Legionnaires' disease. A review

An Atypical Presentation of Legionnaires' Disease

Legionnaires' disease is an atypical pneumonia caused by Legionella pneumophila. Legionella species are found in freshwater sources and are transmitted through inhalation of contaminated aerosols. Patients commonly present with fever, chills, and cough. However, in immunosuppressed patients or severe cases, the disease can lead to multiorgan failure. In recent years, the incidence of Legionnaires' disease has drastically increased and unfortunately is commonly underdiagnosed. Gold-standard diagnosis is made through sputum cultures; however, urine Legionella antigen remains the most common test used for diagnosis. Goal-directed care includes antibiotics and supportive care. This case highlights a rare and unique presentation of Legionnaires' disease presenting with an elevated 2:1 aspartate aminotransferase to alanine transaminase pattern, typically seen with alcoholic hepatitis.

Knowledge to Predict Pathogens: Legionella pneumophila Lifecycle Systematic Review Part II Growth within and Egress from a Host Cell

Legionella pneumophila (L. pneumophila) is a pathogenic bacterium of increasing concern, due to its ability to cause a severe pneumonia, Legionnaires' Disease (LD), and the challenges in controlling the bacteria within premise plumbing systems. L. pneumophila can thrive within the biofilm of premise plumbing systems, utilizing protozoan hosts for protection from environmental stressors and to increase its growth rate, which increases the bacteria's infectivity to human host cells. Typical disinfectant techniques have proven to be inadequate in controlling L. pneumophila in the premise plumbing system, exposing users to LD risks. As the bacteria have limited infectivity to human macrophages without replicating within a host protozoan cell, the replication within, and egress from, a protozoan host cell is an integral part of the bacteria's lifecycle. While there is a great deal of information regarding how L. pneumophila interacts with protozoa, the ability to use this data in a model to attempt to predict a concentration of L. pneumophila in a water system is not known. This systematic review summarizes the information in the literature regarding L. pneumophila's growth within and egress from the host cell, summarizes the genes which affect these processes, and calculates how oxidative stress can downregulate those genes.

Dot/Icm-Dependent Restriction of Legionella pneumophila within Neutrophils

The Dot/Icm type IV secretion system (T4SS) of Legionella pneumophila is essential for lysosomal evasion and permissiveness of macrophages for intracellular proliferation of the pathogen. In contrast, we show that polymorphonuclear cells (PMNs) respond to a functional Dot/Icm system through rapid restriction of L. pneumophila. Specifically, we show that the L. pneumophila T4SS-injected amylase (LamA) effector catalyzes rapid glycogen degradation in the PMNs cytosol, leading to cytosolic hyperglucose. Neutrophils respond through immunometabolic reprogramming that includes upregulated aerobic glycolysis. The PMNs become activated with spatial generation of intracellular reactive oxygen species within the Legionella-containing phagosome (LCP) and fusion of specific and azurophilic granules to the LCP, leading to rapid restriction of L. pneumophila. We conclude that in contrast to macrophages, PMNs respond to a functional Dot/Icm system, and specifically to the effect of the injected amylase effector, through rapid engagement of major microbicidal processes and rapid restriction of the pathogen. IMPORTANCE Legionella pneumophila is commonly found in aquatic environments and resides within a wide variety of amoebal hosts. Upon aerosol transmission to humans, L. pneumophila invades and replicates with alveolar macrophages, causing pneumonia designated Legionnaires' disease. In addition to alveolar macrophages, neutrophils infiltrate into the lungs of infected patients. Unlike alveolar macrophages, neutrophils restrict and kill L. pneumophila, but the mechanisms were previously unclear. Here, we show that the pathogen secretes an amylase (LamA) enzyme that rapidly breakdowns glycogen stores within neutrophils, and this triggers increased glycolysis. Subsequently, the two major killing mechanisms of neutrophils, granule fusion and production of reactive oxygen species, are activated, resulting in rapid killing of L. pneumophila.

Loop-mediated isothermal amplification for detection of Legionella pneumophila in respiratory specimens of hospitalized patients in Ahvaz, southwest Iran

Background

Legionnaires’ disease is an important public health problem that can cause substantial mortality and morbidity. Legionnaires’ disease-risk estimation may be compromised by uncertainties in Legionella-detection methods. The aim of this study was the detection of L. pneumophila in respiratory specimens of hospitalized patients with respiratory symptoms by culture, PCR, and loop-mediated isothermal amplification (LAMP) methods.

Methods

Sputum and bronchoalveolar lavage samples were obtained from patients with pneumonia admitted to teaching hospitals in Ahvaz, Iran from June 2016 to March 2017. Isolation of Legionella spp. was done by culturing the samples directly onto buffered charcoal–yeast extract and modified Wadowsky–Yee agar medium. Then, PCR and LAMP assays were performed for detection of L. pneumophila via its mip gene in respiratory specimens.

Results

A total of 100 respiratory specimens were collected. Our results showed that 1% of the samples were culture positive for Legionella spp., and 3% and 7% of samples were positive for L. pneumophila using the mip gene on PCR and LAMP assays, respectively.

Conclusion

Legionnaires’ disease should be considered in the diagnosis of pulmonary infectious diseases. Also, the LAMP assay is a faster method with higher sensitivity and specificity than conventional methods, such as PCR and culture, for laboratory diagnosis of Legionnaires’ disease.

Greywater reuse - Assessment of the health risk induced by Legionella pneumophila

Greywater (GW), domestic wastewater excluding the streams generated by toilets and kitchens, can serve as an alternative water source. The main options for GW reuse are toilet flushing and garden irrigation, both generating aerosols. These may transmit inhalable pathogens like Legionella and present a potential health risk. This study quantified the health risk that may arise from inhalation of Legionella-contaminated aerosols due to non-potable GW reuse. Data on Legionella concentrations in potable water and GW was collected. Then, Quantitative Microbial Risk Assessment (QMRA) was performed for two possible exposure scenarios: garden irrigation and toilet flushing. This was performed while considering Legionella seasonality. In order to determine the safety of GW reuse regarding Legionella transmission, the obtained results were compared with estimated tolerable risk levels of infection and of disease. Both limits were expressed as Disability-Adjusted Life Years index (DALY) being 10^-4 and 10^-5, respectively. The QMRA revealed that the annual risk associated with reuse of treated and chlorinated GW for garden irrigation and toilet flushing was not significantly higher than the risk associated with using potable water for the same two purposes. In all studied scenarios, the health risk stemming from reusing treated and chlorinated GW was acceptable regarding Legionella infection. In contrast, reuse of untreated or treated but unchlorinated GW should not be practiced, as these are associated with significantly higher health risks.

A dose-ranging trial to optimize the dose of rifampin in the treatment of tuberculosis

RATIONALE

Rifampin at a dose of 10 mg/kg was introduced in 1971 based on pharmacokinetic, toxicity, and cost considerations. Available data in mice and humans showed that an increase in dose may shorten the duration of tuberculosis treatment.

OBJECTIVES

To evaluate the safety and tolerability, the pharmacokinetics, and the extended early bactericidal activity of increasing doses of rifampin.

METHODS

Patients with drug-susceptible tuberculosis were enrolled into a control group of eight patients receiving the standard dose of 10 mg/kg rifampin, followed by consecutive experimental groups with 15 patients each receiving rifampin 20, 25, 30, and 35 mg/kg, respectively, for 14 days. In all patients isoniazid, pyrazinamide, and ethambutol were added in standard doses for the second 7 days of treatment. Safety, pharmacokinetics of rifampin, and fall in bacterial load were assessed.

MEASUREMENTS AND MAIN RESULTS

Grade 1 and 2 adverse events were equally distributed between the five dose groups; there were five grade 3 events of which one was a possibly related hepatotoxicity. Areas under the time-concentration curves and peak serum concentrations of rifampin showed a more than proportional increase with dose. The daily fall in bacterial load over 14 days was 0.176, 0.168, 0.167, 0.265, and 0.261 log10 colony-forming units/ml sputum in the 10, 20, 25, 30, and 35 mg/kg groups, respectively.

CONCLUSIONS

Two weeks of rifampin up to 35 mg/kg was safe and well tolerated. There was a nonlinear increase in exposure to rifampin without an apparent ceiling effect and a greater estimated fall in bacterial load in the higher dosing groups. Clinical trial registered with www.clinicaltrials.gov (NCT 01392911).

In vitro and intracellular activities of peptide deformylase inhibitor GSK1322322 against Legionella pneumophila isolates

GSK1322322, a novel peptide deformylase inhibitor currently in development as an oral and intravenous agent for the treatment of hospitalized community-acquired bacterial pneumonia, showed poor in vitro activity against a panel of 50 Legionella pneumophila strains, with MICs ranging from 1 to 16 μg/ml and an MIC90 of 16 μg/ml, but very potent intracellular activity, with the minimum extracellular concentrations capable of inhibiting intracellular proliferation (MIECs) ranging from 0.12 to 2 μg/ml and 98% of the strains being inhibited by concentrations of ≤ 1 μg/ml.

Human susceptibility to legionnaires' disease

Legionella pneumophila is a facultative intracellular pathogen that is an important cause of pneumonia. Although host factors that may predispose to acquisition of Legionnaire's Disease (LD) include comorbid illnesses (e.g., diabetes, chronic lung disease), age, male sex, and smoking, many individuals have no identifiable risk factors. Some studies suggest that genetic factors may enhance susceptibility to LD. In this chapter we discuss current techniques and scientific methods to identify genetic susceptibility factors. These genetic studies provide insight into the human immune response to intracellular pathogens and may improve strategies for treatment and vaccine development.

Two cases of severe pneumonia after the 2011 Great East Japan Earthquake

In 2011, during the Great East Japan Earthquake and tsunami, 90% of victims died from drowning. We report on two tsunami survivors with severe pneumonia potentially caused by Legionella pneumophila. Both victims aspirated a large quantity of contaminated water; sand, mud and a variety of microbes were thought to have entered into their lower respiratory tracts. One patient had a mycotic intracranial aneurysm; the other patient had co-infections with several organisms, including Scedosporium species. Although scedosporiosis is a relatively rare infectious disease, symptoms are progressive and prognosis is poor. These pathogens are not specific for tsunami lung, but are reported causative agents for pneumonia after near-drowning.

Community-acquired Legionella Pneumonia in the intensive care unit: Impact on survival of combined antibiotic therapy

OBJECTIVES

To compare intensive care unit (ICU) mortality in patients with severe community-acquired pneumonia (SCAP) caused by Legionella pneumophila receiving combined therapy or monotherapy.

METHODS

A prospective multicenter study was made, including all patients with sporadic, community-acquired Legionnaires' disease (LD) admitted to the ICU. Admission data and information on the course of the disease were recorded. Antibiotic prescriptions were left to the discretion of the attending physician and were not standardized.

RESULTS

Twenty-five cases of SCAP due to L. pneumophila were included, and 7 patients (28%) out of 25 died after a median of 7 days of mechanical ventilation. Fifteen patients (60%) presented shock. Levofloxacin and clarithromycin were the antibiotics most commonly used in monotherapy, while the most frequent combination was rifampicin plus clarithromycin. Patients subjected to combination therapy presented a lower mortality rate versus patients subjected to monotherapy (odds ratio for death [OR] 0.15; 95%CI 0.02-1.04; p=0.08). In patients with shock, this association was stronger and proved statistically significant (OR for death 0.06; 95%CI 0.004-0.86; p=0.04).

CONCLUSIONS

Combined antibiotic therapy decreases mortality in patients with SCAP and shock caused by L. pneumophila.

Semi-automated Acanthamoeba polyphaga detection and computation of Salmonella typhimurium concentration in spatio-temporal images

Interaction between bacteria and protozoa is an increasing area of interest, however there are a few systems that allow extensive observation of the interactions. A semi-automated approach is proposed to analyse a large amount of experimental data and avoid a time demanding manual object classification. We examined a surface system consisting of non nutrient agar with a uniform bacterial lawn that extended over the agar surface, and a spatially localised central population of amoebae. Location and identification of protozoa and quantification of bacteria population are performed by the employment of image analysis techniques in a series of spatial images. The quantitative tools are based on intensity thresholding, or on probabilistic models. To accelerate organism identification, correct classification errors and attain quantitative details of all objects a custom written Graphical User Interfaces has also been developed.

Legionella pollution in cooling tower water of air-conditioning systems in Shanghai, China

AIMS

To determine Legionella pollution prevalence, describe the amount of Legionellae with respect to temperature in Shanghai cooling tower water (CTWs) in various types of public sites.

METHODS AND RESULTS

Six urban districts were selected as the study fields, adopting multiple-phase sampling methods. Routine culture was used to identify Legionellae. Of the samples, 58.9% (189/321) were observed to be positive, 19.9% were isolated over 100 CFU ml(-1). Legionella pneumophila serogroup 1 was the most frequently isolated species (155/189, 82.0%), followed by Leg. micdadei that was at the second place (44/189, 23.3%). The mean CFU ml(-1) of Legionellae in CTWs reached its peak from July to September. Over all 15.4% of the samples exceeding 100 CFU ml(-1) were observed in a hospital setting.

CONCLUSIONS

The prevalence of Legionella pollution in CTWs, especially in CTWs of subway stations and hospitals, is worrying, and the positive rate and CFU ml(-1) of Legionellae in CTWs have a close relationship with air temperature.

SIGNIFICANCE AND IMPACT OF THE STUDY

The study demonstrates pollution prevalence rates in different types of sites and various seasons, and provides a proportion of different serogroups of Legionellae. It illuminates an urgent need for dealing with the potential risk of legionellosis in Shanghai, through improved control and prevention strategies.

Phylogenomic and biochemical characterization of three Legionella pneumophila polypeptide deformylases

Legionella pneumophila is a gram-negative facultative intracellular human pathogen that can cause fatal Legionnaires' disease. Polypeptide deformylase (PDF) is a novel broad-spectrum antibacterial target, and reports of inhibitors of PDF with potent activities against L. pneumophila have been published previously. Here, we report the identification of not one but three putative pdf genes, pdfA, pdfB, and pdfC, in the complete genome sequences of three strains of L. pneumophila. Phylogenetic analysis showed that L. pneumophila PdfA is most closely related to the commonly known gamma-proteobacterial PDFs encoded by the gene def. PdfB and PdfC are more divergent and do not cluster with any specific bacterial or eukaryotic PDF. All three putative pdf genes from L. pneumophila strain Philadelphia 1 have been cloned, and their encoded products have been overexpressed in Escherichia coli and purified. Enzymatic characterization shows that the purified PDFs with Ni2+ substituted are catalytically active and able to remove the N-formyl group from several synthetic polypeptides, although they appear to have different substrate specificities. Surprisingly, while PdfA and PdfB with Zn2+ substituted are much less active than the Ni2+ forms of each enzyme, PdfC with Zn2+ substituted was as active as the Ni2+ form for the fMA substrate and exhibited substrate specificity different from that of Ni2+ PdfC. Furthermore, the catalytic activities of these enzymes are potently inhibited by a known small-molecule PDF inhibitor, BB-3497, which also inhibits the extracellular growth of L. pneumophila. These results indicate that even though L. pneumophila has three PDFs, they can be effectively inhibited by PDF inhibitors which can, therefore, have potent anti-L. pneumophila activity.

Antimicrobial Chemotherapy for Legionnaires Disease: Levofloxacin versus Macrolides

BACKGROUND

The community outbreak of legionnaires disease that occurred in Murcia, Spain, in July 2001--to our knowledge, the largest such outbreak ever reported--afforded an unusual opportunity to compare the clinical response of patients with Legionella pneumonia treated with levofloxacin with that of patients treated with macrolides and to determine the role of rifampicin combined with levofloxacin in treating severe legionellosis.

METHODS

An observational, prospective, nonrandomized study was conducted involving 292 patients seen at our hospital (Hospital "J. M. Morales Meseguer"; Murcia, Spain) who received a diagnosis of Legionella pneumonia during the Murcia outbreak. To compare both antibiotic regimens (macrolides vs. levofloxacin), patients were stratified by the severity of pneumonia. Duration of fever, clinical outcome, complications, side effects, and length of hospital stay were recorded. To assess the potential effects of adjuvant therapy with rifampicin, 45 case patients treated with levofloxacin plus rifampicin were evaluated and compared with 45 control pairs who were treated with levofloxacin alone.

RESULTS

With the exception of 2 patients who died, all patients were cured. There were no significant differences between treatment groups in clinical outcome for patients with mild-to-moderate pneumonia. Nevertheless, in patients with severe pneumonia, levofloxacin exerted superior activity; it was associated with fewer complications (3.4% of patients receiving levofloxacin experienced complications, compared with 27.2% of patients receiving macrolides; P=.02) and shorter mean hospital stays (5.5 vs. 11.3 days; P=.04). Addition of rifampicin to the treatment regimen for patients receiveing levofloxacin for severe pneumonia provides no additional benefit.

CONCLUSIONS

Our findings strongly suggest that monotherapy with levofloxacin is a safe and effective treatment for legionnaires disease, including in patients with severe disease. In these patients, levofloxacin appears to be more effective than clarithromycin.

Host-pathogen relationships among Escherichia coli isolates recovered from men with febrile urinary tract infection

BACKGROUND

Host-pathogen relationships in men with febrile urinary tract infection (FUTI) are poorly understood.

METHODS

Phylogenetic background, extended virulence genotypes, and serotypes were determined for 70 Escherichia coli isolates recovered from urine samples obtained from men with FUTI for comparison with available data for 70 E. coli rectal isolates recovered from uninfected men. Bacterial traits were assessed in relation to underlying host characteristics (age, compromise status, and history of urinary tract infection) and acute manifestations (bacteremia, flank pain, and serum prostate-specific antigen [PSA] level).

RESULTS

Compared with rectal isolates, FUTI isolates exhibited a significantly higher prevalence of virulence-associated phylogenetic groups, serotypes, and extraintestinal virulence genes. The latter included traditional prostatitis-associated traits (e.g., hemolysin and cytotoxic necrotizing factor), as well as unconventional traits, such as outer membrane protease T. These bacterial traits occurred largely independent of host age, urological compromise status, urinary tract infection history, and acute manifestations. However, certain traits were less prevalent in association with use of urinary tract instrumentation and significantly predicted elevated PSA levels.

CONCLUSIONS

Considerable virulence capability may be required for an E. coli strain to cause FUTI in men, regardless of whether most compromising conditions are present. Bacterial traits that promote prostatic invasion may be relevant for the pathogenesis of FUTI, even among men without classic manifestations of acute prostatitis.

Major factors affecting the emergence and re-emergence of infectious diseases

The diversity of infectious disease threats currently facing humanity is unprecedented because of the remarkable emergence and reemergence of pathogens worldwide. Because of population mobility, globalization of commerce and the food supply, and the effects of the HIV/AIDS pandemic, infections in the developing world must be addressed to prevent infections in industrialized countries. Because pathogens do not recognize national boundaries, the rapidity with which individuals can circumnavigate the globe incubating infections makes the control of communicable diseases an enormous challenge for governments as well as for the public and primary health care systems. A global strategy for dealing with infectious disease threats must be developed and implemented as soon as possible.

Expression of magA in Legionella pneumophila Philadelphia-1 is developmentally regulated and a marker of formation of mature intracellular forms

Legionella pneumophila displays a biphasic developmental cycle in which replicating forms (RFs) differentiate postexponentially into highly infectious, cyst-like mature intracellular forms (MIFs). Using comparative protein profile analyses (MIFs versus RFs), we identified a 20-kDa protein, previously annotated as "Mip-like" protein, that was enriched in MIFs. However, this 20-kDa protein shared no similarity with Mip, a well-characterized peptidyl-prolyl isomerase of L. pneumophila, and for clarity we renamed it MagA (for "MIF-associated gene"). We monitored MagA levels across the growth cycle (in vitro and in vivo) by immunoblotting and established that MagA levels increased postexponentially in vitro (approximately 3-fold) and nearly 10-fold during MIF morphogenesis in HeLa cells. DNA sequence analysis of the magA locus revealed an upstream divergently transcribed gene, msrA, encoding a peptide methionine sulfoxide reductase and a shared promoter region containing direct and indirect repeat sequences as well as -10 hexamers often associated with stationary-phase regulation. While MagA has no known function, it contains a conserved CXXC motif commonly found in members of the thioredoxin reductase family and in AhpD reductases that are associated with alkylhydroperoxide reductase (AhpC), suggesting a possible role in protection from oxidative stress. MIFs from L. pneumophila strain Lp02 containing a magA deletion exhibited differences in Giménez staining, as well as an apparent increase in cytopathology to HeLa cells, but otherwise were unaltered in virulence traits. As demonstrated by this study, MagA appears to be a MIF-specific protein expressed late in intracellular growth that may serve as a useful marker of development.

Respiratory complications of pregnancy

The pregnant woman is susceptible to a variety of respiratory complications. When a pregnant patient presents with an abnormal chest x-ray or a pulmonary complaint, an understanding of the pathophysiology of pregnancy will guide the clinician in establishing a diagnosis. Pregnancy brings about many changes to a woman's body. One of the more intriguing is a decrease in the T helper cells, resulting in a state of relative immunosuppression. Despite this, the prevalence of infectious pneumonia is not increased in pregnancy. Complications from pneumonia, however, are increased in the pregnant host. Most notably are increases in both mortality related to influenza infection and the risk for dissemination of coccidioidomycosis. Other physiologic changes predispose the pregnant woman to certain disease processes. Hypercoagulability associated with pregnancy results in a marked increase in the incidence of thromboembolic disease. Although rare, pregnancy is also associated with other embolic phenomena including amniotic fluid embolism, air embolism, and trophoblastic embolism. Because of the increases in intravascular volume and cardiac output that occur in pregnancy, women with underlying structural heart disease will frequently present for the first time or have an exacerbation of their disease. This is especially true of mitral stenosis. Peripartum cardiomyopathy also can occur, and for the majority of patients, the heart remains damaged for life. Finally, although uncommon, lymphangioleiomyomatosis will often present or become exacerbated during pregnancy. Patients with this disorder need to be counseled concerning the increased risk associated with pregnancy. This paper reviews the various respiratory complications associated with pregnancy.

Potential virulence role of the Legionella pneumophila ptsP ortholog

We previously identified the Legionella pneumophila ptsP (phosphoenolpyruvate phosphotransferase) ortholog gene as a putative virulence factor in a study of signature-tagged mutagenesis using a guinea pig pneumonia model. In this study, we further defined the phenotypic properties of L. pneumophila ptsP and its complete sequence. The L. pneumophila ptsP was 2,295 bases in length. Its deduced amino acid sequence had high similarity with ptsP orthologs of Pseudomonas aeruginosa, Azotobacter vinelandii, and Escherichia coli, with nearly identical lengths. Here we show that while the mutant grew well in laboratory media, it was defective in both lung and spleen multiplication in guinea pigs. It grew slowly in guinea pig alveolar macrophages despite good uptake into the cells. Furthermore, there was minimal growth in a human alveolar epithelial cell line (A549). Transcomplementation of the L. pneumophila ptsP mutant almost completely rescued its growth in alveolar macrophages, in A549 cells, and in guinea pig lung and spleen. The L. pneumophila ptsP mutant was capable of evasion of phagosome-lysosome fusion and resided in ribosome-studded phagosomes. Pore formation activity of the mutant was normal. The L. pneumophila ptsP mutant expressed DotA and IcmX in apparently normal amounts, suggesting that the ptsP mutation did not affect dotA and icmX regulation. In addition, the mutant was resistant to serum and neutrophil killing. Taken together, these findings show that L. pneumophila ptsP is required for full in vivo virulence of L. pneumophila, most probably by affecting intracellular growth.

A multicenter evaluation of genotypic methods for the epidemiologic typing of Legionella pneumophila serogroup 1: results of a pan-European study

OBJECTIVES: To compare genotypic methods for epidemiologic typing of Legionella pneumophila serogroup (sg) 1, in order to determine the best available method within Europe for implementation and standardization by members of the European Working Group on Legionella Infections. METHODS: Coded isolates (114) of L. pneumophila sg 1 comprising one epidemiologically 'unrelated' (79) and one 'related' panel of isolates (35) were sent to 12 laboratories in 11 European countries. Analysis was undertaken in each laboratory using one or more of the following methods: ribotyping, restriction fragment length polymorphism analysis, restriction endonuclease analysis, pulsed-field gel electrophoresis (PFGE), PCR using arbitrary/repeat sequence primers (AP-, AP/rep-PCR), and amplified fragment length polymorphism (AFLP) analysis. Results were analyzed visually or using gel analysis software. Each method was assessed for its: index of discrimination (D), epidemiologic concordance (E), speed of application and ease of use. In addition, phenotypic analysis was performed in two laboratories using monoclonal antibodies (mAbs). RESULTS: The D of each of the genotypic methods ranged from 0.840 for ribotyping to 0.990 for PFGE using Sfil: E ranged from 0.06 for AP- and AP/rep-PCR to 1.00 for ribotyping using Pstl/EcoRI and AFLP: in general, E was inversely related to D. Although offering only limited discrimination (D=0.838), mAb typing was both rapid and highly epidemiologically concordant (E=1.00). CONCLUSIONS: Two methods, PFGE using Sfil and AFLP, were selected for further study. AFLP is rapid and highly epidemiologically concordant (E=1.00), but is not highly discriminatory. This method will be developed as a rapid screening tool. PFGE using Sfil is highly discriminatory but, in the present study, yielded low values of E (0.12-0.71). Attempts will be made to rigorously standardize this method for use as the reference method. Primary screening of isolates by mAb subgrouping is recommended.

Pneumonia and tuberculosis in pregnancy

Antepartum pneumonia requires prompt evaluation and empiric antimicrobial therapy. The choice of antimicrobial therapy depends on maternal risk factors, symptoms, and clinical presentation. Although laboratory studies such as culture and serology should be obtained, they may not always yield a specific etiologic agent. However, prompt empiric treatment and supportive care should lead to good maternal and fetal outcomes. Similarly, in most cases, proper diagnosis and treatment of TB during pregnancy yield good maternal and fetal outcomes. TB screening is essential for the growing population of individuals with HIV infection and recent immigrants from areas where tuberculosis is endemic.

Legionella species community-acquired pneumonia. A review of 56 hospitalized adult patients

BACKGROUND

In a prospective study, Legionella species (Lsp) was identified as the causative agent in 56 (16.2%) of 346 adult patients hospitalized over the course of 1 year with community-acquired pneumonia (CAP), in the Soroka Medical Center, Beer-Sheva, Israel.

OBJECTIVE

To characterize patients with Lsp CAP in our study.

METHODS

The diagnosis of infection with Lsp was based on serologic testing of antibodies using the indirect immunofluorescent method.

RESULTS

In 35 (62.5%) of the patients, at least one other etiologic agent for CAP was identified in addition to Lsp. The patient population was relatively young, with relatively low rates of chronic comorbidity, and a broad spectrum of disease severity compared with previously published studies. No single epidemiologic, clinical, laboratory, or radiographic characteristic differentiated between Lsp CAP and other CAP patients in our study. Three patients (5.4%) who were not treated with erythromycin died. However, in contrast, nine patients who were treated with beta-lactam antibiotics recovered completely.

CONCLUSIONS

Lsp is a common cause of CAP in our region, usually as a coinfection with another causative agent. Lsp CAP, which cannot be characterized on the basis of clinical, routine laboratory, or radiographic data, requires specific microbiologic or serologic diagnosis. Treatment with erythromycin appears to be important to reduce mortality from this disease, but in a significant number of patients, the disease may be self-limited.

Macrolide antibiotics in paediatric infectious diseases

Erythromycin and other macrolides have enjoyed a renaissance in the 1970s, 1980s and 1990s secondary to the discovery of "new' pathogens such as Chlamydia, Legionella, Campylobacter and Mycoplasma spp. Erythromycin is an important therapeutic agent in the paediatric age group for several reasons: (a) it exhibits proven efficacy for a wide range of infections (upper and lower respiratory tract infections, skin/skin structure infections, prophylaxis of endocarditis/acute rheumatic fever/ophthalmia neonatorum and pre-colonic surgery, campylobacteriosis, chlamydial and ureaplasmal infections, diphtheria, whooping cough, streptococcal pharyngitis) and gastrointestinal (GI) dysmotility states; (b) intravenous formulations are widely available; and (c) it is available in a number of formulations as a generic product, which is likely to result in significant cost savings. Nevertheless, erythromycin and similar earlier macrolides are characterised by a number of drawbacks including a narrow spectrum of antimicrobial activity, unfavourable pharmacokinetic properties and poor GI tolerability. Newer macrolides such as clarithromycin and azithromycin are useful in serving the needs of paediatric patients who are erythromycin-intolerant or who have infections caused by organisms that are intrinsically erythromycin-resistant, or for which a high percentage of strains are resistant (e.g. Haemophilus influenzae, Helicobacter pylori, Mycobacterium avium complex). In addition, these newer macrolides may be considered as alternatives to oral amoxicillin-clavulanic acid, second or third generation cephalosporins, or erythromycin plus sulphonamide in this patient population. Selection between specific macrolides and between macrolides and other antibiotics in the paediatric population is likely to depend, at least for the immediate future, on separate comparisons of product availability, cost, effectiveness and tolerability profiles.

In vitro extracellular and intracellular activities of clavulanic acid and those of piperacillin and ceftriaxone alone and in combination with tazobactam against clinical isolates of Legionella species

The activities of ceftriaxone, piperacillin, tazobactam, clavulanic acid, and combinations of ceftriaxone or piperacillin with tazobactam against 22 clinical Legionella isolates were measured by broth microdilution and macrodilution methods and in macrophages. The broth microdilution MICs that inhibited 90% of strains tested were 2 and 1 microgram/ml for ceftriaxone and tazobactam, respectively. Broth macrodilution MICs were 8 and 1 microgram/ml, respectively, for the two Legionella pneumophila strains tested with piperacillin and were 0.25 and 0.5 microgram/ml, respectively, for clavulanate. No significant intracellular anti-L. pneumophila activity was observed for ceftriaxone (32 micrograms/ml), piperacillin (32 micrograms/ml), tazobactam alone (16 micrograms/ml), clavulanate alone (2 micrograms/ml), or tazobactam in combination with ceftriaxone (ceftriaxone/tazobactam at 32/4 and 16/16 micrograms/ml) or piperacillin (32/4 micrograms/ml). Erythromycin (1 microgram/ml) was active against intracellular L. pneumophila in the same macrophage model of infection. It is very unlikely that tazobactam or clavulanate, alone or in combination with beta-lactam antimicrobial agents, will be effective for the treatment of Legionnaires' disease in humans.

Microbial etiology of acute pneumonia in hospitalized patients

The purpose of this study was to determine the microbial etiology of pneumonia by using strict criteria among a group of hospitalized patients. Patients with acute community-acquired or hospital-acquired pneumonia were studied in a systematic and comprehensive manner for bacterial, viral, chlamydial, mycobacterial, and fungal pathogens. A total of 198 patients with 204 episodes of pneumonia were evaluated. Despite 100 percent follow-up of all surviving patients, a specific etiologic agent could be found in only 103 episodes. Among 154 episodes of community-acquired pneumonia, a diagnosis was made in 79; the most common pathogen was from the genus Legionella, followed by various Gram-negative enteric bacteria, Gram-positive cocci, influenza A virus, and Mycoplasma pneumoniae. The etiologic agent was found in 24 of the 50 patients with hospital-acquired pneumonia; no pathogen predominated. We conclude that even when elaborate diagnostic studies are done, including many invasive procedures, the etiology can be determined in only about half of the patients with acute pneumonia. The pathogens of pneumonia in this study are not markedly different between community-acquired and hospital-acquired infection.

An outbreak of nosocomial Legionnaires' disease in a renal transplant unit in São Paulo, Brazil. Legionellosis Study Team

From June 1989 to March 1990 there were eight cases of Legionnaires' disease caused by Legionella pneumophila serogroup 1 in a renal transplant unit. There were seven cases of pneumonia and one case of pleural effusion. A study was conducted to identify the source of the outbreak. Legionella anisa was cultured from tap water. Twenty-seven staff members of the unit were serologically tested and antibody titres were positive in two. The probable source of infection was the potable water system. Control measures were hyperchlorination and heating of the water, after which there were no further cases during 5 months' follow up. We believe this is the first reported Legionnaires' disease outbreak in Latin America.

Survival of Legionella pneumophila within cysts of Acanthamoeba polyphaga following chlorine exposure

The association between Legionella pneumophila and the free-living amoeba Acanthamoeba polyphaga was studied. Intracellular growth of L. pneumophila within amoebic trophozoite was confirmed by kinetic growth experiments, light and electron microscopy. Cysts produced from infected trophozoites were found to protect the legionellas from at least 50 mg/l free chlorine. The ability of L. pneumophila to survive within the cysts of A. polyphaga is suggested as a possible mechanism by which the organism evades disinfection and spreads to colonize new environments.

Legionella pneumophila associada a insuficiência respiratória aguda: primeiro isolamento no Brasil

Relatam os autores isolamento de Legionella pneumophila sorogrupo 1, acompanhado de evidências sorológicas de infecção atual, em homem de 40 anos com infecção respiratória grave que evoluiu para insuficiência respiratória aguda. Esta foi caracterizada por hipoxemia severa refratária a altas concentrações de oxigênio e radiograficamente por infiltrados difusos em ambos pulmões. Com introdução de clindamicina, amicacina, ceftriaxone e ventilação à volume com Pressão Expiratória Positiva Final (PEEP) de 14 cm de H(2)0, houve estabilização do quadro e gradual recuperação. Suspeitando-se de legionelose, foi colhido sangue e secreção traqueal para exames específicos. A secreção traqueal foi semeada em meio BCYE com isolamento de bacilo gram-negativo, identificado como Legionella pneumophila sorogrupo 1 por características culturais, bioquímicas e reações de imunofluorescência direta e de aglutinação em lâmina. O estudo sorológico revelou títulos de anticorpos 128, 1024, 4096 e 8192 para amostras coletadas na 1ª, 3ª, 4ª e 6ª semanas após o início do quadro. Os resultados definitivos foram obtidos com o paciente em recuperação. É realçada a comprovação da presença de Legionella sp. como agente patológico em nosso meio; a importância das medidas de suporte na evolução do paciente; a necessidade de se pensar neste agente no diagnóstico diferencial de pneumonias e de se pesquisar mais esta etiologia com metodologia laboratorial específica.

Legionnaires' disease: the wollongong experience

Australia experienced its largest Legionnaires' disease epidemic in Wollongong, mid 1987. This paper presents an overview of Legionnaires' disease followed by details of the Wollongong epidemic including areas of particular interest to the physiotherapist, with comparisons of milder and severe cases. Unlike other epidemics, females outnumbered males. Predisposing factors of increasing age, cigarette smoking, respiratory and medical conditions were found. Except cigarette smoking, these factors and initial chest radiograph involving two or more zones, were significant features of the severe group. Patients in these categories require careful monitoring. Blood gases demonstrated consistent hypoxaemia and hypocapnoea. Seventy-eight per cent of cases recorded little or no sputum and implications for treatment are discussed. Impressions and fears of the epidemic are presented and recommendations made.

Acute and chronic Legionnaires' disease and co-existent tuberculosis: a trial of erythromycin

To assess the prevalence of Legionnaires' disease, 115 patients with 'difficult-to-treat' chest infections were screened for Legionnella pneumophila. The results were positive in 10 (37%) of 27 patients with pulmonary tuberculosis, 15 (22%) of 68 with a recent onset acute respiratory infection, and 7 (35%) of 20 patients with history of a chronic respiratory infection. These 32 patients were enrolled in an open therapeutic trial of erythromycin. Less severe cases (17 of 32) received erythromycin stearate orally (500 mg 4-times daily) for up to 28 days, while severe cases were treated for the first few days with intravenous erythromycin lactobionate (4 g/day). Weekly chest X-ray examinations revealed prompt resolution. Most patients had no signs and symptoms detectable after 7 days, and none persisted up to 28 days. There were no therapeutic failures and microbiological tests on Day 28 were negative for Legionella pneumophila. It is suggested that the possibility of co-existing legionellosis should be considered in all patients with difficult to treat acute and chronic chest infections, particularly in developing countries where tuberculosis is very common, and treatment instituted or supplemented with erythromycin as the drug of choice.

Prevalence of legionellosis among adults: a study of community-acquired pneumonia in France

Over a 24-month period, 274 patients with community-acquired pneumonia were hospitalized in Departments of Medicine at hospitals in Bordeaux, Lyon, Marseille, and Toulouse. Etiology of the pneumonia was determined either by organism identification or by indirect immunofluorescence in only 139 cases (51%). The most frequently isolated etiological agents were Streptococcus pneumoniae (34 cases), Legionella pneumophila (29 cases) and Mycoplasma pneumoniae (24 cases). The majority of patients with legionellosis were male (79%), middle aged (mean age: 53 years), and living in urban areas (69%). Their clinical features were atypical and did not differ from those of other pneumonias. Four patients with legionellosis (13.8%) died. L. pneumophila was isolated directly in only three instances. The study confirms the high prevalence of legionellosis (20%) among pneumonias of identified etiology. The fact that these cases had an atypical clinical presentation and that isolation of the organism was difficult reinforce the need to apply the CDC criteria for the interpretation of positive serological titers.

[Pneumonia caused by Legionella pneumophila. Report of the 2d Brazilian case]

Os autores relatam um caso de pneumonia por Legionella pneumophila, diagnosticado pela primeira vez em Porto Alegre, Rio Grande do Sul. A hipótese diagnóstica foi confirmada por imunofluorescência indireta nas amostras de soro do paciente enviadas ao C.D.C. (Atlanta — E.U.A.), com títulos de 1:128 na amostra da fase aguda e 1:512 na amostra da fase de convalescença.