Second serogroup of Legionella quinlivanii isolated from two unrelated sources in the United Kingdom

R.J. BIRTLES, N. DOSHI, N.A. SAUNDERS AND T.G. HARRISON. 1991. A series of strains, presumptively identified as legionellas on the basis of their nutritional requirements and biochemical reactivity, were isolated from two unrelated environmental sources in the UK. Representatives of each of these series had a restriction endonuclease digest pattern indistinguishable from that of the Legionella quinlivanii type strain (1442-AUS-E) and the identity of these strains was confirmed by DNA homology studies. Serological examination of the two strains showed that they were distinct from the type strain 1442-AUS-E but indistinguishable from each other. A second serogroup, L. quinlivanii serogroup 2 (type strain LC870; NCTC 12434), is proposed to accommodate these strains.     

Legionella quinlivanii sp. nov. isolated from water

SixLegionella-like organisms were isolated from the evaporative air conditioning system of a bus in South Australia. All six isolates were presumptively identified as legionellae by their growth requirement forl-cysteine and their cellular branched-chain fatty acids. They were serologically distinct from other legionellae in the slide agglutination test. DNA hybridization studies showed that the six isolates belong to a new species ofLegionella, Legionella quinlivanii (ATCC 43830).Use of trade names is for identification only and does not imply endorsement by the Public Health Service or by the U.S. Department of Health and Human Services.     

A second serogroup of Legionella erythra serologically indistinguishable from Legionella rubrilucens.

Twenty-two red-autofluorescent Legionella strains were identified serologically as either Legionella rubrilucens or L. erythra. A rRNA probe was used for restriction fragment length polymorphism (RFLP) analysis of the strains and the patterns generated were used as an additional method of identifying the strains to species level. In two instances strains which were identified as L. rubrilucens by serology appeared to belong to the species L. erythra by RFLP analysis. This apparent contradiction was resolved by measurements of DNA/DNA homology which confirmed the existence of a second serogroup of L. erythra serologically indistinguishable from L. rubrilucens.     

Beta-glucuronidase activity of Vero cytotoxin-producing strains of Escherichia coli, including serogroup 0157, isolated in the United Kingdom

One hundred and twenty Vero cytotoxin-producing (VT⁺) strains of Escherichia coli 0157 (of H type 7 or non-motile) isolated in the UK, failed to ferment sorbitol after 24 h or to hydrolyse 4-methylumbelliferyl-beta- d -glucuronide (MUG). This combination of properties was not found in 167 of 169 other E. coli strains, including VT⁺strains of other serogroups and VT^-strains of serogroup 0157. As the two exceptions were rare VT^-strains of serotype 0157: H7, we conclude that, although biochemical tests can aid the isolation of VT⁺0157 strains, confirmation of VT production is necessary.     

Isolation of Legionella longbeachae serogroup 1 from potting mixes.

Following a statewide outbreak of legionellosis due to Legionella longbeachae serogroup 1 in South Australia in 1988 and 1989, studies were performed to find a source of the organism. A number of water and soil samples with and without acid decontamination were examined for L. longbeachae by using a selective medium containing vancomycin, aztreonam, and pimafucin. There were no isolations of L. longbeachae from water samples. Organisms resembling L. longbeachae were isolated from a number of samples of potting mixes and from soil surrounding plants in pots collected from the homes of four patients. The organisms were found to persist for 7 months in two potting mixes stored at room temperature. Legionellae were isolated with difficulty from potting mixes which were allowed to dry out. Identification of isolates as L. longbeachae serogroup 1 was confirmed by quantitative DNA hybridization and serological tests. Restriction-fragment-length-polymorphism studies showed minor differences between patient and environmental isolates but differentiated these readily from L. longbeachae serogroup 2 and other antigenically related legionellae. The isolation of L. longbeachae from some potting mixes and the prolonged survival of the organisms in this medium suggest that soil rather than water is the natural habitat of this species and may be the source of human infections.     

A second serogroup of Legionella erythra serologically indistinguishable from Legionella rubrilucens

N.A. SAUNDERS, N. DOSHI AND T.G. HARRISON. 1992. Twenty-two red-autofluorescent Legionella strains were identified serologically as either Legionella rubrilucens or L. erythra. A rRNA probe was used for restriction fragment length polymorphism (RFLP) analysis of the strains and the patterns generated were used as an additional method of identifying the strains to species level. In two instances strains which were identified as L. rubrilucens by serology appeared to belong to the species L. erythra by RFLP analysis. This apparent contradiction was resolved by measurements of DNA/DNA homology which confirmed the existence of a second serogroup of L. erythra serologically indistinguishable from L. rubrilucens.     

Prevalence of de-O-acetylated serogroup C meningococci before the introduction of meningococcal serogroup C conjugate vaccines in the United Kingdom

Meningococcal serogroup C conjugate (MCC) vaccines have been introduced in the UK to combat the rise in serogroup C meningococcal disease. Serogroup C meningococci may occur naturally expressing either O-acetylated (Oac(+)) or de-O-acetylated (Oac(-)) polysaccharide capsules. In a small study in the USA in the 1970s 15% of serogroup C meningococcal case isolates were reported to be Oac(-) though the prevalence of these Oac(-) isolates has not been recorded in the UK. This is of interest as the first MCC vaccines to be introduced are Oac(+) and the potential impact of this on Oac(-) serogroup C isolates is unclear. Serogroup C isolates submitted to the Public Health Laboratory Service Meningococcal Reference Unit in January 1998 (n=113) and January 1999 (n=162) were investigated by dot blotting using monoclonals specific for Oac(+) and Oac(-) serogroup C polysaccharides. This revealed 12% Oac(-) isolates for both January 1998 and January 1999. The proportion of fatal cases was found to similar for both Oac(-) and Oac(+), 14 and 9% for 1998 and 5 and 3% for 1999, indicating that the pathogenic potential of these Oac(-) isolates is similar to Oac(+). The acetylation status of serogroup C isolates needs to be monitored throughout and after the introduction of MCC vaccines.     

Genotyping of Legionella pneumophila serogroup 1 strains isolated in Northern Sicily, Italy

During a three-year period, from April 2002 to May 2005, one hundred-forty-seven samples, taken from technical systems of water distribution at point of use, were repeatedly collected at six different sites in Northern Sicily and assayed for the presence of Legionella pneumophila serogroup 1 and serogroups 2 to 14. At the first samplings, the water distribution systems of all the sites were heavily contaminated, and disinfection treatments by the superheat and flush method were therefore performed. Treatments were always successful against L. pneumophila sg.1, but only in a few cases against all other serogroups. Eighty-six strains of L. pneumophila sg. 1, isolated from 26 of these samples, were characterized by amplified fragment length polymorphism (AFLP) analysis and sequence-based typing (SBT) procedure. Perfectly overlapping results were obtained by both the procedures and four genotypes were identified, accounting for all the isolates. The easy transferability of the SBT data through a web-based database made it possible to identify the presence in Northern Sicily of the two SBT types most commonly circulating in Europe.     

Isolation of Legionella longbeachae serogroup 1 from potting mixes

Following a statewide outbreak of legionellosis due to Legionella longbeachae serogroup 1 in South Australia in 1988 and 1989, studies were performed to find a source of the organism. A number of water and soil samples with and without acid decontamination were examined for L. longbeachae by using a selective medium containing vancomycin, aztreonam, and pimafucin. There were no isolations of L. longbeachae from water samples. Organisms resembling L. longbeachae were isolated from a number of samples of potting mixes and from soil surrounding plants in pots collected from the homes of four patients. The organisms were found to persist for 7 months in two potting mixes stored at room temperature. Legionellae were isolated with difficulty from potting mixes which were allowed to dry out. Identification of isolates as L. longbeachae serogroup 1 was confirmed by quantitative DNA hybridization and serological tests. Restriction-fragment-length-polymorphism studies showed minor differences between patient and environmental isolates but differentiated these readily from L. longbeachae serogroup 2 and other antigenically related legionellae. The isolation of L. longbeachae from some potting mixes and the prolonged survival of the organisms in this medium suggest that soil rather than water is the natural habitat of this species and may be the source of human infections.     

Seroprotection against serogroup C meningococcal disease in adolescents in the United Kingdom: observational study

Objective To determine the persistence of bactericidal antibody titres following immunisation with serogroup C meningococcal glycoconjugate vaccine at age 6-15 years in order to examine changes in persistence of antibodies with age.Design Observational study.Setting Secondary and tertiary educational institutions in the United Kingdom.Participants Healthy adolescents aged 11-20 years previously immunised between 6 and 15 years of age with one of the three serogroup C meningococcal vaccines.Intervention Serum obtained by venepuncture.Main outcome measures Percentage of participants with (rabbit complement) serum bactericidal antibody titres of at least 1:8; geometric mean titres of serogroup C meningococcal serum bactericidal antibody.Results Five years after immunisation, 84.1% (95% confidence interval 81.6% to 86.3%) of 987 participants had a bactericidal antibody titre of at least 1:8. Geometric mean titres of bactericidal antibody were significantly lower in 11-13 year olds (147, 95% confidence interval 115 to 188) than in 14-16 year olds (300, 237 to 380) and 17-20 year olds (360, 252 to 515) (P<0.0001 for both comparisons). Within these age bands, no significant difference in geometric mean titres of bactericidal antibody between recipients of the different serogroup C meningococcal vaccines was seen. More than 70% of participants had received a vaccine from one manufacturer; in this cohort, geometric mean titres were higher in those immunised at aged 10 years or above than in those immunised before the age of 10.Conclusions Higher concentrations of bactericidal antibody are seen five years after immunisation with serogroup C meningococcal vaccine at age 10 years or above than in younger age groups, possibly owing to immunological maturation. This provides support for adolescent immunisation programmes to generate sustained protection against serogroup C meningococcal disease not only for the vaccine recipients but also, through the maintenance of herd immunity, for younger children.     

Identification and serotyping of atypical Legionella pneumophila strains isolated from human and environmental sources

AIMS: To validate identification methods for Legionella pneumophila strains that cannot be serotyped into the known serogroups and to characterize their antigenic diversity. METHODS AND RESULTS: Fifty L. pneumophila strains that could not be serogrouped, but which had been confirmed as L. pneumophila by mip gene sequencing, were further identified phenotypically. We used (i) MONOFLUO anti-Legionella Staining Reagent (Bio-Rad) (50/50), (ii) an in-house prepared immunoblot assay for the detection of L. pneumophila- specific Mip protein epitope (50/50), (iii) fatty acid analysis using the Microbial Identifications System (MIDI) (47/50) and (iv) Oxoid agglutination tests (44/50). The serological diversity was further characterized by testing with five serogroup-cross-reactive monoclonal antibodies, resulting in nine phenons. CONCLUSIONS: The division of L. pneumophila into 15 serogroups does not reflect the serogroup heterogeneity. Results of these tests indicate that there are more serogroups. SIGNIFICANCE AND IMPACT OF THE STUDY: MONOFLUO anti-Legionella Staining Reagent is the only commercially available tool for identifying atypical strains of L. pneumophila. If necessary for epidemiological purposes, the antigenic heterogeneity of these strains can be analysed by monoclonal antibodies.     

Drug resistance among infantile enteropathogenic Escherichia coli strains isolated in the United Kingdom.

Two hundred and thirty-two strains of Escherichia coli belonging to infantile enteropathogenic serotypes isolated in the United Kingdom during 1980 and 1981 were tested for resistance to 10 antimicrobial drugs. Resistance to one or more drugs was found in 134 (57.8%) of the strains, with resistance to sulphonamides, streptomycin, tetracycline, and ampicillin occurring most commonly. Resistance was transferable in 65 out of 104 resistant strains. These findings are a cause for concern because they indicate that the choice of treatment for severe illness is limited and suggest that a large pool of drug-resistant organisms exists in the community.     

Molecular genetic typing of Legionella pneumophila serogroup 1 isolated in town Verkhnyaya Pyshma using international standards

Strains of Legionella pneumophila Pyshma-1 and Pyshma-2 were typed according to the international standard - STB protocol developed by EGWLI. Allelic profile of the strains was determined. Identity of strains on the locus pilE, which codes protein important for virulence of bacterium, was shown. Close similarity of nucleotide sequences in Pyshma-1 and Pyshma-2 strains (mainly, 98-100%) was noted. Both strains differed more from reference strain Philadelphia-1 ATCC 33152. Maximal differences (5-6%) were observed in fragment of mompS gene.The study revealed considerable need for conducting of systemic analysis of collected and newly isolated strains in order to get information picture on endemic strains of L. pneumophila in Russia.     

Complex O-acetylation in Legionella pneumophila serogroup 1 lipopolysaccharide. Evidence for two genes involved in 8-O-acetylation of legionaminic acid.

A putative gene encoding an O-acetyl transferase, lag-1, is involved in biosynthesis of the O-polysaccharide (polylegionaminic acid) in some Legionella pneumophila serogroup 1 strains. To study the effect of the presence and absence of the gene on the O-polysaccharide O-acetylation, lag-1 from strain Philadelphia 1 was expressed in trans in the naturally lag-1-negative OLDA strain RC1, and immunoblot analysis revealed that the lag-1-encoded O-acetyl transferase is active. O-Polysaccharides of different size were prepared from the lipopolysaccharides of wild-type and transformant strains by mild acid degradation followed by gel-permeation chromatography. Using NMR spectroscopy and MALDI-TOF mass spectrometry, it was found that O-acetylation of the first three legionaminic acid residues next to the core occurs in the short-chain O-polysaccharide (<10 sugars) from both strains. Hence, there is another O-acetyl transferase encoded by a gene different from lag-1. In the longer-chain O-polysaccharide, a legionaminic acid residue proximal to the core is N-methylated and could be further 8-O-acetylated in the lag-1-dependent manner. Only strains expressing a functional lag-1 gene were recognized in Western blot analysis by monoclonal antibody 3/1 requiring 8-O-acetylated polylegionaminic acid for binding. The highly O-acetylated outer core region of the lipopolysaccharide is involved in the epitope of another serogroup 1-specific monoclonal antibody termed LPS-1. The O-acetylation pattern of the L. pneumophila serogroup 1 core oligosaccharide was revised using MALDI-TOF mass spectrometry. lag-1-independent O-acetylation of the core and short-chain O-polysaccharide was found to be a common feature of L. pneumophila serogroup 1 strains. The biological importance of conserved lag-1-independent and variable lag-1-dependent O-acetylation is discussed.