Fluoroquinolones vs Macrolides in the Treatment of Legionnaires Disease

[Empirical antibiotic therapy in life-threatening infections-current concepts and controversies]

Along with early administration and the selection of the right drug, it is important to consider pharmacokinetic and pharmacodynamic principles, especially in life-threatening infections. Therefore, successful antibiotic therapy requires a clear understanding of the relationship between microbiology, pharmacology, and intensive care medicine. Open and transparent communication among professionals is essential for improving the quality of care. This article discusses current concepts and controversies by presenting a relevant case study of community-acquired pneumonia. It aims to help clinicians select the right drug for each patient, including the correct dose, the appropriate administration, and the right duration of treatment.

Antibiotic Strategies for Severe Community-Acquired Pneumonia

Despite advancements in health systems and intensive care unit (ICU) care, along with the introduction of novel antibiotics and microbiologic techniques, mortality rates in severe community-acquired pneumonia (sCAP) patients have not shown significant improvement. Delayed admission to the ICU is a major risk factor for higher mortality. Apart from choosing the appropriate site of care, prompt and appropriate antibiotic therapy significantly affects the prognosis of sCAP. Treatment regimens involving ceftaroline or ceftobiprole are currently considered the best options for managing patients with sCAP. Additionally, several other molecules, such as delafloxacin, lefamulin, and omadacycline, hold promise as therapeutic strategies for sCAP. This review aims to provide a comprehensive summary of the key challenges in managing adults with severe CAP, focusing on essential aspects related to antibiotic treatment and investigating potential strategies to enhance clinical outcomes in sCAP patients.

Antimicrobial susceptibility profiles and tentative epidemiological cutoff values of Legionella pneumophila from environmental water and soil sources in China

Legionnaires’ disease (LD), caused by Legionella, including the most prevalent Legionella pneumophila, has been treated primarily with antibiotics. Environmental water and soil are the reservoirs for L. pneumophila. Studying antimicrobial susceptibility using a large number of isolates from various environmental sources and regions could provide an unbiased result. In the present study, antimicrobial susceptibility of 1464 environmental L. pneumophila isolates that were derived from various environmental water and soil sources of 12 cities in China to rifampin (RIF), erythromycin (ERY), clarithromycin (CLA), azithromycin (AZI), ciprofloxacin (CIP), moxifloxacin (MOX), levofloxacin (LEV), and doxycycline (DOX) was investigated, and minimum inhibitory concentration (MIC) data were obtained. We show that regarding macrolides, ERY was least active (MIC₉₀ = 0.5 mg/L), while CLA was most active (MIC₉₀ = 0.063 mg/L). A total of three fluoroquinolones have similar MICs on L. pneumophila. Among these antimicrobials, RIF was the most active agent, while DOX was the most inactive one. We observed different susceptibility profiles between serogroup 1 (sg1) and sg2-15 or between water and soil isolates from different regions. The ECOFFs were ERY and AZI (0.5 mg/L), RIF (0.002 mg/L), CIP, CLA and MOX (0.125 mg/L), LEV (0.063 mg/), and DOX (32 mg/L). Overall, two fluoroquinolone-resistant environmental isolates (0.14%) were first documented based on the wild-type MIC distribution. Not all azithromycin-resistant isolates (44/46, 95.65%) harbored the lpeAB efflux pump. The MICs of the ERY and CLA on the lpeAB + isolates were not elevated. These results suggested that the lpeAB efflux pump might be only responsible for AZI resistance, and undiscovered AZI-specific resistant mechanisms exist in L. pneumophila. Based on the big MIC data obtained in the present study, the same defense strategies, particularly against both CLA and RIF, may exist in L. pneumophila. The results determined in our study will guide further research on antimicrobial resistance mechanisms of L. pneumophila and could be used as a reference for setting clinical breakpoints and discovering antimicrobial-resistant isolates in the clinic, contributing to the antibiotic choice in the treatment of LD.

Tenets of a holistic approach to drinking water-associated pathogen research, management, and communication

In recent years, drinking water-associated pathogens that can cause infections in immunocompromised or otherwise susceptible individuals (henceforth referred to as DWPI), sometimes referred to as opportunistic pathogens or opportunistic premise plumbing pathogens, have received considerable attention. DWPI research has largely been conducted by experts focusing on specific microorganisms or within silos of expertise. The resulting mitigation approaches optimized for a single microorganism may have unintended consequences and trade-offs for other DWPI or other interests (e.g., energy costs and conservation). For example, the ecological and epidemiological issues characteristic of Legionella pneumophila diverge from those relevant for Mycobacterium avium and other nontuberculous mycobacteria. Recent advances in understanding DWPI as part of a complex microbial ecosystem inhabiting drinking water systems continues to reveal additional challenges: namely, how can all microorganisms of concern be managed simultaneously? In order to protect public health, we must take a more holistic approach in all aspects of the field, including basic research, monitoring methods, risk-based mitigation techniques, and policy. A holistic approach will (i) target multiple microorganisms simultaneously, (ii) involve experts across several disciplines, and (iii) communicate results across disciplines and more broadly, proactively addressing source water-to-customer system management.

Molecular Methods for Pathogenic Bacteria Detection and Recent Advances in Wastewater Analysis

With increasing concerns about public health and the development of molecular techniques, new detection tools and the combination of existing approaches have increased the abilities of pathogenic bacteria monitoring by exploring new biomarkers, increasing the sensitivity and accuracy of detection, quantification, and analyzing various genes such as functional genes and antimicrobial resistance genes (ARG). Molecular methods are gradually emerging as the most popular detection approach for pathogens, in addition to the conventional culture-based plate enumeration methods. The analysis of pathogens in wastewater and the back-estimation of infections in the community, also known as wastewater-based epidemiology (WBE), is an emerging methodology and has a great potential to supplement current surveillance systems for the monitoring of infectious diseases and the early warning of outbreaks. However, as a complex matrix, wastewater largely challenges the analytical performance of molecular methods. This review synthesized the literature of typical pathogenic bacteria in wastewater, types of biomarkers, molecular methods for bacterial analysis, and their recent advances in wastewater analysis. The advantages and limitation of these molecular methods were evaluated, and their prospects in WBE were discussed to provide insight for future development.

Treatment of legionellosis including a single intravenous dose of 1.5 g azithromycin: 18-year experience at a tertiary care hospital

OBJECTIVES

Due to recent safety concerns regarding fluoroquinolones and the potential medical and economic benefits, we investigated the efficacy of a single intravenous dose of 1.5 g azithromycin for the treatment of pulmonary legionellosis.

METHODS

Using a nationwide legionellosis registry for pre-selection, 74 patients admitted from 2000-2018 to a tertiary care hospital owing to pneumonia caused by Legionella pneumophila were retrospectively included in this study.

RESULTS

Conventional treatment regimens consisting of fluoroquinolones (n = 20), macrolides (n = 30) or combinations of both (n = 24) and a single intravenous dose of azithromycin (n = 12) have been demonstrated to be equally effective. Single-dose azithromycin treatment was well tolerated and resulted in a shorter hospital stay (P = 0.0464) and shorter antibiotic treatment duration (P = 0.0004) allowing earlier discharge.

CONCLUSION

A single intravenous dose of azithromycin might be a valuable treatment alternative for patients with legionellosis.

Epidemiology of Legionnaires' Disease in Italy, 2004-2019: A Summary of Available Evidence

Legionnaires’ disease (LD) incidence has been increasing in several European countries since 2011. Currently, Italy is experiencing high notification rates for LD, whose cause still remains scarcely understood. We sought to summarize the available evidence on the epidemiology of LD in Italy (2004–2019), characterizing the risk of LD by region, sex, age group, and settings of the case (i.e., community, healthcare, or travel-associated cases). Environmental factors (e.g., average air temperatures and relative humidity) were also included in a Poisson regression model in order to assess their potential role on the annual incidence of new LD cases. National surveillance data included a total of 23,554 LD cases occurring between 2004 and 2019 (70.4% of them were of male gender, 94.1% were aged 40 years and older), with age-adjusted incidence rates increasing from 1.053 cases per 100,000 in 2004 to 4.559 per 100,000 in 2019. The majority of incident cases came from northern Italy (43.2% from northwestern Italy, 25.6% from northeastern Italy). Of these, 5.9% were healthcare-related, and 21.1% were travel-associated. A case-fatality ratio of 5.2% was calculated for the whole of the assessed timeframe, with a pooled estimate for mortality of 0.122 events per 100,000 population per year. Poisson regression analysis was associated with conflicting results, as any increase in average air temperature resulted in reduced risk for LD cases (Incidence Rate Ratio [IRR] 0.807, 95% Confidence Interval [95% CI] 0.744–0.874), while higher annual income in older individuals was associated with an increased IRR (1.238, 95% CI 1.134–1.351). The relative differences in incidence between Italian regions could not be explained by demographic factors (i.e., age and sex distribution of the population), and also a critical reappraisal of environmental factors failed to substantiate both the varying incidence across the country and the decennial trend we were able to identify.

[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.

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.

Disseminated Legionella micdadei infection in a liver transplant patient presenting as pulmonary nodules and a laryngeal lesion

We report a liver transplant patient with disseminated Legionella micdadei infection with pulmonary, laryngeal, and suspected muscle involvement. This organism, which stains weakly acid-fast, primarily affects immunocompromised patients. The diagnosis is difficult to make; in this case, the organism was identified via molecular diagnostics on laryngeal and pulmonary biopsy tissue.

Meta-analysis of fluoroquinolones versus macrolides for treatment of legionella pneumonia

BACKGROUND

Only a single meta-analysis has reported the clinical benefit of fluoroquinolones (FQs) for Legionella pneumonia; however, there is no robust data available to confirm this result, based on current guidelines.

METHODS

We performed a systematic review and meta-analysis comparing FQs with macrolides (MCs) on their efficacy and safety in Legionella pneumonia, using studies published until January 2020. The outcomes included mortality (overall; 30-day), clinical cure, time to apyrexia, length of hospital stay, and adverse events.

RESULTS

Five RCTs and twelve retrospective studies were identified. Clinical cure was comparable between the treatment groups (risk rate (RR) 1.07, 95% confidential interval (CI) 0.86-1.31). Mortality was significantly higher for MCs than for FQs (overall, odd rate (OR) 0.59, 95% CI 0.35-0.98; 30-day, OR 0.41, 95% CI 0.20-0.85). FQs significantly reduced the length of hospital stay, compared to MCs (mean difference -3.58, 95% CI -5.48-1.69). Other outcomes were not significantly different between the treatment groups (time to apyrexia; mean difference -1.83, 95% CI -5.15-1.5, adverse events; OR 0.61, 95% CI 0.33-1.15). In subgroup analyses, levofloxacin significantly reduced the length of hospital stay over two specific MCs (azithromycin and clarithromycin) (mean difference -3.03, 95% CI -5.33-0.72), whereas mortality was not significantly different between the treatment groups (overall, OR 0.49, 95% CI 0.19-1.24; 30-day, OR 0.38, 95% CI 0.13-1.13).

CONCLUSIONS

FQs exhibited superior effects in terms of mortality and length of hospital stay in Legionella pneumonia. These results support current guidelines recommending FQs for the treatment of Legionella pneumonia.

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.

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.

Pharmacotherapy of Lower Respiratory Tract Infections in Elderly-Focused on Antibiotics

Lower respiratory tract infections (LRTIs) refer to the inflammation of the trachea, bronchi, bronchioles, and lung tissue. Old people have an increased risk of developing LRTIs compared to young adults. The prevalence of LRTIs in the elderly population is not only related to underlying diseases and aging itself, but also to a variety of clinical issues, such as history of hospitalization, previous antibacterial therapy, mechanical ventilation, antibiotic resistance. These factors mentioned above have led to an increase in the prevalence and mortality of LRTIs in the elderly, and new medical strategies targeting LRTIs in this population are urgently needed. After a systematic review of the current randomized controlled trials and related studies, we recommend novel pharmacotherapies that demonstrate advantages for the management of LRTIs in people over the age of 65. We also briefly reviewed current medications for respiratory communicable diseases in the elderly. Various sources of information were used to ensure all relevant studies were included. We searched Pubmed, MEDLINE (OvidSP), EMBASE (OvidSP), and ClinicalTrials.gov. Strengths and limitations of these drugs were evaluated based on whether they have novelty of mechanism, favorable pharmacokinetic/pharmacodynamic profiles, avoidance of interactions and intolerance, simplicity of dosing, and their ability to cope with challenges which was mainly evaluated by the primary and secondary endpoints. The purpose of this review is to recommend the most promising antibiotics for treatment of LRTIs in the elderly (both in hospital and in the outpatient setting) based on the existing results of clinical studies with the novel antibiotics, and to briefly review current medications for respiratory communicable diseases in the elderly, aiming to a better management of LRTIs in clinical practice.

Antimicrobial agent susceptibilities of Legionella pneumophila MLVA-8 genotypes

Legionella pneumophila causes human lung infections resulting in severe pneumonia. High-resolution genotyping of L. pneumophila isolates can be achieved by multiple-locus variable-number tandem-repeat analysis (MLVA-8). Legionella infections in humans occur as a result of inhalation of bacteria-containing aerosols, thus, our aim was to study the antimicrobial susceptibilities of different MLVA-8 genotypes to ten commonly used antimicrobial agents in legionellosis therapy. Epidemiological cut-off values were determined for all antibiotics. Significant differences were found between the antimicrobial agents' susceptibilities of the three studied environmental genotypes (Gt4, Gt6, and Gt15). Each genotype exhibited a significantly different susceptibility profile, with Gt4 strains (Sequence Type 1) significantly more resistant towards most studied antimicrobial agents. In contrast, Gt6 strains (also Sequence Type 1) were more susceptible to six of the ten studied antimicrobial agents compared to the other genotypes. Our findings show that environmental strains isolated from adjacent points of the same water system, exhibit distinct antimicrobial resistance profiles. These differences highlight the importance of susceptibility testing of Legionella strains. In Israel, the most extensively used macrolide for pneumonia is azithromycin. Our results point at the fact that clarithromycin (another macrolide) and trimethoprim with sulfamethoxazole (SXT) were the most effective antimicrobial agents towards L. pneumophila strains. Moreover, legionellosis can be caused by multiple L. pneumophila genotypes, thus, the treatment approach should be the use of combined antibiotic therapy. Further studies are needed to evaluate specific antimicrobial combinations for legionellosis therapy.

Recommendations and guidelines for the treatment of pneumonia in Taiwan

Pneumonia is a leading cause of death worldwide, ranking third both globally and in Taiwan. This guideline was prepared by the 2017 Guidelines Recommendations for Evidence-based Antimicrobial agents use in Taiwan (GREAT) working group, formed under the auspices of the Infectious Diseases Society of Taiwan (IDST). A consensus meeting was held jointly by the IDST, Taiwan Society of Pulmonary and Critical Care Medicine (TSPCCM), the Medical Foundation in Memory of Dr. Deh-Lin Cheng, the Foundation of Professor Wei-Chuan Hsieh for Infectious Diseases Research and Education and CY Lee's Research Foundation for Pediatric Infectious Diseases and Vaccines. The final guideline was endorsed by the IDST and TSPCCM. The major differences between this guideline and the 2007 version include the following: the use of GRADE methodology for the evaluation of available evidence whenever applicable, the specific inclusion of healthcare-associated pneumonia as a category due to the unique medical system in Taiwan and inclusion of recommendations for treatment of pediatric pneumonia. This guideline includes the epidemiology and recommendations of antimicrobial treatment of community-acquired pneumonia, hospital-acquired pneumonia, ventilator-associated pneumonia, healthcare-associated pneumonia in adults and pediatric pneumonia.

Environmental surveillance and in vitro activity of antimicrobial agents against Legionella pneumophila isolated from hospital water systems in Campania, South Italy: a 5-year study

BACKGROUND

Legionellosis' treatment failures have been recently reported showing the possibility of resistance development to traditional therapy, especially in healthcare related disease cases. Environmental impact of antibiotic residues, especially in hospital waters, may act on the resistome of Legionella resulting in developing resistance mechanisms.

OBJECTIVES

In this study we investigate the antibiotic susceptibility of environmental Legionella pneumophila (Lpn) strains isolated from hospital water systems in Campania, a region located in Southwest Italy.

METHODS

5321 hospital water samples were investigated for the presence of Lpn. Among positive samples, antibiotic susceptibility was tested for a random subset of 125 Lpn strains (25 Lpn isolates from each of the following serogroups: 1, 3, 5, 6, 8). Susceptibility testing was performed, using the E-test on buffered charcoal yeast extract agar supplemented with α-ketoglutarate, for 10 antimicrobial drugs: azithromycin, cefotaxime, clarithromycin, doxycycline, erythromycin, rifampicin, tigecycline, ciprofloxacin, levofloxacin and moxifloxacin. Non parametric tests were used to determine and assess the significant differences in susceptibility to the different antimicrobics between the serogroups.

RESULTS

Among the isolated strains, none showed resistance to the antibiotics tested. Rifampicin was the most active antibiotic against overall Legionella strains, followed by levofloxacin. Between the macrolides the clarithromycin was overall the most active drug, instead the azithromycin was the less active. Analyzing the different serogroups a significant difference was found between serogroup 1 and non-1 serogroup isolates for doxycycline and tigecycline.

CONCLUSIONS

Antibiotic susceptibility of environmental isolates of Legionella spp. might be useful for the early detection of resistance to antibiotics that directly impacts on mortality and length of hospital stay.

Bacterial pneumonia in kidney transplant recipients

Bacterial pathogens are the most frequent cause of pneumonia after transplantation. Early after transplantation, recipients are at higher risk for nosocomial infections. The most commonly encountered pathogens during this period are gram-negative bacilli (Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa …), but gram-positive coccus such as Staphylococcus aureus or Streptococcus pneumoniae and anaerobic bacteria can also be found. Empirical antibiotic therapy should be guided by previous colonisation of the recipient and bacterial resistance pattern in the hospital. Six months after transplantation, pneumonias are mostly due to community-acquired bacteria (S. pneumonia, H. influenza, Mycoplasma, Chlamydia and others). Opportunistic pathogens take advantage of the state of immunosuppression which is usually highest from one to six months after transplantation. During this period, but also occurring many years later in the setting of a chronically depressed immune system, bacterial pathogens with low intrinsic virulence can cause pneumonia. The diagnosis of pneumonia caused by opportunistic pathogens can be challenging. The delay in diagnosis preventing the early instauration of adequate treatment in kidney transplant recipients with a depressed immune system, frequently coupled with co-morbid conditions and a state of frailty, will affect prognosis and outcome, increasing morbidity and mortality. This review will focus on the most common opportunistic bacterial pathogens causing pneumonia in kidney transplant recipients: Legionella, Nocardia, Mycobacterium tuberculosis/nontuberculous, and Rhodococcus. Recognition of their specificities in the setting of immunosuppression will allow early diagnosis, crucial for initiation of effective therapy and successful outcome. Interactions with immunosuppressive therapy should be considered as well as reducing immunosuppression if necessary.

In vitro activity of various antibiotics against clinical strains of Legionella species isolated in Japan

The activities of various antibiotics against 58 clinical isolates of Legionella species were evaluated using two methods, extracellular activity (minimum inhibitory concentration [MIC]) and intracellular activity. Susceptibility testing was performed using BSYEα agar. The minimum extracellular concentration inhibiting intracellular multiplication (MIEC) was determined using a human monocyte-derived cell line, THP-1. The most potent drugs in terms of MICs against clinical isolates were levofloxacin, garenoxacin, and rifampicin with MIC₉₀ values of 0.015 μg/ml. The activities of ciprofloxacin, pazufloxacin, moxifloxacin, clarithromycin, and azithromycin were slightly higher than those of levofloxacin, garenoxacin, and rifampicin with an MIC₉₀ of 0.03-0.06 μg/ml. Minocycline showed the highest activity, with an MIC₉₀ of 1 μg/ml. No resistance against the antibiotics tested was detected. No difference was detected in the MIC distributions of the antibiotics tested between L. pneumophila serogroup 1 and L. pneumophila non-serogroup 1. The MIECs of ciprofloxacin, pazufloxacin, levofloxacin, moxifloxacin, garenoxacin, clarithromycin, and azithromycin were almost the same as their MICs, with MIEC₉₀ values of 0.015-0.06 μg/ml, although the MIEC of minocycline was relatively lower and that of rifampicin was higher than their respective MICs. No difference was detected in the MIEC distributions of the antibiotics tested between L. pneumophila serogroup 1 and L. pneumophila non-serogroup 1. The ratios of MIEC:MIC for rifampicin (8) and pazufloxacin (2) were higher than those for levofloxacin (1), ciprofloxacin (1), moxifloxacin (1), garenoxacin (1), clarithromycin (1), and azithromycin (1). Our study showed that quinolones and macrolides had potent antimicrobial activity against both extracellular and intracellular Legionella species. The present data suggested the possible efficacy of these drugs in treatment of Legionella infections.

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.

Clinical Utility of Testing for Legionella Pneumonia in Central Texas

RATIONALE

Legionella pneumophila is an uncommon cause of community-acquired pneumonia in the south central region of the United States, and regular testing may not be cost effective in areas of low incidence.

OBJECTIVES

To evaluate the incidence of Legionella in central Texas and to determine the cost effectiveness of Legionella urinary antigen testing.

METHODS

We performed a single-center retrospective cohort study of patients admitted with pneumonia between January 2001 and December 2013. Patients were identified by Binax Legionella urinary antigen and International Classification of Disease, Ninth Revision codes. Demographic characteristics and clinical history of the confirmed Legionella pneumonia cases were obtained by chart review. Descriptive statistics were used to describe patient characteristics.

MEASUREMENTS AND MAIN RESULTS

Over 12 years, 5,807 patients with 11,377 admissions for pneumonia were tested for Legionella urinary antigen. A positive Legionella urinary antigen was found in 17 patients. Cumulative incidence during the study period was 0.23%. Among the Legionella-positive patients, intensive care unit admission and median length of stay were 58.8% and 8.5 days, respectively. Most patients (64.7%) met American Thoracic Society criteria for severe pneumonia. All patients empirically received either a macrolide or fluoroquinolone covering Legionella. There were two in-hospital and three total 90-day deaths in those with a positive urinary antigen. The estimated cost of screening this population with Legionella urinary antigen was $214,438 over 13 years.

CONCLUSIONS

This study reveals the low incidence of Legionella pneumonia in central Texas. Use of guideline-concordant antibiotic treatment provides coverage for Legionella. We speculate that testing in a low-prevalence area would not influence outcomes or be cost effective.

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.

Levofloxacin versus azithromycin for treating legionella pneumonia: a propensity score analysis

OBJECTIVES

Concerns have arisen regarding the equivalence of levofloxacin and some macrolides for treating community-acquired legionella pneumonia (LP). We aimed to compare the outcomes of current patients with LP treated with levofloxacin, azithromycin and clarithromycin.

METHODS

Observational retrospective multicentre study of consecutive patients with LP requiring hospitalization (2000-2014) conducted in two hospitals. The primary outcome assessed was 30-day mortality. To control for confounding, therapy was assessed by multivariate analysis.

RESULTS

We documented 446 patients with LP, of which 175 were treated with levofloxacin, 177 with azithromycin and 58 with clarithromycin. No significant differences in time to defervescence (2 (interquartile range (IQR) 1-4) versus 2 (IQR 1-3) days; p 0.453), time to achieve clinical stability (3 (2-5) versus 3 (2-5) days; p 0.486), length of intravenous therapy (3 (2-5.25) versus 4 (3-6) days; p 0.058) and length of hospital stay (7 (5-10) versus 6 (5-9) days; p 0.088) were found between patients treated with levofloxacin and those treated with azithromycin. Patients treated with clarithromycin had longer intravenous antibiotic treatment (3 (2-5.25) versus 5 (3-6.25) days; p 0.002) and longer hospital stay (7 (5-10) versus 9 (7-14) days; p 0.043) compared with those treated with levofloxacin. The overall mortality was 4.3% (19 patients). Neither univariate nor multivariate analysis showed a significant association of levofloxacin versus azithromycin on mortality (4 (2.3%) versus 9 (5.1%) deaths; p 0.164). The results did not change after incorporation of the propensity score into the models.

CONCLUSIONS

In our study, no significant differences in most outcomes were found between patients treated with levofloxacin and those treated with azithromycin. Due to the small number of deaths, results regarding mortality should be interpreted with caution.

Severe Pneumonia Caused by Legionella pneumophila: Differential Diagnosis and Therapeutic Considerations

Severe legionella pneumonia poses a diagnostic challenge and requires early intervention. Legionnaire's disease can have several presenting signs, symptoms, and laboratory abnormalities that suggest that Legionella pneumophila is the pathogen, but none of these are sufficient to distinguish L pneumophila pneumonia from other respiratory pathogens. L pneumophila is primarily an intracellular pathogen and needs treatment with antibiotics that efficiently enter the intracellular space.

Atypical Pneumonia: Updates on Legionella, Chlamydophila, and Mycoplasma Pneumonia

Community-acquired pneumonia (CAP) has multiple causes and is associated with illness that requires admission to the hospital and mortality. The causes of atypical CAP include Legionella species, Chlamydophila, and Mycoplasma. Atypical CAP remains a diagnostic challenge and, therefore, likely is undertreated. This article reviews the advancements in the evaluation and treatment of patients and discusses current conflicts and controversies of atypical CAP.

Antibiotic susceptibility of Legionella strains isolated from public water sources in Macau and Guangzhou

The purpose of this study was to investigate the susceptibility of waterborne strains of Legionella to eight antimicrobials commonly used in legionellosis therapy. The minimum inhibitory concentrations (MICs) of 66 environmental Legionella strains, isolated from fountains and cooling towers of public facilities (hotels, schools, and shopping malls) in Macau and Guangzhou, were tested using the microdilution method in buffered yeast extract broth. The MIC₅₀/MIC₉₀ values for erythromycin, cefotaxime (CTX), doxycycline (DOC), minocycline (MIN), azithromycin, ciprofloxacin, levofloxacin (LEV), and moxifloxacin were 0.125/0.5 mg/L, 4/8 mg/L, 8/16 mg/L, 4/8 mg/L, 0.125/0.5 mg/L, 0.031/0.031 mg/L, 0.031/0.031 mg/L, and 0.031/0.062 mg/L, respectively. Legionella isolates were inhibited by either low concentrations of macrolides and fluoroquinolones, or high concentrations of CTX and tetracycline drugs. LEV was the most effective drug against different Legionella species and serogroups of L. pneumophila isolates. The latter were inhibited in decreasing order by MIN > CTX >DOC, while non-L. pneumophila isolates were inhibited by CTX> MIN >DOC. In this study, we evaluated drug resistance of pathogenic bacteria from the environment. This may help predict the emergence of drug resistance, improve patient outcomes, and reduce hospitalization costs.

Precision medicine for the treatment of severe pneumonia in intensive care

Despite advances in its management, community-acquired pneumonia (CAP) remains the most important cause of sepsis-related mortality and the reason for many ICU admissions. Severity assessment is the cornerstone of CAP patient management and the attempts to ensure the best site of care and therapy. Survival depends on a combination of host factors (genetic, age, comorbidities, defenses), pathogens (virulence, serotypes) and drugs. To reduce CAP mortality, early adequate antibiotic therapy is fundamental. The use of combination therapy with a macrolide seems to improve the clinical outcome in the subset of patients with high inflammation due to immunomodulation. Guidelines on antibiotic therapy have been associated with beneficial effects, and studies of newer adjunctive drugs have produced promising results. This paper discusses the current state of knowledge regarding of precision medicine and the treatment of severe CAP patients.

Legionellosis in Transplantation

Legionella species are emerging opportunistic pathogens in hematopoietic stem cell and solid organ transplant recipients, associated with significant morbidity and mortality. The clinical and radiological features of Legionella infections can mimic other opportunistic pathogens in these profoundly immunocompromised patients. Diagnosis in transplant patients is challenging as non-pneumophila Legionella infections, for which these patients are at risk, cannot be identified using the urinary antigen test. Changes in management of transplant recipients and changes in Legionella epidemiology suggest that the number of transplant patients potentially exposed to Legionella spp. may be on the rise. Yet, evidence-based, transplant-specific guidelines for managing and preventing Legionella infections are not currently available. In this article, we review the epidemiology, clinical features, diagnostic challenges, treatment options, and preventive strategies of Legionella infections in these high-risk patient populations.

Diagnostic Accuracy of PCR Alone and Compared to Urinary Antigen Testing for Detection of Legionella spp.: a Systematic Review

The diagnosis of Legionnaires' disease (LD) is based on the isolation of Legionella spp., a 4-fold rise in antibodies, a positive urinary antigen (UA), or direct immunofluorescence tests. PCR is not accepted as a diagnostic tool for LD. This systematic review assesses the diagnostic accuracy of PCR in various clinical samples with a direct comparison versus UA. We included prospective or retrospective cohort and case-control studies. Studies were included if they used the Centers for Disease Control and Prevention consensus definition criteria of LD or a similar one, assessed only patients with clinical pneumonia, and reported data for all true-positive, false-positive, true-negative, and false-negative results. Two reviewers abstracted data independently. Risk of bias was assessed using Quadas-2. Summary sensitivity and specificity values were estimated using a bivariate model and reported with a 95% confidence interval (CI). Thirty-eight studies were included. A total of 653 patients had confirmed LD, and 3,593 patients had pneumonia due to other pathogens. The methodological quality of the studies as assessed by the Quadas-2 tool was poor to fair. The summary sensitivity and specificity values for diagnosis of LD in respiratory samples were 97.4% (95% CI, 91.1% to 99.2%) and 98.6% (95% CI, 97.4% to 99.3%), respectively. These results were mainly unchanged by any covariates tested and subgroup analysis. The diagnostic performance of PCR in respiratory samples was much better than that of UA. Compared to UA, PCR in respiratory samples (especially in sputum samples or swabs) revealed a significant advantage in sensitivity and an additional diagnosis of 18% to 30% of LD cases. The diagnostic performance of PCR in respiratory samples was excellent and preferable to that of the UA. Results were independent on the covariate tested. PCR in respiratory samples should be regarded as a valid tool for the diagnosis of LD.

Antibiotic susceptibility of Legionella pneumophila strains isolated from hospital water systems in Southern Italy

OBJECTIVES

The purpose of this study was to describe the susceptibility of environmental strains of Legionella spp. to 10 antimicrobials commonly used for legionellosis therapy. A study of environmental strains could be useful to timely predict the onset of antibiotic resistance in the environment before it is evidenced in clinical specimens.

METHODS

The minimum inhibitory concentrations (MICs) of 100 environmental Legionella pneumophila (Lpn) strains belonging to serogroups (sgs) 1, 6, 8, and 10 were tested using the E-test methodology on buffered charcoal yeast extract agar supplemented with α-ketoglutarate. The most frequent sgs were selected from those obtained during microbiological surveillance conducted in 2014 in a hospital in Southern Italy. The MICs were read after 2 days of incubation at 35 °C in a humidified atmosphere without CO2.

RESULTS

All isolates were inhibited by low concentrations of fluoroquinolones and macrolides. Rifampicin was the most active drug against the isolates in vitro. All Lpn isolates were inhibited by the following drugs (in decreasing order of their MICs): doxycycline>tigecycline>cefotaxime. The MICs of azithromycin, ciprofloxacin, levofloxacin, moxifloxacin, and tigecycline were significantly lower for Lpn non-sg 1 than Lpn sg 1 isolates.

CONCLUSIONS

Susceptibility testing of Legionella strains to appropriate antibiotics should be performed often to evaluate the possible emergence of resistance, to improve the outcomes of patients, and to reduce the direct costs associated with hospitalization.

The association of antibiotic treatment regimen and hospital mortality in patients hospitalized with Legionella pneumonia

BACKGROUND

Guidelines recommend azithromycin or a quinolone antibiotic for treatment of Legionella pneumonia. No clinical study has compared these strategies.

METHODS

We performed a retrospective cohort analysis of adults hospitalized in the United States with a diagnosis of Legionella pneumonia in the Premier Perspectives database (1 July 2008-30 June 2013). Our primary outcome was hospital mortality; we additionally evaluated hospital length of stay, development of Clostridium difficile colitis, and total hospital cost. We used propensity-based matching to compare patients treated with azithromycin vs a quinolone. All analyses were repeated on a subgroup of more severely ill patients, defined as requiring intensive care unit admission or mechanical ventilation or having a predicted probability of hospital mortality in the top quartile for all patients.

RESULTS

Legionella pneumonia was diagnosed in 3152 adults across 437 hospitals. Quinolones alone were used in 28.8%, azithromycin alone was used in 34.0%, and 1.8% received both. Crude hospital mortality was similar: 6.6% (95% confidence interval [CI], 5.0%-8.2%) for quinolones vs 6.4% (95% CI, 5.0%-7.9%) for azithromycin (P = .87); after propensity matching (n = 813 in each group), mortality remained similar (6.3% [95% CI, 4.6%-7.9%] vs 6.5% [95% CI, 4.8%-8.2%], P = .84 for the whole cohort, and 14.9% [95% CI, 10.0%-19.8%] vs 18.3% [95% CI, 13.0%-23.6%], P = .36 for the more severely ill). There was no difference in hospital length of stay, development of C. difficile, or total hospital cost.

CONCLUSIONS

Use of azithromycin alone or a quinolone alone for treatment of Legionella pneumonia was associated with similar hospital mortality. Few patients receive combination therapy.

[Resistance to fluoroquinolones in 2013: what are the consequences in internal medicine?]

Because of their important qualities, fluoroquinolones are amongst the most prescribed antibiotics in the world. The corollary of this success is the rapid increase in resistance to fluoroquinolones, responsible for treatment failures. Moreover, fluoroquinolone-resistance is often accompanied by resistance to other classes of antibiotics. Currently, significant levels of resistance are found both in hospitals and in community settings, severely limiting possibilities for empirical use of fluoroquinolones. A major mechanism explaining the rapid emergence of resistance to fluoroquinolones is their specific impact on human microbiota and the selection of resistant strains in the microbiota, which seems to be an unavoidable ecological side effect. In order to preserve the efficiency of this important class of antibiotics, limiting their use and respecting good practice recommendations are essential.

Quinolones versus macrolides in the treatment of legionellosis: a systematic review and meta-analysis

BACKGROUND

Legionellosis is a life-threatening disease. The clinical superiority of quinolones or macrolides for treating patients with legionellosis has not been established.

METHODS

We performed a systematic review and meta-analysis of studies reporting data that allowed the comparison of quinolones versus macrolides in the treatment of proven legionellosis published from 1 January 1985 to 31 January 2013. We collected baseline aggregate patient characteristics. Studied outcomes included mortality, clinical cure, time to apyrexia, length of hospital stay and occurrence of complications in each treatment group. Treatment effect was assessed using a Mantel-Haenszel random effects model.

RESULTS

Among 1005 abstracts reviewed, 12 studies were selected (n=879 patients). No randomized controlled trial was performed directly comparing quinolone and macrolide efficacy in legionellosis. Mean age was 58.3 years, 27.7% were women and Fine score was ≥ 4 in 35.8%. Among 253 patients who received quinolone monotherapy, 10 died (4.0%). Among 211 patients who received macrolide monotherapy, 23 died (10.9%). The pooled OR of death for treatment with a quinolone versus a macrolide was 0.5 (95% CI 0.2-1.3, n=8 studies, 464 patients). Length of stay was significantly shorter in the quinolone monotherapy group. The difference was 3.0 days (95% CI 0.7-5.3, P=0.001, n=3 studies, 263 patients). Neither of two tests for heterogeneity was significant (I (2)=0% for both, P=1). Other studied outcomes were not significantly different among treatment groups.

CONCLUSIONS

Few clinical data on legionellosis treatment are available. This first meta-analysis showed a trend toward a lower mortality rate and a significant decrease in length of hospital stay among patients receiving quinolones. These results must be confirmed by a randomized controlled trial.

Urine antigen tests for the diagnosis of respiratory infections: legionellosis, histoplasmosis, pneumococcal pneumonia

Urinary antigen testing has grown in popularity for several significant respiratory infections, particularly Legionella pneumophila, Streptococcus pneumoniae, and Histoplasma capsulatum. By capitalizing on the concentration of shed antigen from a variety of pathogens in the kidneys for excretion in the urine, urinary antigen testing can be used to obtain rapid test results related to respiratory infection, independent of an invasive collection such as a bronchoalveolar lavage. This article describes the 3 aforementioned organisms, their role in respiratory disease, and the current status of urinary antigen testing in their respective diagnosis.

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.

Antimicrobial activity of solithromycin against clinical isolates of Legionella pneumophila serogroup 1

The activity of solithromycin was evaluated against clinical Legionella pneumophila serogroup 1 (Lp1) isolates (n = 196) collected in Ontario, Canada, from 1980 to 2011. Its in vitro activity was compared to that of azithromycin (AZM) using the broth microdilution method. Solithromycin had a MIC50 of ≤0.015 μg/ml and a MIC90 of 0.031 μg/ml, making its activity at least 8-fold to 32-fold higher than that of AZM (MIC50 and MIC90, 0.125 μg/ml and 1 μg/ml, respectively). Ninety-nine percent of the isolates had MICs for solithromycin ranging from ≤0.015 μg/ml to 0.031 μg/ml, whereas 83.6% of the isolates showed MICs for AZM ranging from 0.062 μg/ml to 0.25 μg/ml. Interestingly, 96.7% (30 out of 31 clinical isolates) identified with higher AZM MICs (0.5 μg/ml to 2 μg/ml) belonged to the clinically prevalent sequence type 1. To investigate the intracellular activity of solithromycin, in vitro invasion assays were also performed against a subset of representative Lp1 isolates internalized within human lung epithelial cells. Solithromycin and AZM both inhibited growth of all intracellular Lp1 isolates at 1× or 8× MICs, displaying bacteriostatic effects, as would be expected with protein synthesis inhibitor rather than bactericidal activity. Solithromycin demonstrated the highest in vitro and intracellular potency against all Lp1 isolates compared to AZM. Given the rapid spread of resistance mechanisms among respiratory pathogens and the reported treatment failures in legionellosis, the development of this new fluoroketolide, already in phase 3 oral clinical studies, constitutes a promising alternative option for the treatment of legionellosis.