A Novel Diagnostic Scoring System to Differentiate between Legionella pneumophila Pneumonia and Streptococcus pneumoniae Pneumonia

Objective We investigated a novel diagnostic scoring system to differentiate Legionella pneumophila pneumonia from Streptococcus pneumoniae pneumonia. Methods We retrospectively reviewed the clinical data of 62 patients with L. pneumophila pneumonia (L-group) and 70 patients with S. pneumoniae pneumonia (S-group). Results The serum sodium (Na) levels tended to be lower according to the severity [age, dehydration, respiratory failure, orientation disturbance, low blood pressure (A-DROP)] score in the L-group. On a multivariate analysis, we found that four factors were independent predictive markers for inclusion in the L-group: relative bradycardia [hazard ratio (HR) 5.177, 95% confidence interval (CI): 1.072-24.993, p=0.041], lactate dehydrogenase (LDH) levels ≥292 IU/L (HR 6.804, 95% CI: 1.629-28.416, p=0.009), C-reactive protein (CRP) levels ≥21 mg/dL (HR 28.073, 95% CI: 5.654-139.462, p<0.001), and Na levels ≤137 meq/L (HR 5.828, 95% CI: 1.411-24.065, p=0.015). Furthermore, a total score [ranging from 0 to 4, the sum of the points for each factor (0 or 1)] ≥3 points indicated a higher probability of inclusion in the L-group than in the S-group. The diagnostic accuracy of a total score of 3 had a sensitivity of 36.3%, specificity of 100%, and area under the curve of 0.682 (95% CI: 0.558-0.806, p=0.004), and that of a total score of 4 had a sensitivity 27.4%, specificity of 98.2%, and area under the curve (AUC) of 0.627 (95% CI: 0.501-0.754, p=0.045). The diagnostic accuracy had low sensitivity but high specificity. Conclusions We found four markers that might be useful for differentiating L-group from S-group and created a novel diagnostic scoring system.

A case of Legionella pneumophila evaluated with CT and ultrasound

A 36-year-old man was admitted to the emergency department of "SS Annunziata" hospital in Chieti complaining of a sharp chest pain arisen some hours before admission. On examination, the patient looked sweaty; his vital signs showed tachycardia and augmented breath rate; sinus tachycardia and normal ventricular repolarization were observed on ECG, and no abnormalities were observed in the echoscan of the hearth. According to the clinical and electrocardiographic findings, and to previous episode of DVT in anamnesis, a thorax CT scan was performed in order to rule out pulmonary embolism. It showed an "area of parenchymal consolidation involving almost all the left lower lobe with patent bronchial structures"; given the patient's CURB 65 score, he was then admitted to the pneumology ward where empiric treatment with levofloxacin (750 mg PO once daily) was initiated. Thoracic ultrasound was performed using a multifrequency convex transducer, and the posterior left area was examined through intercostal approach, placing the patient in a sitting position. A subpleural patchy hypoechoic lesion with irregular boundaries was detected; the maximum diameter was 11 cm, and the multiple hyperechoic spots inside it (elsewhere defined as "air bronchogram") showed no Doppler signal. Given the positive result of the Legionella urinary antigen test, antibiotic treatment was switched to Levofloxacin 1000 mg PO once daily and Claritromicin 500 mg PO twice daily. After 3 days, his clinical conditions improved dramatically. Ultrasound performed after 5 days from the diagnosis showed decreased dimensions of the lesion previously identified (maximum diameter 8.25 cm) and a marked reduction of the hyperechoic spots in it. The patient was discharged in good clinical conditions, and both thorax CT scan obtained after 1 and 4 months from the diagnosis showed radiological resolution of the parenchymal consolidation. The key to ultrasound visualization of pneumonia is its contact with the pleural surface (86-98% in cases of CAP) and the relative loss of aeration of the portion involved by the infection and a concomitant increase in the fluid content. A paradigmatic US image for parenchymal inflammatory infiltrate has not been established yet; anyway, some typical findings, when combined with the clinical features, can confirm the diagnostic hypothesis.

A new ELISA method for serological diagnosis of Legionella pneumophila: use of five purified proteins, FLA, MOMP, MIP, IP, and PILE, as diagnostic antigen

BACKGROUND

Legionella pneumophila plays an important role in human infection. Commercial ELISA kits commonly used, which take Legionella pneumophila whole-cell protein as the coating antigen, often have cross-reactivity among serogroups or species. In this study, five Legionella pneumophila proteins FLA, MOMP, MIP, IP, and PILE were purified and further applied in serological diagnosis of Legionella pneumophila infections compared with R & D Legionella ELISA kits.

METHODS

The five recombinant plasmids pET-fla, pET-momp, pET-mip, pET-ip, and pET-pile were transformed into E. coli BL21 and then induced them with IPTG. The expression products were analyzed by SDS-PAGE and purified by affinity chromatography. Indirect enzyme-linked immunosorbent assays (ELISAs) were established with the five purified proteins FLA, MOMP, MIP, IP, and PILE altogether as the coating antigen and tested for the presence of IgG, IgM, and IgA antibody independently from 50 positive sera and 40 negative sera, compared with R & D IgG, IgM, and IgA Legionella ELISA kits.

RESULTS

The FLA protein about 42 kDa in size, the MOMP protein about 45 kDa, the MIP protein about 40 kDa, the IP protein about 46 kDa, and the PILE protein about 35.7 kDa were separately expressed and purified. Compared with R & D IgG, IgM, and IgA Legionella ELISA kit, the outcome of indirect ELISAs set up with the five purified proteins showed that for IgG the sensitivity was 90.4%, the specificity was 97.4%, the area under ROC curve was 0.939, the kappa value was 0.865, the 95% confidence interval was 0.883 - 0.995. For IgM the sensitivity was 91.8%, the specificity was 95.1%, the area under ROC curve was 0.935, the kappa value was 0.866, the 95% confidence interval was 0.876 - 0.994. For IgA the sensitivity was 93.6%, the specificity was 95.3%, the area under ROC curve was 0.945, the kappa value was 0.889, the 95% confidence interval was 0.890 - 0.999.

CONCLUSIONS

The proteins FLA, MOMP, MIP, IP, and PILE were successfully expressed and purified, and they seemed to be suitable coating antigens for the serological diagnosis of Legionella pneumophila.

Applications of Legionella pneumophila protein FLA and PILE in serological diagnosis

BACKGROUND

Serological testing for antibody against Legionella pneumophila (LP) is often the primary method of screening for possible Lp infections.

METHODS

This study is an attempt to use the Lp protein FLA and PILE as coating antigen for ELISA. First, the coding sequences of the two proteins were cloned into the pET32a(+) vectors. Then the two proteins were produced and purified. The best working concentration of the two proteins as coating antigen was screened separately by criss-cross serial-dilution analysis. Then an ELISA method was developed for Lp antibody detection. The Lp antibody level of 120 serums was detected by both this new ELISA method and the DRG ELISA kit.

RESULTS

The results suggest that protein FLA and PILE as coating antigen of ELISA to detect Lp antibody in serum shows better specificity and positive rate (5%, 3.4%) than the DRG ELISA kit.

CONCLUSIONS

The new ELISA has a high referential value for Legionnaires' disease (LD) diagnosis and provided valuable information for the development of a serodiagnosis Kit for LD.

Patients' age and the dynamics of IgM for L. pneumophila sg1

MATERIAL AND METHODS

The results of IgM L. pneumophila sg1 test in 304 adults and 270 children performed at NIPH-NIH in 2004-2007 were analyzed to determine the effects of patients' age and the interval between collected sera on the results and the interpretation.

RESULTS

Significant difference in the level of IgM, depending on the age of the patients (P0 = 0.0084) was found. Positive results (in total 20.4% of patients) were the most frequently observed in patients aged 19-29 years (42.5%), and the least--in patients 60 y.o. and < 2 y.o. (7%). Average and median levels of IgM in these two groups (+60 y.o. and < 2 y.o.) were similar and significantly different from the results in the other groups. From 44 adults and 33 children > or = 2 sera were collected. There was a significant difference in the interval between collecting the first and second serum sample in adults (mainly 3-5 weeks) and children (mainly 2-4 weeks). Significant increase of IgM levels was observed in children when the interval between 1 and 2 sample didn't exceed 4 weeks, while in adults this change was also observed at > 5 weeks (25% of patients). No significant differences in the analysis of the IgM ratio in children (1.25-14) and adults (1.5-26) was found, but longer persistence of IgM in adults than in children was observed.

CONCLUSIONS

Demonstrated trend of faster decline in the level of IgM among children than in adults indicated that in suspected case of legionellosis in children, the serum sample should be taken up to 4-5 weeks after the onset, and at intervals of 1-2 weeks maximum.

Dynamics of peripheral blood lymphocyte subpopulations in the acute and subacute phase of Legionnaires' disease

STUDY OBJECTIVE

Absolute lymphocytopenia is recognised as an important hallmark of the immune response to severe infection and observed in patients with Legionnaires' disease. To explore the immune response, we studied the dynamics of peripheral blood lymphocyte subpopulations in the acute and subacute phase of LD.

METHODS AND RESULTS

EDTA-anticoagulated blood was obtained from eight patients on the day the diagnosis was made through detection of L. pneumophila serogroup 1 antigen in urine. A second blood sample was obtained in the subacute phase. Multiparametric flow cytometry was used to calculate lymphocyte counts and values for B-cells, T-cells, NK cells, CD4+ and CD8+ T-cells. Expression of activation markers was analysed. The values obtained in the subacute phase were compared with an age and gender matched control group. Absolute lymphocyte count (×10⁹/l, median and range) significantly increased from 0.8 (0.4-1.6) in the acute phase to 1.4 (0.8-3.4) in the subacute phase. B-cell count showed no significant change, while T-cell count (×10⁶/l, median and range) significantly increased in the subacute phase (495 (182-1024) versus 979 (507-2708), p = 0.012) as a result of significant increases in both CD4+ and CD8+ T-cell counts (374 (146-629) versus 763 (400-1507), p = 0.012 and 119 (29-328) versus 224 (107-862), p = 0.012). In the subacute phase of LD, significant increases were observed in absolute counts of activated CD4+ T-cells, naïve CD4+ T-cells and memory CD4+ T-cells. In the CD8+ T-cell compartment, activated CD8+ T-cells, naïve CD8+ T-cell and memory CD8+ T-cells were significantly increased (p<0.05).

CONCLUSION

The acute phase of LD is characterized by absolute lymphocytopenia, which recovers in the subacute phase with an increase in absolute T-cells and re-emergence of activated CD4+ and CD8+ T cells. These observations are in line with the suggested role for T-cell activation in the immune response to LD.

Sero diagnosis of Legionella infection in community acquired pneumonia

BACKGROUND & OBJECTIVES

Legionella pneumophila has been increasingly recognized as an emerging pathogen responsible for community acquired pneumonia (CAP) worldwide. In India, the actual burden is not known. The present study was thus undertaken to see the presence of Legionella infection in patients with community acquired pneumonia admitted in a tertiary care centre in north India.

METHODS

Both children and adults (n=113) with symptoms of pneumonia were included in the study. Clinical samples (blood, urine, nasopharyngeal aspirates, bronchoalveolar lavage, sputum, etc.) were collected and subjected to culture and other tests. Enzyme linked immunosorbent assay (ELISA) was done by commercial kits for all the three classes of immunoglobulins (IgG, IgM & IgA). Urinary antigen was also detected using commercial kits. Culture was performed on 51 respiratory tract fluid samples. Serum samples of 44 healthy controls were also screened for the presence of anti-legionella antibodies (IgG, IgM & IgA).

RESULTS

Thirty one of the 113 cases (27.43%) were serologically positive. Anti-legionella IgG, IgM and IgA antibodies were positive in 7.96, 15.92 and 11.50 per cent patients respectively. In controls, seropositivity was 9.09 (4/44). IgA was positive in 3 and IgM, IgG combined in one. Antigenuria detection by Microwell ELISA kit showed 17.69 per cent positivity. Four antigenuria positive patients were also serologically positive; of these two patients were positive for IgM, hence considered as confirmed cases of Legionella infection. None of the sample was culture positive.

INTERPRETATION & CONCLUSIONS

Combination of serology and antigenuria detection may be a valuable tool for the diagnosis of Legionella infection in absence of culture positivity. In order to evaluate the actual burden of Legionella in community acquired pneumonia, further studies with larger samples need to be done.

[Microbiological diagnosis of respiratory infections caused by Legionella pneumophila]

Legionella pneumophila is an important causative agent of pneumonia in humans which is difficult to diagnose because the signs and symptoms are nonspecific and do not distinguish Legionella infection from other common causes of pneumonia. Currently, the diagnosis of Legionnaires' disease is based on phenotyping (culture, antibody detection in human sera, antigen detection in urine) and genotyping methods such as PCR (polymerase chain reaction). This review focuses on current diagnostic tests for surveillance of Legionella pneumophila infections in Poland.

Occurrence and distribution of sequence types among Legionella pneumophila strains isolated from patients in Germany: common features and differences to other regions of the world

A total of 105 unrelated clinical isolates of Legionella pneumophila were randomly selected from the German National Legionella strain collection and typed by monoclonal antibody (MAb) subgrouping and a seven-gene locus sequence-based typing (SBT) scheme. According to the case definitions of the European Working Group for Legionella Infections, 19 of the isolates tested were travel-associated, 38 were community-acquired and 48 were of nosocomial origin. Eighty-four of these strains belonged to serogroup 1, 20 belonged to other serogroups, and one isolate could not be serogrouped. The majority of strains among the travel-associated and community-acquired cases were MAb3-1-positive. The most common sequence type (1, 4, 3, 1, 1, 1, 1) was found in 20 isolates in 11 cities; other allelic profiles also found in Europe (2, 3, 9, 10, 2, 1, 6), (1, 3, 9, 10, 2, 1, 6), (2, 6, 17, 14, 13, 11, 11) and (3, 4, 1, 1, 1, 9, 1) were detected among the German isolates but at a low frequency. In contrast, some SBT are unique to Germany, including (3, 4, 1, 3, 35, 9, 11), which was found among five isolates from patients in Berlin. In concordance with European data, a significant portion of the L. pneumophila strains isolated from patients in Germany belong to clones that occur throughout the world and which are responsible for the majority of clinical cases.

[Immunological response (IgM) to Legionella pneumophila infection in children]

Most of the publications report cases of Legionella infection among adults. In our studies the level of IgM to Legionella pneumophila sg 1 was determined by ELISA method in serum samples of 144 children with symptoms of respiratory tract infections. Children were from 5 months to 18 years old. The significant level of IgM was found in 41 sera collected from 34 children aged 2 years and above. There were samples collected from 21 girls and 13 boys. The highest percentage of significant level of IgM was found in the age group 4-10 years (31.8%) and 10-14 years (31.7%). Among the youngest children (below 2 years) the equivocal results were found in 6 samples. The significant difference in IgM level was found between the children age groups. There was not found the significant differences in IgM level depending on gender. Obtained results indicated the importance of such kind of studies and necessity of adjusting cut-off values to age groups of children.

Evaluation of real-time PCR for the early detection of Legionella pneumophila DNA in serum samples

Legionella pneumonia can be difficult to diagnose. Existing laboratory tests all have shortcomings, especially in the ability to diagnose Legionnaires' disease (LD) at an early stage of the disease in a specimen that is readily obtainable. The aim of this study was to assess the performance of PCR as a rapid diagnostic method and to compare the results of different PCR assays of serum samples from patients with LD. Samples included 151 serum samples from 68 patients with proven LD and 60 serum samples from 36 patients with respiratory tract infections other than Legionella. PCR assays were based on the 5S rRNA gene, 16S rRNA gene and the mip gene. The samples from patients with infections caused by pathogens other than Legionella all tested negative in PCR. Among the patients with proven LD 54.4 % (37/68) tested positive in 5S rRNA PCR, 52.9 % (36/68) in mip gene PCR and 30.9 % (21/68) in 16S rRNA PCR in the first available serum sample. The association between threshold cycle value in 5S PCR positive serum samples (n=49) and C-reactive protein value was determined, and showed a strong negative correlation (Pearson correlation coefficient r=−0.63, P<0.0001). In addition to existing tests for the diagnosis of LD, detection of Legionella DNA in serum could be a useful tool for early diagnosis of LD caused by any Legionella species and serogroup, and has the potential to provide a diagnosis in a time frame that could affect initial infection management.

Biochemical and immunologic features of an outbreak of Legionnaires disease: comparative study between community-acquired pneumonias

Legionella pneumophila has been recognized as an important cause of community- and hospital-acquired pneumonia. This study evaluates the interrelationship between that patients group with Legionnaires disease (LD) and the possible factors that may predispose hosts to acquire this infection. Likewise, we search for preliminary biochemical and immunologic evidences that could help physicians to differentiate between LD and other pneumonias. We analyzed biochemical parameters and immunoglobulin levels in 61 LD patients and a control group (n = 30) who were non-Legionella pneumonia diagnosed. We observed statistically significant differences in LD patients versus control group in serum sodium, albumin, gamma-band, IgG levels, (P < .01) and for total proteins, aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) (P < .05). Our study shows a trend between the presence of LD and immunoglobulin deficiencies in the group studied. Deficit in IgG or IgG plus IgM, during the exposure period, may predispose individuals to suffer legionellosis (P < .05). Overall, hypoalbuminemia, hyponatremia, and high AST and LDH levels can represent a useful prognostic marker in patients with severe pulmonary infection suspected to be legionellosis.

Evaluation of Vircell enzyme-linked immunosorbent assay and indirect immunofluorescence assay for detection of antibodies against Legionella pneumophila

We evaluated the abilities of the Vircell immunoglobulin G (IgG) and IgM indirect immunofluorescence assay (IFA) for Legionella pneumophila serogroup 1, the IgM and IgG enzyme-linked immunosorbent assay (ELISA) for Legionella pneumophila serogroup 1, and the IgM-plus-IgG ELISA for Legionella pneumophila serogroups 1 to 6 to diagnose Legionnaires' disease (LD) in a well-described sample of patients with and without LD. Also, we determined the agreements, sensitivities, and specificities of the different Vircell assays in comparison to a validated ELISA (Serion classic ELISA). Clinical sensitivity and specificity were 74.6% and 96.6%, respectively, for the IgM IFA, 65.1% and 88.0% for the IgG IFA, 92.3% and 100% for the IgM ELISA, 43.3% and 96.6% for the IgG ELISA, and 90.8% and 100% for the IgM-plus-IgG ELISA. Compared to Serion classic ELISA, agreement, sensitivity, and specificity were 80.0%, 83.1%, and 78.4%, respectively, for the IgM IFA, 75.2%, 66.0%, and 79.5% for the IgG IFA, 89.5%, 82.0%, and 97.6% for the IgM ELISA, 81.9%, 88.9%, and 78.0% for the IgG ELISA, and 93.5%, 90.0%, and 96.6% for the IgM-plus-IgG ELISA. The value of a positive diagnostic result obtained by the Vircell IgM IFA, the Vircell IgG IFA, and the Vircell IgG ELISA might not be acceptable for a diagnostic assay. Both the high specificities and sensitivities of the Vircell IgM ELISA and the IgM-plus-IgG ELISA and the high correlation with the Serion classic ELISA indicate that they are useful in the diagnosis of LD.

Procalcitonin and neopterin correlation with aetiology and severity of pneumonia

OBJECTIVE

Clinical outcome of pneumonia depends on a multifaceted treatment approach. Not only diagnostic methods but also early indicators of the degree of inflammatory response can aid in therapeutic decisions. The objective was to evaluate the usefulness of procalcitonin and neopterin in distinguishing among aetiologies as well as severity in patients with pneumonia.

PATIENTS

A total of one hundred sixteen patients with clinical, radiographic and microbiological diagnosis of pneumonia were grouped by aetiology, pneumonia severity index, and by the presence of unilobar or multilobar radiographic pulmonary infiltrates. Procalcitonin and neopterin were measured by immunoassays.

RESULTS

Patients with pneumococcal pneumonia presented elevated procalcitonin and neopterin levels, being higher in bacteraemic than in non-bacteraemic pneumonia. Patients with Legionella pneumonia presented elevated neopterin levels and slightly elevated procalcitonin levels. Patients with tuberculosis and Pneumocystis jirovecii pneumonia presented elevated neopterin and low or not detectable procalcitonin. Procalcitonin and neopterin levels were increased in high-risk classes of pneumonia severity index. Both parameters yielded significant correlation to the radiographic extent and also to young age.

CONCLUSIONS

Procalcitonin and neopterin levels vary depending on age, aetiology and severity of pneumonia. Together with clinical and microbiological data, combined measurement can help to identify patients who might benefit from additional therapies.

Legionnaires' disease outbreak in Rome, Italy

Between August and October 2003, 15 cases of Legionnaires' disease were detected in the 9th district of Rome. To identify possible sources of Legionella exposure, a matched case-control study was conducted and environmental samples were collected. Hospital discharge records were also retrospectively analysed for the period July-November 2003, and results were compared with the same period during the previous 3 years. The case-control study revealed a significantly increased risk of disease among those frequenting a specific department store in the district (OR 9.8, 95% CI 2.1-46.0), and Legionella pneumophila was isolated from the store's cooling tower. Genotypic and phenotypic analysis of human and environmental isolates demonstrated that the cluster was caused by a single strain of L. pneumophila serogroup 1, and that the cooling tower of the store was the source of infection. The increased number of hospital admissions for microbiologically undiagnosed pneumonia during the study period may indicate that some legionellosis cases were not identified.

Legionella Pneumonia and Serum Procalcitonin

Procalcitonin is a specific marker of severe bacterial infections with systemic inflammation. Quantitative evaluation of serum procalcitonin was performed in 140 patients with Legionella pneumonia. Positive values (>0.5 ng/mL) were found in 57.1% of the subjects. The positive sample rate was higher in early sera (73.9% in the first week) and decreased progressively. Mean values and the positive sample rate (69.8%) were higher in sera collected in the first 2 weeks of disease. Procalcitonin was positive in 86.7% of legionellosis cases confirmed by culture and mean positive values were significantly higher (P < 0.001) than those of culture-negative subjects. We conclude that procalcitonin can represent a useful prognostic marker for severe suspected Legionella pneumonia in the first 2 weeks of disease.

Role of interferon-gamma in inflammatory responses in murine respiratory infection with Legionella pneumophila

The role of interferon (IFN)-gamma in host inflammatory responses, including inflammatory cytokine production, in experimental pneumonia with Legionella pneumophila was examined in IFN-gamma knockout (IFN-gamma-/-) mice. IFN-gamma-/- mice and wild-type BALB/cA mice were inoculated intranasally with L. pneumophila strain KC. The survival rate of IFN-gamma-/- mice was significantly lower than that of control mice. Viable bacterial counts in lungs and blood showed a rapid and continuous increase in IFN-gamma-/- mice, in contrast to a gradual decrease in the lungs and an intermittent bacteraemia in control mice. Histopathological analysis of L. pneumophila-infected lung tissues demonstrated mild pneumonia in control mice, whereas severe pneumonia was shown in IFN-gamma-/- mice. During the late stages of infection, the number of total bronchoalveolar lavage (BAL) cells was significantly higher in IFN-gamma-/- than in control mice. The concentrations of tumour necrosis factor-alpha and interleukin-1beta in sera of IFN-gamma-/- mice were significantly lower in control mice during the early stages of infection, suggesting suppressed production of inflammatory cytokines in IFN-gamma-/- mice. In contrast, during the late stages of infection, the levels of these cytokines were significantly higher in sera of IFN-gamma-/- mice than in control mice, suggesting severe and systemic infection in IFN-gamma-/- mice. The findings suggest that retardation of host immune responses, including inflammatory cytokine production caused by deficiency of IFN-gamma, might allow the bacteria to grow and cause fulminant pneumonia.

BMS-284756 (T-3811ME) a new fluoroquinolone: in vitro activity against Legionella, efficacy in a guinea pig model of L. pneumophila pneumonia and pharmacokinetics in guinea pigs

The activity of BMS-284756 was studied against extracellular Legionella spp. and intracellular Legionella pneumophila, and for the treatment of guinea pigs with L. pneumophila pneumonia. The BMS-284756 MIC(50) of 22 different Legionella spp. strains was 0.008 mg/L, compared with 0.016 and 0.125 mg/L for levofloxacin and azithromycin, respectively. BMS-284756 (1 mg/L) reduced the intracellular concentrations of two L. pneumophila strains grown in guinea pig alveolar macrophages by c. 1.5 log(10 )cfu/mL, and was more active than erythromycin, but less active than azithromycin or levofloxacin at the same drug concentrations. Efficacy studies of BMS-284756, levofloxacin and azithromycin were performed in guinea pigs with L. pneumophila pneumonia. In infected guinea pigs given BMS-284756 10 mg/kg ip, mean peak plasma levels were 1.8 mg/L at 0.5 h and 0.7 mg/L at 1 h post-dose. The elimination half-life in plasma was 0.5 h, and the AUC(0-24 )was 1.7 mg*h/L, about 2% of the AUC(0-24 )for a single 400 mg oral dose in man. Sixteen of 18 L. pneumophila-infected guinea pigs treated with BMS-284756 10 mg/kg ip once daily for 5 days survived for 7 days post-antimicrobial therapy, as did 11 of 12 guinea pigs treated with azithromycin 15 mg/kg ip once daily for 2 days. All 12 animals that were treated with levofloxacin 10 mg/kg ip once daily for 5 days survived. None of 12 control animals treated with saline survived. Animals treated with BMS-284756 had significantly higher residual lung counts of L. pneumophila at the end of therapy than did animals treated with levofloxacin or azithromycin, which may be attributable to the very low drug concentrations that were obtained. BMS-284756 was more active than erythromycin against L. pneumophila in infected macrophages, and effectively treated animals with experimental L. pneumophila pneumonia. These data support further studies of BMS-284756 for the treatment of Legionnaires' disease.

[A case of severe Legionella pneumonia monitored with serum SP-A, SP-D, and KL-6]

A 67-year-old man was admitted for acute pneumonia on July 20th, 1999. Chest radiographs disclosed dense consolidation in the right lower lung fields. After admission, the pneumonia underwent rapid advance. On the basis of serological findings and cultures of pleural effusion and sputum, the patient was given a diagnosis of acute pneumonia caused by Legionella pneumophila 1 a. He gradually recovered from the pneumonia by means of chemotherapy using EM, RFP, Mino, gammaglobulins and steroids. The serum SP-A, SP-D, and KL-6 peaked on July 23rd, July 30th, and August 12th, respectively.

Potential importance of Legionella species as etiologies in community acquired pneumonia (CAP)

Large percentages of patients with community acquired pneumonia (CAP) do not have a defined etiology. Between 1992-1993, 99 acute and convalescent sera were collected from patients with CAP of unknown etiology. The sera were tested using an indirect immunofluorescence antibody assay (IFA) against the following antigens: Legionella pneumophila, serogroups 3,5,6 and 7 and L. longbeachae, L. anisa, L. bozemanii and Legionella-Like Amoebal Pathogens (LLAP). A four-fold rise in titer to at least one of the antigens tested, was seen in 14% of patients; 8% to L. bozemanii, 4% to L. anisa, 2% to S. lyticum, 2% to LLAP 10 and 1% each to LLAP 1, 6 and 9. Two patients reacted to several antigens. These results indicate that other species of legionella may be important in the etiology of CAP. L. bozemanii was the organism identified in the majority of these infections. Better diagnostic studies i.e. cultures, serologies and urinary antigen testing, which recognize legionella isolates other than L. pneumophila serogroup 1 need to be developed.

The incidence of Legionella pneumophila: a prospective study in a tertiary care hospital in India

The prevalence of Legionella pneumophila causing community-acquired pneumonia (CAP) in patients who were admitted to hospital was investigated. Between April 1997 and December 1998, 60 patients admitted to the All India Institute of Medical Sciences with CAP, were included in the study. Aetiological diagnosis was based on the results of routine microbiological blood culture for bacteria and serological test by enzyme linked immunosorbent assay (ELISA) for L. pneumophila serogroup 1-7. Eight (13%) patients had a conventional bacterial aetiology and nine (15%) had serological evidence of recent infection with L. pneumophila. Legionella pneumophila may be an important cause of CAP in adults in developing countries. Empiric antimicrobial treatment should include a combination of agents to cover both atypical agents and bacterial pathogens.

Single clonal origin of a high proportion of Legionella pneumophila serogroup 1 isolates from patients and the environment in the area of Paris, France, over a 10-year period

Arbitrarily primed PCR with three primers and pulsed-field gel electrophoresis were used to characterize a set of 75 clinical Legionella pneumophila serogroup 1 isolates, with no apparent epidemiological link, obtained from 24 hospitals in Paris, France, from 1987 to 1997. Unexpectedly, 25 clinical isolates from 15 hospitals had an identical profile (termed type A) by both methods. The same profile was subsequently found in 16 of 64 randomly selected environmental L. pneumophila serogroup 1 isolates from 15 different sites in the Paris area. There was no evidence of geographic clustering or a peak incidence of type A isolation. Type A has not been found in France outside the Paris area, suggesting that a particular type of L. pneumophila serogroup 1 is specifically present in the Paris water distribution network.

Detection of Legionella DNA in guinea pig peripheral leukocytes, urine and plasma by the polymerase chain reaction

Legionella DNA has been detected in respiratory tract, serum and urine samples from patients with pneumonia by the polymerase chain reaction. A guinea pig model was used to assess whether Legionella DNA could also be detected in peripheral leukocytes during active infection. Ten guinea pigs were infected intraperitoneally with Legionella pneumophila serogroup 1, and leukocyte, plasma and urine samples were collected immediately before inoculation and on days 1, 3, 7 and 14 thereafter. All samples were tested for Legionella DNA by the polymerase chain reaction. Overall, Legionella DNA was detected in 55% of leukocyte samples, 28% of urine samples and 21% of plasma samples collected after inoculation. The sensitivity of the polymerase chain reaction on leukocytes was highest for samples collected within 3 days of inoculation. Further studies testing leukocyte samples from human Legionella infection are required to confirm these observations.

Remission of hairy cell leukemia without treatment

A patient is described with hairy cell leukemia, in whom a remission occurred spontaneously or in association with Legionnaires or subsequent HIV infection. Possible pathophysiological mechanisms are reviewed. Currently it is seventeen years since the diagnosis of hairy cell leukemia and fourteen years since the infusion of HIV infected blood. Hairy cell leukemia has yet to return and HIV infection has not progressed to AIDS.

IL-10 enhances the growth of Legionella pneumophila in human mononuclear phagocytes and reverses the protective effect of IFN-gamma: differential responses of blood monocytes and alveolar macrophages

Legionella pneumophila is a facultative intracellular pathogen that parasitizes human alveolar macrophages and blood monocytes recruited to the lungs. The inhibitory cytokines IL-10, TGF-beta, and IL-4 generally deactivate macrophages and permit enhanced microbial growth in some models of intracellular infection, but their effects on human alveolar macrophages are unknown. We hypothesized that inhibitory cytokines could facilitate the infection of human alveolar macrophages and monocytes by virulent intracellular lung pathogens. Therefore, we tested the effects of IL-10, TGF-beta, and IL-4 in an in vitro model of human alveolar macrophage and monocyte infection with L. pneumophila. We found that unstimulated alveolar macrophages supported over 100-fold greater L. pneumophila growth than did unstimulated monocytes. IL-10 treatment significantly enhanced L. pneumophila growth in monocytes, and completely reversed the protective effect of IFN-gamma against intracellular L. pneumophila replication. IL-10 had similar but less potent effects on alveolar macrophages. In contrast, TGF-beta and IL-4 had no significant effects on L. pneumophila growth in resting or IFN-gamma-activated monocytes or alveolar macrophages. IL-10 blocked TNF-alpha production by infected cells, but exogenous TNF-alpha did not reverse the activating defect in cells cocultured with IFN-gamma and IL-10. Finally, L. pneumophila-infected monocytes produced substantially more IL-10 than did infected alveolar macrophages. In summary, IL-10 significantly enhances the growth of L. pneumophila in human monocytes, reverses the protective effect of IFN-gamma, blocks TNF-alpha secretion, and is secreted by infected monocytes and alveolar macrophages. Induction of IL-10 may be a virulence mechanism that promotes intracellular bacterial replication in human legionellosis.

Use of the polymerase chain reaction to detect Legionella DNA in urine and serum samples from patients with pneumonia

Legionella pneumonia can be difficult to diagnose. Existing laboratory tests for detecting Legionella species lack sensitivity or provide only a retrospective diagnosis. We used the polymerase chain reaction (PCR) with primers that amplify a 104-base pair segment of the coding region of the 5S tRNA gene to detect Legionella DNA in urine and serum samples from patients with pneumonia. Stored urine and serum samples from patients enrolled in two prospective studies of pneumonia were tested. Legionella DNA was detected in urine and/or serum samples from 18 (64%) of 28 patients with legionella pneumonia diagnosed by conventional tests, but it was not detected in urine or serum samples from 24 patients with pneumonia due to other organisms. The sensitivity of PCR improved to 73% if testing was restricted to samples taken within 4 days of the onset of symptoms. Detection of Legionella DNA in urine and serum promises to be a valuable tool for the rapid diagnosis of legionella pneumonia.

Increased plasma adenosine deaminase activity in the early phase of Legionella pneumophila infection in guinea pigs

We measured adenosine deaminase (ADA) activity in a guinea pig model of Legionella pneumophila infection. Female Hartley guinea pigs were inoculated intraperitoneally with one-quarter of the LD50 dose of L. pneumophila Philadelphia-1 strain. Control groups were inoculated with clinical isolates of Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae or Klebsiella pneumoniae. Each group consisted of 5 animals. ADA activity in plasma was assayed calorimetrically before and at various intervals after infection by measuring the amount of ammonia produced after adenosine was added to plasma samples. ADA activity before inoculation was 25.6 +/- 6.0 IU/1, it reached 174.4 +/- 60.0 IU/1 on day 3 after inoculation of L. pneumophila. ADA activity returned to normal levels on day 14. ADA activity did not increase significantly in guinea pigs infected with the other types of bacteria. These findings suggest that measurement of plasma ADA activity may be useful for the diagnosis of Legionella infection.

[Epidemiologic outbreak of Legionnaire's disease in an open community: 10 years later]

AIM

The aim of this study was to describe an outbreak of pneumonia due to L. pneumophila in Llutxent (Valencia) and to know the evolution of these patients 10 years after.

METHODS

The definition and identification of cases was carried out with the use of IFI techniques. An environmental and epidemiological study was performed for determining the origin and route of disease dissemination. The patients were clinically, functionally and serologically reviewed 10 years after.

RESULTS

From July to August 1983, 35 cases of pneumonia were reported in Llutxent (rate = 1.5%). L. pneumophila serotype 1 was serologically identified and was also found in shower heads and toilet tanks (in the context of the entry of sand into the drinking water supply). Ten years after, the patients had no respiratory symptoms with titers of antibodies versus Legionella sp. being under 1/64.

CONCLUSIONS

The authors emphasize the involvement of the distribution system for drinking water to the population in this first outbreak of Legionnaires disease in an open community. The health care measures taken were effective as demonstrated by no further pneumonias being recorded and after normalization of the rate of antibodies on a 10 year review.

Myocarditis: a rare complication during Legionella infection

Legionella often causes systemic manifestations. The clinical spectrum now includes cardiac legionellosis. The first case of myocarditis was reported by Gross in 1981. To date few additional cases have been described. Myocardial involvement might be more frequent than supposed in legionnaires' disease.

[Comparative study of Legionella pneumonia and other nosocomial-acquired pneumonia]

We studied 20 cases of legionella pneumonia and 23 cases of non-legionella pneumonia. Hyponatremia, elevated GOT and GPT were higher (P < 0.05) in legionella pneumonia group. In spite of the number of cases with diarrhoea, dyspnea, nervous symptoms, myalgia and complication were higher, especially with diarrhoea in legionella pneumonia group when compared to non-legionella pneumonia group, but the number of cases in both types of pneumonia did not show a statistically significant difference.

A framework for investigating geographical variation in diseases, based on a study of Legionnaires' disease

Demonstration of geographical variations in disease can yield powerful insight into the disease pathway, particularly for environmentally acquired conditions, but only if the many problems of data interpretation can be solved. This paper presents the framework, methods and principles guiding a study of the geographical epidemiology of Legionnaires' Disease in Scotland. A case-list was constructed and disease incidence rates were calculated by geographical area; these showed variation. Five categories of explanation for the variation were identified: short-term fluctuations of incidence in time masquerading as differences by place; artefact; and differences in host-susceptibility, agent virulence, or environment. The methods used to study these explanations, excepting agent virulence, are described, with an emphasis on the use of previously existing data to test hypotheses. Examples include the use of mortality, census and hospital morbidity data to assess the artefact and host-susceptibility explanations; and the use of ratios of serology tests to disease to examine the differential testing hypothesis. The reasoning and process by which the environmental focus of the study was narrowed and the technique for relating the geographical pattern of disease to the putative source are outlined. This framework allows the researcher to plan for the parallel collection of the data necessary both to demonstrate geographical variation and to point to the likely explanation.

[The clinical picture of legionnaires' disease]

The results of the clinico-laboratory study of 12 cases of acute pneumonia of Legionella etiology are presented. The laboratory diagnosis of Legionella infection was carried out by the study of paired sera in the passive hemagglutination test with the use of Legionella pneumophila (serotype 1) erythrocyte diagnosticum. The clinical picture of pneumonia was characterized by a severe and moderate course of the disease. Characteristic symptoms indicating the presence of indurations and infiltrations in the lung tissue were registered. Roentgenological examination revealed that the foci of pulmonary tissue infiltration appeared in the segments of the lower lobes of both lungs. In 6 patients neutrophil leukopenia, in 4 patients relative lymphocytopenia, in 5 patients monocytopenia, in 11 patients the increase of the erythrocyte sedimentation rate and in 4 patients normochromic anemia were registered. More seldom changes in the levels of residual nitrogen, urea, fibrinogen and transaminases were observed. In most cases the resolution of pneumonia was observed on weeks 2-3 of treatment. In this treatment erythromycin, rifampicin and oleandomycin, used in combination, used in combination with detoxication and infusion therapy, vitamins, vascular and other symptomatic remedies, proved to be most effective. The cases of Legionella infection under study were sporadic and epidemiologically unrelated. The severity of the course of the disease depended mainly on the general state of the patient prior to infection, age and concomitant diseases.

Cytomegalovirus and legionella species as the cause of liver enzyme elevations in haemodialysis patients

We conclude that reinfection or recurrent infection with CMV or legionella may be responsible for serum glutamic-pyruvic transaminase (SGPT) elevations in up to one fourth of haemodialysis patients. Since NANB infection or asymptomatic coinfection with these agents cannot be discounted with certainty, it seems prudent to maintain haemodialysis patients with abnormal liver-function tests on Body Fluid Precautions, even if they remain asymptomatic.

[Adult respiratory distress syndrome in legionella pneumonia--successful treatment with extracorporeal CO2 elimination procedures]

We report on successful treatment of an 46-year-old patient with ARDS (Adult Respiratory Distress Syndrome), caused by legionella-pneumophilia-pneumonia. The treatment with conventional artifical mechanical ventilation had failed. The new method of extracorporeal CO2-Elimination and low frequency positive pressure ventilation (ECCO2-R-LFPPV), introduced by L. Gattinoni (2) was in that case of severest ARDS very helpful. Supported by antimicrobial therapy with Erythromycin and Rifampicin the lung function could be improved to "restitutio ad integrum". Changes in chest radiographs, clinical parameters of ventilation, gas exchange and haemodynamics as well as the results of sequential pulmonary studies are demonstrated and discussed.

Characteristics of anti-Legionella antibodies in patients infected with Legionella pneumophila serogroups 1, 6, and 10

Nosocomial infections with Legionella pneumophila serogroups 1 and 10 in the Leiden University Hospital and infections with L. pneumophila serogroup 6 in neighboring hospitals gave us an opportunity to study the development of opsonizing antibodies against L. pneumophila serogroups 1, 6, and 10 in the serum of 13 patients. Seven of these patients were infected with L. pneumophila serogroup 1, two were infected with serogroup 6, and four were infected with serogroup 10. The opsonic cross-reactivity of antibodies against these serogroups of L. pneumophila and complement involvement in opsonization were also investigated. Convalescent-phase sera from patients infected with L. pneumophila serogroup 1 or 6 were able to promote ingestion of these serogroups by polymorphonuclear leukocytes, whereas ingestion of L. pneumophila serogroup 10 was enhanced only in the presence of convalescent-phase sera from patients infected with this serogroup. Opsonization of L. pneumophila serogroups 1, 6, and 10 was complement dependent.

Are health care workers at risk for infection during an outbreak of nosocomial Legionnaires' disease?

We studied data from 500 health care workers to answer the question: Are health care workers at risk for infection during an outbreak of nosocomial Legionnaires' disease? These workers were employed at a hospital where eight cases of nosocomial Legionella pneumophila serogroup 1 pneumonia occurred over a 4-week period. The source was potable water. Acute-phase blood samples were collected on the day the water supply was decontaminated, convalescent samples were collected 4 to 6 weeks later from 373 subjects, and a single serum sample was obtained from an additional 127 subjects. Antibody titers to L. pneumophila were determined by an indirect immunofluorescent antibody (IFA) technique and by a microagglutination assay with the epidemic strain as the test antigen. Subjects who had an IFA titer of greater than or equal to 1:256 were retested with an anti-human IgM conjugate. None of the 373 health care workers had a fourfold rise in antibody titer. The geometric mean antibody titer of 73.8 for the 500 health care workers was significantly higher than that of 68.1 for 976 blood donors (p less than 0.01). Only 2.4% had recent infection as evidenced by a microagglutination test, despite the fact that 84% were susceptible. We conclude that in the setting of a short-term outbreak of Legionnaires' disease caused by contaminated potable water the risk of infection among health care workers is low: 2.4% or less.

Clinical chemical responses to experimental airborne legionellosis in the guinea-pig

Legionella pneumophila infection of guinea-pigs by the aerosol route with either of two strains, one (serogroup I) giving an acute the other (serogroup 3) giving a protracted illness, induced a pyrexia and similar pneumonic lesions. With both strains there was a bacteraemia with early decreases in serum iron and zinc and increases in serum copper concentrations. Marked changes in other serum components were evident only in those animals which had protracted illness (serogroup 3-infected animals). These included transient increases in aminotransferase, creatine kinase and sorbitol dehydrogenase activities and triglyceride levels, together with gradual decreases in alkaline phosphatase and leucine aminopeptidase activities. Serum lysozyme activity and acute-phase protein synthesis increased, as did the ratio of phenylalanine to tyrosine. The findings confirm the relevance of the aerosol-infected guinea-pig model for the investigation of the disease processes and evaluation of therapeutic measures for use in man.

Changes in iron and transferrin levels and body temperature in experimental airborne legionellosis

Guinea pigs were infected with either 5 or 100 cfu of Legionella pneumophila by aerosol exposure. Between two and 10 days after infection, groups of animals were killed, and their lungs and spleen were removed and cultured quantitatively. L. pneumophila multiplied in the lungs and spread to the spleen; the organisms were cleared first from the spleen and then the lungs. Significant changes were demonstrated in serum iron and transferrin levels and body temperature. The body temperature correlated directly and the serum iron concentration correlated inversely with the number of L. pneumophila recovered from the lungs but not from the spleen. These data suggest that fever and iron may restrict the growth of L. pneumophila in vivo.

Myelosuppression in Legionnaires' disease

A patient undergoing examination for moderately severe renal insufficiency had fulminant five-lobed pneumonia caused by Legionella pneumophila. Her clinical course was complicated by granulocytopenia. Bone marrow aspiration showed notable inhibition of myelopoiesis, involving all stages of maturation. The presence of a serum inhibitor of granulopoiesis was demonstrated by in vitro bone marrow culture. Normal bone marrow cultured in the presence of serum from two normal control subjects yielded 69 +/- 5.2 (mean +/- SE) and 61 +/- 5 granulocyte colonies. When the patient's serum was substituted for normal human serum only 14.3 +/- 2.3 colonies were formed. Each of the drugs to which she had been exposed was tested in the in vitro system, using therapeutic concentrations, and none showed significant suppression of granulocyte colony formation. These observations indicate that legionnaires' disease was associated with a serum factor that notably inhibited the growth of granulocyte colonies in this patient.

Legionnaires' disease with severe hypoxemia and saddleback fever

In the case of Legionnaires' disease described, severe respiratory problems necessitated mechanical ventilatory support, tracheal intubation, and positive end-expiratory pressure. Fever was eliminated with erythromycin therapy but returned after five days, and lung infiltrates spread. After supplementary treatment with other antibiotics and methylprednisolone sodium succinate, both the fever and the infiltrates disappeared. We feel that the multisystem involvement and the recrudescence of fever in our patient emphasize the wide spectrum of characteristics of Legionnaires' disease and the importance of continuation of antibiotics for a prolonged period to eradicate infection.

Legionnaires' disease: concentrations of selenium and other elements

Selenium concentrations in the serums of 17 acutely ill Legionnaires' disease patients were significantly lower than in their matching convalescent-phase serums. This trend was not observed in ten similarly paired samples of serum from control patients with pneumonia. There were no significant differences in the concentrations of nickel, copper, bromine, rubidium, lead, barium, or titanium in the serums of Legionnaires' disease and control patients.