Legionella pneumophila serogroup 1 subgrouping by monoclonal antibodies--an epidemiological tool

A panel of 10 monoclonal antibodies was used to subgroup 326 strains of Legionella pneumophila serogroup 1. All but two strains could be classified into three major subgroups named after their representative strains Pontiac 1, Olda and Bellingham 1. Of the 50 isolates from patients, 44 representing 32 separate incidents were of the Pontiac subgroup. This subgroup was also found in 16 of 18 buildings epidemiologically associated with Legionnaires' Disease. In contrast, strains of the Olda subgroup predominated in buildings where no infections had occurred. In 9 of the 11 incidents where isolates were available from at least one patient as well as from the suspected environmental source, the monoclonal antibody reaction patterns of strains from patients were identical to those of one or more of their environmental counterparts.     

Legionella pneumophila serogroup 1 subgrouping by monoclonal antibodies--an epidemiological tool.

A panel of 10 monoclonal antibodies was used to subgroup 326 strains of Legionella pneumophila serogroup 1. All but two strains could be classified into three major subgroups named after their representative strains Pontiac 1, Olda and Bellingham 1. Of the 50 isolates from patients, 44 representing 32 separate incidents were of the Pontiac subgroup. This subgroup was also found in 16 of 18 buildings epidemiologically associated with Legionnaires'' Disease. In contrast, strains of the Olda subgroup predominated in buildings where no infections had occurred. In 9 of the 11 incidents where isolates were available from at least one patient as well as from the suspected environmental source, the monoclonal antibody reaction patterns of strains from patients were identical to those of one or more of their environmental counterparts.     

Legionella pneumophila serogroup 1 in a birthing pool

This report describes a risk assessment and subsequent actions following isolation of Legionella pneumophila serogroup 1 in the water supply to a birthing pool during a planned maintenance programme. A literature search for cases of neonatal legionellosis identified 24 reports of cases among babies aged <2 months, two of which were associated with water births. On this basis, the pool was closed until Legionella spp. were undetectable. Control proved difficult as hyperchlorination failed, and a filter fitted to the thermostatic mixer tap supplying the pool slowed filling so much that additional taps were required to achieve a satisfactory flow rate.     

Legionellosis from Legionella pneumophila serogroup 13

We describe 4 cases of Legionella pneumophila serogroup 13-associated pneumonia. These cases originate from a broad geographic range that includes Scotland, Australia, and New Zealand. L. pneumophila serogroup 13 pneumonia has a clinically diverse spectrum that ranges from relatively mild, community-acquired pneumonia to potentially fatal severe pneumonia with multisystem organ failure. All cases were confirmed by culture and direct fluorescent antibody staining or indirect immunofluorescent antibody tests. Proven or putative sources of L. pneumophila serogroup 13 infections in 2 patients included a contaminated whirlpool spa filter and river water. An environmental source was not found in the remaining 2 cases; environmental cultures yielded only other L. pneumophila serogroups or nonpneumophila Legionella species. We describe the clinical and laboratory features of L. pneumophila serogroup 13 infections. L. pneumophila serogroup 13 pneumonia is rarely reported, but it may be an underrecognized pathogenic serogroup of L. pneumophila.     

Intracellular growth of Legionella pneumophila serogroup 1 monoclonal antibody type 2 positive and negative bacteria.

Epidemiological evidence suggests that monoclonal antibody type 2 positive (MAB 2+) Legionella pneumophila serogroup 1 (LP1) more often causes disease than do MAB 2- isolates, and there is evidence that MAB 2- LP1 grow less well in cells than do MAB 2+ bacteria. We tested the intracellular growth rates of ten randomly selected MAB 2- LP1 isolates, by using guinea-pig alveolar macrophages, and human monocyte-derived macrophages. Save a low virulence control, all ten MAB 2- isolates grew as well in cells as a virulent MAB 2+ isolate. Heterogeneity of MAB 2- LP1 growth in cells exists, making poor intracellular growth an unlikely explanation for why MAB 2+ LP1 appear to cause disease more often.     

浙江省61株嗜肺军团菌血清1型菌株的SBT序列分型

目的了解浙江省空调冷却塔/冷凝水中嗜肺军团菌血清1型(Lp1)菌株的序列分型特征。方法选取2005～2011年间浙江省10个地区空调冷却塔/冷凝水中分离的61株Lp1型嗜肺军团菌菌株,采用欧盟军团菌感染工作组(EWGLI)军团菌序列分型(SBT)方法,PCR扩增7对管家基因,对扩增产物进行测序、比对、递交,以获取等位基因号以及SBT序列型,运用DNAsp 5.0软件对测序结果进行核苷酸多态性分析,采用SplitsTree及eBURST软件对分型结果进行聚类分析。结果 61株Lp1型嗜肺军团菌可分为11种SBT序列型,其中5株(5/61)均为新发现序列型;ST-1型在10个地区(市)的冷却塔/冷凝水中均有分布,该序列型菌株占81.9%(50/61)。7个管家基因的核苷酸多态性(Pi)范围为0.01095(mip)～0.05355(pilE)。聚类分析显示,浙江省Lp1型菌株分属多个克隆系,但主要分属ST-1序列群、ST-154序列群和ST-149三大序列群,另有1株为不属于任何序列群的单体。结论聚类分析表明浙江省空调冷却塔/冷凝水中分离的Lp1型嗜肺军团菌存在遗传多样性,序列群分布与国内部分省份的结果相似,以ST-1序列型为主。     

Soil as a source of Legionella pneumophila serogroup 1 (Lp1)

OBJECTIVE: To investigate the potential source of a case of Legionnaires' disease caused by an unusual serotype of Legionella pneumophila serogroup 1 (Lp1) in regional Victoria in May 2001. METHOD: Epidemiological and environmental investigation of the source of infection of a case of Legionnaires' disease in regional Victoria in May 2001. RESULTS: Extensive environmental investigations did not reveal any cooling water tower systems close to the residence or the shopping centre that the case visited prior to illness. The sputum culture and a soil sample from the field at the plant nursery where the case worked prior to illness were both positive for Legionella pneumophilia serogroup 1, MDU pulsovar 97:103. CONCLUSION: Legionella pneumophila has been found in soil and was further found to be associated with a case of Legionella pneumophila. IMPLICATIONS: Public health authorities should consider exposures to soil and potting mixes when investigating cases of Legionella pneumophila where the case has no apparent association with cooling towers. Safe gardening practices should be promoted among the community.     

Legionella pneumophila serogroup 3 infection: importance of serology

We present a case of Legionella pneumophila serogroup 3 (LP3) infection in a patient with severe community-acquired pneumonia (CAP). The diagnosis was complicated by an initial equivocal L. pneumophila urinary antigen test, followed by two negative samples. LP3 was cultured from a sputum sample and the diagnosis was confirmed by serology 15 days into the admission. This case highlights the importance of considering non-LP1 serogroups as causes of CAP and the role of serological testing in diagnosis.     

Endemicity of Legionella pneumophila serogroup 3 in a hospital water supply

A microbiological and epidemiological investigation at the Infectious Diseases Hospital in Turin, Italy, demonstrated Legionella pneumophila serogroup 3 at 10(2) to greater than 4 X 10(3) cfu l-1 from 24 of 32 hot water samples collected from hand-basins in six separate buildings. A sample taken from the public water supply, and a hot water sample (80 degrees C) collected from hot water tanks, did not yield legionellas. Legionella pneumophila serogroup 3 was found in samples taken at the first point of mixed hot and cold water (50 degrees C) at 3 X 10(2) cfu l-1. 12 of 26 samples from the shower-heads yielded 10(3) to 2.5 X 10(5) cfu l-1 and one of 12 water samples from oxygen bubble humidifiers tested yielded 1.6 X 10(4) cfu l-1. No other legionellas species or serogroups of Legionella pneumophila were isolated during the study. No cases of nosocomial pneumonia were detected among 3653 patients' records, nor was there serological evidence of Legionella infection in the 180 patients tested.     

Incidence of Legionella pneumophila infection in tourists: Italy

Legionella pneumophila has frequently been recognised as a cause of infection in tourists. From 1973 to 1987, 117 cases of legionellosis were reported in tourists who spent one or more weeks in Italian summer resorts. 6 (5.1%) patients died. 42 (35.9%) were sporadic cases, and 75 (64.1%) were related to clusters or outbreaks. Among the 117 cases, 63 were reported to the Istituto Superiore di Sanità by the health authorities of other countries. Some travellers became ill while in Italy, others soon after they returned home. All tourists but two had stayed in hotels. L. pneumophila was isolated from the water system of 10 hotels, and in another hotel the same Legionella species was detected by direct immunofluorescence. Persistent and/or recurrent sources of infection seem to be present in some summer resorts on the Adriatic Coast and in the Lake Garda area in northern Italy. Some groups of cases were associated with particular hotels over a period of several months and sometimes years. Investigations have implicated potable water as the likely vehicle and the source of infection for tourists. The need of a greater awareness amongst clinicians that travel is a risk factor for legionellosis, and for better international surveillance and cooperation, is stressed.     

The relationship between the serogroup antigen and lipopolysaccharide of Legionella pneumophila

Serogroup-specific antigen was extracted from a number of Legionella pneumophila strains and compared with phenol-water extracted lipopolysaccharide on the basis of gel filtration, chemical analysis, SDS-PAGE and reaction with serogroup-specific antibody in immunoblots. Serogroup specificity is apparently borne by the O side-chains of the lipopolysaccharide, which, although smooth in type, partitions in the phenol phase. For four serogroup 1 strains tested, there was no qualitative correlation between O side-chain length and pulmonary virulence for guinea-pigs.     

1型嗜肺军团菌的光纤倏逝波生物传感器快速测定法

目的 利用光纤倏逝波生物传感器适合现场快速检测的优势,初步建立1型嗜肺军团菌的快速检测平台.方法 优化最佳检测条件,并在此条件下确定检测Lp1的灵敏度和特异性,同时通过检测人工模拟样品确认该方法检测实际样本的灵敏度和特异性.结果 该方法40 min之内自动完成检测.捕获抗体与目标物最佳反应时间、反应体系与检测抗体的最佳反应时间均为10 min,捕获抗体最佳使用浓度是100 μg/ml,检测抗体最佳使用浓度为20μg/ml.在此条件下得到该方法检测Lp1的灵敏度为1.8×103cfu/ml,检测的特异性强.结论 光纤倏逝波生物传感器快速检测方法为大样本量Lp1污染严重水样的现场快速筛查提供一种新途径.     

Atypical legionellosis: isolation of Legionella pneumophila serogroup 1 from a patient with aspiration pneumonia

It has been suspected that the number of Legionella pneumophila infections is substantially higher than commonly reported, due to subclinical infections. We report a patient where the diagnosis of a legionella infection was made only because of a large-scale surveillance programme for legionellosis. The case demonstrates the possibility of legionellas being involved in lung disease though not necessarily causing overt legionellosis.     

Cytopathogenicity and molecular subtyping of Legionella pneumophila environmental isolates from 17 hospitals

The cytopathogenicity of 22 Legionella pneumophila isolates from 17 hospitals was determined by assessing the dose of bacteria necessary to produce 50% cytopathic effect (CPED50) in U937 human-derived macrophages. All isolates were able to infect and grow in macrophage-like cells (range log10 CPED50: 2.67-6.73 c.f.u./ml). Five groups were established and related to the serogroup, the number of PFGE patterns coexisting in the same hospital water distribution system, and the possible reporting of hospital-acquired Legionnaires' disease cases. L. pneumophila serogroup 1 isolates had the highest cytopathogenicity (P=0.003). Moreover, a trend to more cytopathogenic groups (groups 1-3) in hospitals with more than one PFGE pattern of L. pneumophila in the water distribution system (60% vs. 17%) and in hospitals reporting cases of hospital-acquired Legionnaires' disease (36.3% vs. 16.6%) was observed. We conclude that the cytopathogenicty of environmental L. pneumophila should be taken into account in evaluating the risk of a contaminated water reservoir in a hospital and hospital acquisition of Legionnaires' disease.     

Molecular characterization of a virulence-associated epitope on the lipopolysaccharide of Legionella pneumophila serogroup 1.

For identification of lipopolysaccharide (LPS)-associated epitopes of Legionella pneumophila serogroup 1, LPS of strain Philadelphia 1 was investigated using monoclonal antibodies (MAbs). The O-specific chain of LPS is a homopolymer of 5-acetamidino-7-acetamido-8-O-acetyl-3,5,7,9-tetradeoxy-D-glycero- L-galacto- nonulosonic acid. At least four immunoaccessible epitopes were recognized by different MAbs on the intact LPS. After O-deacetylation of LPS, the reactivity of one of the MAbs (MAb 3/1) was lost, indicating thus that the corresponding epitope is associated with the 8-O-acetyl group. Since the reactivity pattern of the MAb 3/1 is identical with those of the MAb 2 which was considered as a virulence marker for serogroup 1, this epitope may be involved in mediating virulence in L. pneumophila. Four MAbs specific to strains of serogroup 1 other than the monoclonal subtype Philadelphia recognized epitopes on the O-deacetylated LPS of strain Philadelphia 1 and, therefore, the virulence-associated epitope blocks recognition of the immunodeterminants that are accessible on the intact LPS of the strains lacking this epitope.     

Legionellae isolated from clinical and environmental samples in Spain (1983-90): monoclonal typing of Legionella pneumophila serogroup 1 isolates.

Legionella isolates recovered in 21 different Spanish provinces over 8 years from both clinical (67 isolates) and environmental (181) samples, mostly from case-associated buildings, are described; 92.5% of clinical isolates were L. pneumophila serogroup 1 (SG1), only five isolates belonging to other species or serogroups: two L. pneumophila SG6, two SG8 and one L. bozemanii SG1 not clearly related with clinical infection. L. pneumophila SG1 accounted for 53.6% of isolates from the environment, followed by SG8 (27.6%), SG3 (9.4%) and SG6 (7.2%). Three isolates were labelled as SG8/10. Subtyping of L. pneumophila SG1 by the standardized panel of monoclonal antibodies revealed 90.3% of clinical and 78.3% of environmental isolates as belonging to Pontiac subgroup. Pontiac isolates were further divided into 55.3% Philadelphia 1 or Allentown 1, 21.9% Benidorm 030E and 20.4% Knoxville 1. Characterization of samples from four outbreaks in which both clinical and environmental isolates had been recovered permitted the recognition of three Philadelphia 1 or Allentown 1 and one Knoxville 1 strains as the aetiological agents.     

The relationship between the serogroup antigen and lipopolysaccharide of Legionella pneumophila.

Serogroup-specific antigen was extracted from a number of Legionella pneumophila strains and compared with phenol-water extracted lipopolysaccharide on the basis of gel filtration, chemical analysis, SDS-PAGE and reaction with serogroup-specific antibody in immunoblots. Serogroup specificity is apparently borne by the O side-chains of the lipopolysaccharide, which, although smooth in type, partitions in the phenol phase. For four serogroup 1 strains tested, there was no qualitative correlation between O side-chain length and pulmonary virulence for guinea-pigs.