Diagnostic value of bronchoalveolar lavage in patients with opportunistic and nonopportunistic bacterial pneumonia

Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the Infectious Diseases Society of America and the American Thoracic Society

It is important to realize that guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. IDSA considers adherence to these guidelines to be voluntary, with the ultimate determination regarding their application to be made by the physician in the light of each patient's individual circumstances.These guidelines are intended for use by healthcare professionals who care for patients at risk for hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP), including specialists in infectious diseases, pulmonary diseases, critical care, and surgeons, anesthesiologists, hospitalists, and any clinicians and healthcare providers caring for hospitalized patients with nosocomial pneumonia. The panel's recommendations for the diagnosis and treatment of HAP and VAP are based upon evidence derived from topic-specific systematic literature reviews.

A rapid, real-time quantitative polymerase chain reaction test for the identification of pathogens in bronchoalveolar lavage samples

BACKGROUND

Standard bacteriologic culture techniques offer results within 2 days to 3 days, precluding a focused and timely antibiotic therapy in ventilated trauma patients. Our laboratory developed a real-time quantitative polymerase chain reaction (qPCR) test that can detect 25 different bacteria and fungi and methicillin resistance and offers results within 3 hours. The objective of this study was to compare the qPCR method to standard culture techniques.

METHODS

This was a prospective observational cohort study at a Level I trauma center from 2009 to 2012. Adult trauma patients on ventilation, receiving at least one bronchoalveolar lavage (BAL) with culture results were eligible for inclusion. DNA was isolated from the BAL samples and analyzed in 96-well plates using qPCR. Student's t tests were used to examine differences in mean qPCR cycle counts. Sensitivities, specificities, negative predictive values, and positive predictive values were calculated for the qPCR primer sets.

RESULTS

There were 28 BALs in the study. The qPCR method detected a total of 165 organisms, and culture methods found 54. The qPCR test had an overall sensitivity of 85%, specificity of 74%, negative predictive value of 98%, and positive predictive value of 27%. Those organisms that were only identified through qPCR had significantly less DNA than those identified through both qPCR and quantitative culture (28.8 vs. 23.3, p < 0.001). Concurrent antibiotic therapy was found to decrease the qPCR specificity in some primer sets, and methicillin resistance was only found in BAL samples that were concurrent with antibiotics.

CONCLUSION

The qPCR method shows promising initial diagnostic value. Many of the organisms not identified by quantitative culture had late cycle calls, suggesting that they might have been in quantities too low to result in culture identification. Once refined, our qPCR method has the potential to identify pathogens faster and earlier than standard quantitative culture methods, allowing for targeted antibiotic therapy within 3 hours.

LEVEL OF EVIDENCE

Diagnostic test, level II.

Multiplex quantitative PCR for detection of lower respiratory tract infection and meningitis caused by Streptococcus pneumoniae, Haemophilus influenzae and Neisseria meningitidis

Background

Streptococcus pneumoniae and Haemophilus influenzae cause pneumonia and as Neisseria meningitidis they are important agents of meningitis. Although several PCR methods have been described for these bacteria the specificity is an underestimated problem. Here we present a quantitative multiplex real-time PCR (qmPCR) for detection of S. pneumoniae (9802 gene fragment), H. influenzae (omp P6 gene) and N. meningitidis (ctrA gene). The method was evaluated on bronchoalveolar lavage (BAL) samples from 156 adults with lower respiratory tract infection (LRTI) and 31 controls, and on 87 cerebrospinal fluid (CSF) samples from meningitis patients.

Results

The analytical sensitivity was not affected by using a combined mixture of reagents and a combined DNA standard (S. pneumoniae/H. influenzae/N. meningitidis) in single tubes. By blood- and BAL-culture and S. pneumoniae urinary antigen test, S. pneumoniae and H. influenzae were aetiological agents in 21 and 31 of the LTRI patients, respectively. These pathogens were identified by qmPCR in 52 and 72 of the cases, respectively, yielding sensitivities and specificities of 95% and 75% for S. pneumoniae, and 90% and 65% for H. influenzae, respectively. When using a cut-off of 10⁵ genome copies/mL for clinical positivity the sensitivities and specificities were 90% and 80% for S. pneumoniae, and 81% and 85% for H. influenzae, respectively. Of 44 culture negative but qmPCR positive for H. influenzae, 41 were confirmed by fucK PCR as H. influenzae. Of the 103 patients who had taken antibiotics prior to sampling, S. pneumoniae and H. influenzae were identified by culture in 6% and 20% of the cases, respectively, and by the qmPCR in 36% and 53% of the cases, respectively.

In 87 CSF samples S. pneumoniae and N. meningitidis were identified by culture and/or 16 S rRNA in 14 and 10 samples and by qmPCR in 14 and 10 samples, respectively, giving a sensitivity of 100% and a specificity of 100% for both bacteria.

Conclusions

The PCR provides increased sensitivity and the multiplex format facilitates diagnosis of S. pneumoniae, H. influenzae and N. meningitidis and the assay enable detection after antibiotic treatment has been installed. Quantification increases the specificity of the etiology for pneumonia.

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.

Intensified microbiological investigations in adult patients admitted to hospital with lower respiratory tract infections

The objective of this study was to investigate the diagnostic yield of a programme with intensified microbiological investigations in immunocompetent adult patients with lower respiratory tract infections (LRTI). Patients in the study group were included prospectively and consecutively from September 1st 1997 to May 31st 1998 and were compared with a control group from the preceding year. A total of 67 adult patients were included in the study group and they were compared with 122 adult patients in the control group. The study group underwent fibre-optic bronchoscopy (FOB) with bronchoalveolar lavage (BAL). Only 7% in the historic control group were discharged with an aetiological diagnosis of their infections; while the diagnostic yield in the study group increased to 51% of patients. In the study group the presence of new infiltrates on chest X-ray increased the detection of a microbiological aetiology from 37% with no infiltrates to 62% with infiltrates and recent antibiotic therapy reduced the detection of a microbiological cause of infection from 61% in 36 patients who had not received antibiotic therapy to 39% in 31 patients who had received recent antibiotic therapy prior to microbiological sampling. Patients in the study group with known aetiology had higher values of inflammatory markers than patients with unknown aetiology. For Streptococcus pneumoniae infection culture and urine antigen detection were complimentary depending on recent antibiotic therapy since seven of eight culture-positive patients had not received antibiotic therapy within 72 h prior to investigation, while all four patients positive for urine antigens from S. pneumoniae had received antibiotic therapy within 72 h of urine sampling. In conclusion intensified microbiologic investigations increase the diagnostic yield from 7% to 51% of patients in the study group with an aetiologic diagnosis. Routine FOB with BAL had no apparent effect on clinical outcome and seems only justified in selected patients with severe LRTI with infiltrates on chest X-ray and signs of severe inflammation where a high diagnostic yield is achieved.

Quantitative culture of bronchoalveolar lavage fluid in community-acquired lower respiratory tract infections

To evaluate the diagnostic value of quantitative bacterial culture of bronchoalveolar lavage (BAL) fluid obtained by fibreoptic bronchoscopy, 67 consecutive immunocompetent adult patients admitted to hospital with community-acquired lower respiratory tract infections from September 1997 to May 1998 were investigated. Results were compared to the findings in eight healthy control persons investigated in February 1998. There was no difference between study patients and control persons when quantitative culture of total cumulative bacterial findings or bacteria categorized as members of the oropharyngeal normal flora were compared. The culture of normal flora in bronchial washings probably reflects contamination of the lower airways with secretions from upper arways by the fibreoptic procedure itself, as fractionated sampling showed a 10-fold reduct on in quantitative culture results when a primary bronchial washing was compared to a secondary sampling from the same bronchus in the control group. Twenty-four (36%) of 67 patients were cultured as positive in the study group while all control persons were cultured as negative for bacteria categorized as potential pathogens. With a threshold value for positive culture of 10(4) cfu ml(-1) the specificity of lavage culture of potential pathogenic bacteria in relation to actual lower airway infection was 100%. Therefore, quantitative bacterial culture of potential pathogenic bacteria in BAL fluid is very specific but only positive in about one-third of unselected immunocompetent adult patients with a lower respiratory tract infection.

Role of bronchoalveolar lavage in immunocompromised patients with pneumonia treated with a broad spectrum antibiotic and antifungal regimen

BACKGROUND

In a retrospective study the value of bronchoalveolar lavage (BAL) in the diagnosis of pneumonia was investigated in 95 immunocompromised patients suffering from haematological disorders and receiving a regimen of broad spectrum antibiotics and antifungal agents (BSAR).

METHODS

With the exception of four afebrile patients, all had fever, raised C reactive protein (CRP) levels, and new infiltrates visible on chest radiography. All patients underwent BAL to identify the organism causing the pneumonia and surveillance cultures were performed regularly for pathogens at different sites. Following classification of the isolates, patients with positive cultures were subdivided into two groups, pathogenic or contaminated. We investigated whether relevant pathogens were cultured only from the BAL fluid and whether they were susceptible to BSAR.

RESULTS

Although 77 of the 95 patients were thrombocytopenic, bleeding during BAL occurred in only 15% of all patients. Ten days after the procedure the fever improved in 88% of patients, radiographic findings improved in 71%, and CRP levels improved in 75% of patients; 22% of patients died within 28 days. Pathologically relevant isolates were found in 65% of all patients. Respiratory pathogens were detected only in the BAL fluid of 29 of the 95 patients (35% Gram positive species, 40% Gram negative species, 11% Mycobacterium, 11% fungi, and 3% cytomegalovirus). In 16 of these 29 patients (55%) the pathogens cultured only from the BAL fluid were resistant to treatment. Pathogens detected only in the BAL fluid were not susceptible to a standard broad spectrum antibiotic and antifungal regimen including teicoplanin, ceftriaxon, tobramycin, and amphotericin B in 12 of the 29 patients (41%).

CONCLUSIONS

Our data suggest that 12 patients were treated with broad spectrum antimicrobial agents which were not directed at the appropriate organism on in vitro sensitivity tests without BAL. BAL is a relatively safe procedure in the diagnosis of pneumonia, supplying important information in immunocompromised patients as well as in immunocompromised patients receiving BSAR.

Pulmonary infections in hospitalized patients with cirrhosis

We have further characterized pulmonary infections by bronchoalveolar lavage in hospitalized patients with cirrhosis. Sixty-seven consecutive patients admitted to the Ohio State University Medical Center from 1992 to 1995 with liver disease who underwent bronchoscopy with bronchoalveolar lavage were identified. Twenty-one patients with cirrhosis and pneumonia were further analyzed. During the same period, we consecutively identified 23 patients without liver disease or immunosuppression, 19 patients with HIV infections, and 30 patients with cancer or pharmacologic immunosuppression who had bronchoscopy with bronchoalveolar lavage for pneumonia. These groups were included in these analyses as a control and immunosuppressed controls, respectively. Bronchoscopy isolated respiratory pathogens in 16 patients (76.2%) with cirrhosis and 6 patients (26.1%) in the control group (p = 0.002). Fungal organisms were most commonly found in patients with cirrhosis although several patients had more than one organism identified. The control group had mostly bacterial pathogens; the immunosuppressed controls were commonly infected with opportunistic organisms. Six (85.7%) of 7 patients with cirrhosis and fungal pneumonia died of their respiratory illness. Hospitalized patients with cirrhosis commonly have opportunistic pulmonary infections; diagnostic bronchoscopy and empiric antifungal therapy should be considered in those who do not respond to antibiotics.