Recurrent Pseudomonas aeruginosa pneumonia in an intensive care unit

The Effects of Glutamine Supplementation on Reducing Mortality and Morbidity among Burn Patients: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Glutamine (GLN) has been proven to improve the prognosis of severely burned patients. GLN supplementation in critical illness has gained extreme popularity among researchers over the years, and its safety and efficacy are still under question. Therefore, we aim to study the role of GLN supplements in decreasing mortality, length of hospitalization (LOH), and infection in severely burned patients. PRISMA guidelines were used to design and conduct this systematic review. MEDLINE, Cochrane, and EMBASE databases were used to search for randomized controlled trials (RCTs) in January 2022. In order to assist in the search, MeSH terms such as burn injury, GLN, and RCT were used. As a result of reviewing the literature, 1112 publications were found. We included only 7 RCTs after implanting our inclusion criteria. There were 328 patients enrolled in the study, with 166 patients (50.61%) were allocated to GLN supplementation and 162 patients in the control groups (49.39%). The risk of infection was significantly lower among patients who received GLN supplementation than those in the control groups (RR = 0.41, 95% CI, 0.18 to 0.92, p = 0.030). The risk of death was significantly lower among GLN-receiving patients compared to non-GLN-receiving patients (RR = 0.09, 95% CI, 0.01 to 0.63, p = 0.016). GLN supplementation has been linked to lower hospital mortality and infection-related morbidity in burn patients. Furthermore, larger-scale and higher-quality studies are needed to assess whether there are any statistically and clinically significant changes.

Prediction models of methicillin sensitive Staphylococcus aureus ventilator associated pneumonia relapse in trauma and brain injury patients: A retrospective analysis

PURPOSE

To describe the incidence and risk factors of methicillin sensitive Staphylococcus aureus ventilator associated pneumonia (MSSA-VAP) relapse in trauma and non-traumatic brain injury patients.

MATERIALS AND METHODS

Retrospective observational monocentric cohort study of consecutive ICU patients who developed a first episode of MSSA-VAP after trauma and non-traumatic brain injury. MSSA-VAP relapse encompass MSSA-VAP treatment failure (persistence or recurrence of MSSA) or other pathogen - VAP.

RESULTS

A total of 165 patients (71% of trauma and 29% of non-traumatic brain injury) with MSSA-VAP were included. MSSA-VAP relapse occurred in 54 (33%) patients, including 28 (17%) MSSA-VAP treatment failure and 46 (28%) other pathogen-VAP. Empirical first-line antibiotic therapy was appropriate in 96% of cases. In multivariate analysis, the presence of Streptococcus species (Odds ratio [OR] 7.37) and oropharyngeal flora (OR 3.64) as initial MSSA co-pathogen, suggested aspiration at the time of admission and independently predicted MSSA-VAP treatment failure. Initial Glasgow coma scale (OR 0.89), need for emergent surgery (OR 5.71) and the presence of an acute respiratory distress syndrome at the time of the first MSSA-VAP (3.99), independently predicted the onset of other pathogen - VAP.

CONCLUSION

Early and simple factors may help to identify patients with high-risk of MSSA-VAP relapse.

Aerosolized tobramycin for Pseudomonas aeruginosa ventilator-associated pneumonia in patients with acute respiratory distress syndrome

BACKGROUND

Ventilator-associated pneumonia (VAP) due to Pseudomonas aeruginosa has a high mortality and recurrence rate, especially in patients with acute respiratory distress syndrome (ARDS). Therefore, new therapeutic strategies against severe pneumonia are needed. This study evaluated the efficacy of aerosolized tobramycin for P. aeruginosa VAP in ARDS patients.

METHODS

A retrospective analysis was performed on patients who developed VAP caused by P. aeruginosa during the course of ARDS at the intensive care unit (ICU) of Kumamoto University Hospital. Aerosolized tobramycin inhalation solution (TIS) 240 mg was administered daily for 14 days in addition to systemic antibiotics.

RESULTS

A total of 44 patients (TIS group, n = 22; control group, n = 22) were included in the analysis. No significant differences were found between the two groups in terms of clinical characteristics, including acute physiology and chronic health evaluation II score upon ICU admission. The TIS group had significantly lower recurrence of P. aeruginosa VAP (22.7% vs. 52.4%, P = 0.04) and ICU mortality (22.7% vs. 63.6%, P < 0.01) than the control group. Bacterial concentration in tracheal aspirate (mean log 10 cfu/mL ± SD on days 2-5: 1.2 ± 1.3 vs. 5.0 ± 2.3, P < 0.01) decreased more rapidly and markedly in the TIS group compared with the control group.

CONCLUSION

Aerosolized tobramycin was an effective therapeutic strategy for P. aeruginosa VAP patients with ARDS.

Ventilator-Associated Pneumonia Patients who Do Not Reduce Bacteria from the Lungs have a Worse Prognosis

The authors determined the significance of serial semi-quantitative bronchoalveolar lavage (BAL) culture results in patients undergoing therapy for ventilator-associated pneumonia. A total of 32 patients underwent at least 2 nonbronchoscopic BAL studies. Fourteen patients had methicillin-resistant Staphylococcus aureus(MRSA). Of these, 11 had more than 100 colony-forming units (cfu) of MRSA/mL of BAL from the follow-up BAL. Eighteen patients had an organism other than MRSA, and 7 of these patients had > 100 cfu of bacteria/mL of BAL from the follow-up BAL. Of the 18 patients with > 100 cfu of bacteria/mL of BAL at follow-up, 14 (79%) died, whereas only 5 of 14 (36%) patients who cleared their bacteria at follow-up died within 28 days. The inability to reduce the bacterial burden from the lower respiratory tract within the first few days of therapy for ventilator-associated pneumonia was associated with increased mortality.

Recurrent Pseudomonas aeruginosa Infection in Chronic Lung Diseases: Relapse or Reinfection?

Background

Pseudomonas aeruginosa infection is particularly associated with progressive and ultimately chronic recurrent respiratory infections in chronic obstructive pulmonary disease, bronchiectasis, chronic destroyed lung disease, and cystic fibrosis. Its treatment is also very complex because of drug resistance and recurrence.

Methods

Forty eight cultures from 18 patients with recurrent P. aeruginosa pneumonia from 1998 to 2002 were included in this study. Two or more pairs of sputum cultures were performed during 2 or more different periods of recurrences. The comparison of strains was made according to the phenotypic patterns of antibiotic resistance and chromosomal fingerprinting by pulsed field gel electrophoresis (PFGE) using the genomic DNA of P. aeruginosa from the sputum culture.

Results

Phenotypic patterns of antibiotic resistance of P. aeruginosa were not correlated with their prior antibiotic exposition. Fifteen of 18 patients (83.3%) had recurrent P. aeruginosa pneumonia caused by the strains with same PFGE pattern.

Conclusion

These data suggest that the most of the recurrent P. aeruginosa infections in chronic lung disease occurred due to the relapse of prior infections. Further investigations should be performed for assessing the molecular mechanisms of the persistent colonization and for determining how to eradicate clonal persistence of P. aeruginosa.

Acinetobacter baumannii infection in prior ICU bed occupants is an independent risk factor for subsequent cases of ventilator-associated pneumonia

OBJECTIVE

We aimed to evaluate risk factors for ventilator-associated pneumonia (VAP) due to Acinetobacter baumannii (AbVAP) in critically ill patients.

METHODS

This was a prospective observational study conducted in an intensive care unit (ICU) of a district hospital (6 beds). Consecutive patients were eligible for enrolment if they required mechanical ventilation for >48 hours and hospitalization for >72 hours. Clinical, microbiological, and laboratory parameters were assessed as risk factors for AbVAP by univariate and multivariate analysis.

RESULTS

193 patients were included in the study. Overall, VAP incidence was 23.8% and AbVAP, 11.4%. Previous hospitalization of another patient with Acinetobacter baumannii infection was the only independent risk factor for AbVAP (OR (95% CI) 12.016 (2.282-19.521) P < 0.001). ICU stay (25 ± 17 versus 12 ± 9  P < 0.001), the incidence of other infections (OR (95% CI) 9.485 (1.640-10.466) P = 0.002) (urinary tract infection, catheter related infection, and bacteremia), or sepsis (OR (95% CI) 10.400 (3.749-10.466) P < 0.001) were significantly increased in patients with AbVAP compared to patients without VAP; no difference was found with respect to ICU mortality.

CONCLUSION

ICU admission or the hospitalization of patients infected by Acinetobacter baumannii increases the risk of AbVAP by subsequent patients.

Implications of endotracheal tube biofilm in ventilator-associated pneumonia response: a state of concept

INTRODUCTION

Biofilm in endotracheal tubes (ETT) of ventilated patients has been suggested to play a role in the development of ventilator-associated pneumonia (VAP). Our purpose was to analyze the formation of ETT biofilm and its implication in the response and relapse of VAP.

METHODS

We performed a prospective, observational study in a medical intensive care unit. Patients mechanically ventilated for more than 24 hours were consecutively included. We obtained surveillance endotracheal aspirates (ETA) twice weekly and, at extubation, ETTs were processed for microbiological assessment and scanning electron microscopy.

RESULTS

Eighty-seven percent of the patients were colonized based on ETA cultures. Biofilm was found in 95% of the ETTs. In 56% of the cases, the same microorganism grew in ETA and biofilm. In both samples the most frequent bacteria isolated were Acinetobacter baumannii and Pseudomonas aeruginosa. Nineteen percent of the patients developed VAP (N = 14), and etiology was predicted by ETA in 100% of the cases. Despite appropriate antibiotic treatment, bacteria involved in VAP were found in biofilm (50%). In this situation, microbial persistence and impaired response to treatment (treatment failure and relapse) were more frequent (100% vs 29%, P = 0.021; 57% vs 14%, P = 0.133).

CONCLUSIONS

Airway bacterial colonization and biofilm formation on ETTs are early and frequent events in ventilated patients. There is microbiological continuity between airway colonization, biofilm formation and VAP development. Biofilm stands as a pathogenic mechanism for microbial persistence, and impaired response to treatment in VAP.

Discovery and characterization of inhibitors of Pseudomonas aeruginosa type III secretion

The type III secretion system (T3SS) is a clinically important virulence mechanism in Pseudomonas aeruginosa that secretes and translocates up to four protein toxin effectors into human cells, facilitating the establishment and dissemination of infections. To discover inhibitors of this important virulence mechanism, we developed two cellular reporter assays and applied them to a library of 80,000 compounds. The primary screen was based on the dependence of the transcription of T3SS operons on the T3SS-mediated secretion of a negative regulator and consisted of a transcriptional fusion of the Photorhabdus luminescens luxCDABE operon to the P. aeruginosa exoT effector gene. Secondary assays included direct measurements of the T3SS-mediated secretion of a P. aeruginosa ExoS effector-beta-lactamase fusion protein as well as the detection of the secretion of native ExoS by the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of culture supernatants. Five inhibitors in three chemical classes were demonstrated to inhibit type III secretion selectively with minimal cytotoxicity and with no effects on bacterial growth or on the type II-mediated secretion of elastase. These inhibitors also block the T3SS-mediated secretion of a YopE effector-beta-lactamase fusion protein from an attenuated Yersinia pestis strain. The most promising of the inhibitors is a phenoxyacetamide that also blocks the T3SS-mediated translocation of effectors into mammalian cells in culture. Preliminary studies of structure-activity relationships in this phenoxyacetamide series demonstrated a strict requirement for the R-enantiomer at its stereocenter and indicated tolerance for a variety of substituents on one of its two aromatic rings.

Ventilator-Associated Pneumonia

The area of the alveolar epithelium of the lung is approximately 70 m². This area is constantly in contact with the ambient air and is therefore vulnerable to contamination with airborne microbes and particles of respirable size. Due to the configuration of the respiratory tract, airborne particles having diameters in the range of 0.5-2.0 μ can reach and deposit in the terminal part of the tracheobronchial tree - most bacteria are of this size. In reality, very few bacteria cause infections by spreading via the airborne route (e.g., mycobacteria, viruses, and legionella). Most bacteria cause pneumonia by first colonizing the upper respiratory tract and later descending into the tracheobronchial tree.

Enteral glutamine supplementation reducing infectious morbidity in burns patients: a randomised controlled trial

PURPOSE

Enteral glutamine supplements have been shown to reduce infectious morbidity in trauma patients, but their effect on patients with burns is not completely studied. The objective of this study was to measure the impact of enteral glutamine supplementation on infectious morbidity and in turn, the hospital-stay in patients with burns.

METHODS

Thirty patients with burns were randomly divided into two groups with 15 patients in each, the study (glutamine supplemented) and control group. Patients were randomised to receive either isonitrogenous mixture without glutamine or isonitrogenous mixture with glutamine until complete healing of the burn wound occurred. Incidence of positive blood culture, wound culture, total leucocyte count, hospital-stay and mortality was recorded.

RESULTS

The results showed that the incidence of positive blood culture was considerably reduced in the study group (0.20±0.41) vs. control (0.73±0.96; p = 0.065). The incidence of positive wound culture was significantly reduced in the study group (1.00 ± 1.25) vs. control (3.53 ± 2.47; p = 0.001). In addition, the wound healing was better and hospital-stay days were reduced in the study group (22.73 ± 9.13 days) vs. (39.73 ± 18.27 days; p = 0.003).

CONCLUSIONS

These results indicate that enteral glutamine supplementation in adult burn patients could abate the degree of infectious morbidity and reduce hospital-stay.

Risk factors for relapse of ventilator-associated pneumonia in trauma patients

BACKGROUND

Our goal was to define risk factors for ventilator-associated pneumonia (VAP) relapse and examine the implications, if any, for initial therapy in trauma patients.

METHODS

Trauma patients cared for in the surgical intensive care unit during a 48-month period with confirmed VAP recurrence were evaluated. Recurrent VAP was defined as a positive quantitative culture (> or = 10(4) colony-forming units/mL in a bronchoalveolar lavage or protected catheter lavage specimen) > or = 4 days after initiation of antibiotics for the primary episode. Recurrence with at least one of the initial causative pathogens was defined as a relapse. Initial causal pathogen, Acute Physiology and Chronic Health Evaluation II score, injury severity score, Glasgow Coma Score (GCS), age, white blood cell count (WBC), and duration of hospital stay before diagnosis were analyzed in univariate and multivariate regression models.

RESULTS

A total of 55 patients met the criteria of recurrent VAP. Of these 55 recurrences, 19 (35%) were relapses. Acute Physiology and Chronic Health Evaluation II score, injury severity score, and GCS were not associated with VAP relapse by univariate analyses. Patients who relapsed had primary VAP involving nonfermenting gram-negative bacilli (NFGNB) (Acinetobacter, Pseudomonas, and Stenotrophomonas species) more frequently than other organisms (68% vs. 32%, p = 0.001). Primary VAP with NFGNB was found to be a significant predictor of VAP relapse by univariate and multivariate logistic regression analysis (OR = 5.1, p = 0.003; OR = 4.63, p = 0.005, respectively).

CONCLUSIONS

There is a high rate of VAP relapse associated with primary infection by NFGNB, suggesting initial treatment failure. Trauma patients with primary VAP involving these organisms may benefit from increased surveillance for relapse.

Frequency and predictors of ventilator-associated pneumonia recurrence: a meta-analysis

Large clinical series focusing on the risk factors associated with recurrence after the onset of an initial episode of ventilator-associated pneumonia (VAP) produced inconsistent results. A meta-analysis would be helpful to shed light on the issue. Our objective was to estimate the frequency of VAP recurrence and to identify risk factors associated with it. PubMed, Scopus, Current Contents, and references of retrieved articles were searched without language restrictions. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by using both the Mantel-Haenszel fixed-effect and the DerSimonian-Laird random effects models. The overall frequency of VAP recurrence in 969 patients of the seven eligible reports was 26.8%. Among the 20 evaluated risk factors, only acute lung injury/acute respiratory distress syndrome (OR, 1.76; 95% CI, 1.12-2.75) and shock (OR, 1.55; 95% CI, 1.01-2.41) at the day of diagnosis of the first VAP episode were found to be associated with VAP recurrence. There was also evidence, albeit inconsistent, that severity of illness at intensive care unit admission was associated with VAP recurrence. Recurrence involves almost one in four cases of VAP and is associated with acute lung injury/acute respiratory distress syndrome and shock, but not with first-episode causative pathogens. Recognition of these predictors may permit the timely implementation of measures to prevent recurrence of VAP.

Early predictors for infection recurrence and death in patients with ventilator-associated pneumonia

OBJECTIVE

Early recognition of predictors of unfavorable evolution of ventilator-associated pneumonia (VAP) might prompt therapeutic measures that might improve outcome. The objective of this study was to describe resolution of VAP variables and to determine early predictors of VAP recurrence and death.

DESIGN AND SETTING

Description of the natural course of VAP resolution and multivariable analyses of predictors of VAP recurrence and death by day 28 after VAP onset based on the 401 patients included in the PNEUMA trial, a multiple-center, randomized study comparing 8 vs. 15 days of antibiotics for microbiologically proven VAP. Every patient included in that trial had received appropriate empirical antibiotics.

MEASUREMENTS AND MAIN RESULTS

By day 28 after VAP onset, 27% of patients had VAP recurrence and 18% had died. On day 8 after VAP onset, predictors of VAP recurrence included intensive care unit admission Simplified Acute Physiology Score II (odds ratio [OR], 1.02), radiologic score (OR, 1.17), temperature (OR, 1.34), nonfermenting Gram-negative bacilli (OR, 2.00) or methicillin-resistant Staphylococcus aureus (OR, 2.50) as pathogens responsible for VAP, and mechanical ventilation dependency (OR, 2.08). Day 8 predictors of 28-day death were age (OR, 1.06), female sex (OR, 2.30), Sepsis-Related Organ Failure Assessment score (OR, 1.26), and nonfermenting Gram-negative bacilli (OR, 2.83) as pathogens responsible for VAP. However, the duration of antimicrobial therapy (8 vs. 15 days) was not associated with any of the studied adverse outcomes.

CONCLUSIONS

For patients benefiting from appropriate empirical antibiotics for VAP, early predictors of infection recurrence or death included demographic characteristics, such as age or female sex, disease severity at VAP onset, nonfermenting Gram-negative bacilli or methicillin-resistant S. aureus as VAP-causative pathogens, prolonged mechanical ventilation dependency, persistent fever, and severity of lung injury. Future studies should attempt to determine whether specific diagnostic or therapeutic strategies could markedly improve VAP outcomes when early criteria for treatment failure are present.

[Assessment of patients with poor resolution of HAP]

Emphasis in VAP management is now shifting to the effectiveness of antibiotic therapy and its effect on subsequent mortality. As many as 62% of patients with VAP meet a set of objective criteria for failure to respond. The predominant microorganisms associated with failure of therapy are Pseudomonas aeruginosa and methicillin-resistant S. aureus (MRSA). Multiple causes of failure to respond in VAP exist: compromised host immunity, occult antibiotic resistance, inadequate antibiotic dosing, and concomitant or subsequent superinfections. The diagnosis of antibiotic failure and distinguishing failure from superinfection or noninfectious mimics is difficult because clinical criteria alone are inadequate. Microbiologic response is accurate only if quantitative cultures are used. Biochemical markers may be more accurate than clinical but still don't discriminate between causes. The appropriate diagnostic strategy and treatment algorithms have not been fully addressed and more research is clearly needed.

Hospital-acquired pneumonia in the 21st century: a review of existing treatment options and their impact on patient care

Hospital-acquired pneumonia is a common nosocomial infection, with significant morbidity and mortality, and represents a major therapeutic challenge to clinicians. The therapeutic approach must be patient-oriented and institution-specific. The specific risk factors of each patient, such as previous antibiotic exposure, underlying diseases, length of hospital stay and the local patterns of antimicrobial resistance, should guide physicians in their decision of the initial optimal empirical therapy. Delays in the initiation or inappropriate/inadequate initial therapy are related to increased mortality and worse outcomes. In responding patients, as soon as culture data are available, efforts should be made to change the initial broad spectrum antibiotic regimen to a more targeted one (de-escalation). The optimal duration of treatment is a matter of debate, but courses longer than 1 week are rarely justified.

Etiology of Ventilator-Associated Pneumonia

This review focuses on the top ten causes of ventilator-associated pneumonia (VAP), updating an earlier study. These pathogens have specific risk factors, different patterns of clinical resolution, and a wide range of attributable mortality. The discussion herein analyzes these aspects, placing particular emphasis on risk factors, attributable mortality, resistance, and the implications for management.

Nosocomial lung infections in adult intensive care units

Nosocomial respiratory tract infections are the leading type of nosocomial infections. Despite the development of new antibiotic therapies, they are associated with an increased morbidity and mortality. Patients with comorbidities are especially predisposed to acquire these infections, as are patients exposed to respiratory therapy. Aspiration of colonized secretions from the oropharynx is the main mechanism of infection development. Barrier techniques to reduce aspiration and antimicrobial agents to alter bacterial flora are important in preventing pneumonia episodes. The initial institution of an adequate antibiotic regimen is a determinant of outcome. Nosocomial pneumonias are often difficult to treat due to antibiotic-resistant bacteria. Antibiotic policies are crucial in avoiding a progression in antibiotic resistance.

A rational approach to the evaluation and treatment of the infected patient in the intensive care unit

Critically ill patients are at increased risk of acquiring nosocomial infections. A thorough clinical evaluation and the selection of appropriate diagnostic techniques are important elements in the evaluation of these patients. Nonetheless, this selection process can be difficult because of the wide spectrum of disease that is seen in the ICU and the lack of standardized studies that have evaluated the different diagnostic methods that are available. Many different antimicrobials are available for the treatment of ICU-acquired infections. Most antimicrobial regimens have not been evaluated in large-scale, prospective, randomized trials. Until this information is available, the clinician must make an effort to be familiar with the different clinical and epidemiologic variables that can be used to stratify patients at the moment of selecting antimicrobial therapy. The information provided in this article, used in association with good clinical judgment, will help the critical care physician provide optimal initial management of the infected patient in the ICU.

Decreased mortality and infectious morbidity in adult burn patients given enteral glutamine supplements: A prospective, controlled, randomized clinical trial*

OBJECTIVE

Enteral glutamine supplements have been shown to reduce infectious morbidity in trauma patients, but their effect on burn patients is not known. The objective of this study was to measure the impact of enteral glutamine supplementation on infectious morbidity, length of care, and the immune system in burn patients.

DESIGN

Double-blinded, randomized clinical trial.

SETTING

Burn center.

PATIENTS

Forty-five adults with severe burns.

INTERVENTIONS

Patients were randomized to receive either glutamine or an isonitrogenous control mixture until complete healing occurred. Length of care, incidence of positive blood culture, and mortality were recorded. Phagocytosis by circulating polymorphonuclear cells was measured every 3 days.

MEASUREMENTS AND MAIN RESULTS

Patient characteristics were similar in both groups. Four patients were excluded from the analysis, because three of them died within 72 hrs and the fourth could not receive enteral nutrition and amino acid supplements for the first 10 days. Of the remaining 41 patients, length of care in the survivors was not different between groups (0.9 vs. 1.0 days/percent total body surface area for glutamine vs. control, respectively), positive blood culture was three times more frequent in control than in glutamine treatment (4.3 vs. 1.2 days/patient, p <.05), and Pseudomonas aeruginosa was detected in six patients on control and zero on glutamine (p <.05). Phagocytosis by polymorphonuclear cells was not different between groups. Mortality rate was significantly lower in glutamine than in control: intention to treat, two vs. 12 (p <.05); per protocol analysis, zero vs. eight (p <.01).

CONCLUSIONS

Enteral glutamine supplementation in adult burn patients reduces blood infection by a factor of three, prevents bacteremia with P. aeruginosa, and may decrease mortality rate. It has no effect on level of consciousness and does not appear to influence phagocytosis by circulating polymorphonuclear cells.

Factors predicting ventilator-associated pneumonia recurrence

OBJECTIVE

To determine the factors associated with ventilator-associated pneumonia recurrence in patients alive after 8 days of treatment for a first episode.

DESIGN

A 16-month, prospective, observational cohort study of patients diagnosed with a first ventilator-associated pneumonia episode. Predictors of recurrence were assessed by logistic regression analysis.

SETTING

Two intensive care units in a university hospital.

PATIENTS

Bronchoscopy was performed in 124 patients with clinically or radiologically suspected ventilator-associated pneumonia. Ventilator-associated pneumonia was confirmed by the presence of at least two of the following criteria: >/=2% of cells with intracellular bacteria found on direct examination of bronchoalveolar lavage fluid, protected specimen brush sample culture >/=103 colony-forming units/mL, or bronchoalveolar lavage culture >/=104 colony-forming units/mL. Ventilator-associated pneumonia recurrence was confirmed using the same microbiological criteria. Antibiotic treatment for ventilator-associated pneumonia lasted 14 days.

MEASUREMENTS AND MAIN RESULTS

Clinical, radiologic, and biological data at intensive care unit admission, on the day of bronchoscopy (D1) and on D8, and outcome variables were prospectively recorded. Ventilator-associated pneumonia recurred in 28 patients (all of them still on mechanical ventilation on D8), 21 +/- 9 days after the first episode (82% after D14). Factors significantly associated with recurrence were: acute respiratory failure as initial reason for mechanical ventilation, D1 radiologic score >7, D8 radiologic score >8, adult respiratory distress syndrome on D8, mechanical ventilation persistence on D8, D8 temperature >38 degrees C, and D8 temperature >D1 temperature, but not disease-severity scores at inclusion and D8, or first-episode pathogen(s). Multivariate analysis identified D1 radiologic score >7 (odds ratio = 3.9; 95% confidence interval, 1.3-11.6), D8 temperature >38 degrees C (odds ratio = 4.4; 95% confidence interval, 1.4-13.4), and adult respiratory distress syndrome on D8 (odds ratio = 14.6; 95% confidence interval, 1.5-143.5) as predictors of recurrence.

CONCLUSIONS

Factors of ventilator-associated pneumonia recurrence evaluated on D8 of a 14-day course of antibiotics are linked to the severity of lung injury and persistence of fever, but not to first-episode pathogen(s).

Resolution of ventilator-associated pneumonia: prospective evaluation of the clinical pulmonary infection score as an early clinical predictor of outcome

OBJECTIVES

To prospectively evaluate the performance of the Clinical Pulmonary Infection Score (CPIS) and its components to identify early in the hospital course of ventilator-associated pneumonia (VAP) which patients are responding to therapy.

DESIGN

Prospective, multicenter, in a cohort of mechanically ventilated patients.

SETTING

The intensive care unit of six hospitals located in the metropolitan area of Buenos Aires, Argentina.

PATIENTS

Sixty-three patients, from a cohort of 472 mechanically ventilated patients hospitalized for >72 hrs, had clinical evidence of VAP and bacteriologic confirmation by bronchoalveolar lavage (BAL) or blood cultures.

INTERVENTIONS

Bronchoscopy with BAL fluid culture and blood cultures after establishing a clinical diagnosis of VAP. All patients received antibiotics, 46 before bronchoscopy and 17 immediately after bronchoscopy.

MEASUREMENTS AND RESULTS

CPIS was measured at 3 days before VAP (VAP-3); at the onset of VAP (VAP); and at 3 (VAP+3), 5 (VAP+5), and 7 (VAP+7) days after onset. CPIS rose from VAP-3 to VAP and then fell progressively in the population as a whole (p <.001), and the fall in CPIS was significant in 31 survivors, but not in 32 nonsurvivors. From the individual components of the CPIS, only the Pao /Fio ratio distinguished survivors from nonsurvivors, beginning at VAP+3. When CPIS was <6 at 3 or 5 days after VAP onset, mortality was lower than in the remaining patients (p =.018). These differences also related to the finding that those receiving adequate therapy had a slight fall in CPIS and a significant increase of Pao /Fio at VAP+3, whereas those getting inadequate therapy did not.

CONCLUSIONS

Serial measurements of CPIS can define the clinical course of VAP resolution, identifying those with good outcome as early as day 3, and could possibly be of help to define strategies to shorten the duration of therapy.

Therapy of nosocomial pneumonia

HAP remains a major cause of morbidity and mortality among hospitalized patients. Although early appropriate therapy results in improved outcomes, the cause of HAP frequently is not known at the time antimicrobial therapy is initiated. Most cases of HAP result from microaspiration of oropharyngeal secretions previously colonized with pathogenic bacteria, and the spectrum of potential pathogens is broad. Taking several factors into account can narrow this spectrum, including severity of illness, length of stay before the onset of pneumonia, and presence of risk factors for specific pathogens. When therapy has been initiated, follow-up of microbial studies and careful monitoring of the patient's course is important. The clinical improvement, even when therapy is appropriate, frequently takes days; therapy should not be changed for the first 2 to 3 days unless frank deterioration is noted. Patients who fail to respond or experience clinical deterioration should be re-examined carefully, and thought should be given to the possibility of other noninfectious processes.

Management of antimicrobial use in the intensive care unit

Indications for the use of antimicrobials in critically ill patients are similar to those for other hospitalised patients. However, the selection of agents depends on the particular characteristics of patients in the intensive care unit (ICU), the form of presentation of infection, the type of infection and the bacteriological features of the causative pathogens. The use of antimicrobials in patients admitted to medical-surgical ICUs varies between 33 and 53%. The selection of empirical antimicrobials to be included in treatment protocols of the most common infections depends on the strong interrelationship between patient characteristics, predominant pathogens in each focus. and antimicrobials used for treatment. Epidemiological studies carried out in the past have identified the microorganisms most frequently responsible for community-acquired and nosocomial infections in patients admitted to ICUs. Susceptibility to antimicrobial agents may be different between each geographical area, between each hospital and even within the same hospital service. In addition, susceptibility patterns may change temporarily in relation to the use of particular antimicrobials or in association with other unknown factors so that assessment of endemic antimicrobial resistance patterns is very useful in order to tailor the antimicrobial regimens of therapeutic protocols. Antimicrobial use should not be a routine procedure. The clinical course of the patient (an indicator of effectiveness) should be closely monitored as well as the possible appearance of adverse effects and/or multiresistant pathogens. Controls are based on the assessment of plasma drug concentrations and microbiological surveillance to detect the presence of multiresistant strains or new antibacterial-resistant pathogens. Prevention of the development of multiresistant pathogens is the main goal of the ICU antimicrobial policy. Although a series of general strategies to reduce the presence of multiresistant pathogens have been proposed, the implementation of these recommendations in ICUs requires the cooperation of a member of the intensive care team.

Efficacy of meropenem as monotherapy in the treatment of ventilator-associated pneumonia

We performed a prospective, open label, randomized study in intensive care unit patients with ventilator-associated pneumonia (VAP) to determine the efficacy and safety of empiric intravenous (i.v.) meropenem monotherapy compared with the combination of ceftazidime plus amikacin. A total of 140 patients receiving mechanical ventilation and diagnosed with pneumonia were included in the study. Patients were randomized to receive either 1 g meropenem i.v. every 8 hours or 2 g ceftazidime i.v. every 8 hours plus 15 mg/kg amikacin daily, administered to patients with normal renal function as two daily doses. Satisfactory clinical responses (cure or improvement) were achieved at the end of treatment in 68.1% of meropenem-treated patients and 54.9% in the ceftazidime/amikacin-treated group (relative risk 1.25; 95% confidence interval >1.00, 1.55). When non-evaluable patients were excluded from the analysis, the satisfactory clinical response was 82.5% and 66.1% for the meropenem and ceftazidime/amikacin patients, respectively (p = 0.044). Logistic regression demonstrated that treatment with meropenem and both the basic traumatic and medical pathologies were significantly associated with a satisfactory response. Adverse events judged to be possibly or probably related to treatment were reported by seven (10.1%) patients in the meropenem group and by eight patients (11.3%) in the ceftazidime/amikacin group. The results of this study confirm that monotherapy with meropenem is well tolerated and provides superior efficacy to the conventional combination of ceftazidime and amikacin in combating VAP.

Pseudomonas aeruginosa phage lysate as an immunobiological agent. 1. Selection of Pseudomonas aeruginosa clinical strains for phage lysate preparation

A total of 2087 Pseudomonas aeruginosa isolates collected during the period 1994-1997 were used as starting material. Out of 1704 in-patient isolates, 299 strains were selected for the preparation of phage lysates but only five strains provided stable lysates, i.e., maintained the ability to be repeatedly and completely lysed by the appropriate phage in the course of several years. A set of 193 out-patients (189) and water sources (4) isolates failed to yield strains suitable for phage lysate preparation; 190 strains isolated abroad from patients with cystic fibrosis or respiratory infections included three isolates which, despite having a high degree of mucus production, were suitable for lysate preparation. The antigenic pattern of the phage lysates was ascertained by SDS-polyacrylamide gel electrophoresis.

Hospital-acquired pneumonia: epidemiology, etiology, and treatment

Despite improvements in diagnosis, treatment, and prevention, hospital-acquired pneumonia (HAP) remains the number one cause of nosocomial mortality. This article reviews the current knowledge regarding the incidence, epidemiology, and causes of HAP, with the appreciation that the available information is incomplete and that controversies are common, and thus the authors provide a rational approach to the initial management of HAP in immunocompetent adults. A discussion of therapy and what to do with patients who do not respond to the empiric therapy are included. The American Thoracic Society (ATS) statement on HAP has served as a foundation for this review but has been supplemented by newer literature that was not available when the ATS statement was developed.

Recurrent Pseudomonas aeruginosa pneumonia in ventilated patients: relapse or reinfection?

A prospective observational study was performed to determine whether recurrent episodes of pneumonia caused by Pseudomonas aeruginosa in ventilated patients were due to a relapse of the previous clone or to reinfection with a new one. Diagnosis was based on quantitative cultures of secretions obtained by bronchoscopy. Comparison of strains was made by chromosomal fingerprinting based on pulsed field gel electrophoresis (PFGE). Thirty-three (89.1%) of 37 patients survived the initial week after pneumonia diagnosis; six survivors (18.1%) had multiple episodes caused by the same species. Presence of adult respiratory distress syndrome (83.3% versus 22.2%, p = 0.02) was the only factor significantly associated with clinical recurrences. The 16 isolates from five patients (nine recurrences) were analyzed by PFGE. All new isolates from recurrent episodes, excepting one, were considered as relapses. These data suggest that most recurrent episodes of P. aeruginosa pneumonia in ventilated patients occur due to persistence of strains present in a prior infection.

Risk factors for infection by Acinetobacter baumannii in intubated patients with nosocomial pneumonia

STUDY OBJECTIVE

To investigate the epidemiology of infection by Acinetobacter baumannii in patients with ventilator-associated pneumonia (VAP).

DESIGN

Prospective clinical study.

SETTING

Three medical-surgical ICUs in teaching hospitals.

PATIENTS

We followed up 707 mechanically ventilated patients and 148 episodes of VAP with etiologic diagnosis.

RESULTS

A baumannii was isolated in 12 (8.1%) episodes in 148 patients. Five of these episodes were directly responsible for death. Using logistic regression analysis, the risk of VAP due to A baumannii was found to be high in patients with neurosurgery (odds ratio [OR]=10.03; 95% confidence interval [CI]=1.55 to 64.90), ARDS (OR=9.73; 95% CI=1.60 to 59.24), head trauma (OR=5.17; 95% CI=0.88 to 30.34), and large-volume pulmonary aspiration (OR=2.90; 95% CI=0.80 to 10.53).

CONCLUSIONS

Intubated patients who develop pneumonia and have any of the above factors are at an increased risk of Acinetobacter infection.

Diagnosis and treatment of ventilator-associated pneumonia--impact on survival. A decision analysis

STUDY OBJECTIVE

To determine the impact of antibiotic treatment of ventilator-associated pneumonia (VAP) on survival.

DESIGN

Decision analysis.

PATIENTS

A hypothetical cohort of immunocompetent patients receiving mechanical ventilation who have suspected bacterial pneumonia. The analysis was performed separately for the following diagnostic techniques: clinical criteria, bronchoscopic protected specimen brush (PSB), and nonbronchoscopic protected BAL (pBAL). Additional factors accounted for in the analysis included the presence or absence of prior antibiotic use, mortality of antibiotic-treated and untreated pneumonia, mortality attributable to VAP, development of antibiotic resistance, and mortality due to adverse drug reactions.

MEASUREMENTS AND RESULTS

The overall survival of patients who receive antibiotic therapy was compared to survival if antibiotic therapy had been withheld. Antibiotic treatment of clinically diagnosed VAP was associated with lower overall survival than withholding treatment. Antibiotic treatment of VAP diagnosed by invasive (PSB) or semi-invasive (pBAL) techniques was associated with better survival than withholding treatment, although withholding antibiotic therapy was favored as the mortality rate of antibiotic-treated VAP approached 70%.

CONCLUSIONS

Invasive or semi-invasive diagnostic techniques should be used to diagnose VAP, guide therapy, and thereby potentially improve survival. A prospective, randomized trial assessing outcome according to diagnostic technique is needed.

Ventilator-associated pneumonia due to Pseudomonas aeruginosa

OBJECTIVE

Ventilator-associated pneumonia (VAP) caused by Pseudomonas aeruginosa has been associated with higher case fatality rates than VAP caused by other bacterial etiologies. The causes of this excess mortality are unclear.

DESIGN

Retrospective review of 38 consecutive ventilated patients with Pseudomonas pneumonia, documented by highly reliable methods. Charts of five additional patients were unavailable for review.

SETTING

Medical ICUs of a university-affiliated Veterans Affairs Medical Center and a university-affiliated municipal hospital.

MEASUREMENTS

Prospectively collected hospital admission acute physiologic and chronic health examination (APACHE) II scores and cause of ICU admission. Retrospectively calculated organ failure and APACHE scores, VAP score. Clinical and microbiologic variables. Antibiotic treatment and outcome. Direct cause of death by standard definitions.

RESULTS

Overall mortality was 69% (26/38), significantly higher than the APACHE II predicted mortality of 42.6% (p=0.037). At least 38% (10/26) of deaths were directly attributable to Pseudomonas VAP. Multivariate analysis of factors associated with death found infectious cause for ICU admission (odds ratio [OR]=8.67; 95% confidence interval [CI], 0.86 to 85.94) and number of organ dysfunctions on the day of diagnosis (OR=1.73, 95% CI, 1.02 to 2.92) were significant. Septic shock from Pseudomonas VAP, septic shock from subsequent infection, and multiple organ dysfunction syndrome were the most common immediate causes of death. Mortality increased linearly with increasing APACHE III score on the day of diagnosis. Of initial antibiotic regimens, 67% (26/36) were considered failures. Persistent pneumonia occurred in 35% of patients while recurrent pneumonia was unusual (1/38).

CONCLUSIONS

Development of Pseudomonas pneumonia results in a mortality rate in excess of that due to the presenting illness. The attributable mortality determined by several means appears to approach 40%. The excess mortality appears to be related to the host defense response to the pneumonia rather than any characteristic of the pneumonia. Even standard antibiotic regimens fail frequently and do not prevent the excess mortality. Since at least 38% of deaths can be directly attributable to the Pseudomonas pneumonia, improvement in therapy is needed.

An approach to empiric therapy of nosocomial pneumonia

Because many studies show that antibiotic therapy is effective for nosocomial pneumonia, it is necessary to have an approach to antibiotic selection to reduce mortality. Empiric therapy can be chosen, based on an assessment of patient risk factors for specific organisms and on an evaluation of the severity of illness present. Empiric regimens must be selected from a knowledge of antibiotic pharmacodynamics, as well as from an appreciation of the antimicrobial spectrum of the various antibacterials. When using such an approach, it is necessary to realize the limitations of effective therapy and to evaluate a number of relevant issues if the patient is not improving during treatment.