Suspicion Of Pneumonia Research Articles

Further Identification of CTX-M-2 Extended-Spectrum β-Lactamase in Pseudomonas aeruginosa

β-Lactamase production is the main mechanism for β-lactam resistance in gram-negative rods. The more threatening β-lactamases that have successfully emerged and are believed to spread only in Enterobacteriaceae are CTX-M-type extended-spectrum β-lactamases (ESBLs) (5). The acquired β-lactamases with wide activity spectra that are important in Pseudomonas aeruginosa include class B metallo-β-lactamases (mostly IMP and VIM types and especially SPM-1 in Brazil) and class A ESBLs, particularly VEB-, PER-, and GES-type enzymes (3, 8, 9). However, a single CTX-M-1-producing P. aeruginosa isolate has been reported from The Netherlands (1), as well as CTX-M-2- and CTX-M-43-positive P. aeruginosa isolates in Bolivia (2). This study reports the identification of a CTX-M-2-producing P. aeruginosa strain isolated from a Brazilian teaching hospital. During June 2005, a 63-year-old male patient with a recent hospitalization history was admitted to the intensive care unit for suspicion of pneumonia. He received ceftriaxone and clindamycin as first-line therapy. Four days later, he presented with septic shock and died. A blood culture grew P. aeruginosa (isolate P6208). Isolate P6208 was resistant to all β-lactams tested, except imipenem and ceftazidime. A double-disk synergy test was performed with ticarcillin-clavulanic acid- and cefotaxime-cefepime-containing disks. The production of an ESBL was evidenced only under unusual conditions (with a distance between the disks of 1.5 cm center to center) (Fig. ​(Fig.1).1). Isolate P6208 was also resistant to fluoroquinolones, amikacin, gentamicin, and tobramycin and was susceptible to colistin. The MICs of imipenem, ceftazidime, cefepime, and cefotaxime determined by using Etest strips (AB Biodisk, Solna, Sweden) were 1 μg/ml, 2 μg/ml, >256 μg/ml, and >32 μg/ml, respectively. FIG. 1. Double-disk synergy test with blaCTX-M-2-positive P. aeruginosa clinical isolate P6208. Arrows indicate double-disk synergy. Abbreviations: CAZ, ceftazidime; TCC, ticarcillin-clavulanic acid; CTX, cefotaxime; FEP, cefepime. HindIII-restricted total DNA from isolate P6208 as described previously (6) was used for cloning in pBK-CMV and was then transformed into Escherichia coli TOP10 and selected on agar plates containing ticarcillin (50 μg/ml) and kanamycin (30 μg/ml). The E. coli TOP10(p6208) recombinant strain displaying an ESBL phenotype was obtained. The sequencing of the 2,340-bp cloned DNA insert of recombinant plasmid p6208 identified a blaCTX-M-2 gene. It was preceded by an ISCR1 element located 498-bp upstream and followed by the qacEΔ1 gene cassette. This ISCR1-blaCTX-M-2 structure has already been identified in several enterobacterial species (7). Plasmid extraction performed by the Kieser method (4) did not evidence any plasmid. In addition, repetitive attempts to transfer the blaCTX-M-2 gene by electroporation failed, using both E. coli TOP10 and P. aeruginosa PAO1 as recipient strains. Thus, the blaCTX-M-2 gene might be likely chromosomally located in isolate P6208. This study identified a CTX-M-2-producing P. aeruginosa in Brazil. This finding is important since clinical laboratories may misidentify CTX-type enzymes in those nonfermenters, jeopardizing the choice of antimicrobial chemotherapy and the implementation of infection control measures. This report underlines that P. aeruginosa may become a hidden location for blaCTX-M genes.

Should We Change Antibiotic Prophylaxis for Lung Surgery? Postoperative Pneumonia Is the Critical Issue

The recommended antibiotic prophylaxis by second-generation cephalosporins reduces the incidence of wound infection and empyema, but its effectiveness on postoperative pneumonias (POPs) after major lung resection lacks demonstration. We investigated risk factors and characteristics of POPs occurring when antibiotic prophylaxis by second-generation cephalosporin or an alternative prophylaxis targeting organisms responsible for bronchial colonization was used. An 18-month prospective study on all patients undergoing lung resections for noninfectious disease was performed. Prophylaxis by cefamandole (3 g/24 h, over 48 hours) was used during the first 6 months, whereas amoxicillin-clavulanate (6 g/24 h, over 24 hours) was used during the subsequent 12 months. Intraoperative bronchial aspirates were systematically cultured. Patients with suspicion of pneumonia underwent bronchoscopic sampling for culture. Included were 168 patients in the first period and 277 patients in the second period. The incidence of POP decreased by 45% during the second period (P = 0.0027). A significant reduction in antibiotic therapy requirement for postoperative infections (P = 0.0044) was also observed. Thirty-day mortality decreased from 6.5% to 2.9% (P = 0.06). Multivariate analysis showed that type of resection, intraoperative colonization, chronic obstructive pulmonary disease, gender, body mass index, and type of prophylaxis were independent risk factors of POP. A case control-study that matched patients of the two periods according to these risk factors (except for antibiotic prophylaxis) confirmed that the incidence of POP was lowered during the second period. Targeted antibiotic prophylaxis may decrease the rate of POPs after lung resection and improve outcome.

Evaluation of the lung in children with suspected pneumonia: usefulness of ultrasonography

The authors sought to evaluate the sensitivity of chest ultrasound (US) versus chest radiography in detecting lung consolidation and pleural effusion in children with a clinical suspicion of pneumonia. Thirty-two chest radiographs and 32 chest US examinations were performed in 28 consecutive patients (aged 4 months to 17 years) with a clinical suspicion of pneumonia. Chest US examinations were carried out with a convex-array broadband probe (2-5 MHz) and a high-frequency linear-array broadband probe (5-12 MHz). The results obtained were compared with those of chest radiography. Chest radiography identified subpleural consolidation in 22 patients, perihilar consolidation in 7, and pleural effusion in eight. In the same 22 patients, chest US showed 22 cases of subpleural consolidation but no cases of perihilar consolidation; pleural effusion was detected in 15 patients. Chest US is capable of identifying subpleural consolidation with the same sensitivity as chest radiography and is highly accurate in demonstrating pleural effusion. For this reason, chest US may be a valuable aid and possible alternative to standard chest radiography in the evaluation and follow-up of children with suspected pneumonia.

Poor Performance of Universal Sample Processing Method for Diagnosis of Pulmonary Tuberculosis by Smear Microscopy and Culture in Uganda

Laboratory methods to improve smear microscopy are an urgent priority for global tuberculosis control. The novel universal sample processing (USP) method has been reported to improve conventional diagnostic testing for tuberculosis while also providing inhibitor-free specimens for molecular assays. However, no studies evaluating the method in the field have been conducted. In this study, we compared the performance of the USP method to that of the standard N-acetyl-L-cysteine-NaOH (NALC) method for conventional diagnosis of tuberculosis in 252 adults admitted to Mulago Hospital in Kampala, Uganda, with a clinical suspicion of pneumonia. A single early-morning sputum specimen collected from each patient was divided into two aliquots, each of which was assigned a random identification number. One randomly numbered specimen was processed by the USP method and the other by the NALC method. Mycobacterial cultures were more frequently negative in USP compared to NALC specimen aliquots (58% versus 43%; P < 0.001). There was no difference in the proportion of contaminated mycobacterial cultures (12% versus 11%; P = 0.87). The sensitivity and specificity of smear microscopy for the USP method were 52% and 86%, respectively, and were not significantly different from those for the NALC method (56% and 86%, respectively) using mycobacterial culture results as a reference standard. These results suggest that the USP method did not provide any significant advantage over the standard NALC method for conventional diagnosis of tuberculosis in our setting and illustrate the importance of well-designed, field-level evaluations of novel diagnostic techniques.

Computer-aided diagnosis in chest radiography for detection of childhood pneumonia

Objectives This article presents a novel approach based on computer-aided diagnostic (CAD) scheme and wavelet transforms to aid pneumonia diagnosis in children, using chest radiograph images. The prototype system, named Pneumo-CAD, was designed to classify images into presence (PP) or absence of pneumonia (PA). Materials and methods The knowledge database for the Pneumo-CAD comprised chest images confirmed as PP or PA by two radiologists trained to interpret chest radiographs according to the WHO guidelines for the diagnosis of pneumonia in children. The performance of the Pneumo-CAD was evaluated by a subset of images randomly selected from the knowledge database. The retrieval of similar images was made by feature extraction using wavelets transform coefficients of the image. The energy of the wavelet coefficients was used to compose the feature vector in order to support the computational classification of images as PP or PA. Methodology I worked with a rank-weighted 15-nearest-neighbour scheme, while methodology II employed a distance-dependent weighting for image classification. The performance of the prototype system was assessed by the ROC curve. Results Overall, the Pneumo-CAD using the Haar wavelet presented the best accuracy in discriminating PP from PA for both, methodology I (AUC = 0.97) and methodology II (AUC = 0.94), reaching sensitivity of 100% and specificity of 80% and 90%, respectively. Conclusion Pneumo-CAD could represent a complementary tool to screen children with clinical suspicion of pneumonia, and so to contribute to gather information on the burden of-pneumonia estimates in order to help guide health policies toward preventive interventions.

Diagnostic strategies for nosocomial pneumonia

This review describes advances in clinical and microbiological modalities for diagnosis of nosocomial pneumonia and the role of biological markers. Serial assessments with the clinical pulmonary infection score identifies nonsurvivors and allows discontinuation of antibiotics when there is low suspicion of pneumonia. Studies evaluating its clinical utility show mixed results. A meta-analysis revealed that an invasive approach does not affect mortality but reduces costs, antibiotic exposure, and multidrug resistance. In contrast to these findings, a recent trial comparing nonquantitative endotracheal aspirate and quantitative bronchoalveolar lavage cultures showed similar clinical outcomes and antibiotic utilization. The role of quantitative endotracheal aspirate for diagnosis of pneumonia not related to mechanical ventilation was recently evaluated. Procalcitonin and soluble triggering receptor expressed on myeloid cells-1 aid in diagnosis, identify sepsis related to ventilator-associated pneumonia and patients with worst outcomes. The diagnostic modality chosen depends on availability, personnel experience, and the patient's clinical status. Recent guidelines support the use of quantitative cultures in an integrated clinical and microbiological algorithm. The decision to adjust antibiotics involves clinical reassessment and interpretation of culture results. Biological markers have a potential role as screening and prognostic tools.

Physician Practice Patterns: Chest X-Ray Ordering for the Evaluation of Acute Cough Illness in Adults

The authors examine which clinical factors contribute to the clinician suspicion of pneumonia, as well as the relationship between clinical factors, clinician suspicion of pneumonia, and ordering chest X-rays (CXR). Three hundred consecutive adults presenting to the clinic with acute cough in the winter of 2003 were studied. Using standardized encounter forms, data were collected on sociodemographics, illness impact, symptoms, tobacco use, past medical history, vital signs, physical examination findings, chest X-ray result, and clinician diagnoses. Clinicians rated their suspicion of pneumonia on a 5-point Likert scale. Multivariable logistic regression analysis was used to determine independent predictors of clinician suspicion of pneumonia and of ordering of CXRs. Clinician suspicion of pneumonia was low in the majority of patients presenting for evaluation of cough (63%). Higher clinician suspicion of pneumonia was predicted by advanced patient age (odds ratio [OR]: 4.6; 95% confidence interval [CI] [1.2-18.1]), shortness of breath (2.4; [1.0-6.0]), fever (5.5; [1.8-17.5]), tachycardia (3.8; [1.1-13.1]), rales (23.8; [5.7-98.7]), and rhonchi (14.6; [5.2-40.5]). CXRs were ordered in 19% of patients presenting with acute cough. Intermediate clinician suspicion of pneumonia (OR: 7.9; 95% CI: [2.8, 22.5]) (v. low suspicion), advanced patient age ([.greaterequal] 65 years) (9.2; [2.7, 31.6]) (v. ages 18-44 years), and decreased breath sounds on examination (5.1; [1.8, 14.3]) are independent predictors of ordering a CXR. Among patients with a clinical diagnosis of pneumonia (n = 31), CXRs were ordered in only 61%. Advanced patient age and physical findings on chest examination influence clinician practice in obtaining CXRs, beyond their contribution to clinician suspicion of pneumonia. Physicians do not appear to endorse recommendations that the diagnosis of community-acquired pneumonia be based on or confirmed by CXR.

Postoperative Pneumonia after Major Lung Resection

Postoperative pneumonia (POP) is a life-threatening complication of lung resection. The incidence, causative bacteria, predisposing factors, and outcome are poorly understood. Prospective observational study. A prospective study of all patients undergoing major lung resections for noninfectious disease was performed over a 6-mo period. Culture of intraoperative bronchial aspirates was systematically performed. All patients with suspicion of pneumonia underwent bronchoscopic sampling and culture before antibiotherapy. One hundred and sixty-eight patients were included in the study. Bronchial colonization was identified in 31 of 136 patients (22.8%) on analysis of intraoperative samples. The incidence of POP was 25% (42 of 168). Microbiologically documented and nondocumented pneumonias were recorded in 24 and 18 cases, respectively. Haemophilus species, Streptococcus species, and, to a much lesser extent, Pseudomonas and Serratia species were the most frequently identified pathogens. Among colonized and noncolonized patients, POP occurred in 15 of 31 and 20 of 105 cases, respectively (p = 0.0010; relative risk, 2.54). Death occurred in 8 of 42 patients who developed POP and in 3 of 126 of patients who did not (p = 0.0012). Patients with POP required noninvasive ventilation or reintubation more frequently than patients who did not develop POP (p < 0.0000001 and p = 0.00075, respectively). POP was associated with longer intensive care unit and hospital stay (p < 0.0000001 and p = 0.0000005, respectively). Multivariate analysis showed that chronic obstructive pulmonary disease, extent of resection, presence of intraoperative bronchial colonization, and male sex were independent risk factors for POP. Pneumonia acquired in-hospital represents a relatively frequent complication of lung resections, associated with an important percentage of postoperative morbidity and mortality.

Bronchoalveolar lavage cytological alveolar damage in patients with severe pneumonia

IntroductionHistological examination of lung specimens from patients with pneumonia shows the presence of desquamated pneumocytes and erythrophages. We hypothesized that these modifications should also be present in bronchoalveolar lavage fluid (BAL) from patients with hospital-acquired pneumonia.MethodsWe conducted a prospective study in mechanically ventilated patients with clinical suspicion of pneumonia. Patients were classified as having hospital-acquired pneumonia or not, in accordance with the quantitative microbiological cultures of respiratory tract specimens. A group of severe community-acquired pneumonias requiring mechanical ventilation during the same period was used for comparison. A specimen of BAL (20 ml) was taken for cytological analysis. A semiquantitative analysis of the dominant leukocyte population, the presence of erythrophages/siderophages and desquamated type II pneumocytes was performed.ResultsIn patients with confirmed hospital-acquired pneumonia, we found that 13 out of 39 patients (33.3%) had erythrophages/siderophages in BAL, 18 (46.2%) had desquamated pneumocytes and 8 (20.5%) fulfilled both criteria. Among the patients with community-acquired pneumonia, 7 out of 15 (46.7%) had erythrophages/siderophages and 6 (40%) had desquamated pneumocytes on BAL cytology. Only four (26.7%) fulfilled both criteria. No patient without hospital-acquired pneumonia had erythrophages/siderophages and only 3 out of 18 (16.7%) had desquamated pneumocytes on BAL cytology.ConclusionCytological analysis of BAL from patients with pneumonia (either community-acquired or hospital-acquired) shows elements of cytological alveolar damage as hemorrhage and desquamated type II pneumocytes much more frequently than in BAL from patients without pneumonia. These elements had a high specificity for an infectious cause of pulmonary infiltrates but low specificity. These lesions could serve as an adjunct to diagnosis in patients suspected of having ventilator-associated pneumonia.

Does the Lateral Chest Radiograph Help Pediatric Emergency Physicians Diagnose Pneumonia? A Randomized Clinical Trial

To determine whether the addition of the lateral chest radiograph to the frontal view influences the pediatric emergency physician's diagnosis and management of patients with pneumonia. A randomized clinical trial was conducted, involving 570 patients, 1-16 years of age, visiting a pediatric emergency department (ED) for whom frontal and lateral chest radiographs were ordered for the clinical suspicion of pneumonia. Pediatric emergency physicians reviewed the frontal film alone in group 1 and both the frontal and the lateral films in group 2. The interpretation of each radiograph was then compared with consensus interpretation by pediatric radiologists who interpreted both views. There were 604 eligible children; 34 families declined to participate. Three hundred three were randomized into group 1, whereas 267 were randomized into group 2. The clinicians' interpretations were equal in sensitivity for group 1 at 91% and 87% in group 2 (p = 0.321) and equal in specificity for group 1 at 58% and 57% in group 2 (p = 0.888). The addition of the lateral chest radiograph to the frontal view did not improve the sensitivity or specificity of pediatric emergency physicians in their diagnosis of pneumonia in children.

Drug Treatment of Pneumococcal Pneumonia in the Elderly

Streptococcus pneumoniae has been recognised as a major cause of pneumonia since the time of Sir William Osler. Drug-resistant S. pneumoniae (DRSP), which have gradually become resistant to penicillins as well as more recently developed macrolides and fluoroquinolones, have emerged as a consequence of indiscriminate use of antibacterials coupled with the ability of the pneumococcus to adapt to a changing antibacterial milieu. Pneumococci use cell wall choline components to bind platelet-activating factor receptors, colonise mucosal surfaces and evade innate immune defenses. Numerous virulence factors that include hyaluronidase, neuraminidase, iron-binding proteins, pneumolysin and autolysin then facilitate cytolysis of host cells and allow tissue invasion and bloodstream dissemination. Changes in pneumococcal cell wall penicillin-binding proteins account for resistance to penicillins, mutations in the ermB gene cause high-level macrolide resistance and mutations in topoisomerase IV genes coupled with GyrA gene mutations alter DNA gyrase and lead to high-level fluoroquinolone resistance. Risk factors for lower respiratory tract infections in the elderly include age-associated changes in oral clearance, mucociliary clearance and immune function. Other risks for developing pneumonia include poor nutrition, hypoalbuminaemia, bedridden status, aspiration, recent viral infection, the presence of chronic organ dysfunction syndromes including parenchymal lung disease and recent antibacterial therapy. Although the incidence of infections caused by DRSP is rising, the effect of an increase in the prevalence of resistant pneumococci on mortality is not clear. When respiratory infections occur, rapid diagnosis and prompt, empirical administration of appropriate antibacterial therapy that ensures adequate coverage of DRSP is likely to increase the probability of a successful outcome when treating community-acquired pneumonia in elderly patients, particularly those with multiple risk factors for DRSP. A chest x-ray is recommended for all patients, but other testing such as obtaining a sputum Gram's smear is not necessary and should not prolong the time gap between clinical suspicion of pneumonia and antibacterial administration. The selection of antibacterials should be based upon local resistance patterns of suspected organisms and the bactericidal efficacy of the chosen drugs. If time-dependent agents are chosen and DRSP are possible pathogens, dosing should keep drug concentrations above the minimal inhibitory concentration that is effective for DRSP. Treatment guidelines and recent studies suggest that combination therapy with a beta-lactam and macrolide may be associated with a better outcome in hospitalised patients, and overuse of fluoroquinolones as a single agent may promote quinolone resistance. The ketolides represent a new class of macrolide-like antibacterials that are highly effective in vitro against macrolide- and azalide-resistant pneumococci. Pneumococcal vaccination with the currently available polysaccharide vaccine is thought to confer some preventive benefit (preventing invasive pneumococcal disease), but more effective vaccines, such as nonconjugate protein vaccines, need to be developed that provide broad protection against pneumococcal infection.

Clinicopathologic and radiographic features and etiologic agents in cats with histologically confirmed infectious pneumonia: 39 cases (1991-2000).

To determine clinicopathologic and radiographic features and etiologic agents in cats that died as a result of infectious pneumonia. Retrospective study. 39 cats. Medical records of cats in which infectious pneumonia was confirmed by histologic examination of necropsy specimens were reviewed. Signalment, clinical signs, and results of a CBC, viral serologic tests, and thoracic radiography were evaluated. Infectious agents were classified as bacterial, viral, fungal, protozoal, or parasitic. Histologic features (severity, duration, anatomic location, and distribution) were analyzed. Clinical signs referable to the respiratory tract were not detected in 14 of 39 (36%) cats, and results of a CBC (4/18 cats) and radiography (3/13) were unremarkable. Sixteen of 39 (41%) cats lacked clinical signs of systemic illness. Etiologic agents identified included bacteria (n = 21), viruses (11), fungi (6), protozoa (2), and parasites (1). Cats with clinical signs related to the respiratory tract (19/24 [79%] cats) were more likely to have severe histologic changes than cats without signs related to the respiratory system (6/14). Twenty-nine of 38 (76%) cats had histologic evidence of systemic disease, whereas the remaining cats had lesions limited to the respiratory tract. Infectious pneumonia is uncommon in cats. Cats with infectious pneumonia may lack clinical signs and have unremarkable results for a CBC and thoracic radiography, yet frequently have systemic infections. Therefore, clinicians should maintain an index of suspicion for pneumonia and evaluate the respiratory tract when infection is detected in other organ systems.

Treatment of severe nosocomial pneumonia: a prospective randomised comparison of intravenous ciprofloxacin with imipenem/cilastatin

BACKGROUNDA prospective multicentre study was undertaken to compare the efficacy of intravenous ciprofloxacin or imipenem in the treatment of severe nosocomial pneumonia requiring mechanical ventilation.METHODSPatients with a clinical suspicion of...

DIAGNOSTIC TESTING FOR VENTILATOR-ASSOCIATED PNEUMONIA

This article discusses the interpretation of the diagnostic tests in the management of ventilated patients with suspicion of pneumonia. The specific steps for diagnostic evaluation are identified. An accurate interpretation of the significance of the bacterial burden requires previous evaluation of the sample quality, knowledge of administration of new antibiotics within the prior 48 hours, and evaluation of presence of comorbidities. Finally, the article presents a review of the current debate of impact on outcome.

The Clinical Utility of Invasive Diagnostic Techniques in the Setting of Ventilator-Associated Pneumonia

To evaluate the clinical utility of bronchoscopy with protected brush catheter (PBC) and BAL for patients with ventilator-associated pneumonia (VAP). Prospective cohort study. Ten tertiary care ICUs in Canada. Ninety-two mechanically ventilated patients with a clinical suspicion of VAP who underwent bronchoscopy were compared with 49 patients with a clinical suspicion of pneumonia who did not. None. We compared antibiotic use, duration of mechanical ventilation, ICU stay, and mortality. In addition, for patients who received bronchoscopy, we administered a questionnaire (before and after bronchoscopy) to evaluate the effect of PBC or BAL on (1) physician perception of the probability of VAP, (2) physician confidence in the diagnosis of VAP, and (3) changes to antibiotic management. After bronchoscopy results became available, from the physician's perspective, the diagnosis of VAP was deemed much less likely (p < 0.001), confidence in the diagnosis increased (p = 0.03), and level of comfort with the management plan increased (p = 0.02). Following the results of invasive diagnostic tests, in the group that underwent bronchoscopy, patients were receiving fewer antibiotics (31/92 vs 9/49, p = 0.05) and more patients had treatment with all their antibiotics discontinued (18/92 vs 3/49, p = 0.04) compared with the group that did not undergo bronchoscopy. Duration of mechanical ventilation and ICU stay were similar between the two groups, but mortality was lower in the group that underwent bronchoscopy with PBC or BAL (18.5% vs 34.7%, p = 0.03). Invasive diagnostic testing may increase physician confidence in the diagnosis and management of VAP and allows for greater ability to limit or discontinue antibiotic treatment. Whether performing PBC or BAL affects clinically important outcomes requires further study.

THE CLINICAL UTILITY OF INVASIVE DIAGNOSTIC TECHNIQUES IN THE SETTING OF VENTILATOR-ASSOCIATED PNEUMONIA

Objective To evaluate the clinical utility of bronchoscopy with protected brush catheter (PBC) and BAL for patients with ventilator-associated pneumonia (VAP). Design Prospective cohort study. Setting Ten tertiary care ICUs in Canada. Patients Ninety-two mechanically ventilated patients with a clinical suspicion of VAP who underwent bronchoscopy were compared with 49 patients with a clinical suspicion of pneumonia who did not. Interventions None. Measurements and results We compared antibiotic use, duration of mechanical ventilation, ICU stay, and mortality. In addition, for patients who received bronchoscopy, we administered a questionnaire (before and after bronchoscopy) to evaluate the effect of PBC or BAL on (1) physician perception of the probability of VAP, (2) physician confidence in the diagnosis of VAP, and (3) changes to antibiotic management. After bronchoscopy results became available, from the physician's perspective, the diagnosis of VAP was deemed much less likely (p Conclusions Invasive diagnostic testing may increase physician confidence in the diagnosis and management of VAP and allows for greater ability to limit or discontinue antibiotic treatment. Whether performing PBC or BAL affects clinically important outcomes requires further study.

Relationship of Microbiologic Diagnostic Criteria to Morbidity and Mortality in Patients With Ventilator-Associated Pneumonia

To evaluate whether the mortality and the morbidity of ventilator-associated pneumonia, defined by positive result of protected specimen brush culture, was different from that defined by other methods. Matched-cohort study. All patients with clinical suspicion of pneumonia were investigated with protected specimen brush, bronchoalveolar lavage, and blind bronchial samplings. Two groups were defined: brush-positive patients (positive culture of the protected specimen brush) and brush-negative patients (negative culture of the protected specimen brush, but positive culture with another method). A 14-bed medicosurgical intensive care unit (ICU) in an 850-bed teaching hospital. All patients with documented ventilator-associated pneumonia over 4 years 9 months. A total of 102 cases documented by protected specimen brush culture and 223 documented by another sampling procedure. Patients were matched according to diagnosis on admission, age, sex, date of admission, Acute Physiology and Chronic Health Evaluation II (APACHE II) score, and date of onset of pneumonia. Mortality rate, duration of mechanical ventilation, duration of ICU stay, duration of hospital stay, sampling methods, and microbiologic cultures. A total of 76 pairs were submitted for analysis. The effectiveness of matching was 81.85%. There was no difference in mortality between brush-positive patients and brush-negative patients. The ICU fatality rate was 38% in the brush-positive group and 39.4% in the brush-negative group (odds ratio [OR], 0.95; 95% confidence interval [CI], 0.46-1.93). The hospital fatality rate was 41% (OR, 1; 95% CI, 0.5-2.01). The mean (SD) duration of ventilation was 26 (23) days in the 2 groups (range, 3-132 days). The duration of ICU stay was 33 (27.4) days in the 2 groups (range, 3-152 days). When confounding factors are controlled, patient outcome is the same if ventilator-associated pneumonia has been diagnosed by protected specimen brush or by another sampling method.

Effect of Previous Antimicrobial Therapy on the Accuracy of the Main Procedures Used to Diagnose Nosocomial Pneumonia in Patients Who are Using Ventilation

We evaluated the effect of antibiotic treatment received before the suspicion of pneumonia on the diagnostic yield of protected specimen brush (PSB), direct examination (BAL D) and culture (BAL C) of lavage fluid on consecutive mechanically ventilated patients with suspected nosocomial pneumonia. Bronchoscopy was always performed before any treatment for suspected pneumonia. One hundred and sixty-one patients with suspected pneumonia underwent PSB and BAL before any institution or change in antibiotic therapy (AB). Sixty-five patients received AB for an earlier septic episode (ON AB group) and 96 patients did not (OFF AB group). All but two strains recovered were highly resistant to previous AB. Sensitivity and specificity of each test were not different between the ON AB and OFF AB groups as well as the percentage of complete agreement between the 3 procedures, 74 and 67% respectively. We conclude that previous AB received to treat an earlier septic episode unrelated to suspected pneumonia do not affect the diagnostic yield of PSB and BAL.

Usefulness of Microscopic Examination of Intracellular Organisms in Lavage Fluid in Ventilator-Associated Pneumonia

To assess the usefulness of quantification of bronchoalveolar lavage (BAL) cells containing intracellular organisms (ICO) in the diagnosis of ventilator-associated pneumonia. The reliability of cytologic analysis in comparison with the protected specimen brush (PSB) and BAL quantitative cultures has been assessed in a prospective study. An intensive care unit of a tertiary-referral teaching hospital. A total of 33 ventilated patients with suspected pneumonia based on clinical grounds and radiographic findings. All patients underwent fiberoptic bronchoscopy within the first 24 h after clinical suspicion of pneumonia. Specimens were obtained by PSB and BAL and were processed for quantitative cultures using standard methods. Two 0.5-ml samples of resuspended original BAL fluid were centrifuged and stained with Gram and modified May-Grünwald-Giemsa for differential cell counts and percentage of cells with ICO. Pneumonia was the final diagnosis in 16 (49 percent) of the 33 patients. In 14 (42 percent) patients, pneumonia was excluded and in the remaining 3 the diagnosis was uncertain. Twelve of the 16 patients with pneumonia had their conditions diagnosed by PSB, 14 by BAL, and 10 by quantification of ICO. Only one patient's condition was diagnosed exclusively by cytologic examination. There were no false-positive results with any of the diagnostic techniques. Microscopic identification of ICO in cells recovered by BAL allows early and accurate diagnosis of pneumonia in mechanically ventilated patients. However, the sensitivity of this technique is lower than with either PSB or BAL.

Clinical Significance of Borderline Quantitative Protected Brush Specimen Culture Results

In patients with clinical suspicion of pneumonia, quantitative cultures of protected brushing specimens (PBS) yielding > or = 10(3) CFU/ml of at least one microorganism have been found useful for differentiating airway colonization and lung infection, especially in mechanically ventilated patients. The amount of secretions collected by protected catheter brushing is small and difficult to determine accurately. Thus, the clinical significance of PBS cultures yielding organisms in concentrations > or = 10(2) but < 10(3) CFU/ml, in the absence of active antimicrobial treatment, is unknown. The 34 consecutive results of PBS cultures yielding organisms in concentrations > or = 10(2) but < 10(3) CFU/ml in 30 patients under mechanical ventilation or weaned for < or = 4 days were prospectively studied. No patients were receiving agents active on the organism recovered. In 5 cases, the diagnosis of pneumonia was ruled out by recovery without treatment (n = 4) or negative postmortem lung cultures (n = 1). A second PBS was cultured in 29 episodes (2.7 +/- 1.8 days after the first PBS). In 12 instances (Group 1), cultures of the second PBS yielded > or = 10(3) CFU/ml of the same organism as that found in the first PBS (S. pneumoniae, 1; S. aureus, 1; H. influenzae, 1; E. coli, 1; P. aeruginosa, 4; and A. baumannii, 4), and these patients were therefore treated with appropriate antibiotics. A total of 17 patients had a negative repeat PBS culture (no growth or trivial concentrations) and were considered free of pneumonia and given no antibiotic treatment for this episode.(ABSTRACT TRUNCATED AT 250 WORDS)