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

Case report: The value of early application of mNGS technology in the diagnosis and treatment of severe Legionnaires' disease: reports of two cases with different outcomes

Background

Legionnaires' disease has a high clinical mortality rate, and early diagnosis and treatment are critical. Increasing evidence shows that metagenomic next-generation sequencing (mNGS) has excellent potential for the early identification of pathogens. To help clinicians better recognize Legionnaires' disease in its early stage and to illustrate the diagnostic value of mNGS technology, we reviewed and summarized two cases of severe Legionnaires' disease.

Methods and analysis

We selected two patients with severe Legionnaires' disease who were admitted to our department in recent years. We discuss experience with them and the shortcomings in their treatment by summarizing their medical history, disease evolution, tests, and diagnostic and therapeutic processes.

Results

In both patients, the diagnosis of Legionnaires' disease was confirmed through analysis of the bronchoalveolar lavage fluid (BALF). The middle-aged male patient was cured and discharged due to early detection and diagnosis. The elderly immunocompromised patient died due to a delay in diagnosis.

Conclusion

This study highlights the importance of the early recognition and diagnosis of severe Legionnaires' disease and the advantages of mNGS in identifying the pathogen.

Atypical pneumonia (Review)

Atypical pneumonia encompasses diverse pathogens, such as Chlamydia pneumoniae, Mycoplasma pneumoniae and Legionella species, which differ from typical bacterial pneumonia in their extrapulmonary manifestations. Clinical differentiation relies on systemic involvement rather than on standalone symptoms. Despite challenges in distinct diagnosis, syndromic approaches and weighted point systems aid in accurate presumptive diagnoses. Antibiotic treatment, often non-β-lactams due to the unique cell structures of atypical pathogens, targets intracellular processes. Macrolides, tetracyclines, quinolones and ketolides are effective due to their intracellular penetration, crucial for combating these intracellular pathogens. The prevalence of atypical pneumonia varies globally, with Europe, Asia/Africa and Latin America reporting detection rates between 20-28%. Streptococcus pneumoniae remains a primary cause of pneumonia; however, atypical pathogens contribute significantly to this disease, being more prevalent in outpatient settings and among young adults. Legionella stands out in severe hospitalized cases and is associated with higher mortality rates. Diagnosis proves challenging due to overlapping symptoms with other respiratory infections. Differentiation among pathogens, such as Chlamydia pneumoniae, Mycoplasma pneumoniae and Legionella relies on subtle clinical variations and imaging findings. Diagnostic methods include serological studies, cultures and polymerase chain reaction, each with limitations in sensitivity or specificity. Prognosis varies widely. Atypical pneumonia can progress to severe forms with fatal outcomes, causing multi-organ damage. Complications extend beyond the respiratory system, affecting the cardiovascular system, exacerbating conditions such as chronic obstructive pulmonary disease and asthma, and potentially linking to conditions such as lung cancer. Increasing antibiotic resistance poses a significant challenge, influencing treatment outcomes and prolonging illness duration.

Severe community‑acquired pneumonia caused by Legionella gormanii in combination with influenza A subtype (H1N1) virus in an immunocompetent patient detected by metagenomic next‑generation sequencing: A case report

Legionella pneumonia is an atypical form of pneumonia caused by Legionella gormanii that can also lead to multiple organ diseases, including acute respiratory distress syndrome and multiple organ dysfunction syndrome. Legionella gormanii requires a long incubation period for culture in clinical practice using BCYE medium. The specificity of serum for serological detection is low, resulting in a relatively high rate of missed Legionella diagnoses. Contracting the H1N1 virus can lead to the misdiagnosis of Legionella gormanii. Metagenomic next-generation sequencing (mNGS) is a novel tool that can rapidly and accurately identify potential Legionella gormanii strains. A severe case of community-acquired pneumonia in a 79-year-old patient was reported. The patient was diagnosed with Legionella gormanii and influenza A subtype (H1N1) virus using mNGS at The First Affiliated Hospital, Zhejiang University School of Medicine. After anti-Legionella and antiviral therapy, the number of reads identifying Legionella gormanii in bronchoalveolar lavage fluid using mNGS decreased from 665 to 112 as the patient's condition gradually improved. A search of PubMed revealed few reports of Legionella gormanii in association with the influenza A subtype (H1N1) virus. Patients with severe pneumonia caused by Legionella and influenza A subtype H1N1 virus infections should be screened early for infections using methods such as mNGS. This approach enables early and precise treatment, simplifying the administration of antibiotics and enhancing patient outcomes.

High-glucose conditions attenuate the response of macrophages to Legionella pneumophila infection by inhibiting NOD1 and MAPK signaling

BACKGROUND

Patients with diabetes are particularly susceptible to Legionella pneumophila (LP) infection, but the exact pathogenesis of LP infection in diabetic patients is still not fully understood. Herein, we investigated the effect of diabetes on immune function during LP infection in vitro and in vivo.

METHODS

The time course of LP infection in macrophages under normal and high-glucose (HG) conditions was examined in vitro. Western blot was used to determine nucleotide-binding oligomerization domain 1 (NOD1), kinase 1/2 (ERK1/2), mitogen-activated protein kinase p38 (MAPK p38), and c-Jun N-terminal kinases (JNK). Enzyme-linked immunosorbent assay (ELISA) was used to assess the secretion of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). Cell Counting Kit-8 (CCK8) assay assessed U937 cell viability after treating cells with different concentrations of high sugar medium and ML130 (NOD1 inhibitor). For the in vivo study, normal and streptozocin-induced diabetic guinea pigs were infected with LP for 6, 24, and 72 h, after which NOD1, MAPK-related signals, TNF-α, and IL-6 expression in lung tissues were assessed using immunohistochemistry, western blot, and RT-PCR.

RESULTS

HG attenuated the upregulation of NOD1 expression and reduced TNF-α and IL-6 secretion caused by LP compared with LP-infected cells exposed to normal glucose levels (all p < 0.05). In diabetic guinea pigs, HG inhibited the upregulation of NOD1 expression in lung tissues and the activation of p38, ERK1/2, and cJNK caused by LP infection compared to control pigs (all p < 0.05).

CONCLUSION

HG attenuates the response of macrophages to LP infection by inhibiting NOD1 upregulation and the activation of MAPK signaling.

Legionella pneumonia in hospitalized adults with respiratory failure: Quinolones or macrolides?

The optimal antimicrobial regimen for adults with respiratory failure due to Legionella pneumonia remains controversial. A systematic review was performed to assess the impact on outcomes comparing quinolones versus macrolides. A literature search was conducted in PubMed, Cochrane Library and Web of Science between 2012 and 2022. It yielded 124 potentially articles and ten observational studies met the inclusion criteria. A total of 4271 patients were included, 2879 (67 %) were male. A total of 1797 (42 %) subjects required intensive care unit (ICU) admission and 942 (52 %) mechanical ventilation. Fluoroquinolones and macrolides alone were administered in 1397 (33 %) and 1500 (35 %) subjects, respectively; combined therapy in 204 (4.8 %) patients. Overall mortality was 7.4 % (319 patients), with no difference between antibiotics. When data from the three studies with severe pneumonia were pooled together, mortality with fluoroquinolones alone was statistically superior to macrolides alone (72.8 % vs 30.8 %, p value 0.027). Hospital length of stay and complications were comparable. Our findings suggest that macrolides and quinolones were comparable for hospitalized Legionella pneumonia. However, in severe pneumonia, a randomized clinical trial is an unmet clinical need. PROSPERO registration number: CRD42023389308.

An Epidemiological Study on Legionnaires' Disease in Gyeonggi Province, Korea: Occurrence, Infection Routes, and Risk Factors for Mortality (2016-2022)

Background and Objectives: Legionnaires' disease (LD) is an acute respiratory disease with increasing annual numbers of reported domestic and global cases. This study aimed to establish foundational data for the prevention and control of LD by investigating the occurrence and infection routes of reported and suspected cases of LD in Gyeonggi Province, Korea, from January 2016 to December 2022, and by and analyzing the risk factors for death. Materials and Methods: A sex-and-age standardization was performed on LD patients and suspected cases reported in Gyeonggi Province. The monthly average number of confirmed cases was visualized using graphs, and a survival analysis was performed using Kaplan-Meier survival curves. The mortality risk ratio was estimated using the Cox proportional hazards model. Results: The incidence of LD in Gyeonggi Province mirrored the national trend, peaking in July with the highest number of confirmed and suspected cases. While there was no significant difference in survival rates by age, the survival rate was higher for suspected cases when analyzed separately. Comparing the death ratio by infection route, nosocomial infections showed the highest death ratio, and intensive care unit (ICU) admission and the presence of coinfections were significantly correlated with mortality. Factors such as nosocomial infection, admission within 1 to 3 days following diagnosis, and the development of complications were factors contributing to a higher risk of death. Conclusions: The general characteristics of patients with LD were similar to those suggested by previous studies. The proportion of community-acquired infections was lower than in previous studies, but the length of hospital stay was similar for survivors and the deceased, and the mortality rate within 30 days after diagnosis was higher for nosocomial infections. In conclusion, nosocomial infection, a period of up to 3 days from admission to diagnosis, and complications were significantly related to the mortality rate of LD.

Hairy Cell Leukemia (HCL) Presenting As Severe Acute Respiratory Distress Syndrome (ARDS) With Legionella pneumophila: Coincidence or Causation?

Due to a low index of suspicion coupled with specific growth conditions and non-specific clinical manifestations, Legionella (L.) pneumophila is a frequently misdiagnosed cause of pneumonia in immunocompromised patients, especially those with hematological malignancies. We present a case of severe acute respiratory distress syndrome (ARDS) secondary to Legionnaire's disease in a patient with newly diagnosed hairy cell leukemia (HCL) to highlight the importance of early recognition, diagnosis, and treatment of Legionnaire's disease to reduce morbidity and mortality.

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.

Environmental Monitoring of Legionella in Hospitals in the Campania Region: A 5-Year Study

Legionella is a pathogen that colonizes soils, freshwater, and building water systems. People who are most affected are those with immunodeficiencies, so it is necessary to monitor its presence in hospitals. The purpose of this study was to evaluate the presence of Legionella in water samples collected from hospitals in the Campania region, Southern Italy. A total of 3365 water samples were collected from January 2018 to December 2022 twice a year in hospital wards from taps and showers, tank bottoms, and air-treatment units. Microbiological analysis was conducted in accordance with the UNI EN ISO 11731:2017, and the correlations between the presence of Legionella and water temperature and residual chlorine were investigated. In total, 708 samples (21.0%) tested positive. The most represented species was L. pneumophila 2-14 (70.9%). The serogroups isolated were 1 (27.7%), 6 (24.5%), 8 (23.3%), 3 (18.9%), 5 (3.1%), and 10 (1.1%). Non-pneumophila Legionella spp. represented 1.4% of the total. Regarding temperature, the majority of Legionella positive samples were found in the temperature range of 26.0-40.9 °C. An influence of residual chlorine on the presence of the bacterium was observed, confirming that chlorine disinfection is effective for controlling contamination. The positivity for serogroups other than serogroup 1 suggested the need to continue environmental monitoring of Legionella and to focus on the clinical diagnosis of other serogroups.

Epidemiology and direct health care costs of hospitalised legionellosis in New Zealand, 2000-2020

BACKGROUND

Legionellosis is a collective term used for disease caused by Legionella species which result in community and hospital acquired pneumonia worldwide. The aim of this analysis was to describe the epidemiology of legionellosis hospitalisations in Aotearoa New Zealand (NZ) over a 21-year period and quantify the health care costs.

METHOD

This study combined national legionellosis notification and hospital discharge data that were linked via the National Health Index (NHI) to provide a more complete dataset of hospitalised cases. The direct cost of hospital care was estimated by multiplying the diagnosis-related group cost-weight by the national price and inflating to 2020/2021 values.

RESULTS

There were 1479 records matched across notifications and discharge databases, including 990 with principal and 489 with additional diagnosis of legionellosis. Incidence rose to an average of 143 cases per annum for 2016-2020, a rate of 3·2/100,000. The median LOS was 6 days (IQR 4-13·5) with direct costs of $2·1 million per annum over that period. Rates were highest in those aged 65 years and above, male, and of European/Other ethnicity. Hospitalisations showed a peak in spring and summer.

CONCLUSION

The rate of hospitalised legionellosis in New Zealand rose from 2000 to 2015, largely reflecting improved diagnosis. This preventable disease results in substantial health care costs. Greater efforts are needed to identify and control sources of exposure. Surveillance could be improved by routine integration of notification and hospital discharge data.

Severe pneumonia caused by Legionella pneumophila detected by a multiplex polymerase chain reaction assay and confirmed by serology

Legionella pneumophila is a rarely diagnosed microorganism in Serbia. It causes legionellosis, usually a mild respiratory infection. However, in some cases it can be severe and even life threatening. In June 2020, during the COVID-19 pandemic, a patient with symptoms of the aforesaid infection, namely severe pneumonia and acute respiratory distress syndrome, was admitted to the hospital. The multiplex polymerase chain reaction (PCR) test (The BioFire FilmArray Pneumonia Panel plus) detected the presence of L. pneumophila in the patient’s bronchial secretions. The specific culture for the detection of that organism, however, remained sterile. The patient’s paired sera had been sent for serology and the results in both of them came back positive for Legionella spp. 1–6, while the assays specific for each one of the 10 serogroups detected more than a fourfold increase of antibody titers in an uncommon serogroup 2 only. The patient was treated with moxifloxacin; he recovered well and was discharged after 26 days of hospitalization. Having being diagnosed with the L. pneumophila infection correctly through the multiplex PCR test, the patient was given the right therapy with moxifloxacin. The serologic assays corroborated this result and revealed the uncommon group 2, thus confirming the necessity of carrying out all the tests available to attain the exact diagnosis of legionellosis.

Legionnaires' Disease: Update on Diagnosis and Treatment

Legionellosis is the infection caused by bacteria of the genus Legionella, including a non-pneumonic influenza-like syndrome, and Legionnaires’ disease is a more serious illness characterized by pneumonia. Legionellosis is becoming increasingly important as a public health problem throughout the world; although it is an underreported disease, studies have consistently documented a high incidence. In addition, health costs associated with the disease are high. Diagnosis of Legionnaires’ disease is based mainly on the detection of Legionella pneumophila serogroup 1 antigen in urine. However, there have been advances in detection tests for patients with legionellosis. New methodologies show greater sensitivity and specificity, detect more species and serogroups of Legionella spp., and have the potential for use in epidemiological studies. Testing for Legionella spp. is recommended at hospital admission for severe community-acquired pneumonia, and antibiotics directed against Legionella spp. should be included early as empirical therapy. Inadequate or delayed antibiotic treatment in Legionella pneumonia has been associated with a worse prognosis. Either a fluoroquinolone (levofloxacin or moxifloxacin) or a macrolide (azithromycin preferred) is the recommended first-line therapy for Legionnaires’ disease; however, little information is available regarding adverse events or complications, or about the duration of antibiotic therapy and its association with clinical outcomes. Most published studies evaluating antibiotic treatment for Legionnaires’ disease are observational and consequently susceptible to bias and confounding. Well-designed studies are needed to assess the usefulness of diagnostic tests regarding clinical outcomes, as well as randomized trials comparing fluoroquinolones and macrolides or combination therapy that evaluate outcomes and adverse events.

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.

Legionella pneumophila-Virulence Factors and the Possibility of Infection in Dental Practice

Legionella pneumophila is defined as a bacterium that can cause severe pneumonia. It is found in the natural environment and in water, and is often found in water tanks. It can be an integral part of biofilms in nature, and the protozoa in which it can live provide it with food and protect it from harmful influences; therefore, it has the ability to move into a sustainable but uncultured state (VBNC). L. pneumophila has been shown to cause infections in dental practices. The most common transmission route is aerosol generated in dental office water systems, which can negatively affect patients and healthcare professionals. The most common way of becoming infected with L. pneumophila in a dental office is through water from dental instruments, and the dental unit. In addition to these bacteria, patients and the dental team may be exposed to other harmful bacteria and viruses. Therefore, it is vital that the dental team regularly maintains and decontaminates the dental unit, and sterilizes all accessories that come with it. In addition, regular water control in dental offices is necessary.

Diagnostic accuracy of urinary antigen tests for legionellosis: A systematic review and meta-analysis

BACKGROUND

Urinary antigen tests (UATs) have been used for the early detection of legionellosis and have demonstrated moderate sensitivity and high specificity. However, the most recent systematic review and meta-analysis published in 2009 evaluated the accuracy of UATs; since then, UAT accuracy may have changed owing to advances and developments in UAT technology and epidemiological changes in the frequency of Legionella species that cause legionellosis. Therefore, this systematic review and meta-analysis aimed to update the accuracy of UATs for legionellosis among patients with suspected pneumonia.

METHODS

Overall, 1326 studies were screened, 21 of which fulfilled the eligibility criteria for quality assessment and meta-analysis. Data from 5772 patients, including 1368 (23.7%) with the target condition (i.e., suspected legionellosis), were included in the analysis. The overall quality of the included studies, which was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool, was unclear.

RESULTS

The calculated pooled sensitivity and specificity were 0.79 (95% confidence interval [CI], 0.71-0.85) and 1.00 (95% CI, 0.99-1.00), respectively. Subpopulation analysis revealed that the accuracy of UATs for sensitivity and specificity for Legionella pneumophilia serogroup 1 was 0.86 (95% CI, 0.78-0.91) and 1.00 (95% CI, 0.99-1.00), respectively.

CONCLUSIONS

This study demonstrated that the sensitivity and specificity of UATs were moderate and high, respectively, which is comparable to the results reported in 2009. Therefore, UATs may be a useful method for the early detection of legionellosis caused by Legionella pneumophila serogroup 1.

CLINICAL TRIAL REGISTRATION

The review protocol was prospectively registered with the University Hospital Medical Information Network Clinical Trials Registry (UMIN000041080).

Legionella pneumophila pneumonia with rapid clinical course in a lung cancer patient

We report an acute clinical course of pneumonia caused by Legionella pneumophila in a patient receiving chemotherapy for lung cancer and corticosteroid therapy. A 57-year-old man presented with fever and dyspnoea and was admitted to our hospital. Chest computed tomography revealed a new left lower lung infiltrate, tumour progression in the right upper lung region, metastases to lymph nodes and pleural effusion. The urinary antigen test for Legionella was positive. The patient's oxygen requirement increased on the day of admission, and he died the day after hospitalization. Legionnaires' disease may manifest with an acute presentation, and patients in Japan with physical risk factors for this disease could get infected despite the absence of environmental risk factors. Early treatment for suspected Legionnaire's disease should be considered.

Legionella Pneumonia in the ICU: A Tertiary Care Center Experience Over 10 Years

OBJECTIVES:

Few studies have reported the complications and outcomes of patients with Legionella pneumonia requiring ICU admission. The objective of our study is to report the clinical course, complications, and 30-day mortality of patients with Legionella pneumonia admitted to the critical care units at our medical center over a 10-year period.

DESIGN:

Retrospective observational study.

SETTING:

Tertiary care teaching hospital.

PATIENTS:

All adult (≥ 18 yr old) patients with Legionella pneumonia admitted to the ICUs from January 1, 2010, to December 31, 2019.

INTERVENTIONS:

None.

MEASUREMENTS AND MAIN RESULTS:

A total of 88 patients with Legionella pneumonia were admitted to ICUs over the 10-year period. The majority of infections (n = 80; 90.9%) were community acquired. The median (interquartile range) age of patients was 60 years (51.5–71.0 yr); 58 (66%) were male, and 41 (46.6%) identified their race as Black. The median (interquartile range) Sequential Organ Failure Assessment score at ICU admission was 6 (3–9). The distribution of infections showed seasonal dominance with most cases (86%) occurring in the summer to early fall (May to October). Invasive mechanical ventilation was required in 62 patients (70.5%), septic shock developed in 57 patients (64.8%), and acute respiratory distress syndrome developed in 42 patients (47.7%). A majority of patients developed acute kidney injury (n = 69; 78.4%), with 15 (21.7%) receiving only intermittent hemodialysis and 15 (21.7%) requiring continuous renal replacement therapy. Ten patients required venovenous extracorporeal membrane oxygenation support; eight (80%) survived and were successfully decannulated. Overall 30-day mortality was 26.1% (n = 23). Advanced age, higher Sequential Organ Failure Assessment score at admission, and not receiving Legionella-specific antimicrobial therapy within 24 hours of hospital admission were predictors of 30-day mortality.

CONCLUSIONS:

Patients with Legionella pneumonia may require ICU admission and major organ support. Legionella-targeted antibiotics should be included in the empiric regimen for any patient with severe pneumonia. Outcomes of extracorporeal membrane oxygenation therapy in this population are encouraging.

Complement-mediated autoimmune haemolytic anaemia as an initial presentation of Legionnaires' disease

A 42-year-old diabetic man presented to the hospital with severe sepsis and multiorgan dysfunction. A probable respiratory source of sepsis was suspected because of suggestive clinical and radiological findings. He was critically ill and was therefore admitted to intensive care for further management including ventilatory support and renal replacement therapy. He was also found to have marked anaemia requiring multiple blood transfusions with clinical and laboratory evidence pointing towards severe haemolysis. Further workup for the aetiology of pneumonia established a diagnosis of Legionella by confirmatory tests namely legionella antigen in the urine and exponentially rising serum antibody titres. The cause for the severe haemolysis was found to be complement-mediated autoimmune haemolysis as determined by direct antiglobulin test positive for complement components C3 and negative for IgG. Such clinically significant autoimmune haemolysis as a presenting feature, rather than a late complication, has never before been reported in the literature.

[Management of Adult Community-Acquired Pneumonia and Prevention - Update 2021 - Guideline of the German Respiratory Society (DGP), the Paul-Ehrlich-Society for Chemotherapy (PEG), the German Society for Infectious Diseases (DGI), the German Society of Medical Intensive Care and Emergency Medicine (DGIIN), the German Viological Society (DGV), the Competence Network CAPNETZ, the German College of General Practitioneers and Family Physicians (DEGAM), the German Society for Geriatric Medicine (DGG), the German Palliative Society (DGP), the Austrian Society of Pneumology Society (ÖGP), the Austrian Society for Infectious and Tropical Diseases (ÖGIT), the Swiss Respiratory Society (SGP) and the Swiss Society for Infectious Diseases Society (SSI)]

The present guideline provides a new and updated concept of the management of adult patients with community-acquired pneumonia. It replaces the previous guideline dating from 2016.The guideline was worked out and agreed on following the standards of methodology of a S3-guideline. This includes a systematic literature search and grading, a structured discussion of recommendations supported by the literature as well as the declaration and assessment of potential conflicts of interests.The guideline has a focus on specific clinical circumstances, an update on severity assessment, and includes recommendations for an individualized selection of antimicrobial treatment.The recommendations aim at the same time at a structured assessment of risk for adverse outcome as well as an early determination of treatment goals in order to reduce mortality in patients with curative treatment goal and to provide palliation for patients with treatment restrictions.

Early Detection of Legionella pneumophila and Aspergillus by mNGS in a Critically Ill Patient With Legionella Pneumonia After Extracorporeal Membrane Oxygenation Treatment: Case Report and Literature Review

Legionella pneumophila can cause pneumonia, leading to severe acute respiratory distress syndrome (ARDS). Because of its harsh growth requirements, limited detection methods, and non-specific clinical manifestations, diagnosing Legionella pneumonia remains still challenging. Metagenomic next-generation sequencing (mNGS) technology has increased the rate of detection of Legionella. This study describes a patient who rapidly progressed to severe ARDS during the early stage of infection and was treated with extracorporeal membrane oxygenation (ECMO). Although his bronchoalveolar lavage fluid (BALF) was negative for infection and his serum was negative for anti-Legionella antibody, mNGS of his BALF and blood showed only the presence of Legionella pneumophila (blood mNGS reads 229, BALF reads 656). After antibiotic treatment and weaning from ECMO, however, he developed a secondary Aspergillus and Klebsiella pneumoniae infection as shown by mNGS. Mechanical ventilation and antibiotic treatment were effective. A search of PubMed showed few reports of secondary Aspergillus infections after Legionella infection. Severe pneumonia caused by any type of pathogenic bacteria may be followed by Aspergillus infection, sometimes during extremely early stages of infection. Patients with severe pneumonia caused by Legionella infection should undergo early screening for secondary infections using methods such as mNGS, enabling early and precise treatment, thereby simplifying the use of antibiotics and improving patient prognosis.

Are Fluoroquinolones or Macrolides Better for Treating Legionella Pneumonia? A Systematic Review and Meta-analysis

BACKGROUND

The Infectious Diseases Society of America recommends either a fluoroquinolone or a macrolide as a first-line antibiotic treatment for Legionella pneumonia, but it is unclear which antibiotic leads to optimal clinical outcomes. We compared the effectiveness of fluoroquinolone versus macrolide monotherapy in Legionella pneumonia using a systematic review and meta-analysis.

METHODS

We conducted a systematic search of literature in PubMed, Cochrane, Scopus, and Web of Science from inception to 1 June 2019. Randomized controlled trials and observational studies comparing macrolide with fluoroquinolone monotherapy using clinical outcomes in patients with Legionella pneumonia were included. Twenty-one publications out of an initial 2073 unique records met the selection criteria. Following PRISMA guidelines, 2 reviewers participated in data extraction. The primary outcome was mortality. Secondary outcomes included clinical cure, time to apyrexia, length of hospital stay (LOS), and the occurrence of complications. The review and meta-analysis was registered with PROSPERO (CRD42019132901).

RESULTS

Twenty-one publications with 3525 patients met inclusion criteria. The mean age of the population was 60.9 years and 67.2% were men. The mortality rate for patients treated with fluoroquinolones was 6.9% (104/1512) compared with 7.4% (133/1790) among those treated with macrolides. The pooled odds ratio assessing risk of mortality for patients treated with fluoroquinolones versus macrolides was 0.94 (95% confidence interval, .71-1.25, I2 = 0%, P = .661). Clinical cure, time to apyrexia, LOS, and the occurrence of complications did not differ for patients treated with fluoroquinolones versus macrolides.

CONCLUSIONS

We found no difference in the effectiveness of fluoroquinolones versus macrolides in reducing mortality among patients with Legionella pneumonia.

Genetic Diversity of the Legionella pneumophila dotA Gene Detected on Surfaces of Respiratory Therapy Equipment

Legionellosis is a neglected disease due to the absence of well-defined clinical symptoms and difficulties in isolating the causal organism. Legionella spp. is known to colonize the lumen of respiratory therapy equipment(RTE) and evade conventional detection by entering the viable but non-culturable state. Monitoring these surfaces for Legionella pneumophila in addition to routine monitoring of water could aid in decreasing incidences of hospital-acquired infections by this pathogen. In this study swabs of different respiratory therapy equipment were tested for the presence of Legionella by conventional culture-based methods versus molecular detection of culture-independent template by polymerase chain reaction (PCR). Genetic diversity of the genes amplified were studied using bioinformatic tools. The dotA genes were genetically diverse indicating no clonality. This communication highlights that the persistence of virulence genes like dotA on abiotic surfaces can result in the mobilization of these genes to other species and give rise to virulent forms especially in a healthcare setting.

Legionellosis after hematopoietic stem cell transplantation

Limited data are available on legionellosis after hematopoietic stem cell transplant (HSCT). The aim of this study was to report the cases of legionellosis and to identify predictors of legionellosis, legionellosis-associated death, and non-relapse mortality (NRM). All cases of post-HSCT legionellosis from the EBMT registry were included and matched with controls in a 3:1 ratio for the analyses of risk factors. In the years 1995-2016, 80 cases from 52 centers in 14 countries were identified (mainly from France, Italy, and Spain). Median time from HSCT to legionellosis was 203 days (range, 0-4099); 19 (23.8%) patients developed early legionellosis (within-day +30 post-HSCT). Patients were mainly male (70%), after allogeneic HSCT (70%), with acute leukemia (27.5%), lymphoma (23.8%), or multiple myeloma (21.3%), and the median age of 46.6 (range, 7.2-68.2). Predictors of legionellosis were allogeneic HSCT (OR = 2.27, 95%CI:1.08-4.80, p = 0.03) and recent other infection (OR = 2.96, 95%CI:1.34-6.52, p = 0.007). Twenty-seven (33.8%) patients died due to legionellosis (44% after early legionellosis), NRM was 50%. Predictors of NRM were female sex (HR = 2.19, 95%CI:1.13-4.23, p = 0.02), early legionellosis (HR = 2.24, 95%CI:1.13-4.46, p = 0.02), and south-eastern geographical region (HR = 2.16, 95%CI:1.05-4.44, p = 0.036). In conclusion, legionellosis is a rare complication after HSCT, mainly allogeneic, occurring frequently within 30 days after HSCT and associated with high mortality.

Lymphopenia Is Associated With Poor Outcomes of Patients With Community-Acquired Pneumonia and Sepsis

Background

Lymphopenia is a marker of poor prognosis in patients with community-acquired pneumonia (CAP), yet its impact on outcomes in patients with CAP and sepsis remains unknown. We aim to investigate the impact of lymphopenia on outcomes, risk of intensive care unit (ICU) admission, and mortality in CAP patients with sepsis.

Methods

This was a retrospective, observational study of prospectively collected data from an 800-bed tertiary teaching hospital (2005–2019).

Results

Of the 2203 patients with CAP and sepsis, 1347 (61%) did not have lymphopenia, while 856 (39%) did. When compared with the nonlymphopenic group, patients with sepsis and lymphopenia more frequently required ICU admission (P = .001), had a longer hospital length of stay (P ˂ .001), and presented with a higher rate of in-hospital (P ˂ .001) and 30-day mortality (P = .001). Multivariable analysis showed that C-reactive protein ≥15 mg/dL, lymphopenia, pleural effusion, and acute respiratory distress syndrome within 24 hours of admission were risk factors for ICU admission; age ≥80 years was independently associated with decreased ICU admission. In addition, age ≥80 years, chronic renal disease, chronic neurologic disease, being a nursing home resident, lymphopenia, and pleural effusion were independently associated with increased 30-day mortality, whereas pneumococcal vaccination, diabetes mellitus, and fever were independently associated with reduced 30-day mortality.

Conclusions

Lymphopenia was independently associated with risk of ICU admission and higher in-hospital and 30-day mortality in patients with CAP and sepsis. Early identification of lymphopenia could help identify septic patients with CAP who require or will shortly require critical care.

Trends in the incidence and mortality of legionellosis in Japan: a nationwide observational study, 1999-2017

This study examined temporal trend, seasonality, and geographical variations of legionellosis incidence and mortality in Japan. This nationwide observational study used the Japanese Vital Statistics and Infectious Diseases Weekly Report (1999-2017) data to calculate legionellosis crude and age-adjusted incidence and mortality rates per 100,000 population by age and sex. Incidence was compared among the 4 seasons and regional incidence among 47 prefectures. Of 13,613 (11,194 men) people with legionellosis in Japan, 725 (569 men) were fatal. Increasing incidence trend occurred from 0.0004 (1999) to 1.37 (2017) per 100,000 population. People aged ≥ 70 years accounted for 43.1% overall; men's age-adjusted incidence rate was consistently approximately five times higher than for women. Significantly higher incidence occurred in summer than in winter (p = 0.013). Geographically, highest incidence (≥ 2.0 per 100,000 population) occurred in Hokuriku District, with increasing trends in Hokkaido and middle-part of Japan. Estimated fatality rates decreased consistently at 5.9% (95% confidence interval: - 8.1, - 3.5) annually, from 1999 to 2017, with no trend change point. Increasing legionellosis incidence occurred in Japan during 1999-2017, with declining estimated fatality rates. In this aging society and warming world, disease clinical burden may further deteriorate in future due to increasing incidence trends.

Travel Trouble With Legionella in the Era of COVID-19: A Case Report

A 56-year-old male was admitted to the hospital with severe sepsis secondary to pneumonia. His presentation was challenging and confusing due to the accompanying coronavirus disease 2019 (COVID-19) infection attributed to his travel history and diagnosed via radiological findings. He received dexamethasone with ceftriaxone and azithromycin. Despite the fact he was on appropriate antibiotics, his condition worsened, and he was eventually diagnosed with Legionella pneumonia, which was thought to be resistant to macrolides. His condition improved significantly when antibiotics were switched to levofloxacin. It is important to keep in mind other causes of community-acquired pneumonia (CAP) during the ongoing COVID-19 era. What makes this case unique is that it presented a confusing scenario due to the patient's concurrent COVID-19 infection and his failure to improve with the administration of azithromycin.

Health after Legionnaires' disease: A description of hospitalizations up to 5 years after Legionella pneumonia

BACKGROUND AND OBJECTIVES

Research on Legionnaires' Disease (LD) suggests there may be long-term health complications, but data are limited. This study investigated whether Intensive Care Unit (ICU) admission during LD hospitalization may be associated with adverse health outcomes and characterized subsequent discharge diagnoses in patients with LD up to 5 years post-LD.

METHODS

We conducted a retrospective case series study with follow up for 5 years among patients hospitalized at a Department of Veterans Affairs (VA) Medical Center between 2005 and 2010 with LD. Data were collected from medical records on health history, LD severity (including ICU admission), and discharge diagnoses for 5 years post-LD or until death. We used ordinal logistic regression to explore associations between ICU admission and hospitalizations post-LD. Frequency counts were used to determine the most prevalent discharge diagnoses in the 5 years post-LD.

RESULTS

For the 292 patients with laboratory-confirmed LD, those admitted to the ICU during LD hospitalization were more likely to have a greater number of hospitalizations within 5 years compared to non-ICU patients (ORHosp 1.92 CI95% 1.25, 2.95). Fifty-five percent (161/292) had ≥ 1 hospitalization within 5 years post-LD. After accounting for pre-existing diagnosis codes in patients with at least one hospitalization in the 2 years prior to LD (n = 77/161 patients, 47.8%), three of the four most frequent new diagnoses in the 5 years post-LD were non-chronic conditions: acute renal failure (n = 22, 28.6%), acute respiratory failure (n = 17, 22.1%) and unspecified pneumonia (n = 15, 19.5%).

CONCLUSIONS

Our findings indicate that LD requiring ICU admission is associated with more subsequent hospitalizations, a factor that could contribute to poorer future health for people with severe LD. In addition to chronic conditions prevalent in this study population, we found new diagnoses in the 5-year post-LD period including acute renal failure. With LD incidence increasing, more research is needed to understand conditions and factors that influence long term health after LD.

Legionnaire's disease presenting as bilateral central scotomata: a case report

Background

Legionnaire’s disease is one of the major causes of community-acquired pneumonia and is occasionally complicated by neurological symptoms. However, reports of ocular lesions due to Legionnaire’s disease are limited.

Case presentation

We report the case of a patient with Legionnaire’s disease presenting as bilateral central scotomata due to retinal lesions. The patient consulted due to fever and bilateral central scotomata, as well as other extrapulmonary symptoms. Optical coherence tomography (OCT) showed bilateral accumulations of fluid under the retina, and the patient was diagnosed with bilateral exudative retinal detachment. Later, Legionnaire’s disease was confirmed by pulmonary infiltrates on chest imaging and positive urinary antigen for Legionella pneumophila. After administration of antibiotics, the bilateral central scotomata and bilateral subretinal fluid accumulations completely resolved, as did the other extrapulmonary symptoms and the pulmonary infiltrates. Thus, the bilateral central scotomata due to exudative retinal detachment were thought to be caused by Legionnaire’s disease.

Conclusions

This case demonstrates that Legionnaire’s disease can present as bilateral central scotomata. We may consider the possibility of extrapulmonary involvement complicating Legionnaire’s disease when we encounter bilateral ocular lesions in patients with fever and pneumonia.

Legionella and SARS-CoV-2 Coinfection in a Patient With Pneumonia - An Outbreak in Northern Portugal

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has plagued virtually every continent and country, and Portugal is no exception. The high number of cases has caused a major burden on health services and obvious economic consequences, forcing an important reformulation in the health sectors' organization. In the past weeks, counties in the country's northern coastal region have reported an increasing number of Legionella cases, whose origin is yet to be determined. This exacerbates the already important pressure on the region's health facilities. We present a case of a patient diagnosed with Legionella pneumonia and concomitant coronavirus disease 2019 (COVID-19) pneumonia, highlighting the need for etiological investigation not only for common community agents but also for pandemic pathogens and regional outbreaks.

Severe Sepsis With Septic Shock as a Consequence of a Severe Community-Acquired Pneumonia Resulting From a Combined Legionella pneumophila and Streptococcus pneumoniae Infection

Community-acquired pneumonia (CAP) is a frequent cause of intensive care unit (ICU) admission in adults and the sixth leading cause of death worldwide. Although co-infections have been previously reported, the co-existence of Streptococcus pneumoniae and Legionella pneumophila is exceedingly rare. Despite the fact that Streptococcus pneumoniae is the most common etiology in the majority of cases, atypical organisms such as Legionella pneumophila should be considered as etiologic agents among all CAP cases that require hospitalization. Unlike Legionella, extra-pulmonary findings are uncommon in patients with Streptococcus pneumoniae pneumonia. In this report, the authors describe an unusual case of septic shock resulting from a combined Legionella pneumophila and Streptococcus pneumoniae infection associated with rhabdomyolysis, acute kidney injury, acute hypoxemic respiratory failure, pancreatitis, and acute liver injury.

Antibiotic Resistance of Legionella pneumophila in Clinical and Water Isolates-A Systematic Review

The current systematic review investigates the antibiotic susceptibility pattern of Legionella pneumophila isolates from the 1980s to the present day, deriving data from clinical and/or water samples from studies carried out all over the world. Eighty-nine papers meeting the inclusion criteria, i.e., “Legionella pneumophila” and “resistance to antibiotics”, were evaluated according to pre-defined validity criteria. Sixty articles referred to clinical isolates, and 18 articles reported water-related L. pneumophila isolates, while 11 articles included both clinical and water isolates. Several methods have been proposed as suitable for the determination of MICs, such as the E-test, broth and agar dilution, and disk diffusion methods, in vivo and in vitro, using various media. The E-test method proposed by the European Society of Clinical Microbiology and Infectious Diseases (EUCAST) seems to be the second most frequently used method overall, but it is the preferred method in the most recent publications (2000–2019) for the interpretation criteria. Erythromycin has been proved to be the preference for resistance testing over the years. However, in the last 19 years, the antibiotics ciprofloxacin (CIP), erythromycin (ERM), levofloxacin (LEV) and azithromycin (AZM) were the ones that saw an increase in their use. A decrease in the sensitivity to antibiotics was identified in approximately half of the reviewed articles.

In Vitro and Intracellular Activities of Omadacycline against Legionella pneumophila

Omadacycline is an aminomethylcycline antibiotic with in vitro activity against pathogens causing community-acquired bacterial pneumonia (CABP). This study investigated the activity of omadacycline against Legionella pneumophila strains isolated between 1995 and 2014 from nosocomial or community-acquired respiratory infections. Omadacycline exhibited extracellular activity similar to comparator antibiotics; intracellular penetrance was found by day 3 of omadacycline exposure. These results support the utility of omadacycline as an effective antibiotic for the treatment of CABP caused by L. pneumophila.

Persistent Legionella contamination of water faucets in a tertiary hospital in Japan

OBJECTIVE

The feasibility of the decontamination procedure for Legionella pneumophila of water systems in healthcare facilities varies by water purification and disinfection methods in each country. We evaluated the efficacy of feasible decontamination strategies in Japan.

METHODS

This study was conducted at Tokyo Medical University Hospital (1015 beds) between 2015 and 2018. Samples from the water system and cooling tower were cultured periodically. Hyper-chlorination of cool tap water (>0.2 ppm), increases in the temperature of hot water (>55 °C), and flushing were used as decontamination strategies. The case of healthcare-associated legionellosis was surveyed. Environmental and clinical isolates were genotyped.

RESULTS

1439 environmental samples were collected; 19 (1.3%) samples tested positive for L. pneumophila from water faucets of patient rooms, toilets, waste rooms, and water sourced from wells. Genotyping of 12 isolates confirmed that the same strains were present in eight environmental isolates and two isolates from patients over three years. Although the environmental contamination of the water system was persistent, the number of positive locations of hospital environments gradually decreased; eight in 2015, four in 2016, three in 2017, and four in 2018, respectively.

CONCLUSIONS

Monitoring contamination, hyper-chlorination, controlling temperature, and flushing were effective as a Legionella decontamination strategy.

Associations between untraditional risk factors, pneumonia/lung cancer, and hospital fatality among hypertensive men in Guangzhou downtown

Mortality of primary hypertension is high worldwide. Whether untraditional factors exist in modern life and affect the mortality is not well studied. The aim of the study was to evaluate the risk factors for fatality rate of hypertensive men in downtown area. A cross-sectional study was performed on hypertensive men, who were hospitalized into our hospital and lived in eligible urban areas. The characteristics of the patients and factors for the fatality were analyzed and of the risks or the contributors on the status were investigated. 14354 patients were identified. Mean age was 68.9 ± 12.4 year old (y) and dead ones was 75.9 ± 9.5 y. The overall hospitalized fatality was 5.9%, which was increased with age: fatality with 0.7%, 2.2%, 2.9%, 7.1%, 11.1% and 16.6% was for age group ≦ 49 y, 50-59 y, 60-69 y, 70-79 y, 80-89 y and ≧ 90 y respectively. The increased fatality was significantly positively correlated with the incidence of pneumonia, P < 0.05, r = 0.99. Pneumonia was prone to involve in men with older age and severer organ damage by hypertension. Similar to traditional risks such as coronary heart disease and stroke, pneumonia and lung cancer were also significantly associated with the fatality. Odds ratio (95% CI) for pneumonia and lung cancer were 6.18 (4.35-8.78) and 1.55 (1.14-2.11). The study provides evidence that pneumonia and lung cancer are highly associated with fatality of hypertensive men in downtown area, indicating that in order to reduce the fatality of hypertension, these lung diseases should be prevented and treated intensively in modern life.

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.

Estimating the True Burden of Legionnaires' Disease

Over the past decade, the reported incidence of Legionnaires' disease (LD) in the northeastern United States has increased, reaching 1-3 cases per 100,000 population. There is reason to suspect that this is an underestimate of the true burden, since LD cases may be underdiagnosed. In this analysis of pneumonia and influenza (P&I) hospitalizations, we estimated the percentages of cases due to Legionella, influenza, and respiratory syncytial virus (RSV) by age group. We fitted mixed-effects models to estimate attributable percents using weekly time series data on P&I hospitalizations in Connecticut from 2000 to 2014. Model-fitted values were used to calculate estimates of numbers of P&I hospitalizations attributable to Legionella (and influenza and RSV) by age group, season, and year. Our models estimated that 1.9%, 8.8%, and 5.1% of total (all-ages) inpatient P&I hospitalizations could be attributed to Legionella, influenza, and RSV, respectively. Only 10.6% of total predicted LD cases had been clinically diagnosed as LD during the study period. The observed incidence rate of 1.2 cases per 100,000 population was substantially lower than our estimated rate of 11.6 cases per 100,000 population. Our estimates of numbers of P&I hospitalizations attributable to Legionella are comparable to those provided by etiological studies of community-acquired pneumonia and emphasize the potential for underdiagnosis of LD in clinical settings.

Pathogens distribution and drug resistance in patients with acute cerebral infarction complicated with diabetes and nosocomial pulmonary infection

Background

This study aims to investigate the pathogen distribution and drug resistance in patients with acute cerebral infarction complicated with diabetes mellitus and nosocomial pulmonary infection.

Methods

From August 2015 to December 2017, 172 pathogenic bacterial strains from patients with acute cerebral infarction complicated with diabetes mellitus and nosocomial pulmonary infection in our hospital were identified, and the drug sensitivity was analyzed.

Results

Among these 172 strains of pathogenic bacteria, gram negative bacteria was the main cause of pulmonary infection in hospitalized patients with acute cerebral infarction, accounting for 75.6% of all pathogens. Furthermore, 80% of diabetic patients with cerebral infarction had lung infection induced by gram negative bacteria, which was significantly higher than that in non-diabetic patients (72.2%). Moreover, the drug resistance rate in the diabetic group (68.3%) was significantly higher than that in the non-diabetic group (54.3%). Gram positive bacteria accounted for 19.1% of all pathogenic bacteria. The infection rate of gram-positive bacteria in diabetic patients with cerebral infarction was 14.7%, which was lower than that in the non-diabetic group (22.6%). The drug-resistance rate was higher in the diabetic group (45.5%) than in the non-diabetic group (28.2%). Furthermore, the fungal infection rate in patients with lung infection in these two groups was 5.3 and 5.2%, respectively, and fungi presented with high sensitivity to commonly used antifungal agents.

Conclusion

In patients with acute cerebral infarction complicated with diabetes mellitus and nosocomial pulmonary infection, the majority of pathogens are multidrug-resistant gram negative bacilli. Pathogen culture should be conducted as soon as possible before using antibiotics, and antimicrobial agents should be reasonably used according to drug sensitivity test results.

Long-term persistence of infectious Legionella with free-living amoebae in drinking water biofilms

Prolific growth of pathogenic Legionella pneumophila within engineered water systems and premise plumbing, and human exposure to aerosols containing this bacterium results in the leading health burden of any water-related pathogen in developed regions. Ecologically, free-living amoebae (FLA) are an important group of the microbial community that influence biofilm bacterial diversity in the piped-water environment. Using fluorescent microscopy, we studied in-situ the colonization of L. pneumophila in the presence of two water-related FLA species, Willaertia magna and Acanthamoeba polyphaga in drinking water biofilms. During water flow as well as after periods of long-stagnation, the attachment and colonization of L. pneumophila to predeveloped water-biofilm was limited. Furthermore, W. magna and A. polyphaga showed no immediate interactions with L. pneumophila when introduced to the same natural biofilm environment. A. polyphaga encysted within 5-7 d after introduction to the tap-water biofilms and mostly persisted in cysts till the end of the study period (850 d). W. magna trophozoites, however, exhibited a time delay in feeding on Legionella and were observed with internalized L. pneumophila cells after 3 weeks from their introduction to the end of the study period and supported putative (yet limited) intracellular growth. The culturable L.pneumophila in the bulk water was reduced by 2-log over 2 years at room temperature but increased (without a change in mip gene copies by qPCR) when the temperature was elevated to 40 °C within the same closed-loop tap-water system without the addition of nutrients or fresh water. The overall results suggest that L. pneumophila maintains an ecological balance with FLA within the biofilm environment, and higher temperature improve the viability of L. pneumophila cells, and intracellular growth of Legionella is possibly cell-concentration dependent. Observing the preferential feeding behavior, we hypothesize that an initial increase of FLA numbers through feeding on a range of other available bacteria could lead to an enrichment of L. pneumophila, and later force predation of Legionella by the amoeba trophozoites results in rapid intracellular replication, leading to problematic concentration of L. pneumophila in water. In order to find sustainable control options for legionellae and various other saprozoic, amoeba-resisting bacterial pathogens, this work emphasizes the need for better understanding of the FLA feeding behavior and the range of ecological interactions impacting microbial population dynamics within engineered water systems.

Urinary antigen testing in community-acquired pneumonia in adults: an update

INTRODUCTION

Community-acquired pneumonia (CAP) continues to be a leading cause of hospitalization and mortality worldwide. Streptococcus pneumoniae and Legionella pneumophila remain the major etiological agents and are responsible for a significant proportion of CAP mortality. Among diagnostic tests for CAP, urine antigen detection of S. pneumoniae and L. pneumophila is widely accepted due to the simplicity of collection and the rapidity of the test results. Areas covered: This comprehensive review outlines the urinary antigen tests available, discusses their sensitivity and specificity, and assesses the usefulness of their results as the basis for targeted therapy. Expert commentary: There have been advances in urine antigen detection tests for patients with CAP. New methodologies show greater sensitivity, detect S. pneumoniae and L. pneumophila in a single test, and also detect pneumococcal serotypes. In addition, urine antigen detection tests have shown a high specificity, which means that a positive result practically indicates the causative pathogen of CAP. Therefore, a positive result can lead to a targeted therapy that is likely to improve patient outcomes and reduce the risk of resistance and adverse events. However, well-designed studies are needed to evaluate the usefulness of urine antigen detection tests with regard to clinical outcomes.

Atypical pathogens in hospitalized patients with community-acquired pneumonia: a worldwide perspective

BACKGROUND

Empirical antibiotic coverage for atypical pathogens in community-acquired pneumonia (CAP) has long been debated, mainly because of a lack of epidemiological data. We aimed to assess both testing for atypical pathogens and their prevalence in hospitalized patients with CAP worldwide, especially in relation with disease severity.

METHODS

A secondary analysis of the GLIMP database, an international, multicentre, point-prevalence study of adult patients admitted for CAP in 222 hospitals across 6 continents in 2015, was performed. The study evaluated frequency of testing for atypical pathogens, including L. pneumophila, M. pneumoniae, C. pneumoniae, and their prevalence. Risk factors for testing and prevalence for atypical pathogens were assessed through univariate analysis.

RESULTS

Among 3702 CAP patients 1250 (33.8%) underwent at least one test for atypical pathogens. Testing varies greatly among countries and its frequency was higher in Europe than elsewhere (46.0% vs. 12.7%, respectively, p < 0.0001). Detection of L. pneumophila urinary antigen was the most common test performed worldwide (32.0%). Patients with severe CAP were less likely to be tested for both atypical pathogens considered together (30.5% vs. 35.0%, p = 0.009) and specifically for legionellosis (28.3% vs. 33.5%, p = 0.003) than the rest of the population. Similarly, L. pneumophila testing was lower in ICU patients. At least one atypical pathogen was isolated in 62 patients (4.7%), including M. pneumoniae (26/251 patients, 10.3%), L. pneumophila (30/1186 patients, 2.5%), and C. pneumoniae (8/228 patients, 3.5%). Patients with CAP due to atypical pathogens were significantly younger, showed less cardiovascular, renal, and metabolic comorbidities in comparison to adult patients hospitalized due to non-atypical pathogen CAP.

CONCLUSIONS

Testing for atypical pathogens in patients admitted for CAP in poorly standardized in real life and does not mirror atypical prevalence in different settings. Further evidence on the impact of atypical pathogens, expecially in the low-income countries, is needed to guidelines implementation.

Community acquired pneumonia by Legionella pneumophila: Study of 136 cases

OBJECTIVE

Most of the data on Legionella pneumonia in our country come from the Mediterranean area, and there are few studies from the Northwest area. This study tries to assess the situation of this infection in this area.

METHOD

Retrospective study of all patients with positive Legionella antigenuria treated at the University Hospital Lucus Augusti in Lugo (Spain) from 2001, the year in which this test was introduced in our centre, until 2015. We analysed epidemiological data, risk factors, clinical, radiological and biochemical findings, and clinical outcome.

RESULTS

The sampled included 136 patients. When comparing the first five years of the study with the last five, the incidence increased from 10.9 to 64.5 cases/1,000,000; the number of antigenuria requests increased 3.4 times, and compared to other pneumonia aetiologies Legionella increased from 0.9% to 15%. The mean age was 64.1years and 84.6% were males; 74.3% had comorbidities. Males were significantly younger (62.7±16.6 vs 71.9±17.3) and consumed more alcohol (26.1% vs 0%) and tobacco (67.8% vs 14.3%). Diagnosis was established within the first 72hours in 88.9% of cases and most received levofloxacin (95.6%). Hospitalisation was needed in 85% of cases, 11.7% in ICU and 4.4% died.

CONCLUSIONS

After the introduction of antigenuria there was an increase in the incidence of Legionella pneumonia recorded in our health area. Its rate in recent years has been one of the highest in our country. Despite the fact that the patients had advanced age and comorbidities, mortality was low.

Antimicrobial strategy for severe community-acquired legionnaires' disease: a multicentre retrospective observational study

Background

Legionnaires' disease (LD) is an important cause of community-acquired pneumonia with high mortality rates in the most severe cases.

Objectives

To evaluate the effect of antimicrobial strategy on ICU mortality.

Methods

Retrospective, observational study including patients admitted to 10 ICUs for severe community-acquired LD over a 10 year period (2005-15) and receiving an active therapy within 48 h of admission . Patients were stratified according to the antibiotic strategy administered: (i) fluoroquinolone-based versus non-fluoroquinolone-based therapy; and (ii) monotherapy versus combination therapy. The primary endpoint was in-ICU mortality. A multivariable Cox model and propensity score analyses were used.

Results

Two hundred and eleven patients with severe LD were included. A fluoroquinolone-based and a combination therapy were administered to 159 (75%) and 123 (58%) patients, respectively. One hundred and forty-six patients (69%) developed acute respiratory distress syndrome and 54 (26%) died in the ICU. In-ICU mortality was lower in the fluoroquinolone-based than in the non-fluoroquinolone-based group (21% versus 39%, P  =   0.01), and in the combination therapy than in the monotherapy group (20% versus 34%, P  =   0.02). In multivariable analysis, a fluoroquinolone-based therapy, but not a combination therapy, was associated with a reduced risk of mortality [HR = 0.41, 95% CI 0.19-0.89; P  =   0.02].

Conclusions

Patients with severe LD receiving a fluoroquinolone-based antimicrobial regimen in the early course of management had a lower in-ICU mortality, which persisted after adjusting for significant covariates.

Legionella Effector AnkX Disrupts Host Cell Endocytic Recycling in a Phosphocholination-Dependent Manner

The facultative intracellular bacterium Legionella pneumophila proliferates within amoebae and human alveolar macrophages, and it is the causative agent of Legionnaires' disease, a life-threatening pneumonia. Within host cells, L. pneumophila establishes a replicative haven by delivering numerous effector proteins into the host cytosol, many of which target membrane trafficking by manipulating the function of Rab GTPases. The Legionella effector AnkX is a phosphocholine transferase that covalently modifies host Rab1 and Rab35. However, a detailed understanding of the biological consequence of Rab GTPase phosphocholination remains elusive. Here, we broaden the understanding of AnkX function by presenting three lines of evidence that it interferes with host endocytic recycling. First, using immunogold transmission electron microscopy, we determined that GFP-tagged AnkX ectopically produced in mammalian cells localizes at the plasma membrane and tubular membrane compartments, sites consistent with targeting the endocytic recycling pathway. Furthermore, the C-terminal region of AnkX was responsible for association with the plasma membrane, and we determined that this region was also able to bind the phosphoinositide lipids PI(3)P and PI(4)P in vitro. Second, we observed that mCherry-AnkX co-localized with Rab35, a regulator of recycling endocytosis and with major histocompatibility class I protein (MHC-I), a key immunoregulatory protein whose recycling from and back to the plasma membrane is Rab35-dependent. Third, we report that during infection of macrophages, AnkX is responsible for the disruption of endocytic recycling of transferrin, and AnkX's phosphocholination activity is critical for this function. These results support the hypothesis that AnkX targets endocytic recycling during host cell infection. Finally, we have demonstrated that the phosphocholination activity of AnkX is also critical for inhibiting fusion of the Legionella-containing vacuole (LCV) with lysosomes.

Legionnaire's Disease: Cardiac Manifestations

Most cardiac infections with Legionella are secondary to bacteremias arising from a pulmonary focus. Other possible sites of origin are infected sternotomy wounds or equipment contaminated by Legionella spp. Legionella endocarditis is truly a "stealth" infection, with almost no hallmarks of bacterial endocarditis. The key step in making the diagnosis of Legionella endocarditis is for the physician to be aware of the clinical causes of culture-negative infective endocarditis and to include Legionella cardiac involvement in this differential. Many times the issue of endocarditis arises only on examination of resected valvular material.