The lung in the immunocompromised patient. Infectious complications Part 1

Evaluation of a PCR-electrospray ionization mass spectrometry platform for detection and identification of fungal pathogens directly from prospectively collected bronchoalveolar lavage specimens

The incidence of invasive fungal infections is on the rise worldwide due to the growth of the immunocompromised population. We report here the use of a diagnostic assay that utilizes a universal extraction method, broad spectrum PCR amplification and analysis via electrospray ionization mass spectrometry (PCR/ESI-MS) to detect and identify more than 200 pathogenic fungi directly from bronchoalveolar lavage (BAL) specimens in less than 8 hours. In this study, we describe both analytical and clinical performance of the assay, when run with prospectively collected clinical BAL specimens. In 146 patients with probable and possible fungal infections defined by EORTC/MSG (European Organization for Research and Treatment of Cancer/Mycoses Study Group) criteria, the PCR/ESI-MS assay demonstrated a sensitivity of 90.9% (95% CI: 76.4–96.9%) and a specificity of 82.3% (95% CI: 74.2–88.2%). This data demonstrates the utility of a non-culture based broad fungal targets molecular diagnostic tool for rapid and accurate diagnosis of invasive fungal infections in patients at risk of developing fungal diseases.

Role of bronchoalveolar lavage in the management of immunocompromised patients with pulmonary infiltrates

Pulmonary infiltrates are a significant cause of morbidity and mortality in immunocompromised patients and remain a diagnostic challenge due to the broad range of etiologies that include infection and malignancy. Empiric therapy may be sub-optimal and can adversely impact outcome. Therefore, a confirmed diagnosis is necessary and flexible bronchoscopy with bronchoalveolar lavage (BAL) may be a useful diagnostic tool. Samples are obtained for microbiological and cytological testing, but the procedure carries risk of complications including the adverse events related to moderate sedation. A review of published literature on BAL in immunocompromised patients from the year 2000 was undertaken focusing on diagnostic yield, complication rate, mortality as well as factors impacting these outcomes. Studies in which the majority of patients were supported on mechanical ventilation were excluded. A total of 23 studies (7 prospective and 16 retrospective) met inclusion criteria. This covered 3,395 procedures in 3,192 patients with a mean age of 47.4 years; 60.3% male gender. Diagnostic yield ranged from 26% to 69% with no clear association between diagnostic yield and etiology of immunosuppression or clinical/radiological presentation. Post BAL modification of treatment as an indicator for clinical utility ranged from 11% to 84%; and complication rate ranged from 1% to 52%. No specific factors were associated with increased adverse event rate. This review provides a summary of the data on the use of BAL for diagnosis of pulmonary infiltrates in immunocompromised patients, highlighting the heterogeneity of patients, significant variation in findings reported and the need for more data to optimize patient selection.

Respiratory Multiplex Polymerase Chain Reaction: An Important Diagnostic Tool in Immunocompromised Patients

Background:

Viruses and atypical pathogens can cause significant respiratory illness in immunocompromised patients. Multiplex polymerase chain reaction (MPCR) has improved the diagnostic yield of pathogens, and it is easier to identify the co-infections also. The present study was done to evaluate the performance of MPCR on bronchoalveolar lavage (BAL) samples in immunocompromised patients.

Methods:

Atotal of 177 BAL specimens collected over a 19 months period from immunocompromised patients with respiratory illness were analyzed with the MPCR and aerobic culture. Patients were divided into four according to the pathogens. Category V (only viral), Category NV (nonviral, i.e., bacteria and atypical), Category M (mixed, i.e., both viral and nonviral pathogen), and Category UK (unknown etiology).

Results:

MPCR identified the causative pathogen in 59.3% of patients while culture could identify only in 37.8% of patients. Most frequent etiological agent was Klebsiella pneumoniae (32%), followed by cytomegalovirus (21%), and Pneumocystis jirovecii (10%). Numbers of patients in each category were Category V (9.6%), Category NV (43.5%), Category M (19.8%), and Category UK (27.1%). Mortality was significantly higher in patients of Category M having mixed infections.

Conclusion:

MPCR is highly sensitive and rapid tool which can be considered in the routine diagnostic algorithm of respiratory illness in immunocompromised patients.

Transbronchial cryobiopsy in immunocompromised patients with pulmonary infiltrates: a pilot study

BACKGROUND

In immunocompromised patients with pulmonary infiltrates, transbronchial lung biopsies (TBB) obtained by forceps has been shown to increase the diagnostic yield over simple bronchoalveolar lavage. Cryo-TBB is a novel modality for obtaining lung biopsies. We aimed to evaluate for the first time the efficacy and safety of cryo-TBB in immunocompromised patients.

METHODS

Fifteen immunocompromised patients with pulmonary infiltrates underwent cryo-TBB. During the procedure two to three biopsy samples were taken. Procedure characteristics, complications, and the diagnostic yield were retrospectively evaluated.

RESULTS

Most patients (n = 11) were immunocompromised due to hematological malignancies. The remaining four patients were receiving chronic immunosuppressive treatment due to previous solid-organ transplantation (n = 2) or collagen-vascular disease (n = 2). No major complications occurred in the cryo-TBB group. The mean surface area of the specimen taken by cryo-TBB was 9 mm(2). The increase in surface area and quality of biopsy samples translated to a high percentage of alveolated tissue (70 %) that enabled a clear histological detection of the following diagnoses: noncaseating granulomatous inflammation (n = 2), acute interstitial pneumonitis consistent with drug reaction (n = 5), nonspecific interstitial pneumonia fibrotic variant (n = 1), diffuse alveolar damage (n = 3), organizing pneumonia (n = 3), and pulmonary cryptococcal pneumonia (n = 1). Diagnostic information obtained by cryo-TBB led to change in the management of 12 patients (80 %).

CONCLUSION

Cryo-TBB in immunocompromised patients with pulmonary infiltrates provides clinically important diagnostic data with a low complication rate. These advantages should be further compared with traditional forceps TBB in a prospective randomized trial.

Cytologic findings of acute leukemia in bronchoalveolar lavage fluid

Bronchoalveolar lavage (BAL) is often performed in patients with acute leukemia developed with respiratory failure or pulmonary infiltrates. Patients usually undergo BAL to rule out infection. Occasionally, however, leukemic infiltrate may be detected. We present a series of 11 cases in which the diagnosis of leukemia was made on the BAL material. We retrospectively reviewed all BAL samples from January 1, 2006 to December 31, 2008. There were a total of 1,130 cases, of which 139 showed malignant cytology, including 10 with leukemia. Sixteen samples were unsatisfactory and 904 were benign, of which 32 had identifiable microorganisms. In additional to the 10 leukemia cases identified, two more were reviewed after the search criteria. The 12 patients (seven men, five women) ranged from 22 to 75 years old. All patients had previously biopsy-proven leukemia [two acute myelomonocytic leukemia, two acute promyelocytic leukemia, two acute myeloid leukemia (AML) with inv16, two therapy-related AML, one acute monocytic leukemia, one chronic myeloid leukemia in blast face, one AML with maturation, one myelodysplastic syndrome with excess blasts, and one large granular leukemia]. Four had a prior diagnosis of myelodysplastic syndrome. The time from initial diagnosis of leukemia to BAL ranged from 1 to 233 days, with 8 of 10 occurring within 8 days of diagnosis. Symptoms that prompted BAL included shortness of breath/hypoxia (8), fever (3), chest pain (2), and cough (2). Chest X-rays in all cases revealed opacities or consolidations mimicking an inflammatory process. Seven patients subsequently died, while three were alive, and, in remission, and two were lost to follow-up. The presence of a leukemic infiltrate can mimic infection. BAL is a relatively safe and useful diagnostic tool in this setting for differentiating a leukemic infiltrate from an infection/inflammatory infiltrate. The prognosis of patients with lung involvement of acute leukemia is poor.

Group V phospholipase A2 in bone marrow-derived myeloid cells and bronchial epithelial cells promotes bacterial clearance after Escherichia coli pneumonia

Group V-secreted phospholipase A(2) (GV sPLA(2)) hydrolyzes bacterial phospholipids and initiates eicosanoid biosynthesis. Here, we elucidate the role of GV sPLA(2) in the pathophysiology of Escherichia coli pneumonia. Inflammatory cells and bronchial epithelial cells both express GV sPLA(2) after pulmonary E. coli infection. GV(-/-) mice accumulate fewer polymorphonuclear leukocytes in alveoli, have higher levels of E. coli in bronchoalveolar lavage fluid and lung, and develop respiratory acidosis, more severe hypothermia, and higher IL-6, IL-10, and TNF-α levels than GV(+/+) mice after pulmonary E. coli infection. Eicosanoid levels in bronchoalveolar lavage are similar in GV(+/+) and GV(-/-) mice after lung E. coli infection. In contrast, GV(+/+) mice have higher levels of prostaglandin D(2) (PGD(2)), PGF(2α), and 15-keto-PGE(2) in lung and express higher levels of ICAM-1 and PECAM-1 on pulmonary endothelial cells than GV(-/-) mice after lung infection with E. coli. Selective deletion of GV sPLA(2) in non-myeloid cells impairs leukocyte accumulation after pulmonary E. coli infection, and lack of GV sPLA(2) in either bone marrow-derived myeloid cells or non-myeloid cells attenuates E. coli clearance from the alveolar space and the lung parenchyma. These observations show that GV sPLA(2) in bone marrow-derived myeloid cells as well as non-myeloid cells, which are likely bronchial epithelial cells, participate in the regulation of the innate immune response to pulmonary infection with E. coli.

[Immunodeficiency and immunocompromised patients. Opportunistic infection of the lungs]

The number of patients suffering from innate, acquired or iatrogenic immunodeficiency is constantly rising. Thus the number of clinically relevant infections caused by rare or unusual pathogens is also increasing. Histopathological investigations allow the identification of difficult to culture infectious agents as well as the differentiation of tissue invasive infections from superficial colonization. In this review morphological reaction patterns and their differential diagnoses of the most common bacterial, viral and mycotic infections in the lungs of immunocompromised patients are discussed.

Surgical treatment of pulmonary aspergilloma

The objective of this study was to analyze the outcome of surgical treatment of pulmonary aspergilloma. To that end, we evaluated 14 adult patients so treated between 1981 and 2009 at the Botucatu School of Medicine University Hospital, in the city of Botucatu, Brazil. Data were collected from the medical records of the patients. Ten patients (71%) presented with simple pulmonary aspergilloma, and 4 (29%) presented with complex pulmonary aspergilloma. Hemoptysis was the most common symptom, and tuberculosis was the most prevalent preexisting lung disease. Two patients (14%) underwent surgery on more than one occasion. There were no intraoperative deaths. Half of the patients developed postoperative complications, prolonged air leak and empyema being the most common.

Microbial aetiologic agents associated with pneumonia in immunocompromised hosts

Pulmonary infections are a major cause of morbidity and mortality in the immunosuppressed patients. The aim of this study was to determine the etiologic agents and predisposing factors associated with pneumonia infections in immunocompromised patients. Cross-sectional survey of 100 immunocompromised patients due to HIV and Mycobacterium tuberculosis infections were enlisted for the study. The patients completed a structured questionnaire to abstract information on demographic features and risk factors. Sputum samples were collected from the patients with clinical suspicion of having pneumonia and the sputa examined by cultural methods. The tuberculosis patients had the highest number of isolates, 119 (70%) while those with co-infections of HIV/AIDS and tuberculosis had 41(24.1%) and those with only HIV infection were 10 (5.9%). The distribution of isolates were as follows, Staphylococcus aureus 63 (37.9%), Streptococcus pyogenes 44 (25.9%), Streptococcus pneumoniae 27 (15.9%), Candida albicans 24 (14.1%), Klebsiella pneumoniae 7 (4.1%), Proteus mirabilis 4 (2.4%) and Escherichia coli 1 (0.5%). Those with previous history of alcoholism and tobacco smoking had relatively high isolates. This study demonstrated that secondary infections are prevalent in the immunocompromised patients due to HIV/AIDS and TB or co-infection with TB/HIV-AIDS. This may lead to drug resistance, DOTS or HAART programme, thereby leading to high mortality and morbidity.

Diagnostic yield of bronchoscopy with bronchoalveolar lavage in febrile patients with hematologic malignancies and pulmonary infiltrates

Infectious complications are a major cause of morbidity and mortality in immunosuppressed patients. Febrile patients with hematologic malignancies and pulmonary infiltrates have high mortality rates, especially if mechanical ventilation is required. The diagnostic value of fiberoptic bronchoscopy (FOB) with bronchoalveolar lavage (BAL) in these patients is controversial. We retrospectively analyzed the microbiological results of BAL samples obtained during 249 FOB examinations from 199 febrile patients with hematologic malignancies and pulmonary infiltrates (underlying diseases: acute leukemia 103 patients, lymphoma 84 patients, other malignancies 12 patients). Two hundred forty-six examinations could be evaluated. Seventy-three out of 246 BAL samples were sterile; 55 samples showed microbiological findings classified as contamination or colonization. One hundred eighteen samples showed positive microbiological results of bacteria and/or fungi classified as causative pathogens. Thereof, in 70 samples, only bacterial pathogens were detectable (Gram-positive, 35; Gram-negative, 30; mixed Gram-positive and Gram-negative, 5). Thirteen samples showed both fungi and bacterial pathogens. In 33 samples, only fungi were detectable, thereof, in 15 samples Aspergillus species, in 16 samples Candida species, and in 2 both. In two samples, a viral pathogen could be detected. Three nonlethal complications (bleeding, arrhythmia) occurred that required early termination of FOB. In 94 (38.2%) patient episodes, antibiotic treatment was modified as a result of microbiological findings in BAL samples. Our results show that FOB with BAL is a valuable diagnostic tool with low complication rates in high-risk febrile patients with hematologic malignancies and pulmonary infiltrates, contributing crucial results for the individual case, and also improving epidemiologic knowledge.

BAL neutrophils, serum procalcitonin, and C-reactive protein to predict bacterial infection in the immunocompromised host

BACKGROUND

Bacterial pulmonary infection is a common life-threatening complication in immunocompromised patients. The results of BAL cultures are not immediately available, and their microbiological yield might be limited by empiric antibiotic prescriptions. We evaluated clinical signs and symptoms, leukocyte counts, C-reactive protein (CRP) levels, procalcitonin levels, and BAL fluid neutrophil percentages as potential markers for bacterial infection in a cohort of immunocompromised patients with pulmonary complications.

METHODS

One hundred seven consecutive patients who had been referred for bronchoscopy due to suspected pulmonary infection were included in this study. Based on clinical, laboratory, radiologic, microbiological, and histologic results, patients were classified as having proven bacterial infection (n = 27), possible bacterial infection (n = 11), and no bacterial infection (n = 69).

RESULTS

Most common underlying conditions were hematologic malignancy (n = 62) and solid organ transplantation (n = 20). Clinical parameters were similar in patients with and without bacterial infection (difference was not significant). The percentage of BAL fluid neutrophils had the highest area under the curve (0.818; 95% confidence interval [CI], 0.700 to 0.935; p < 0.001), followed by absolute neutrophil counts (0.797; 95% CI, 0.678 to 0.916; p < 0.001), procalcitonin level (0.746; 95% CI, 0.602 to 0.889; p = 0.001), and CRP level (0.688; 95% CI, 0.555 to 0.821; p = 0.015) to predict proven bacterial infection (in opposition to no or possible bacterial infection) in the receiver operating characteristic analysis. Conversely, neither infiltrates (p = 0.123) nor leukocyte counts (p = 0.429) were useful in diagnosing bacterial infection. The percentage of BAL fluid neutrophils and procalcitonin level were independent predictors of bacterial infection in the multivariate regression.

CONCLUSIONS

Neutrophil percentage in BAL fluid, procalcitonin level, and CRP level might be potentially useful to differentiate bacterial infection from nonbacterial conditions in immunocompromised hosts with pulmonary complications.

Evaluation of persistent pulmonary infiltrates in pediatric oncology patients

PURPOSE

To evaluate the role of bronchoalveolar lavage (BAL), computed-tomography-guided biopsy (CTB), and open lung biopsy (OLB) in the management of persistent pulmonary infiltrates in pediatric oncology patients.

METHODS

Retrospective review of clinical records of pediatric oncology patients who underwent BAL, CTB, and OLB over a 7-year period. Data was compared across the three procedures using chi-square analysis. Logistic regression was used to adjust potential confounding variables for diagnostic yield.

RESULTS

There were 113 consecutive patients who underwent 140 separate procedures during their hospitalization. Thirty (26%) patients had a previous BMT. BALs were more likely to occur as the first line of investigation (98% vs. 47%, 45%; P < 0.01) and in patients with diffuse infiltrates (64% vs. 6%, 26%; P < 0.01) when compared to CTB and OLB, respectively. OLBs were performed less frequently in neutropenic patients (26% vs. 53%, 54%; P < 0.05), more often led to change in management directly because of procedure (61% vs. 12%, 33%; P < 0.01), and had higher diagnostic yield (61% vs. 24%, 36%; P < 0.01) when compared to CTB and BAL, respectively. Diagnostic yield of OLB was significantly higher regardless of diffuse or focal nature of infiltrate. Major adverse events after a procedure were not significantly different across the three procedures. Logistic regression demonstrated that having an OLB was independently associated with identifying the cause of pulmonary infiltrate.

CONCLUSION

OLB appears to be safe, has the best diagnostic yield, and leads to change in management more often than CTB or BAL in pediatric oncology patients with persistent pulmonary infiltrates.

Pulmonary complications following hematopoietic stem cell transplantation: diagnostic approaches

Pulmonary complications are a significant cause of morbidity and mortality in hematopoietic stem cell transplant recipients. Pulmonary infiltrates in such patients pose a major challenge for clinicians because of the wide differential diagnosis of infectious and noninfectious conditions. It is rare for the diagnosis to be made by chest radiograph, and commonly these patients will need further invasive and noninvasive studies to confirm the etiology of the pulmonary infiltrates. This review describes the role of the different diagnostic tools available to reach a diagnosis in a timely manner in this patient population.

Fungal infections as a complication of therapy for sarcoidosis

BACKGROUND

Treatment of symptomatic sarcoidosis usually includes systemic immunosuppressive agents. These agents may render the patient more susceptible to opportunistic infections. In addition, the fungal infection may be difficult to distinguish from the underlying sarcoidosis.

AIM

To examine the presentation and management of invasive fungal infections in sarcoidosis patients.

DESIGN

Retrospective record review.

METHODS

We reviewed the notes of all sarcoidosis patients (n = 753) seen at our clinic over an 18-month period.

RESULTS

Seven patients (0.9%) with previously diagnosed sarcoidosis developed fungal infections: two each with Histoplasma capsulatum and Blastomyces dermatitidis and three others with Cryptococcus neoformans. No cases of invasive aspergillus or tuberculosis were identified. The diagnosis of fungal infection was made by bronchoscopy (four cases), open-lung biopsy (one case), bone-marrow aspirate (one case), and spinal fluid examination (one case). All patients were receiving corticosteroids at the time of worsening chest X-ray or clinical status. Four patients were also receiving methotrexate prior to infection. No patient with systemic fungal infection was receiving either infliximab or cyclophosphamide. All patients responded to anti-fungal therapy and a reduction in immunosuppression.

DISCUSSION

Fungal infections occur rarely in treated patients with sarcoidosis. Deterioration of chest X-ray, especially a localized infiltrate, warrants investigation.

In vitro activity of the histatin derivative P-113 against multidrug-resistant pathogens responsible for pneumonia in immunocompromised patients

The in vitro activity of the histatin derivative P-113, alone or combined with eight antibiotics, was investigated against multidrug-resistant strains isolated from clinical specimens of immunocompromised patients with pneumonia. The gram-negative isolates were susceptible to P-113. S. aureus showed less susceptibility. Synergy was demonstrated when P-113 was combined with beta-lactams against gram-negative organisms.

Cytosolic phospholipase A2-alpha is necessary for platelet-activating factor biosynthesis, efficient neutrophil-mediated bacterial killing, and the innate immune response to pulmonary infection: cPLA2-alpha does not regulate neutrophil NADPH oxidase activity

The role of a cytosolic phospholipase A(2)-alpha (cPLA(2)-alpha) in neutrophil arachidonic acid release, platelet-activating factor (PAF) biosynthesis, NADPH oxidase activation, and bacterial killing in vitro, and the innate immune response to bacterial infection in vivo was examined. cPLA(2)-alpha activity was blocked with the specific cPLA(2)-alpha inhibitor, Pyrrolidine-1 (human cells), or by cPLA(2) -alpha gene disruption (mice). cPLA(2)-alpha inhibition or gene disruption led to complete suppression of neutrophil arachidonate release and PAF biosynthesis but had no effect on neutrophil NADPH oxidase activation, FcgammaII/III or CD11b surface expression, primary or secondary granule secretion, or phagocytosis of Escherichia coli in vitro. In contrast, cPLA(2)-alpha inhibition or gene disruption diminished neutrophil-mediated E. coli killing in vitro, which was partially rescued by exogenous arachidonic acid or PAF but not leukotriene B(4). Following intratracheal inoculation with live E. coli in vivo, pulmonary PAF biosynthesis, inflammatory cell infiltration, and clearance of E. coli were attenuated in cPLA(2)-alpha(-/-) mice compared with wild type littermates. These studies identify a novel role for cPLA(2)-alpha in the regulation of neutrophil-mediated bacterial killing and the innate immune response to bacterial infection.

The diagnosis of pneumonia in renal transplant recipients using invasive and noninvasive procedures

STUDY OBJECTIVES

We used invasive and noninvasive procedures to determine the causes of pneumonia in renal transplant recipients.

SUBJECTS AND METHODS

We retrospectively surveyed 565 renal transplant recipients (transplants received March 1984 to August 2001) to find those with pneumonia. Noninvasive diagnostic methods included serologic testing, and blood and sputum cultures with stains. Invasive procedures included fiberoptic bronchoscopy and percutaneous transthoracic procedures.

RESULTS

A total of 92 patients were enrolled. Of these, 71 patients had a definite etiologic diagnosis of pneumonia. The major infectious pathogens were bacterial (n = 21) and mixed bacterial infection (n = 10), Mycobacterium tuberculosis (TB) [n = 18], and fungi (n = 8). Noninvasive and invasive procedures led to the diagnosis of pneumonia in 31.5% (n = 29) and 45.6% (n = 42) of patients, respectively. Bronchoscopy was used in 64 patients, with a diagnostic yield of 38 cases (59.3%). Patients were 3.62 times more likely to contract pneumonia within 12 months of renal transplantation than they were > or =12 months thereafter (95% confidence interval, 1.33 to 9.84). Twenty-seven of the 92 patients (29.3%) died. The pneumonia mortality rate has dropped significantly since 1996 (41.8% vs 10.8%, p = 0.002).

CONCLUSION

Both invasive and noninvasive procedures are useful in the diagnosis of pneumonia, with declining mortality, in renal transplant recipients. Bacterial and mixed bacterial infection, TB, and fungal infection are the most common pathogens; cases are most likely to occur within 1 year after renal transplantation.

Prognostic factors of non-HIV immunocompromised patients with pulmonary infiltrates

STUDY OBJECTIVES

To assess the outcome and the prognostic factors in 200 non-HIV immunocompromised patients with pulmonary infiltrates (PIs).

DESIGN

Prospective observational study.

SETTING

An 800-bed university hospital.

PATIENTS

Two hundred non-HIV immunocompromised patients (hematologic malignancies, 79 patients; hematopoietic stem cell transplants [HSCTs], 61 patients; and solid-organ transplants, 60 patients).

METHODS

Investigation of prognostic factors related to mortality using a multiple logistic regression model.

RESULTS

Specific diagnosis of the PI was obtained in 78% of the cases (infectious origin was determined in 74%). The overall mortality rate was 39% (78 of 200 patients). Patients with HSCT had the highest mortality rate (53%). A requirement for mechanical ventilation (odds ratio [OR], 28; 95% confidence interval [CI], 9 to 93), an APACHE (acute physiology and chronic health evaluation) II score of > 20 (OR, 5.5; 95% CI, 2 to 14.7), and a delay of > 5 days in establishing a specific diagnosis (OR, 3.4; 95% CI, 1.2 to 9.6) were the variables associated with mortality at the multivariate analysis. The subgroup analysis based on underlying disease confirmed the prognostic significance of these variables and the infectious etiology for the PI.

CONCLUSIONS

Mortality in immunocompromised patients is high, particularly in patients undergoing HSCT. Achieving an earlier diagnosis potentially may improve the mortality rate of these patients.

Pulmonary infiltrates in immunosuppressed patients: analysis of a diagnostic protocol

A diagnostic protocol was started to study the etiology of pulmonary infiltrates in immunosuppressed patients. The diagnostic yields of the different techniques were analyzed, with special emphasis on the importance of the sample quality and the role of rapid techniques in the diagnostic strategy. In total, 241 patients with newly developed pulmonary infiltrates within a period of 19 months were included. Noninvasive or invasive evaluation was performed according to the characteristics of the infiltrates. Diagnosis was achieved in 202 patients (84%); 173 patients (72%) had pneumonia, and specific etiologic agents were found in 114 (66%). Bronchoaspirate and bronchoalveolar lavage showed the highest yields, either on global analysis (23 of 35 specimens [66%] and 70 of 134 specimens [52%], respectively) or on analysis of each type of pneumonia. A tendency toward better results with optimal-quality samples was observed, and a statistically significant difference was found in sputum bacterial culture. Rapid diagnostic tests yielded results in 71 of 114 (62.2%) diagnoses of etiological pneumonia.

Pulmonary infiltrates in non-HIV immunocompromised patients: a diagnostic approach using non-invasive and bronchoscopic procedures

BACKGROUND

The development of pulmonary infiltrates is a frequent life threatening complication in immunocompromised patients, requiring early diagnosis and specific treatment. In the present study non-invasive and bronchoscopic diagnostic techniques were applied in patients with different non-HIV immunocompromised conditions to determine the aetiology of the pulmonary infiltrates and to evaluate the impact of these methods on therapeutic decisions and outcome in this population.

METHODS

The non-invasive diagnostic methods included serological tests, blood antigen detection, and blood, nasopharyngeal wash (NPW), sputum and tracheobronchial aspirate (TBAS) cultures. Bronchoscopic techniques included fibrobronchial aspirate (FBAS), protected specimen brush (PSB), and bronchoalveolar lavage (BAL). Two hundred consecutive episodes of pulmonary infiltrates were prospectively evaluated during a 30 month period in 52 solid organ transplant recipients, 53 haematopoietic stem cell transplant (HSCT) recipients, 68 patients with haematological malignancies, and 27 patients requiring chronic treatment with corticosteroids and/or immunosuppressive drugs.

RESULTS

An aetiological diagnosis was obtained in 162 (81%) of the 200 patients. The aetiology of the pulmonary infiltrates was infectious in 125 (77%) and non-infectious in 37 (23%); 38 (19%) remained undiagnosed. The main infectious aetiologies were bacterial (48/125, 24%), fungal (33/125, 17%), and viral (20/125, 10%), and the most frequent pathogens were Aspergillus fumigatus (n=29), Staphylococcus aureus (n=17), and Pseudomonas aeruginosa (n=12). Among the non-infectious aetiologies, pulmonary oedema (16/37, 43%) and diffuse alveolar haemorrhage (10/37, 27%) were the most common causes. Non-invasive techniques led to the diagnosis of pulmonary infiltrates in 41% of the cases in which they were used; specifically, the diagnostic yield of blood cultures was 30/191 (16%); sputum cultures 27/88 (31%); NPW 9/50 (18%); and TBAS 35/55 (65%). Bronchoscopic techniques led to the diagnosis of pulmonary infiltrates in 59% of the cases in which they were used: FBAS 16/28 (57%), BAL 68/135 (51%), and PSB 30/125 (24%). The results obtained with the different techniques led to a change in antibiotic treatment in 93 cases (46%). Although changes in treatment did not have an impact on the overall mortality, patients with pulmonary infiltrates of an infectious aetiology in whom the change was made during the first 7 days had a better outcome (29% mortality) than those in whom treatment was changed later (71% mortality; p=0.001).

CONCLUSIONS

Non-invasive and bronchoscopic procedures are useful techniques for the diagnosis of pulmonary infiltrates in immunocompromised patients. Bronchial aspirates (FBAS and TBAS) and BAL have the highest diagnostic yield and impact on therapeutic decisions.

Therapeutic efficacy of liposomal gentamicin in clinically relevant rat models

Sterically stabilized liposomes are able to localize selectively at sites of infection, potentially permitting targeted drug delivery. Up to now, the majority of studies investigating therapeutic efficacy of liposomes have been conducted in animals with an intact host defense infected with high antibiotic-susceptible bacteria. In the present study, the therapeutic efficacy of gentamicin encapsulated in sterically stabilized liposomes, alone or in combination with the free drug was studied in rats with intact host defense as well as leukopenic rats. Rats were inoculated with a high gentamicin-susceptible or low-gentamicin susceptible Klebsiella pneumoniae in the left lung, resulting in an acute unilateral pneumonia. Survival rates demonstrate the valuable therapeutic properties of the liposome-encapsulated drug in these clinically relevant animal models.

Therapeutic efficacy of liposome-encapsulated gentamicin in rat Klebsiella pneumoniae pneumonia in relation to impaired host defense and low bacterial susceptibility to gentamicin

Long-circulating liposomes (LCL) may be used as targeted antimicrobial drug carriers as they localize at sites of infection. As a result, LCL-encapsulated gentamicin (LE-GEN) has demonstrated superior antibacterial activity over the free drug in a single-dose study of immunocompetent rats with Klebsiella pneumoniae pneumonia. In the present study, the therapeutic efficacy of LE-GEN was evaluated by monitoring rat survival and bacterial counts in blood and lung tissue in clinically relevant models, addressing the issue of impaired host defense and low bacterial antibiotic susceptibility. The results show that in immunocompetent rats infected with the high-GEN-susceptibility K. pneumoniae strain, a single dose of LE-GEN is clearly superior to an equivalent dose of free GEN. Yet complete survival can also be obtained with multiple doses of free GEN. In leukopenic rats infected with the high-GEN-susceptible K. pneumoniae strain, free GEN at the maximum tolerated dose (MTD) was needed to obtain survival. However, with the addition of a single dose of LE-GEN to free-GEN treatment, complete survival can be obtained using a sevenfold-lower cumulative amount of GEN than with free-GEN treatment alone. In leukopenic rats infected with low-GEN-susceptible K. pneumoniae cells, free GEN at the MTD did not result in survival. The use of LE-GEN is needed for therapeutic success. Increasing LE-GEN bilayer fluidity resulted in an increased GEN release from the liposomes and hence improved rat survival, thus showing the importance of the liposome lipid composition for therapeutic efficacy. These results warrant further clinical studies of liposomal formulations of aminoglycosides in immunocompromised patients with severe infections.