Treatment strategies for Legionella infection

Epidemiological analysis of Legionella pneumonia in Japan: A national inpatient database study

BACKGROUND

Legionella pneumonia, a severe form of pneumonia, is caused by Legionella bacteria. The epidemiology of Legionnaires' disease in Japan, including seasonal trends, risk factors for severe disease, and fatality rates, is unclear. This study examined the epidemiology of Legionella pneumonia in Japan.

METHODS

This retrospective cohort study included data of adult patients hospitalized for Legionella pneumonia (identified using the ICD-10 code, A481) in the Japanese Diagnosis Procedure Combination inpatient database, from April 2011 to March 2021. We performed multivariable logistic regression analysis to explore the prognostic factors of in-hospital mortality.

RESULTS

Of 7370 enrolled hospitalized patients from 1140 hospitals (male, 84.4%; aged >50 years, 87.9%), 469 (6.4%) died during hospitalization. The number of hospitalized patients increased yearly, from 658 in 2016 to 975 in 2020. Multivariable logistic regression analysis revealed that higher in-hospital mortality was associated with older age, male sex, lower body mass index, worsened level of consciousness, comorbidities (congestive heart failure, chronic renal diseases, and metastasis), hospitalization from November to May, and ambulance use. However, lower in-hospital mortality was associated with comorbidity (liver diseases), hospitalization after 2013, and hospitalization in hospitals with higher case volume.

CONCLUSIONS

The characterized epidemiology of Legionella pneumonia in Japan revealed a high mortality rate of 6.4%. To the best of our knowledge, this is the first study to demonstrate a higher mortality rate in winter and in patients with congestive heart failure and metastasis. Further research is needed to understand the complex interplay between the prognostic factors of Legionella pneumonia.

Recommendations on off-label use of intravenous azithromycin in children

OBJECTIVE

Intravenous azithromycin (AZM) has been widely used in children worldwide, but there still remains much concern regarding its off-label use, which urgently needs to be regulated. Therefore, we developed a rapid advice guideline in China to give recommendations of rational use of intravenous AZM in children.

METHODS

This guideline focuses on antimicrobial therapy with intravenous AZM in children. The Delphi research method was used to select questions. A systematic literature review was also conducted. Data were pooled and ranked according to the GRADE system. Recommendations were developed based on expert clinical experience, patients' values and preferences, and evidence availability. After an external review, the recommendations were revised and approved.

RESULTS

This guideline included eighteen recommendations that covered four domains: (a) Indications: the treatment of pneumonia caused by atypical but common pathogens, such as Mycoplasma pneumoniae, Chlamydia trachomatis or Chlamydophila pneumoniae and Legionella pneumophila, more typical bacteria as well as the treatment of bronchitis of presumed bacterial aetiologies; (b) Usage and dosage: administration route, infusion concentrations, treatment duration, course of sequential treatment, and dosage stratified by age; (c) Adverse reactions and treatment: the management of gastrointestinal reactions, arrhythmias, pain or phlebitis at the infusion site, and anaphylaxis; and (d) Special population: children with renal or liver dysfunction, congenital heart disease, and obesity. This guideline will hopefully help promote a rational use of intravenous AZM in children worldwide.

CONCLUSION

This guideline has summarised the evidence and has developed recommendations on the use of intravenous AZM in children worldwide. Further attention and well-designed researches should be conducted on the off-label use of intravenous AZM in children.

Legionella antimicrobial sensitivity testing: comparison of microbroth dilution with BCYE and LASARUS solid media

OBJECTIVES

There is a lack of international unification for AST methodology for Legionella pneumophila. Current literature contains multiple possible methods and this study compares each of them to determine methodological concordance.

METHODS

Antibiotic susceptibility of 50 L. pneumophila strains was determined using broth microdilution (BMD), serial antimicrobial dilution in traditional buffered charcoal yeast extract (BCYE) agar (as well as comparison with gradient strip overlay on BCYE) and in a novel charcoal-free agar (LASARUS) for rifampicin, azithromycin, levofloxacin and doxycycline.

RESULTS

The deviation of tested media relative to BMD highlighted the overall similarity of BMD and LASARUS across all antimicrobials tested (within one serial dilution). BCYE agar dilution showed an increased MIC of up to five serial dilutions relative to BMD, while MICs by gradient strip overlay on BCYE were elevated by two to three serial dilutions, with the exception of doxycycline, which was decreased by three serial dilutions relative to MIC values determined by BMD. The MIC range for azithromycin was wider than for other antimicrobials tested and found to be caused by the presence or absence of the lpeAB gene.

CONCLUSIONS

BMD-based antimicrobial susceptibility testing (AST) methodology should be the internationally agreed gold standard for Legionella spp. AST, as is common for other bacterial species. Traditional BCYE gave significantly elevated MIC results and its use should be discontinued for Legionella spp., while MIC determination using LASARUS solid medium gave results concordant (within one serial dilution) with BMD for all antimicrobials tested. To the best of our knowledge, this study is the first to identify the lpeAB gene in UK isolates.

DNA supercoiling differences in bacteria result from disparate DNA gyrase activation by polyamines

DNA supercoiling is essential for all living cells because it controls all processes involving DNA. In bacteria, global DNA supercoiling results from the opposing activities of topoisomerase I, which relaxes DNA, and DNA gyrase, which compacts DNA. These enzymes are widely conserved, sharing >91% amino acid identity between the closely related species Escherichia coli and Salmonella enterica serovar Typhimurium. Why, then, do E. coli and Salmonella exhibit different DNA supercoiling when experiencing the same conditions? We now report that this surprising difference reflects disparate activation of their DNA gyrases by the polyamine spermidine and its precursor putrescine. In vitro, Salmonella DNA gyrase activity was sensitive to changes in putrescine concentration within the physiological range, whereas activity of the E. coli enzyme was not. In vivo, putrescine activated the Salmonella DNA gyrase and spermidine the E. coli enzyme. High extracellular Mg2+ decreased DNA supercoiling exclusively in Salmonella by reducing the putrescine concentration. Our results establish the basis for the differences in global DNA supercoiling between E. coli and Salmonella, define a signal transduction pathway regulating DNA supercoiling, and identify potential targets for antibacterial agents.

Antimicrobial Susceptibility Patterns of Legionella spp. Strains Isolated from Water Systems in Morocco

Objective: Legionella is a waterborne pathogen that causes a severe form of pneumonia called Legionnaires' diseases, which is normally acquired by inhalation of aerosols containing Legionella originating from natural and man-made water systems. The aim of this study was to describe the level of antimicrobial susceptibility of environmental Legionella spp. strains to preferred and recommended therapeutic agents to treat Legionella disease. Methods: The minimum inhibitory concentrations (MICs) of 60 environmental Legionella spp. strains were tested using the broth dilution method. Susceptibility testing was performed for 12 antimicrobial agents: macrolides (erythromycin, azithromycin [AZI], and clarithromycin [CLA]), fluoroquinolones (ciprofloxacin, levofloxacin, moxifloxacin, and gemifloxacin), a ketolide (telithromycin), cefotaxime (CEF), tigecycline (TIG), doxycycline (DOX), and rifampicin (RIF). Results: All tested strains of Legionella spp. were inhibited by low concentrations of fluoroquinolones and macrolides. Regarding the macrolides, CLA was the most active antibiotic, and AZI was the least active. RIF was the most effective antibiotic against the isolates in vitro. All isolates were inhibited by the following antibiotics (in decreasing order of their MICs): DOX>CEF>TIG. Conclusions: No resistance against these drugs was detected, and all isolates were inhibited by low concentrations of the tested antibiotics. Susceptibility testing of environmental Legionella spp. isolates must be monitored often to detect and evaluate the possible development of antibiotic resistance.

Successful Treatment of Legionnaires' Disease with Tigecycline in an Immunocompromised Man with a Legion of Antibiotic Allergies

Legionella species are Gram-negative bacilli that are relatively rare causes of community-acquired pneumonia but can be associated with significant morbidity and mortality if unrecognized or improperly treated. Limited data exist regarding the use of tigecycline, a third generation glycylcycline, in the treatment of Legionnaires' disease. We present an immunocompromised patient with Legionnaires' disease and allergies to both fluoroquinolones and macrolides, which are first-line treatment options for Legionnaires' disease. He was successfully treated using tigecycline, a third generation glycylcycline, indicating that tigecycline may serve as a safe and effective alternative therapeuticl option for treatment of Legionnaires’ disease.

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.

A Proactive Environmental Approach for Preventing Legionellosis in Infants: Water Sampling and Antibiotic Resistance Monitoring, a 3-Years Survey Program

A proactive environmental monitoring program was conducted to determine the risk and prevent nosocomial waterborne infections of Legionella spp. in infants. Sink taps in a neonatal intensive care unit (NICU) and two obstetric clinics were monitored for Legionella spp. A total of 59 water samples were collected during a 3-year period and 20 of them were found colonized with Legionella pneumophila. Standard culture, molecular, and latex agglutination methods were used for the detection and identification of Legionella bacteria. Hospital personnel also proceeded with remedial actions (hyperchlorination and thermal shock treatment) in the event of colonization. The minimal inhibitory concentration (MIC) values of erythromycin, ciprofloxacin was determined for Legionella isolates using the e-test method. Our data indicate that the majority of neonatal sink-taps were colonized at least once during the study with Legionella spp. Among 20 isolates, 5 were considered as low-level resistant, 3 in erythromycin and 2 in ciprofloxacin, while no resistant strains were detected. Environmental surveillance in neonatal and obstetric units is suggested to prevent waterborne infections, and thus to reduce the risk of neonatal nosocomial infections.

Disseminated extrapulmonary Legionella pneumophila infection presenting with panniculitis: case report and literature review

BACKGROUND

Legionellosis is a well-known cause of pneumonia. Primary cutaneous and subcutaneous infection caused by Legionella pneumophila is rare and the diagnosis is challenging.

CASE PRESENTATION

A 38-year-old Thai woman with systemic lupus erythematosus and myasthenia gravis treated with prednisolone and azathioprine presented to our hospital with low-grade fever, diarrhea, and indurated skin lesions on both thighs. Initial examination showed plaques on both inner thighs. Magnetic resonance imaging showed myositis and swelling of the skin and subcutaneous tissue. Diagnosis of panniculitis due to L. pneumophila was carried out by histopathology, Gram stain, and 16S rRNA gene sequencing method of tissue biopsy from multiple sites on both thighs. Myocarditis was diagnosed by echocardiography. The final diagnosis was disseminated extrapulmonary legionellosis. Treatment comprised intravenous azithromycin for 3 weeks and the skin lesions, myositis and myocarditis resolved. Oral azithromycin and ciprofloxacin were continued for 3 months to ensure eradication of the organism. The patient's overall condition improved.

CONCLUSIONS

To our knowledge, we report the first case of L. pneumophila infection manifesting with panniculitis, possible myositis, and myocarditis in the absence of pneumonia. The diagnosis of extrapulmonary Legionella infection is difficult, especially in the absence of pneumonia. A high index of suspicion and appropriate culture with special media or molecular testing are required. Initiation of appropriate treatment is critical because delaying therapy was associated with progressive infection in our patient.

Legionella feeleii: an unusual organism associated with cutaneous infection in an immunocompromised patient

We report a 23-year-old immunocompromised woman who, following cardiac transplantation, presented with an unusual cutaneous eruption. She developed a widespread pustular rash, systemic symptoms and a high temperature with raised inflammatory markers. The diagnosis was reached when a skin biopsy was cultured onto Legionella agar (buffered charcoal yeast extract) and Legionella feeleii was isolated. The patient was treated with 6 weeks of moxifloxacin and her cutaneous lesions gradually resolved. Cutaneous Legionella infections are uncommon and usually affect immunocompromised patients.

Tigecycline as a Second-Line Agent for Legionnaires' Disease in Severely Ill Patients

Treatment of Legionnaires’ disease in severely ill or immunosuppressed patients presents a clinical challenge. Tigecycline (TG) achieves high concentrations intracellularly and has been shown to be effective against L. pneumophila in animal and cell models. We report our experience using TG as second-line therapy. Clinical response was seen in most patients after switching to TG alone or as a combination therapy.

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.

Legionella pneumophila Pneumonia in Two Infants Treated with Adrenocorticotropic Hormone

Patients with infantile spasms, an intractable epileptic disorder, often are treated with adrenocorticotropic hormone. Legionella pneumophila is a rare cause of pneumonia in children. We describe 2 infants with Legionella pneumonia whose infection occurred within 1 month after starting adrenocorticotropic hormone.

Nosocomial legionellosis and invasive aspergillosis in a child with T-lymphoblastic leukemia

Invasive aspergillosis of the lungs and the central nervous system and Legionella pneumophilia serotype 1 infection of the lungs were diagnosed in a 22-month old child during inpatient induction treatment for T-lymphoblastic leukemia. Environmental investigations i.e. samples from the hospital water system did not reveal any Legionella. The patient may have been exposed to waterborne pathogens despite terminal water filtration due to a technical device to release residual tap water from the hose after showering. A sodium chloride nose spray was found to be contaminated with the A. fumigatus isolate of the patient.

Legionella pneumonia in the Niagara Region, Ontario, Canada: a case series

BACKGROUND

Legionella pneumophila, a major cause of Legionnaires' disease, accounts for 2-15 % of all community-acquired pneumonia requiring hospitalization and up to 30 % of community-acquired pneumonia requiring intensive care unit admission. Early initiation of appropriate antimicrobial therapy is a crucial step in the prevention of morbidity and mortality. However, recognition of Legionnaires' disease continues to be challenging because of its nonspecific clinical features. We sought to describe hospitalized community-acquired Legionnaires' disease to increase awareness of this important and potentially lethal disease.

METHODS

A retrospective multicenter observational study was conducted with all patients with confirmed Legionnaires' disease in the Niagara Region of the Province of Ontario, Canada, from June to December 2013.

RESULTS

From June to December 2013, there were 14 hospitalized cases of Legionnaires' disease in the Niagara Region. Of these, 86 % (12 patients) had at least one comorbidity and 71 % (10 patients) were cigarette smokers. In our cohort, Legionnaires' disease was diagnosed with a combination of a urinary Legionella antigen test and a Legionella real-time polymerase chain reaction assay. Delay in effective antimicrobial therapy in the treatment of Legionella infection led to clinical deterioration. The majority of patients had met systemic inflammatory response syndrome criteria with fever >38 °C (71 %), heart rate >90 beats per minute (71 %), and respiratory rate >20 breaths per minute (86 %). Eleven patients (79 %) required admission to the intensive care unit or step-down unit, and nine patients (64 %) required intubation. Clinical improvement after initiation of antimicrobials was protracted.

CONCLUSIONS

Legionnaires' disease should be considered during the late spring and summer months in patients with a history of tobacco use and various comorbidities. Clinically, patients presented with severe, nonspecific, multisystem disease characterized by shortness of breath, abnormal vital signs, and laboratory derangements including hyponatremia, elevated creatine kinase, and evidence of organ dysfunction. In addition, antimicrobial therapy with newer macrolides or respiratory fluoroquinolones should be initiated for severe community-acquired pneumonia requiring intensive care unit admission, prior to laboratory confirmation of diagnosis, especially when a clinical suspicion of Legionella infection exists.

Motor neuron disease mortality rates in U.S. states are associated with well water use

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with an unknown cause and invariably fatal outcome. We sought to evaluate a correlation between motor neuron disease (MND) mortality rates and residential radon levels that was previously reported for counties in the United Kingdom. We examined the relationships between age-adjusted MND mortality rates in U.S. states with residential radon levels, well water use, and other variables using structural equation modeling. We observed a significant correlation between MND mortality rates and radon levels. However, in structural equation models, radon did not have a significant, direct effect on MND mortality rates. Conversely, MND mortality rates were significantly and directly predicted by race and by the percentage of the population of each state using well water (p < 0.001 and p = 0.022). We observed similar, significant effects for well water use and MND mortality for males and females separately (p < 0.05). In conclusion, we hypothesize that the association of MND mortality rates with well water use reflects contamination of wells with Legionella, a bacterium common in well water that is known to cause neurologic disease. A Legionella hypothesis is a biologically plausible cause of ALS and suggests new avenues for etiologic research.

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.

Legionnaires' disease

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

Severe Neonatal Legionella Pneumonia: Full Recovery After Extracorporeal Life Support

Legionella pneumophila is responsible for hospital or community-acquired pneumonia. Neonatal legionellosis is associated with rapidly severe clinical course and high mortality rates. We describe a case of hospital-acquired Legionella pneumonia in a newborn with undiagnosed tracheoesophageal fistula and acute respiratory failure requiring venovenous extracorporeal membrane oxygenation support before fistula repair. Standardized multiplex polymerase chain reaction assay allowed early diagnosis. Extracorporeal life support associated with appropriate antibiotic therapy, surfactant, and steroid therapy was effective in achieving complete recovery. This is the first report of successful neonatal extracorporeal life support for respiratory failure secondary to L pneumophila.

Hidden Selection of Bacterial Resistance to Fluoroquinolones In Vivo: The Case of Legionella pneumophila and Humans

Background

Infectious diseases are the leading cause of human morbidity and mortality worldwide. One dramatic issue is the emergence of microbial resistance to antibiotics which is a major public health concern. Surprisingly however, such in vivo adaptive ability has not been reported yet for many intracellular human bacterial pathogens such as Legionella pneumophila.

Methods

We examined 82 unrelated patients with Legionnaire's disease from which 139 respiratory specimens were sampled during hospitalization and antibiotic therapy. We both developed a real time PCR assay and used deep-sequencing approaches to detect antibiotic resistance mutations in L. pneumophila and follow their selection and fate in these samples.

Findings

We identified the in vivo selection of fluoroquinolone resistance mutations in L. pneumophila in two infected patients treated with these antibiotics. By investigating the mutational dynamics in patients, we showed that antibiotic resistance occurred during hospitalization most likely after fluoroquinolone treatment.

Interpretation

In vivo selection of antibiotic resistances in L. pneumophila may be associated with treatment failures and poor prognosis. This hidden resistance must be carefully considered in the therapeutic management of legionellosis patients and in the control of the gradual loss of effectiveness of antibiotics.

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Legionellosis is a pneumonia caused by the inhalation of aerosols containing Legionella, mainly L. pneumophila.

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Its average mortality rate is 10%, despite availability of effective antibiotics such as the macrolides and the fluoroquinolones.

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Using modern molecular approaches, we identified the selection of fluoroquinolone resistance in L. pneumophila in patients under fluoroquinolone therapy.

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This may lead to reduction of treatment efficacy and prognosis worsening.

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Our findings should lead to revised guidelines for therapeutic management and prognosis evaluation of legionellosis.

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.

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.

Cutaneous legionellosis: case report and review of the medical literature

Discrete nodules developed on the leg of a 27-year-old immunosuppressed woman after an allogeneic stem cell transplant. Biopsy and culture grew Legionella pneumophila serogroup 8. On day 7 of azithromycin treatment, respiratory distress and abnormal liver transaminases developed, and the patient died on day 14. Review of the medical literature identified 19 reports of Legionella species-associated skin or soft tissue infections (total of 20 patients, 13 with confirmed infection). Manifestations of the 13 confirmed cases included erythematous macular rash (n = 7), erythema after thoracentesis (n = 1), abscess formation (n = 4), respiratory symptoms (n = 6), and abnormal chest radiographs (n = 8). Six required surgical exploration and débridement, and 7 were immunocompromised. Rash and respiratory infection improved with antibiotics in 10, but 3 died. Immunosuppression may predispose transplant recipients to Legionella infections. Diagnostic biopsies may facilitate appropriate treatment.

The effect of a large Legionnaires' disease outbreak in Southwest Edinburgh on acute and critical care services

OBJECTIVE

The largest outbreak of Legionnaires Disease (LD) in the UK for a decade occurred in Edinburgh in June 2012. We describe the clinical and public health management of the outbreak.

SETTING

Three acute hospitals covering an urban area of ~480,000.

METHODS

Data were collected on confirmed and suspected cases and minutes of the Incident Management Team meetings were reviewed to identify key actions.

RESULTS

Over 1600 urine samples and over 600 sputum samples were tested during the outbreak. 61 patients with pneumonia tested positive for Legionella pneumophila serogroup 1 by urinary antigen detection, culture, respiratory PCR or serology. A further 23 patients with pneumonia were treated as suspected cases on clinical and epidemiological grounds but had no microbiological diagnosis. 36% of confirmed and probable cases required critical care admission. Mean ICU length of stay was 11.3 (±7.6) days and mean hospital length of stay for those who were admitted to ICU was 23.0 (±17.2) days. For all hospitalized patients the mean length of stay was 15.7 (±14) days. In total there were four deaths associated with this outbreak giving an overall case fatality of 6.5%. Hospital and critical care mortality was 6.1% and 9.1%, respectively.

CONCLUSION

A significant proportion of patients required prolonged multiple organ support or complex ventilation. Case fatality compared favourably to other recent outbreaks in Europe. Access to rapid diagnostic tests and prompt antibiotic therapy may have mitigated the impact of pre-existing poor health among those affected.

In vitro intracellular activity and in vivo efficacy of modithromycin, a novel bicyclolide, against Legionella pneumophila

The in vitro and in vivo activities of modithromycin, a novel bicyclolide, against Legionella pneumophila were compared with those of telithromycin, clarithromycin, azithromycin, and levofloxacin. All the test agents decreased the intracellular growth of viable L. pneumophila bacteria over 96 h of incubation in both types of cells used, A/J mouse-derived macrophages and A549 human alveolar epithelial cells, at extracellular concentrations of 4× and 16× MIC, respectively. However, when the agents were removed from the medium after exposure for 2 h, regrowth of intracellular bacteria occurred in both cell systems when they were exposed to telithromycin, clarithromycin, and levofloxacin but not when they were exposed to modithromycin and azithromycin. Once-daily administration of modithromycin at a dose of 10 mg/kg of body weight for 5 days led to a significant decrease of intrapulmonary viable L. pneumophila bacteria in immunosuppressed A/J mice. The efficacy of modithromycin was superior to the efficacies of telithromycin and clarithromycin and comparable to the efficacies of azithromycin and levofloxacin. In addition, modithromycin and azithromycin inhibited the intrapulmonary regrowth of bacteria even at 72 h after the last treatment, but telithromycin and levofloxacin did not. These results suggested that modithromycin has longer-lasting cellular pharmacokinetic features like azithromycin. In conclusion, modithromycin, as well as azithromycin, has excellent in vitro and in vivo bactericidal activities and persistent efficacy against intracellular L. pneumophila. Modithromycin should be a useful agent for treatment of pulmonary infections caused by this pathogen.

Legionella feeleii serotype 2 pneumonia in a man with chronic lymphocytic leukemia: a challenging diagnosis

Legionella feeleii has rarely been reported as causing pneumonia in patients with hematologic malignancies. We present a case of Legionella feeleii serotype 2 pneumonia with empyema in a man with chronic lymphocytic leukemia and describe the methods of identifying this organism using both standard methods and newer diagnostic techniques.

Disseminated Legionella pneumophila infection in an immunocompromised patient treated with tigecycline

We describe an immunocompromised patient with disseminated Legionella pneumophila infection. A chronic leg ulcer was probably the port of entry for the infection. Treatment required several operations and prolonged antimicrobial treatment. To our knowledge, this is the first case report of Legionella soft tissue infection and pneumonia treated with tigecycline.