECTIVES

The objectives of this study were to evaluate if a strategy based on routine endotracheal aspirate (ETA) cultures is better than using the American Thoracic Society/Infectious Diseases Society of America (ATS/IDSA) guidelines to prescribe antimicrobials in ventilator-associated pneumonia (VAP).

METHODS

This was a prospective, observational, cohort study conducted in a 15-bed ICU and comprising 283 patients who were mechanically ventilated for ≥48 h. Interventions included twice-weekly ETA; BAL culture was done if VAP was suspected. BAL (collected at the time of VAP) plus ETA cultures (collected≤7 days before VAP) (n=146 different pairs) were defined. We compared two models of 10 days of empirical antimicrobials (ETA-based vs ATS/IDSA guidelines-based strategies), analyzing their impact on appropriateness of therapy and total antimicrobial-days, using the BAL result as the standard for comparison.

RESULTS

Complete ETA and BAL culture concordance (identical pathogens or negative result) occurred in 52 pairs; discordance (false positive or false negative) in 67, and partial concordance in two. ETA predicted the etiology in 62.4% of all pairs, in 74.0% of pairs if ETA was performed≤2 days before BAL, and in 46.2% of pairs if ETA was performed 3 to 7 days before BAL (P=.016). Strategies based on the ATS/IDSA guidelines and on ETA results led to appropriate therapy in 97.9% and 77.4% of pairs, respectively (P<.001). The numbers of antimicrobial-days were 1,942 and 1,557 for therapies based on ATS/IDSA guidelines and ETA results, respectively (P<.001).

CONCLUSIONS

The ATS/IDSA guidelines-based approach was more accurate than the ETA-based strategy for prescribing appropriate, initial, empirical antibiotics in VAP, unless a sample was available≤2 days of the onset of VAP. The ETA-based strategy led to fewer days on prescribed antimicrobials.

Rep-PCR genotyping of infectious Acinetobacter spp. strains from patients treated in Intensive Care Unit of Emergency Department (ICU of ED)--preliminary report

PURPOSE

Strains of Acinetobacter spp. are responsible for a considerable percentage of hospital infections. These pathogens have colonized hospital environment and developed resistance to many currently available antibiotics. The aim of this study was one year-long analysis of the occurrence of multiresistant strains of Acinetobacter spp. in population of patients hospitalized in ICU of ED and determination of their genetic similarity.

MATERIAL/METHODS

Subject of research was the population of patients admitted to ED of University Hospital in Bialystok in the period from 01.08.2010 to 01.08.2011. In the analysed group of patients, infections were identified on the basis of the guidelines of CDC. Identification and drug susceptibility of strains was specified using the automatic methods with the analyzer Vitek 2XL. Genotyping using Rep-PCR method in DiversiLab system was performed on strains of Acinetobacter spp. to determinate their genetic similarity.

RESULTS

During analyzed period 405 patients were hospitalized, from 14 of them multiresistant strains of Acinetobacter spp. were isolated. Conducted genetic research allowed to detect 5 clones. Rep-PCR method in DiversiLab system enabled to learn that different clone of multiresistant strain of Acinetobacter spp. is responsible for variable forms of infection.

CONCLUSIONS

Results of conducted research suggest that genotyping with rep-PCR method in DiversiLab system is useful tool in diagnostics of clones of multiresistant pathogens isolated from patients requiring intensive care, hospitalized in ED. Genotyping with rep-PCR method combined with epidemiological investigation enables to establish ways of spreading of multiresistant strains of Acinetobacter spp. in ED.

Risk factors of Candida colonization in the oropharynx of patients admitted to an intensive care unit

OBJECTIVES

Candida colonization is an important precursor for candidiasis. However, there is little information about its risk factors in critically ill patients. We aimed to identify risk factors for oropharyngeal Candida colonization in critically ill patients.

PATIENTS, MATERIALS AND METHODS

This is a prospective observational study of 110 patients admitted to a medical intensive care unit (MICU). Oropharyngeal swabs were obtained on day one and day four. Characteristics of patients colonized with Candida species at admission or not colonized were compared. In addition, patients becoming colonized during their ICU stay were compared to patients who did not.

RESULTS

Independent risk factors for a positive Candida sample at the time of admission were: a history of proton pump inhibitor (PPI) use before admission (OR: 5.24, 95% CI: 1.36-20.19), the presence of diabetes mellitus (OR: 2.84, 95%CI: 1.02-7.92) and a lower BMI (OR: 0.9, 95% CI: 0.84-0.97). Chronic kidney disease was associated with a decreased frequency of Candida colonization (OR: 0.26, 95% CI: 0.01-0.46). No independent risk factors could be identified for patients who gained Candida during their ICU hospitalization. Patients with Candida colonization frequently had abnormal oral bacterial flora.

CONCLUSIONS

Diabetes mellitus, PPI use and a lower BMI are risk factors for Candida colonization in critically ill patients being admitted to the MICU.

Recovery of Gram-negative bacilli in stored endotracheal aspirates

This study assessed the recovery rates of Gram-negative bacilli from stored endotracheal aspirates frozen with and without glycerol. Samples frozen with glycerol showed a significant difference in isolate recovery, 89.7% versus 69.2% (P = 0.02). This study demonstrates that it is possible to achieve high recovery rates of potentially pathogenic organisms from endotracheal aspirates when stored with glycerol, thus broadening the scope of active surveillance cultures for both clinical and research purposes.

Epidemiology of bacterial colonization at intensive care unit admission with emphasis on extended-spectrum β-lactamase- and metallo-β-lactamase-producing Gram-negative bacteria – an Indian experience

An important risk factor for nosocomial infection in an intensive care unit (ICU) is prior colonization. This study was undertaken to determine the spectrum of bacterial colonization and predisposing risk factors in patients being admitted to an ICU in India, with special emphasis on extended-spectrum β-lactamase (ESBL)- and metallo-β-lactamase (MBL)-producing Gram-negative bacteria. Nasal, oral and rectal swab samples were collected and processed for isolation of ESBL-producing Gram-negative bacteria and MBL-producing Pseudomonas aeruginosa and Acinetobacter species. Bacterial colonization (of one or more sites) on admission was detected in 51 out of 96 patients included in the study. Non-fermenters, i.e. P. aeruginosa and Acinetobacter baumannii, were the most common colonizers, present in 37 patients, with simultaneous colonization in 12 patients. A total of 16 patients were colonized with MBL-producing members of the family Enterobacteriaceae, out of which 11 isolates (from 5 patients) were also carrying ESBL-encoding genes. As for MBLs, most of our patients have shown colonization with ESBL-producing bacteria. On admission, 47 of 51 patients (92 %) have been colonized by ESBL-producing members of the family Enterobacteriaceae, at one or more of the three anatomical sites. The most common MBL subtype was bla IMP (51.56 %), whereas bla CTX was the most common gene (84.9 %) identified among ESBL producers. Risk factors for colonization on admission to the ICU were hospitalization for more than 48 h, use of ≥3 groups of antibiotics, co-morbidities and mechanical ventilation for more than 48 h prior to ICU admission. There is an increasing incidence of MBLs and ESBLs in the Indian population. The identified risk factors can be used as a guide for empiric antibiotic therapy targeted to these resistant bacteria.

Viral colonization in intubated patients: initial pathogen pattern and follow-up

INTRODUCTION

Colonization of the lower respiratory tract is an independent risk factor for ventilator-associated pneumonia. Little is known about the frequency of viral colonization on intubation and during mechanical ventilation.

METHODS

Overall, 65 eligible intubated patients with no initial signs of pulmonary infection were studied over a period of up to 7 days. Tracheobronchial aspirates were taken: (i) within 48 h after intubation; and (ii) when clinical signs of nosocomial tracheobronchitis were present, before extubation, or after 7 days. Presence of respiratory viruses was investigated using quantitative polymerase chain reaction.

RESULTS

Patients were 67 +/- 11 years old and had been in hospital for 5.1 +/- 8.4 days when intubated (major cause for intubation: cardio-pulmonary resuscitation 25/65, 38%). The average Acute Physiology and Chronic Evaluation II score was 27.3 +/- 4.9. Microbiology detected Candida spp. (17/65; 26%) and Staphylococcus aureus (methicillin sensitive: 11/65; 17%; methicillin resistant: 3/65; 5%) and only few respiratory viruses (4/65, 6%). Thirty-eight percent of the samples (25/65) were sterile. At the given endpoints, 27/65 (42%) patients were available for follow-up and only one aspirate became positive for respiratory syncytial virus (RSV).

CONCLUSIONS

After endotracheal intubation, fungi, but not viruses were most frequently isolated. Only one patient acquired RSV, therefore colonization with respiratory viruses does not seem to play a major role early after intubation.

Patterns and density of early tracheal colonization in intensive care unit patients

OBJECTIVE

The study aimed to describe the patterns and density of early tracheal colonization among intubated patients and to correlate colonization status with levels of antimicrobial peptides and inflammatory cytokines.

DESIGN

The was a prospective cohort study.

SETTING

The study was conducted in medical and cardiovascular intensive care units of a tertiary referral hospital.

PATIENTS

Seventy-four adult patients admitted between March 2003 and May 2006 were recruited for the study.

INTERVENTIONS

Tracheal aspirates were collected daily for the first 4 days of intubation using standardized, sterile technique and sent for quantitative culture and cytokines, lactoferrin and lysozyme measurements.

MEASUREMENTS AND MAIN RESULTS

The mean acute physiology and chronic health evaluation (APACHE II) score in this cohort was 24 +/- 7. Proportion of subjects colonized by any microorganism increased over the first 4 days of intubation (47%, 60%, 70%, 70%, P = .08), but density of colonization for bacteria or yeast did not change significantly. No known risk factors predicted tracheal colonization on day 1 of intubation. Several patterns of colonization were observed (persistent, transient, new colonization, and clearance of initial colonization).The most common organisms cultured were Candida albicans and coagulase-negative Staphylococcus. Levels of cytokines, lactoferrin, or lysozyme did not change over time and were not correlated with tracheal colonization status. Four subjects (6%) had ventilator-associated pneumonia.

CONCLUSIONS

The density of tracheal colonization did not change significantly over the first 4 days of intubation in medical intensive care unit patients. There was no correlation between tracheal colonization and the levels of antimicrobial peptides or cytokines. Several different patterns of colonization may have to be considered while planning interventions to reduce airway colonization.

Ventilator-associated pneumonia caused by multidrug-resistant organisms or Pseudomonas aeruginosa: prevalence, incidence, risk factors, and outcomes

PURPOSE

The aim of this study was to clarify the prevalence and incidence of, risk factors for, and outcomes from suspected ventilator-associated pneumonia (VAP) associated with the isolation of either Pseudomonas or multidrug-resistant (MDR) bacteria ("high risk" pathogens) from respiratory secretions.

MATERIALS AND METHODS

Data were collected as part of a large, multicentered trial of diagnostic and therapeutic strategies for patients (n = 739) with suspected VAP.

RESULTS

At enrollment, 6.4% of patients had Pseudomonas species, and 5.1% of patients had at least 1 MDR organism isolated from respiratory secretions. Over the study period, the incidence of Pseudomonas and MDR organisms was 13.4% and 9.2%, respectively. Independent risk factors for the presence of these pathogens at enrollment were duration of hospital stay >or=48 hours before intensive care unit (ICU) admission (odds ratio, 2.37 [95% CI, 1.40-4.02]; P = .001] and prolonged duration of ICU stay before enrollment (odds ratio, 1.50 [95% CI, 1.17-1.93]; P = .002] per week. Fewer patients whose specimens grew either Pseudomonas or MDR organisms received appropriate empirical antibiotic therapy compared to those without these pathogens (68.5% vs 93.9%, P < .001). The isolation of high risk pathogens from respiratory secretions was associated with higher 28-day (relative risk, 1.59 [95% CI, 1.07-2.37]; P = .04] and hospital mortality (relative risk, 1.48 [95% CI, 1.05-2.07]; P = .05), and longer median duration of mechanical ventilation (12.6 vs 8.7 days, P = .05), ICU length of stay (16.2 vs 12.0 days, P = .05), and hospital length of stay (55.0 vs 41.8 days, P = .05).

CONCLUSIONS

In this patient population, the incidence of high-risk organisms newly acquired during an ICU stay is low. However, the presence of high risk pathogens is associated with worse clinical outcomes.

Intragastric generation of antimicrobial nitrogen oxides from saliva--physiological and therapeutic considerations

Salivary nitrite is suggested to enhance the antimicrobial properties of gastric juice by conversion to nitric oxide (NO) and other reactive nitrogen intermediates in the stomach. Intubated patients exhibit extremely low gastric levels of NO, because they do not swallow their saliva. The present investigation was designed to examine the antibacterial effects of human saliva and gastric juice. Furthermore, we studied a new mode of NO delivery, involving formation from acidified nitrite, which could prevent bacterial growth in the gastric juice of intubated patients in intensive care units. The growth of Escherichia coli ATCC 25922 and the formation of NO and nitroso/nitrosyl species were determined after incubation of gastric juice with saliva from healthy volunteers that was rich (nitrate ingestion) or poor (overnight fasting) in nitrite. In a stomach model containing gastric juice from intubated patients, we inserted a catheter with a silicone retention cuff filled with ascorbic acid and nitrite and determined the resulting antibacterial effects on E. coli and Candida albicans. Saliva enhanced the bactericidal effect of gastric juice, especially saliva rich in nitrite. Formation of NO and nitroso/nitrosyl species by nitrite-rich saliva was 10-fold greater than that by saliva poor in nitrite. In our stomach model, E. coli and C. albicans were killed after exposure to ascorbic acid and nitrite. In conclusion, saliva rich in nitrite enhances the bactericidal effects of gastric juice, possibly through the generation of reactive nitrogen intermediates, including NO. Acidified nitrite inside a gas-permeable retention cuff may be useful for restoring gastric NO levels and host defense in critically ill patients.

Microbial airway colonization is associated with noninvasive ventilation failure in exacerbation of chronic obstructive pulmonary disease*

OBJECTIVE

Abnormal airway colonization in patients with chronic obstructive pulmonary disease (COPD) needing invasive mechanical ventilation (IMV) is considered a first step in the acquisition of nosocomial pneumonia. Noninvasive ventilation (NIV) could potentially avoid this, but airway colonization has not been studied in patients who undergo NIV. We hypothesized that patients undergoing NIV would have lower rates of colonization than patients undergoing IMV. The aim of the study was to assess the microbial airway colonization in patients with exacerbated COPD needing NIV and IMV.

DESIGN

A 2-yr prospective cohort study.

SETTING

Respiratory intensive and intermediate care unit.

PATIENTS

Eighty-six patients with exacerbated COPD undergoing NIV on admission (64 successes and 22 failures, according to subsequent intubation), and 51 patients undergoing IMV on admission.

INTERVENTIONS

Quantitative culture specimens of sputum or tracheal aspirate were collected on admission and at follow-up (day 3) during NIV or IMV, respectively. Clinical assessment, including severity scores, and arterial blood gas measurements were also determined.

MEASUREMENTS AND MAIN RESULTS

Compared with the NIV-success group, colonization by potentially pathogenic microorganisms was greater in the NIV-failure group on admission (13 [59%] vs. 14 [22%]; p < .001) and at follow-up while patients still underwent NIV (14 [93%] vs. 7 [14%]; p < .001), and it was even higher than during IMV at follow-up (20 [50%]; p = .027). Colonization by nonfermenting Gram-negative bacilli, mainly Pseudomonas aeruginosa, was significantly associated with NIV failure on admission (OR, 5.6; p = .016) and at follow-up (OR, 23.5; p < .001). Moreover, colonization by these microorganisms at follow-up (OR, 8.8; p = .008) and inadequate antimicrobial treatment (OR 11.3; p = .001) were associated with increased hospital mortality.

CONCLUSIONS

Airway colonization by nonfermenting Gram-negative bacilli is strongly associated with NIV failure. Because it occurs before intubation, this would be a marker rather than just a consequence of NIV failure necessitating intubation. The efficacy of decreasing airway colonization in preventing NIV failure needs to be assessed.

Determinants of the Length of Mechanical Ventilation in Patients with COPD in the Intensive Care Unit

BACKGROUND

About 10% of the patients with chronic obstructive pulmonary disease (COPD) are at high risk for prolonged mechanical ventilation (MV >21 days), and mortality ranges from 55 to 78% in these patients.

OBJECTIVE

To determine the potential risk factors for MV over periods of 1, 2 and 3 weeks in patients with COPD.

PATIENTS AND METHOD

The characteristics of patients during the stable period of their disease, on admission to the intensive care unit (ICU) and during the ICU stay were recorded prospectively and analyzed retrospectively for this study. t test, chi(2) test and logistic regression analysis were used for statistical analysis.

RESULTS

86 patients with COPD requiring MV were included in the study. 73, 33, and 13% of the patients required MV longer than 1, 2 and 3 weeks, respectively. There were no significant relationships between the duration of MV and bronchiectasis or the presence of community-acquired pneumonia on admission, baseline pulmonary function test results or blood gas parameters on admission. Development of ventilator-associated pneumonia (VAP; odds ratio, OR: 6; 95% confidence interval, CI: 2-23, p = 0.011) and sepsis (OR: 10; 95% CI: 2-54, p = 0.007) were independent predictors for MV >7 days. VAP was still a risk factor for MV >15 days with an OR of 14 (95% CI: 3-66, p = 0.001). On the other hand MV >21 days was primarily determined by increasing age (OR: 1.2; 95% CI: 1-1.3, p = 0.042), severity of the disease on admission measured by APACHE II score (OR: 1.4; 95% CI: 1-1.7, p = 0.002) and albumin levels (OR: 0.10, 95% CI: 0.01-0.54, p = 0.007).

CONCLUSION

Advanced age, severity of disease on admission and development of VAP during ICU stay are the main determinants of MV duration in patients with COPD.

Multiresistant coagulase-negative staphylococci disseminate frequently between intubated patients in a multidisciplinary intensive care unit

Introduction

The intensive care unit is burdened with a high frequency of nosocomial infections often caused by multiresistant nosocomial pathogens. Coagulase-negative staphylococci (CoNS) are reported to be the third causative agent of nosocomial infections and the most frequent cause of nosocomial bloodstream infections. CoNS are a part of the normal microflora of skin but can also colonize the nasal mucosa, the lower airways and invasive devices. The main aim of the present study was to investigate colonization and the rate of cross-transmissions of CoNS between intubated patients in a multidisciplinary intensive care unit.

Materials and methods

Twenty consecutive patients, ventilated for at least 3 days, were included. Samples were collected from the upper and lower airways. All samples were cultured quantitatively and CoNS were identified by morphology and biochemical tests. A total of 199 CoNS isolates from 17 patients were genetically fingerprinted by pulsed-field gel electrophoresis in order to identify clones and to monitor dissemination within and between patients.

Results

An unexpected high number of transmission events were detected. Five genotypes were each isolated from two or more patients, and 14/20 patients were involved in at least one and up to eight probable transmission events.

Conclusions

A frequent transmission of CoNS was found between patients in the intensive care unit. Although transmission of bacteria does not necessarily lead to infection, it is nevertheless an indication that infection control measures can be improved.

Anaerobic bacteria commonly colonize the lower airways of intubated ICU patients

OBJECTIVES

To investigate respiratory tract colonization by aerobic and anaerobic bacteria in mechanically ventilated patients.

METHODS

Bacterial colonization of the stomach and the respiratory tract was qualitatively and quantitatively analyzed over time in 41 consecutive mechanically ventilated patients in a Swedish intensive care unit (ICU), with special emphasis on elucidation of the role of anaerobic bacteria in the lower respiratory tract. Samples were taken from the oropharynx, gastric juice, subglottic space and trachea within 24 h (median 14 h) of intubation, and then every third day until day 18 and every fifth day until day 33.

RESULTS

The patients were often heavily colonized with microorganisms not considered to belong to a healthy normal oropharyngeal and gastric flora on admission to the ICU. A majority harbored enterococci, coagulase-negative staphylococci and Candida spp. in at least one site on day 1. Anaerobic bacteria, mainly peptostreptococci and Prevotella spp., were isolated from subglottic and/or tracheal secretions in 59% of the patients. Different routes of tracheal colonization for different groups of microorganisms were found. Primary or concomitant colonization of the oropharynx with staphylococci, enterococci, enterobacteria and Candida was often seen, while Pseudomonas spp., other non-fermenting Gram-negative rods and several anaerobic species often primarily colonized the trachea, indicating exogenous or direct gastrointestinal routes of colonization.

CONCLUSIONS

Mechanically ventilated patients were heavily colonized in their lower airways by potential pathogenic microorganisms, including a high load of anaerobic bacteria. Different routes of colonization were shown for different species.

Ventilator-associated pneumonia

Ventilator-associated pneumonia is the most serious infectious complication in critically ill patients, associated with increased length of intensive care unit treatment and high mortality rates. Investigations focused on outcome variables have improved the database to estimate diagnostic and therapeutic management strategies. This knowledge has diminished the importance of the discussion on how to diagnose the pneumonia. This review summarizes recent data on epidemiology and mortality, risk factors and prevention, diagnosis, microbiology and antimicrobial treatment of ventilator-associated pneumonia.