Evaluation of the Winthrop-University Hospital criteria to identify Legionella pneumonia

A case of Legionella pneumonia after robot-assisted radical prostatectomy

Introduction

Postoperative Legionella pneumonia is very rare.

Case presentation

A 71-year-old male patient with prostate cancer (cT2bN0M0) underwent a robotic-assisted radical prostatectomy. On the 5th postoperative day, the patient developed chills and a fever of 39.2°C. Chest radiography revealed decreased permeability in the right middle lung field, leading to the diagnosis of postoperative pneumonia. Antimicrobial therapy was initiated immediately. Blood tests on postoperative day 10 revealed mild liver function abnormalities, electrolyte abnormalities, and a markedly elevated inflammatory response. Legionella pneumonia was suspected based on blood sample results and systemic symptoms, such as diarrhea and nausea. Furthermore, Legionella antigens were detected in the patient's urine, prompting further administration of levofloxacin. The patient's subsequent clinical course was favorable.

Conclusion

When bacterial pneumonia fails to respond to antimicrobial therapy and systemic symptoms develop, atypical pneumonia, caused by pathogens such as Legionella pneumophila, should be considered even in cases of postoperative pneumonia.

L. pneumophila Infection Diagnosed by tNGS in a Lady with Lymphadenopathy

We report a case of a 34-year-old lady with multiple joint pain. Autoimmune diseases were considered first with a positive result of anti-Ro antibody and her right knee joint cavity effusion. Later, bilateral interstitial changes in her lungs and mediastinal lymphadenopathy were found after chest CT scanning. Empirical quinolone therapy was given although pathological examinations of blood, sputum and bronchoalveolar lavage fluid (BALF) did not find anything. Finally, Legionella pneumophila was identified by target next-generation sequencing (tNGS) detection. This case highlighted the timely use of tNGS, a new tool with fast speed, high accuracy and effective cost, could help to identify atypical infection and start an early therapy.

Clinical and Laboratory Diagnosis of Legionella Pneumonia

Legionella pneumonia is a relatively rare but extremely progressive pulmonary infection with high mortality. Traditional cultural isolation remains the gold standard for the diagnosis of Legionella pneumonia. However, its harsh culture conditions, long turnaround time, and suboptimal sensitivity do not meet the clinical need for rapid and accurate diagnosis, especially for critically ill patients. So far, pathogenic detection techniques including serological assays, urinary antigen tests, and mass spectrometry, as well as nucleic acid amplification technique, have been developed, and each has its own advantages and limitations. This review summarizes the clinical characteristics and imaging findings of Legionella pneumonia, then discusses the advances, advantages, and limitations of the various pathogenetic detection techniques used for Legionella pneumonia diagnosis. The aim is to provide rapid and accurate guiding options for early identification and diagnosis of Legionella pneumonia in clinical practice, further easing healthcare burden.

Atypical Pathogens in Adult Community-Acquired Pneumonia and Implications for Empiric Antibiotic Treatment: A Narrative Review

Atypical pathogens are intracellular bacteria causing community-acquired pneumonia (CAP) in a significant minority of patients. Legionella spp., Chlamydia pneumoniae and psittaci, Mycoplasma pneumoniae, and Coxiella burnetii are commonly included in this category. M. pneumoniae is present in 5-8% of CAP, being the second most frequent pathogen after Streptococcus pneumoniae. Legionella pneumophila is found in 3-5% of inpatients. Chlamydia spp. and Coxiella burnetii are present in less than 1% of patients. Legionella longbeachae is relatively frequent in New Zealand and Australia and might also be present in other parts of the world. Uncertainty remains on the prevalence of atypical pathogens, due to limitations in diagnostic means and methodological issues in epidemiological studies. Despite differences between CAP caused by typical and atypical pathogens, the clinical presentation alone does not allow accurate discrimination. Hence, antibiotics active against atypical pathogens (macrolides, tetracyclines and fluoroquinolones) should be included in the empiric antibiotic treatment of all patients with severe CAP. For patients with milder disease, evidence is lacking and recommendations differ between guidelines. Use of clinical prediction rules to identify patients most likely to be infected with atypical pathogens, and strategies of narrowing the antibiotic spectrum according to initial microbiologic investigations, should be the focus of future investigations.

A risk model to identify Legionella among patients admitted with community-acquired pneumonia: A retrospective cohort study

BACKGROUND

Guidelines recommend testing hospitalized patients with community-acquired pneumonia (CAP) for Legionella pneumophila only if the infection is severe or risk factors are present. There are no validated models for predicting Legionella.

OBJECTIVE

To derive and externally validate a model to predict a positive Legionella test.

DESIGN, SETTING AND PARTICIPANTS

Diagnostic study of adult inpatients with pneumonia using data from 177 US hospitals in the Premier Healthcare Database (training and hold-out validation sets) and 12 Cleveland Clinic Health System (CCHS) hospitals (external validation set). We used multiple logistic regression to predict positive Legionella tests in the training set, and evaluated performance in both validation sets.

MAIN OUTCOME AND MEASURES

The outcome was a positive Legionella test. Potential predictors included demographics and co-morbidities, disease severity indicators, season, region, and presence of a local outbreak.

RESULTS

Of 166,689 patients hospitalized for pneumonia, 43,070 were tested for Legionella and 642 (1.5%) tested positive. The strongest predictors of a positive test were a local outbreak (odds ratio [OR], 3.4), June-October occurrence (OR, 3.4), hyponatremia (OR, 3.3), smoking (OR, 2.4), and diarrhea (OR, 2.0); prior admission within 6 months (OR, 0.27) and chronic pulmonary disease (OR, 0.49) were associated with a negative test. Model c-statistics were 0.79 in the Premier and 0.77 in the CCHS validation samples. High-risk patients were only slightly more likely to have been tested than lower-risk patients. Compared to actual practice, the model-based testing strategy detected twice as many cases.

CONCLUSIONS

Although Legionella is an uncommon cause of pneumonia, patient characteristics can identify individuals at high risk, allowing for more efficient testing.

Usefulness of the Legionella Score for differentiating from COVID-19 pneumonia to legionella pneumonia

Legionella pneumophila is a major causative pathogen of community-acquired pneumonia (CAP), but recently the novel coronavirus disease 2019 (COVID-19) became the most common causative pathogen of CAP. Because L. pneumophila CAP is clinically distinct from bacterial CAPs, the Japan Society for Chemotherapy (JSC) developed a simple scoring system, the Legionella Score, using six parameters for the presumptive diagnosis of L. pneumophila pneumonia. We investigated the clinical and laboratory differences of L. pneumophila CAP and COVID-19 CAP and validated the Legionella Score in both CAP groups. We analyzed 102 patients with L. pneumophila CAP and 956 patients with COVID-19 CAP. Dyspnea and psychiatric symptoms were more frequently observed and cough was less frequently observed in patients with L. pneumophila CAP than those with COVID-19 CAP. Loss of taste and anosmia were observed in patients with COVID-19 CAP but not observed in those with L. pneumophila CAP. C-reactive protein and lactate dehydrogenase levels in L. pneumophila CAP group were significantly higher than in the COVID-19 CAP group. In contrast, sodium level in the L. pneumophila CAP group was significantly lower than in the COVID-19 CAP group. The median Legionella Score was significantly higher in the L. pneumophila CAP group than the COVID-19 CAP group (score 4 vs 2, p < 0.001). Our results demonstrated that the JSC Legionella Score had good diagnostic ability during the COVID-19 pandemic. However, physicians should consider COVID-19 CAP when loss of taste and/or anosmia are observed regardless of the Legionella Score.

Validating a clinical prediction score for Legionella-related community acquired pneumonia

BACKGROUND

Legionella-related community acquired pneumonia (CAP) is a disease with an increasing incidence and a high mortality rate, especially if empirical antibiotic therapy is inadequate. Antibiotic treatment highly relies on clinical symptoms, although proven non-specific, because currently available diagnostic techniques provide insufficient accuracy for detecting Legionella CAP on admission. This study validates a diagnostic scoring system for detection of Legionella-related CAP, based on six items on admission (Legionella prediction score).

METHODS

We included patients with Legionella-related CAP admitted to five large Dutch hospitals between 2006 and 2016. Controls were non-Legionella-related CAP patients. The following six conditions were rewarded one point if present: fever > 39.4 °C; dry cough; hyponatremia (sodium) < 133 mmol/L; lactate dehydrogenase (LDH) > 225 mmol/L; C-reactive protein (CRP) > 187 mg/L and platelet count < 171 × 10⁹/L. The accuracy of the prediction score was assessed by calculating the area under the curve (AUC) through logistic regression analysis.

RESULTS

We included 131 cases and 160 controls. A score of 0 occurred in non-Legionella-related CAP patients only, a score of 5 and 6 in Legionella-related CAP patients only. A cut-off ≥ 4 resulted in a sensitivity of 58.8% and a specificity of 93.1%. The AUC was 0.89 (95% CI 0.86-0.93). The strongest predictors were elevated LDH, elevated CRP and hyponatremia.

CONCLUSIONS

This multi-centre study validates the Legionella prediction score, an easily applicable diagnostic scoring system, in a large group of patients and finds high diagnostic accuracy. The score shows promise for future prospective validation and could contribute to targeted antibiotic treatment of suspected Legionella CAP.

Accuracy of a score predicting the presence of an atypical pathogen in hospitalized patients with moderately severe community-acquired pneumonia

BACKGROUND

Atypical pathogens (AP), present in some patients with community-acquired pneumonia (CAP), are intrinsically resistant to betalactam drugs, the mainstay of empirical antibiotic treatment. Adding antibiotic coverage for AP increases the risk of adverse effects and antimicrobial selection pressure, while withholding such coverage may worsen the prognosis if an AP is causative. A clinical model predicting the presence of AP would allow targeting atypical coverage for patients most likely to benefit.

METHODS

This is a secondary analysis of a multicentric randomized controlled trial that included 580 adults patients hospitalized for CAP. A predictive score was built using independent predictive factors for AP identified through multivariate analysis. Accuracy of the score was assessed using area under the receiver operating curve (AUROC), sensitivity, and specificity.

RESULTS

Prevalence of AP was 5.3%. Age < 75 years (OR 2.7, 95% CI 1.2-6.2), heart failure (OR 2.6, 95% CI 1.1-6.1), absence of chest pain (OR 3.0, 95% CI 1.1-8.2), natremia < 135 mmol/L (OR 3.0, 95% CI 1.4-6.6) and contracting the disease in autumn (OR 2.7, 95% CI 1.3-5.9) were independently associated with AP. A predictive score using these factors had an AUROC of 0.78 (95% CI 0.71-0.85). A score of 0 or 1 (present in 33% of patients) had 100% sensitivity and 35% specificity.

CONCLUSION

Use of a score built on easily obtained clinical and laboratory data would allow safe withholding of atypical antibiotic coverage in a significant number of patients, with an expected positive impact on bacterial resistance and drug adverse effects.

TRIAL REGISTRATION

NCT00818610.

Co-infection with Legionella and SARS-CoV-2: a case report

INTRODUCTION

We report a case of COVID-19 with Legionella co-infection that was treated successfully.

CASE REPORT

A 73-year-old man presented to the hospital with symptoms of fatigue that continued for the next 5 days. The patient was receiving docetaxel and prednisolone chemotherapy for prostate cancer. Laboratory findings on admission showed positive urine Legionella antigen test and SARS-CoV-2 test. He was administered antiviral and antibacterial agents, and a corticosteroid. Pneumonia exacerbated on day 2 of hospitalization. The patient underwent tracheal intubation and began receiving multidisciplinary care. On day 8 of hospitalization, his oxygenation improved, and the patient was extubated. He discharged on day 27 of hospitalization.

CONCLUSIONS

The patient had a favorable outcome with early diagnosis and early treatment of both diseases. Patients with severe COVID-19 disease need to be evaluated for co-infection. Further, early diagnosis and early treatment of the microbial bacteria causing the co-infection are important.

Lower serum phosphate levels in patients with Legionella pneumonia relative to patients with non-Legionella pneumonia

Introduction:

Few studies have evaluated serum phosphate levels in patients with Legionella pneumonia admitted to hospitals in Japan. This study aimed to assess serum phosphate levels among inpatients with Legionella pneumonia on admission and compare them to those of inpatients with non-Legionella community-acquired pneumonia.

Methods:

This case-control study included patients aged ≥16 years who were treated for Legionella pneumonia from April 2011 through March 2017 and those aged ≥16 years who were treated for non-Legionella community-acquired pneumonia from August 2014 through July 2015. Legionella pneumonia was diagnosed based on a positive result on the urinary antigen test, as well as radiographic examinations. Serum phosphate levels on admission were compared between Legionella and non-Legionella patients. In addition, serum phosphate levels on admission and on hospital day 5–7 were compared in Legionella patients.

Results:

We evaluated 8 Legionella patients and 61 non-Legionella patients. Median serum phosphate levels on admission were 1.90 and 2.80 mg/dL in Legionella and non-Legionella patients, respectively (P = 0.008). By hospital day 5–7, serum phosphate levels in Legionella patients had increased to 2.61 mg/dL (P = 0.029, relative to admission), which did not significantly differ from those of non-Legionella patients on admission (P = 0.372).

Conclusion:

Serum phosphate levels on admission were approximately 32% lower in Legionella pneumonia patients compared to non-Legionella pneumonia patients, but both were comparable by hospital day 7.

Fatal Fulminant Legionnaires' Disease in a Patient on Maintenance Hemodialysis

We herein report a case of fulminant Legionnaires' disease with autopsy findings in a patient on maintenance hemodialysis (HD). Chronic kidney disease is a strong risk factor for Legionnaires' disease, although there have been only a few reports in HD patients. Because most patients on HD are anuric, the use of rapid assay kits to detect antigens in urine samples for the diagnosis of Legionnaires' disease is not always feasible. We suggest the use of clinical predictive tools or the loop-mediated isothermal amplification (LAMP) method, which can be applied for anuric patients, such as those on HD, with pneumonia.

Clinical Presentation of Community-Acquired Legionella Pneumonia Identified by Universal Testing in an Endemic Area

The rapid identification of Legionella pneumonia is essential to optimize patient treatment and outcomes, and to identify potential public health risks. Previous studies have identified clinical factors which are more common in Legionella than non-Legionella pneumonia, and scores have been developed to assist in diagnosing cases. Since a Legionella pneumonia outbreak at VA Pittsburgh in 2012, nearly all patients with pneumonia have been tested for Legionella. The purpose of this study was to evaluate distinguishing characteristics between Legionella and non-Legionella pneumonia with the application of universal testing for Legionella in all cases of community-acquired pneumonia. We performed a retrospective case-control study matching Legionella and non-Legionella pneumonia cases occurring in the same month. Between January 2013 and February 2016, 17 Legionella and 54 non-Legionella cases were identified and reviewed. No tested characteristics were significantly associated with Legionella cases after Bonferroni correction. Outcomes of Legionella and non-Legionella pneumonia were comparable. Therefore, in veterans who underwent routine Legionella testing in an endemic area, factors typically associated with Legionella pneumonia were non-discriminatory.

Pneumococcal and Legionella Urinary Antigen Tests in Community-acquired Pneumonia: Prospective Evaluation of Indications for Testing

BACKGROUND

Adult, community-acquired pneumonia (CAP) guidelines from the Infectious Diseases Society of America (IDSA) and American Thoracic Society (ATS) include indications for urinary antigen tests (UATs) for Streptococcus pneumoniae (SP) and Legionella pneumophila (LP). These recommendations were based on expert opinions and have not been rigorously evaluated.

METHODS

We used data from a multicenter, prospective, surveillance study of adults hospitalized with CAP to evaluate the sensitivity and specificity of the IDSA/ATS UAT indications for identifying patients who test positive. SP and LP UATs were completed on all included patients. Separate analyses were completed for SP and LP, using 2-by-2 contingency tables, comparing the IDSA/ATS indications (UAT recommended vs not recommended) and UAT results (positive vs negative). Additionally, logistic regression was used to evaluate the association of each individual criterion in the IDSA/ATS indications with positive UAT results.

RESULTS

Among 1941 patients, UATs were positive for SP in 81 (4.2%) and for LP in 32 (1.6%). IDSA/ATS indications had 61% sensitivity (95% confidence interval [CI] 49-71%) and 39% specificity (95% CI 37-41%) for SP, and 63% sensitivity (95% CI 44-79%) and 35% specificity (95% CI 33-37%) for LP. No clinical characteristics were strongly associated with positive SP UATs, while features associated with positive LP UATs were hyponatremia, fever, diarrhea, and recent travel.

CONCLUSIONS

Recommended indications for SP and LP urinary antigen testing in the IDSA/ATS CAP guidelines have poor sensitivity and specificity for identifying patients with positive tests; future CAP guidelines should consider other strategies for determining which patients should undergo urinary antigen testing.

Validation of a diagnostic score model for the prediction of Legionella pneumophila pneumonia

BACKGROUND

Community-acquired pneumonia (CAP) due to Legionella has a high mortality rate in patients who do not receive adequate antibiotic therapy. In a previous study, we developed a simple Legionella Score to distinguish patients with Legionella and non-Legionella pneumonia based on clinical information at diagnosis. In the present study, we validated this Legionella Score for the presumptive diagnosis of Legionella CAP.

METHODS

This validation cohort included 109 patients with Legionella CAP and 683 patients with non-Legionella CAP. The Legionella Score includes six parameters by assigning one point for each of the following items: being male, absence of cough, dyspnea, C-reactive protein (CRP) ≥ 18 mg/dL, lactate dehydrogenase (LDH) ≥ 260 U/L, and sodium < 134 mmol/L.

RESULTS

When the Legionella CAP and non-Legionella CAP were compared by univariate analysis, most of the evaluated symptoms and laboratory test results differed substantially. The six parameters that were used for the Legionella Score also indicated clear differences between the Legionella and non-Legionella CAP. All Legionella patients had a score of 2 points or higher. The median Legionella Scores were 4 in the Legionella CAP cases and 2 in the non-Legionella CAP cases. A receiver operating characteristics curve showed that the area under the curve was 0.93. The proposed best cutoff, total score ≥3, had sensitivity of 93% and specificity of 75%.

CONCLUSION

Our Legionella Score was shown to have good diagnostic ability with a positive likelihood of 3.7 and a negative likelihood of 0.10.

Clinical presentation of Legionella pneumonia: Evaluation of clinical scoring systems and therapeutic efficacy

To evaluate scoring systems to predict Legionella pneumonia and therapeutic efficacy against Legionella pneumonia, the Japanese Society of Chemotherapy Legionella committee has collected data on cases of Legionella pneumonia from throughout Japan. We analyzed 176 patients with Legionella pneumonia and compared them with 217 patients with Streptococcus pneumoniae pneumonia and 202 patients with Mycoplasma pneumoniae pneumonia. We evaluated four scoring systems, the Winthrop-University Hospital score, Community-Based Pneumonia Incidence Study Group score, and Japan Respiratory Society score, but they demonstrated limited sensitivity and specificity for predicting Legionella pneumonia. Using six clinical and laboratory parameters (high fever, high C-reactive protein, high lactate dehydrogenase, thrombocytopenia, hyponatremia, and unproductive cough) reported by Fiumefreddo and colleagues, only 6% had Legionnella pneumonia when less than 2 parameters were present. The efficacy rates of antibiotics at the time of termination were 94.6% for intravenous antibiotics, including ciprofloxacin and pazufloxacin, and 95.5% for oral antibiotics, including ciprofloxacin, levofloxacin, garenoxacin, moxifloxacin, and clarithromycin. Our results suggested that the previously reported clinical scoring systems to predict Legionnella pneumonia are not useful, but 6 simple diagnostic score accurately ruled out Legionnella pneumonia, which may help to optimize initial empiric therapy. Quinolones and clarithromycin still showed good clinical efficacy against Legionella pneumonia.

Early Radiographic and Tomographic Manifestations of Legionnaires' Disease

PURPOSE

Legionnaires' disease (LD) may occur sporadically or in the course of outbreaks, where the typical radiological manifestations of the disease may better be delineated. We took advantage of a rare community-based epidemic of LD (181 patients) that occurred in 2012 in Quebec City, Canada, to describe the radiographic features of LD and compare the its tomographic presentation with that of community-acquired pneumonia caused by common bacteria other than Legionella pneumophila.

METHODS

From the 181 individuals affected in the outbreak, we obtained the chest radiographs of 159 individuals (mean 63 ± 15 years of age) for detailed analysis; 33 patients had a computed tomography (CT) scan performed during the course of their illness. In a case-control study, we compared the CT scans of patients with LD with those of patients who had received a diagnosis of community-acquired pneumonia caused by a pathogen other than Legionella and confirmed by chest CT scan.

RESULTS

Overall, LD most often presented as an airspace consolidation involving 1 of the lower lobes. Pleural effusion and mediastinal adenopathies were apparent only in a minority, whereas no pneumothorax or cavitation was noted. We did not find any significant difference in chest CT scan findings in patients with LD vs those with community-acquired pneumonia from other bacterial origin. No radiological finding was clearly associated with an increased risk of intensive care unit admission or mortality.

CONCLUSIONS

The early radiographic and tomographic manifestations of LD are nonspecific and similar to those found in community-acquired pneumonia from other bacterial origin.

Discrimination between Legionnaires' Disease and Pneumococcal Pneumonia Based on the Clinical and Laboratory Features: A Quantitative Approach Using the Modified Winthrop-University Hospital Weighted Point System

Objective Legionnaires' disease (LD) is a common form of lobar pneumonia, but the optimum diagnostic modality has long been a subject of debate due to incomplete sensitivity and specificity. A delay in the initiation of specific therapy for LD is associated with increased mortality. The decision to treat a patient for Legionella must be made quickly. The purpose of this study was to evaluate the ability of the modified Winthrop-University Hospital WUH system to identify LD while discriminating against pneumococcal pneumonia at the time of hospitalization for community-acquired pneumonia. Methods Five patients with LD and 13 patients with pneumococcal pneumonia were retrospectively analyzed. Results The WUH system identified 4 of 5 patients with LD (sensitivity, 80%) while excluding legionellosis in 12 of 13 patients with pneumococcal pneumonia (specificity, 92%). The positive and negative likelihood ratios were 10.4 and 0.2. The area under the receiver operating characteristic curve was 0.969. Conclusion The WUH system is useful for obtaining a rapid presumptive clinical diagnosis of LD. Further investigation with a larger number of patients is strongly recommended.

Antibiotic stewardship in community-acquired pneumonia

INTRODUCTION

Community-acquired pneumonia (CAP) continues to be associated with significant mortality and morbidity. As with other infectious diseases, in recent years there has been a marked increase in resistance to the antibiotics commonly used against the pathogens that cause CAP. Antimicrobial stewardship denotes coordinated interventions to improve and measure the appropriate use of antibiotics by encouraging the selection of optimal drug regimens. Areas covered: Several elements can be applied to antibiotic stewardship strategies for CAP in order to maintain or improve patient outcomes. In this regard, antibiotic de-escalation, duration of antibiotic treatment, adherence to CAP guidelines recommendations about empirical treatment, and switching from intravenous to oral antibiotic therapy may each be relevant in this context. Antimicrobial stewardship strategies, such as prospective audit with intervention and feedback, clinical pathways, and dedicated multidisciplinary teams, that have included some of these elements have demonstrated improvements in antimicrobial use for CAP without negatively affecting clinical outcomes. Expert commentary: Although there are a limited number of randomized clinical studies addressing antimicrobial stewardship strategies in CAP, there is evidence that antibiotic stewardship initiatives can be securely applied, providing benefits to both healthcare systems and patients.

Two Cases of Hypophosphatemia with Increased Renal Phosphate Excretion in Legionella Pneumonia

We encountered 2 cases of hypophosphatemia due to Legionella pneumonia. Both cases showed increased urinary phosphate excretion and renal tubular dysfunction, which ameliorated with recovery from Legionella pneumonia. Serum fibroblast growth factor-23 level was suppressed, whereas serum 1,25(OH)2 vitamin D and parathyroid hormone levels were normal. Delayed elevation of serum 1,25(OH)2 vitamin D levels was observed with improvement in renal tubular function. These findings suggested hypophosphatemia might be mediated by renal tubular dysfunction.

Legionnaires' disease

Since first identified in early 1977, bacteria of the genus Legionella are recognised as a common cause of community-acquired pneumonia and a rare cause of hospital-acquired pneumonia. Legionella bacteria multisystem manifestations mainly affect susceptible patients as a result of age, underlying debilitating conditions, or immunosuppression. Water is the major natural reservoir for Legionella, and the pathogen is found in many different natural and artificial aquatic environments such as cooling towers or water systems in buildings, including hospitals. The term given to the severe pneumonia and systemic infection caused by Legionella bacteria is Legionnaires' disease. Over time, the prevalence of legionellosis or Legionnaires' disease has risen, which might indicate a greater awareness and reporting of the disease. Advances in microbiology have led to a better understanding of the ecological niches and pathogenesis of the condition. Legionnaires' disease is not always suspected because of its non-specific symptoms, and the diagnostic tests routinely available do not offer the desired sensitivity. However, effective antibiotics are available. Disease notification systems provide the basis for initiating investigations and limiting the scale and recurrence of outbreaks. This report reviews our current understanding of this disease.

Predictors of positive or negative legionella urinary antigen test in community-acquired pneumonia

BACKGROUND

Legionella pneumonia remains a diagnostic challenge. The legionella urinary antigen test (LUT) primarily detects Legionella pneumophila serogroup 1, accounting for 64% of Danish cases, and is often the only legionella test performed. We aimed to identify variables predictive of a positive or negative test result and to explore how the LUT was used in clinical practice.

METHODS

The study was an audit-based cohort study. LUT-positive patients were compared with three randomly selected age- and gender-matched LUT-negative referent patients admitted at a Danish university hospital during 2003-2013. Data were extracted from charts and databases. Positive and negative likelihood ratios (LR+ and LR-) were calculated. For CURB-65 and sepsis, sensitivity analyses were made due to incomplete data.

RESULTS

In all, 25 cases were compared with 75 referents. Factors associated with LUT positivity included recent travel outside Scandinavia (LR + 5.3), Na(+) < 130 mEq/L (LR + 4.3), confusion (LR + 4.2), C-reactive protein (CRP) > 200 mg/L (LR + 3.5), temperature > 39 °C (LR + 3.5), and CURB-65 score ≥ 3 (LR + 3.0-15.0, depending on the model). Decreasing the likelihood of LUT positivity were CRP < 200 mg/L (LR- 0.1), absence of sepsis (LR- 0.1-0.2, depending on the model), absence of tachycardia (heart rate < 90) (LR- 0.2) and normal pulmonary auscultation (LR- 0.3). Additional legionella tests were performed in 60% of the cases and 13% of the referents.

CONCLUSION

Classical features of severe pneumonia are associated with a positive LUT. The LUT is often used inappropriately and should be accompanied by PCR analysis.

Ruling out Legionella in community-acquired pneumonia

BACKGROUND

Assessing the likelihood for Legionella sp. in community-acquired pneumonia is important because of differences in treatment regimens. Currently used antigen tests and culture have limited sensitivity with important time delays, making empirical broad-spectrum coverage necessary. Therefore, a score with 6 variables recently has been proposed. We sought to validate these parameters in an independent cohort.

METHODS

We analyzed adult patients with community-acquired pneumonia from a large multinational database (Community Acquired Pneumonia Organization) who were treated between 2001 and 2012 with more than 4 of the 6 prespecified clinical variables available. Association and discrimination were assessed using logistic regression analysis and area under the curve (AUC).

RESULTS

Of 1939 included patients, the infectious cause was known in 594 (28.9%), including Streptococcus pneumoniae in 264 (13.6%) and Legionella sp. in 37 (1.9%). The proposed clinical predictors fever, cough, hyponatremia, lactate dehydrogenase, C-reactive protein, and platelet count were all associated or tended to be associated with Legionella cause. A logistic regression analysis including all these predictors showed excellent discrimination with an AUC of 0.91 (95% confidence interval, 0.87-0.94). The original dichotomized score showed good discrimination (AUC, 0.73; 95% confidence interval, 0.65-0.81) and a high negative predictive value of 99% for patients with less than 2 parameters present.

CONCLUSIONS

With the use of a large independent patient sample from an international database, this analysis validates previously proposed clinical variables to accurately rule out Legionella sp., which may help to optimize initial empiric therapy.

Current clinical management of Legionnaires’ disease

Legionella pneumophila is increasingly recognized as a cause of both sporadic and epidemic community-acquired pneumonia. Clinical manifestations of Legionnaires' disease are not specific and current diagnostic scores are of limited use. Urinary antigen detection is an effective test for rapid diagnosis of infection caused by L. pneumophila serogroup 1. Improved outcomes regarding the time to defervescence, development of complications and length of stay, have been recently observed for patients treated with levofloxacin monotherapy. Current case-fatality rates for hospitalized patients with community-acquired Legionella pneumonia are lower than those traditionally reported for this infection. Effective preventive strategies are needed.

A Fatal Case of Relapsing Pneumonia Caused by Legionella pneumophila in a Patient with Rheumatoid Arthritis After Two Injections of Adalimumab

We present a rare fatal case of relapsing pneumonia caused by Legionella pneumophila in a patient with rheumatoid arthritis after only two injections of adalimumab. A 78-year-old Japanese woman with a 14-year history of rheumatoid arthritis was prescribed adalimumab because her disease activity remained high. However, 8 days after her second injection of adalimumab, she was admitted to our hospital and diagnosed with pneumonia caused by L. pneumophila. Following intravenous antibiotic therapy, she recovered completely from pneumonia and was discharged on day 10, but pneumonia relapsed, resulting in death 79 days after the first episode of pneumonia. L. pneumophila can lead to recurrence of pneumonia that can ultimately prove fatal, similar to the present case. A review of the pertinent literature is also presented.

A culture-proven case of community-acquired legionella pneumonia apparently classified as nosocomial: diagnostic and public health implications

We report a case of Legionella pneumonia in a 78-year-old patient affected by cerebellar haemangioblastoma continuously hospitalised for 24 days prior to the onset of overt symptoms. According to the established case definition, this woman should have been definitely classified as a nosocomial case (patient spending all of the ten days in hospital before onset of symptoms). Water samples from the oncology ward were negative, notably the patient's room and the oxygen bubbler, and the revision of the case history induced us to verify possible contamination in water samples collected at home. We found that the clinical strain had identical rep-PCR fingerprint of L. pneumophila serogroup 1 isolated at home. The description of this culture-proven case of Legionnaires' disease has major clinical, legal, and public health consequences as the complexity of hospitalised patients poses limitations to the rule-of-thumb surveillance definition of nosocomial pneumonia based on 2-10-day incubation period.

Community-acquired Legionella pneumophila pneumonia: a single-center experience with 214 hospitalized sporadic cases over 15 years

Legionella pneumophila has been increasingly recognized as a cause of community-acquired pneumonia (CAP) and an important public health problem worldwide. We conducted the present study to assess trends in epidemiology, diagnosis, clinical features, treatment, and outcomes of sporadic community-acquired L. pneumophila pneumonia requiring hospitalization at a university hospital over a 15-year period (1995-2010). Among 3934 nonimmunosuppressed hospitalized patients with CAP, 214 (5.4%) had L. pneumophila pneumonia (16 cases were categorized as travel-associated pneumonia, and 21 were part of small clusters). Since the introduction of the urinary antigen test, the diagnosis of L. pneumophila using this method remained stable over the years (p = 0.42); however, diagnosis by means of seroconversion and culture decreased (p < 0.001 and p = 0.001, respectively). The median age of patients with L. pneumophila pneumonia was 58.2 years (SD 13.8), and 76.4% were male. At least 1 comorbid condition was present in 119 (55.6%) patients with L. pneumophila pneumonia, mainly chronic heart disease, diabetes mellitus, and chronic pulmonary disease. The frequency of older patients (aged >65 yr) and comorbidities among patients with L. pneumophila pneumonia increased over the years (p = 0.06 and p = 0.02, respectively). In addition, 100 (46.9%) patients were classified into high-risk classes according to the Pneumonia Severity Index (groups IV-V). Twenty-four (11.2%) patients with L. pneumophila pneumonia received inappropriate empirical antibiotic therapy at hospital admission. Compared with patients who received appropriate empirical antibiotic, patients who received inappropriate therapy more frequently had acute onset of illness (p = 0.004), pleuritic chest pain (p = 0.03), and pleural effusion (p = 0.05). The number of patients who received macrolides decreased over the study period (p < 0.001), whereas the number of patients who received levofloxacin increased (p < 0.001). No significant difference was found in the outcomes between patients who received erythromycin and clarithromycin. However, compared with macrolide use during hospital admission, levofloxacin therapy was associated with a trend toward a shorter time to reach clinical stability (median, 3 vs. 5 d; p = 0.09) and a shorter length of hospital stay (median, 7 vs. 10 d; p < 0.001). Regarding outcomes, 38 (17.8%) patients required intensive care unit (ICU) admission, and the inhospital case-fatality rate was 6.1% (13 of 214 patients). The frequency of ICU admission (p = 0.34) and the need for mechanical ventilation (p = 0.57) remained stable over the study period, but the inhospital case-fatality rate decreased (p = 0.04). In the logistic regression analysis, independent factors associated with severe disease (ICU admission and death) were current/former smoker (odds ratio [OR], 2.96; 95% confidence interval [CI], 1.01-8.62), macrolide use (OR, 2.40; 95% CI, 1.03-5.56), initial inappropriate therapy (OR, 2.97; 95% CI, 1.01-8.74), and high-risk Pneumonia Severity Index classes (OR, 9.1; 95% CI, 3.52-23.4). In conclusion, L. pneumophila is a relatively frequent causative pathogen among hospitalized patients with CAP and is associated with high morbidity. The annual number of L. pneumophila cases remained stable over the study period. In recent years, there have been significant changes in diagnosis and treatment, and the inhospital case-fatality rate of L. pneumophila pneumonia has decreased.

Legionnaires’ Disease

Infection with Legionella spp. is an important cause of serious community- and hospital-acquired pneumonia, occurring sporadically and in outbreaks. Outbreaks of Legionnaires' disease have recently received considerable media attention, and some factors indicate that the problem will increase in future. Infection with Legionella spp. ranks among the three most common causes of severe pneumonia in the community setting, and is isolated in 1-40% of cases of hospital-acquired pneumonia. Underdiagnosis and underreporting are high. Only 2-10% of estimated cases are reported. Detection of a single case should not be considered an isolated sporadic event, but rather indicative of unrecognized cases. There are no clinical features unique to Legionnaires' disease; however, suspicion should be raised by epidemiologic information commensurate with the diagnosis and the presence of headache, confusion, hyponatremia, elevated creatine kinase and/or severe pneumonia. An arterial oxygen partial pressure <60mm Hg on presentation and progression of pulmonary infiltrates despite appropriate antibacterial therapy should always alert clinicians to this cause.Macrolides, fluoroquinolones and rifampin (rifampicin) are the most widely used drugs in treatment. Fluoroquinolones or azithromycin are the treatment of choice in immunosuppressed patients and those with severe pneumonia. Incorporation of the legionella urinary antigen test in emergency departments in hospitals and progressive improvement in this test will, in the near future, permit appropriate diagnosis and treatment of this frequent, sometimes severe, illness.

Optimizing Treatment Outcomes in Severe Community-Acquired Pneumonia

Severe community-acquired pneumonia (CAP) is a life-threatening condition that requires intensive care unit (ICU) admission. Clinical presentation is characterized by the presence of respiratory failure, severe sepsis, or septic shock. Severe CAP accounts for approximately 5-35% of hospital-treated cases of pneumonia with the majority of patients having underlying comorbidities. The most common pathogens associated with this disease are Streptococcus pneumoniae, Legionella spp., Haemophilus influenzae, and Gram-negative enteric rods. Microbial investigation is probably helpful in the individual case but is likely to be more useful for defining local antimicrobial policies. The early and rapid initiation of empiric antimicrobial treatment is critical for a favorable outcome. It should include intravenous beta-lactam along with either a macrolide or a fluoroquinolone. Modifications of this basic regimen should be considered in the presence of distinct comorbid conditions and risk factors for specific pathogens. Other promising nonantimicrobial new therapies are currently being investigated. The assessment of severity of CAP helps physicians to identify patients who could be managed safely in an ambulatory setting. It may also play a crucial role in decisions about length of hospital stay and time of switching to oral antimicrobial therapy in different groups at risk. The most important adverse prognostic factors include advancing age, male sex, poor health of patient, acute respiratory failure, severe sepsis, septic shock, progressive radiographic course, bacteremia, signs of disease progression within the first 48-72 hours, and the presence of several different pathogens such as S. pneumoniae, Staphylococcus aureus, Gram-negative enteric bacilli, or Pseudomonas aeruginosa. However, some important topics of severity assessment remain controversial, including the definition of severe CAP. Prediction rules for complications or death from CAP, although far from perfect, should identify the majority of patients with severe CAP and be used to support decision-making by the physician. They may also contribute to the evaluation of processes and outcomes of care for patients with CAP.

Distinctive features between community-acquired pneumonia (CAP) due to Chlamydophila psittaci and CAP due to Legionella pneumophila admitted to the intensive care unit (ICU)

The spectrum of community-acquired pneumonia (CAP) due to Chlamydophila psittaci ranges from mild, self-limited CAP, to acute respiratory failure. We performed a retrospective study of 13 consecutive patients with CAP due to C. psittaci and 51 patients with legionellosis admitted in one intensive care unit (ICU) (1993-2011). As compared to patients with legionellosis, patients with psittacosis were younger (median age 48 [38-59] vs. 60 [50-71] years, p = 0.007), less frequently smokers (38 vs. 79 %, p < 0.001), with less chronic disease (15 vs. 57 %, p = 0.02), and longer duration of symptoms before admission (median 6 [5-13] vs. 5 [3-7] days, p = 0.038). They presented with lower Simplified Acute Physiology Score II (median 28 [19-38] vs. 39 [28-46], p = 0.04) and less extensive infiltrates on chest X-rays (median 2 [1-3] vs. 3 [3-4] lobes, p = 0.007). Bird exposure was mentioned in 100 % of psittacosis cases, as compared to 5.9 % of legionellosis cases (p < 0.0001). Extrapulmonary manifestations, biological features, and mortality (15.4 vs. 21.6 %, p = 0.62) were similar in both groups. In conclusion, severe psittacosis shares many features with severe legionellosis, including extrapulmonary manifestations, biological features, and outcome. Psittacosis is an important differential diagnosis for legionellosis, especially in cases of bird exposure, younger age, and more limited disease progression over the initial few days.

Legionella pneumonia presenting with bilateral flank pain, hyponatraemia and acute renal failure

Legionnaires' disease (LD) is an often overlooked but a possible cause of sporadic community acquired pneumonia. High fever, cough and gastrointestinal symptoms are non-specific symptoms. Hyponatremia is more common in LD than pneumonia linked with other causes. A definitive diagnosis is usually confirmed by culture, urinary antigen testing for Legionella species. Macolide or quinolone antibiotic is the treatment of choice. We describe a case of Legionella pneumonia presenting with high fever, bilateral flank pain and oliguria. It is important for clinicians to be aware of this diagnosis when managing patients with flank pain. The case highlights the problems in differentiating LD from renal colic and the importance of proper history, physical examination with laboratory tests for appropriate management.

Spontaneous rupture of the spleen associated with Legionella pneumonia

Spontaneous rupture of the spleen associated with Legionella pneumonia is a rare and life-threatening complication; only three cases have been reported to date. The authors describe a case of a 47-year-old man who presented with pneumonia and abdominal pain. He underwent a splenectomy, and was successfully treated with clarithromycin and levofloxacin.

[Four cases of respiratory infections caused by Legionella pneumophila serogroup 3]

Legionella pneumonia tends to be severe and is known to be fatal. Introduction of the urinary Legionella antigen test and changes in the Infectious Disease Law have led to increased numbers of reports, and milder cases are now occasionally seen. We experienced three cases demonstrating mild respiratory infections and one case demonstrating nosocomial pneumonia associated by Legionella pneumophila serogroup 3. Case 1 showed multiple ground-glass opacities on HRCT and productive cough. Cases 2 and 3 showed abnormal findings on chest X-ray, and chest CT findings in both cases suggested chronic respiratory infection. Case 4 experienced fever and hypoxia, and pulmonary edema was noted on X-ray. All of them four cases were diagnosed with respiratory infections isolated L. pneumophila serogroup 3 by culture results, and three of them cases were treated in the outpatient clinic. Thus, milder cases of Legionella pneumonia may be encountered during routine care, and tests for Legionella should be performed in such cases.

Role of Rifampin-Based Combination Therapy for Severe Community-Acquired Legionella pneumophila Pneumonia

Objective:

To review the literature concerning the role of rifampin in the combination treatment of Legionella pneumophila pneumonia.

Data Sources:

A search of MEDLINE and Ovid databases was conducted (January 1970-May 2011) using the search terms Legionella pneumophila, pneumonia, Legionnaires' disease, rifampin or rifampicin, macrolide, fluoroquinolone, erythromycin, clarithromycin, levofloxacin, ciprofloxacin, and moxifloxacin

Study Selection and Data Extraction:

In vivo studies published in English that compared antimicrobial therapies including rifampin for the treatment of Legionella pneumonia, as well as in vitro studies including an assessment of rifampin bioactivity, were included.

Data Synthesis:

Macrolides and fluoroquinolones have been effective as monotherapy in the treatment of L. pneumophila pneumonia. This review includes evidence summaries from 4 bioactivity evaluations. 6 clinical studies, and 6 reported cases of combination rifampin use. Combined with supporting evidence, the role of combination rifampin therapy is further delineated.

Conclusions:

Interpretation of the data is limited by the potential for selection bias and lack of consistent comparators. Rifampin therapy should be considered only for patients with severe disease or significant comorbid conditions (eg. uncontrolled diabetes, smoking, or obstructive lung disease) including immunocompromised hosts and those refractory to conventional monotherapy regimens. Caution for significant adverse drug events and drug-drug interactions should be taken with the addition of rifampin.

Diagnosis of community-acquired pneumonia in adults

Community-acquired pneumonia (CAP) is a common presentation to both primary and secondary care, representing approximately 5% of the acute medical intake in the UK. Treatment is often based on an empirical approach, using broad-spectrum antibiotic regimens, with which the majority of patients will achieve clinical cure. However, in cases of severe CAP, initial treatment failure or severe comorbidity, a more rigorous diagnostic approach is required. This review assesses the evidence base behind the common diagnostic methods for CAP, and presents the case for a rapid and accurate microbiological and radiological diagnosis in improving management and outcomes of this common condition.

Atypical pneumonia--time to breathe new life into a useful term?

The term atypical pneumonia was originally used to describe an unusual presentation of pneumonia. It is now more widely used in reference to either pneumonia caused by a relatively common group of pathogens, or to a distinct clinical syndrome the existence of which is difficult to demonstrate. As such, the use of atypical pneumonia is often inaccurate, potentially confusing, and of dubious scientific merit. We need to return to the original meaning of atypical pneumonia and restrict its use to describe pneumonia that is truly unusual in clinical presentation, epidemiology, or both.

Dual detection of Legionella pneumophila and Legionella species by real-time PCR targeting the 23S-5S rRNA gene spacer region

Although the majority of cases of Legionnaires’ disease (LD) are caused by Legionella pneumophila, an increasing number of other Legionella species have been reported to cause human disease. There are no clinical presentations unique to LD and hence accurate laboratory tests are required for early diagnosis. Therefore, we designed a real-time PCR assay that targets the 23S-5S rRNA intergenic spacer region (23S-5S PCR) and allows for detection of all Legionella species and discrimination of L. pneumophila from other Legionella species. In total, 271 isolates representing 50 Legionella species were tested and the assay was validated using 39 culture-positive and 110 culture-negative patient specimens collected between 1989 and 2006. PCR-positive results were obtained with all 39 culture-positive samples (100% sensitivity). Specimens that tested positive according to 23S-5S PCR, but were culture-negative, were further analysed by DNA sequencing of the amplicon or the macrophage infectivity potentiator (mip) gene. In addition to L. pneumophila, Legionella longbeachae, Legionella cincinnatiensis and Legionella micdadei were identified in the specimens. The assay showed a 7-log dynamic range displaying a sensitivity of 7.5 CFU/mL or three genome equivalents per reaction. Sixty-one specimens containing viruses or bacteria other than Legionellae were negative according to 23S-5S PCR, demonstrating its specificity. Use of this assay should contribute to the earlier detection of respiratory disease caused by Legionella species, as well as to increased rates of detection.

Clinical predictors for Legionella in patients presenting with community-acquired pneumonia to the emergency department

Background

Legionella species cause severe forms of pneumonia with high mortality and complication rates. Accurate clinical predictors to assess the likelihood of Legionella community-acquired pneumonia (CAP) in patients presenting to the emergency department are lacking.

Methods

We retrospectively compared clinical and laboratory data of 82 consecutive patients with Legionella CAP with 368 consecutive patients with non-Legionella CAP included in two studies at the same institution.

Results

In multivariate logistic regression analysis we identified six parameters, namely high body temperature (OR 1.67, p < 0.0001), absence of sputum production (OR 3.67, p < 0.0001), low serum sodium concentrations (OR 0.89, p = 0.011), high levels of lactate dehydrogenase (OR 1.003, p = 0.007) and C-reactive protein (OR 1.006, p < 0.0001) and low platelet counts (OR 0.991, p < 0.0001), as independent predictors of Legionella CAP. Using optimal cut off values of these six parameters, we calculated a diagnostic score for Legionella CAP. The median score was significantly higher in Legionella CAP as compared to patients without Legionella (4 (IQR 3–4) vs 2 (IQR 1–2), p < 0.0001) with a respective odds ratio of 3.34 (95%CI 2.57–4.33, p < 0.0001). Receiver operating characteristics showed a high diagnostic accuracy of this diagnostic score (AUC 0.86 (95%CI 0.81–0.90), which was better as compared to each parameter alone. Of the 191 patients (42%) with a score of 0 or 1 point, only 3% had Legionella pneumonia. Conversely, of the 73 patients (16%) with ≥4 points, 66% of patients had Legionella CAP.

Conclusion

Six clinical and laboratory parameters embedded in a simple diagnostic score accurately identified patients with Legionella CAP. If validated in future studies, this score might aid in the management of suspected Legionella CAP.

Atypical pneumonias: current clinical concepts focusing on Legionnaires' disease

PURPOSE OF REVIEW

This review provides clinicians with an overview of the clinical features of the atypical pneumonias. Atypical community-acquired pneumonia pathogens cause systemic infections with pneumonia. The key to the clinical diagnosis of atypical pneumonias depends on recognizing the characteristic pattern of extrapulmonary organ involvement different for each pathogen. As Legionella is likely to present as severe pneumonia and does not respond to beta-lactams, it is important to presumptively diagnose Legionnaires' disease clinically so that Legionella coverage is included in empiric therapy. This study reviews the clinical features and nonspecific laboratory markers of atypical pathogens, focusing on Legionnaires' disease.

RECENT FINDINGS

Case reports/outbreaks increase our understanding of Legionnaires' disease transmission. Both Mycoplasma pneumoniae and Chlamydophilia pneumoniae may cause asthma. Antimicrobial therapy of Chlamydophilia pneumoniae/Mycoplasma pneumoniae is important to decrease person-to-person spread and to decrease potential long-term sequelae.

SUMMARY

Atypical pulmonary pathogens cause systemic infections accompanied by a variety of characteristic extrapulmonary features. Clinically, it is possible to differentiate Legionnaires' disease from the other typical/atypical pneumonias. Rapid clinical diagnosis of atypical pathogens, particularly Legionnaires' disease, is important in selecting effective empiric therapy and prompting definitive laboratory testing.

Severe Legionella pneumonia: rapid presumptive clinical diagnosis with Winthrop-University Hospital's weighted point score system (modified)

Legionnaires' disease is a systemic infection involving the lungs and accompanied by a characteristic pattern of extrapulmonary organ involvement. Legionnaires' disease is one of the non-zoonotic causes of atypical community-acquired pneumonia (CAP). Legionnaires' disease commonly presents as severe CAP requiring hospitalization and intensive care. Each atypical CAP has its own characteristic pattern of extrapulmonary laboratory clinical findings and abnormalities that are the basis of clinical syndromic diagnosis. Studies have been unsuccessful in identifying individual clinical and laboratory parameters that are specific for Legionella. Individually, clinical and laboratory abnormalities lack diagnostic specificity. The diagnostic specificity of clinical and laboratory findings is increased when combined and are the basis of a clinical syndromic diagnosis. The importance of serial nonspecific laboratory abnormalities with Legionnaires' disease is emphasized. The sensitivity and specificity of a clinical syndromic diagnosis are enhanced if they are based on a weighted point score system. A diagnostic weighted point score system is based on the varying diagnostic importance of clinical and laboratory diagnostic findings. The Winthrop-University Hospital's Infectious Disease Division's rapid clinical diagnostic weighted point system is based on a weighted point score of clinical and laboratory findings. The case presented is that of a 55-year-old man with severe CAP who required hospitalization and intensive care admission. The presumptive clinical diagnosis of Legionella CAP was based on the Winthrop-University Hospital Infectious Disease Division's weighted point score system, which permitted early empiric anti-Legionella antimicrobial therapy and prompted specific Legionella testing. Legionnaires' disease is definitively diagnosed by serology or a urinary Legionella antigen test. This case of severe Legionnaires' CAP was confirmed by urinary antigen test reported on hospital day 6. The Winthrop-University Hospital is weighted point score system (modified) permits a rapid clinical presumptive diagnosis of Legionnaires' disease and is an accurate predictor of Legionella CAP.

Streptococcus pneumoniae and Legionella pneumophila pneumonia in HIV-infected patients

We compared the epidemiological data, clinical features and mortality of community-acquired pneumonia (CAP) by Streptococcus pneumoniae and Legionella in HIV-infected patients and determined discriminative features. An observational, comparative study was performed (January 1994 to December 2004) in 15 HIV patients with CAP by Legionella and 46 by S. pneumoniae. No significant differences were observed in delay until initiation of appropriate antibiotic therapy. Smoking, cancer and chemotherapy were more frequent in patients with Legionella pneumonia (p=0.03, p=0.00009 and p=0.01). Patients with Legionella pneumonia had a higher mean CD4 count (p=0.04), undetectable viral load (p=0.01) and received highly active antiretroviral therapy more frequently (p=0.004). AIDS was more frequent in patients with S. pneumoniae pneumonia (p=0.03). Legionella pneumonia was more severe (p=0.007). Extrarespiratory symptoms, hyponatraemia and increased creatine phosphokinase were more frequent in Legionella pneumonia (p=0.02, p=0.002 and p=0.006). Respiratory failure, need for ventilation and bilateral chest X-ray involvement were of note in the Legionella group (p=0.003, p=0.002 and p=0.002). Mortality tended to be higher in the Legionella group (6.7 vs 2.2%). In conclusion, CAP by Legionella has a higher morbimortality than CAP by S. pneumoniae in HIV-infected patients. Detailed analysis of CAP presentation features allows suspicion of Legionnaires' disease in this subset.

The atypical pneumonias: clinical diagnosis and importance

The most common atypical pneumonias are caused by three zoonotic pathogens, Chlamydia psittaci (psittacosis), Francisella tularensis (tularemia), and Coxiella burnetii (Q fever), and three nonzoonotic pathogens, Chlamydia pneumoniae, Mycoplasma pneumoniae, and Legionella. These atypical agents, unlike the typical pathogens, often cause extrapulmonary manifestations. Atypical CAPs are systemic infectious diseases with a pulmonary component and may be differentiated clinically from typical CAPs by the pattern of extrapulmonary organ involvement which is characteristic for each atypical CAP. Zoonotic pneumonias may be eliminated from diagnostic consideration with a negative contact history. The commonest clinical problem is to differentiate legionnaire's disease from typical CAP as well as from C. pneumoniae or M. pneumonia infection. Legionella is the most important atypical pathogen in terms of severity. It may be clinically differentiated from typical CAP and other atypical pathogens by the use of a weighted point system of syndromic diagnosis based on the characteristic pattern of extrapulmonary features. Because legionnaire's disease often presents as severe CAP, a presumptive diagnosis of Legionella should prompt specific testing and empirical anti-Legionella therapy such as the Winthrop-University Hospital Infectious Disease Division's weighted point score system. Most atypical pathogens are difficult or dangerous to isolate and a definitive laboratory diagnosis is usually based on indirect, i.e., direct flourescent antibody (DFA), indirect flourescent antibody (IFA). Atypical CAP is virtually always monomicrobial; increased IFA IgG tests indicate past exposure and not concurrent infection. Anti-Legionella antibiotics include macrolides, doxycycline, rifampin, quinolones, and telithromycin. The drugs with the highest level of anti-Legionella activity are quinolones and telithromycin. Therapy is usually continued for 2 weeks if potent anti-Legionella drugs are used. In adults, M. pneumoniae and C. pneumoniae may exacerbate or cause asthma. The importance of the atypical pneumonias is not related to their frequency (approximately 15% of CAPs), but to difficulties in their diagnosis, and their nonresponsiveness to beta-lactam therapy. Because of the potential role of C. pneumoniae in coronary artery disease and multiple sclerosis (MS), and the role of M. pneumoniae and C. pneumoniae in causing or exacerbating asthma, atypical CAPs also have public health importance.

Retrospective study of 30 cases of Legionella pneumonia in the Kansai region

Thirty Legionella pneumonia cases were clinically investigated retrospectively from 1999 to 2005 at the Respiratory Medicine Department of Kyoto University and affiliated hospitals. Twenty-eight cases were sporadic and two cases were part of an outbreak. The patients consisted of 28 men and 2 women, with a mean age of 58.8 years (range 25-87). Nineteen cases were smokers and 19 had some underlying disease. The mean period from the disease occurrence to presenting at a hospital was 4.8 days (range 1-15). The mean period from presenting at hospital to Legionella pneumonia diagnosis was 4.6 days (range 0-22). Urinary antigen detection tests for Legionella pneumophilla were performed for 25 cases, and resulted in the diagnosis of 22 cases. Other diagnostic tests with positive findings were culture (buffered charcoal-yeast extract agar, BCYE), the polymerase chain reaction (PCR) test, and serological diagnosis (enzyme immunoassay and microagglutination test). Legionella species diagnosis was obtained by culture and serology for 13 cases: 10 cases had Legionella pneumophila serogroup 1, 2 cases had Legionella pneumophila serogroup 6, and 1 case had Legionella longbeachea. Fluoloquinolones (Fq) are most often used for therapy, especially in recent cases, and were predominantly the chosen treatment (70%). Death due to Legionella pneumonia occurred in 4 cases: 3 cases had severe underlying diseases, and 1 case took 18 days to diagnose (doctors' delay). To detect the majority of Legionella pneumonia cases, a combination of diagnostic examinations is still needed. Regarding the management of community-acquired pneumonia, both the cost and the indication of diagnostic examinations for Legionella infection should be considered simultaneously.

Community-acquired pneumonia by Legionella pneumophila serogroups 1–6 in Brazil

A prospective cohort study of adult patients hospitalized due to community-acquired pneumonia was carried out for 1 year in a Brazilian university general hospital to detect the incidence of community-acquired pneumonia by Legionella pneumophila serogroups 1-6. During a whole year, a total of 645 consecutive patients who were hospitalized due to a initial presumptive diagnosis of respiratory disease by ICD-10 (J00-J99), excluding upper respiratory diseases, were screened to detect the patients with community-acquired pneumonia. Fifty-nine consecutive patients hospitalized due to community-acquired pneumonia between July 19, 2000 and July 18, 2001, were included in the study. They had determinations of serum antibodies to L. pneumophila serogroups 1-6 by indirect immunofluorescence antibody test at the Infectious Diseases Laboratory of University of Louisville (KY, USA) and urinary antigen tests for L. pneumophila serogroup 1. Three patients had community-acquired pneumonia by L. pneumophila serogroups 1-6, two patients being diagnosed by seroconversion and positive urinary antigen tests; the other had negative serologies but strongly positive urinary antigen test. The incidence of community-acquired pneumonia by L. pneumophila serogroups 1-6 in our hospital was 5.1%.