Serotypes and subtypes of Neisseria meningitidis serogroup B strains associated with meningococcal disease in Canada, 1977-1989

Typing of Neisseria meningitidis serogroup B disease isolates was carried out using a panel of serotype-and subtype-specific monoclonal antibodies (MAbs) in enzyme-linked immunosorbent assays (ELISA). Three hundred and sixty-two strains isolated from 1977 to 1986 were typed using five serotyping and seven subtyping reagents and outer membrane vesicles as antigens. Serotype 2b accounted for 30% of the disease isolates. The most common subtype was P1.2, which occurred on 18.5% of all strains or 48.6% of the serotype 2b strains. Of the 362 strains typed, 135 (37.3%) were serotyped and 122 (33.7%) were subtyped. Overall, 185 (51.1%) of the strains could be assigned a serotype and (or) subtype. Strains (221) isolated during the years 1987-1989 were typed using a panel of 6 serotyping and 12 subtyping reagents by whole-cell ELISA. Strains of serotypes 4 (21.7%) and 15 (20.8%) were the most common and carried a wide variety of subtypes. The most common subtypes were P1.2 (11.8%) and P1.16 (9.5%). Of the 221 strains analyzed, 132 (59.7%) were assigned a serotype and 123 (55.7%) a subtype and with all 18 MAbs, 192 (86.9%) of the strains were serotyped and (or) subtyped. Two different MAbs to the four epitopes 2a, 15, P1.2, and P1.16 gave discordant reactions of 0.3, 6.6, 2.6, and 2.2%, respectively, when used to analyze over 300 strains of N. meningitidis.     

The effect of nisin on Listeria monocytogenes in culture medium and long-life cottage cheese

M.A.S.S. FERREIRA AND B.M. LUND. 1996. The sensitivity to nisin of 27 strains of Listeria monocytogenes , four of L. innocua and one of L. ivanovii was estimated at pH 6.8 and pH 5.5. Strains of L. monocytogenes showed differences in sensitivity which were not correlated with serotype. Strains of L. innocua were as resistant as the most resistant strains of L. monocytogenes , whereas the strain of L. ivanovii was relatively sensitive. Two of the most resistant strains of L. monocytogenes multiplied in aerated liquid medium adjusted to pH 5.0 with HCl, incubated at 20°C; nisin, 500 IU ml^-1, prevented multiplication and caused death. Following inoculation of a resistant strain into long-life cottage cheese, pH 4.6–4.7, the number of viable L. monocytogenes decreased approximately 10-fold during storage at 20°C for 7 d; addition of nisin, 2000 IU g^-1, to the cottage cheese increased the rate of inactivation to approximately a 1000-fold decrease in 3 d.     

Antigenic determinants and specificity of antisera against acidophilic bacteria

Polyclonal antisera, produced against whole cells of Thiobacillus thiooxidans, T. ferrooxidans and Leptospirillum ferrooxidans, gave highly specific reactions when cross-reacted with 23 strains of acidophilic bacteria using an immunofluorescence (IF) staining technique. Strains of identical serotype exhibited maximum cross-reaction whereas strains of different serotype reacted only weakly. Lipopolysaccharides (LPS) examined by SDS-PAGE showed different, serotype-specific migration patterns indicating their rough or smooth character. LPS patterns may therefore be used for serological classification of acidophilic bacteria. Surface antigens of four strains were identified by immunoblot staining; LPS and some proteins were antigenic determinants with LPS the most specific.The authors are with the Universität Hamburg, Institut für Allgemeine Botanik, Abteilung für Mikrobiologie, Ohnhorststrasse 18, D-22609 Hamburg, Germany     

Enterotoxin-producing strains of Bacillus thuringiensis isolated from food

P.H. DAMGAARD, H.D. LARSEN, B.M. HANSEN, J. BRESCIANI AND K. JØRGENSEN. 1996. Strains of Bacillus thuringiensis were isolated from various food items (pasta, pitta bread and milk) and were found to belong to either H-serotype kurstaki or neoleonensis. The strains were bioassayed against Pieris brassicae and insecticidal activity of strains was found to correspond to the presence of the cry1.A -gene. All strains, except one, were found to express cytotoxic effects on Vero cells as an indicator of enterotoxin activity. Further, the B. thuringiensis strains HD-1 (serotype kurstuki ), NB-125 (serotype tenebrionis ) and HD-567 (serotype isruelensis ) which are used commercially for insect pest management, were also found to have cytotoxic effects on Vero cells.     

Culture media for the differentiation of isolates of Yersinia ruckeri, based on detection of a virulence factor

M.D. FURONES, M.L. GILPIN AND C.B. MUNN. 1993. Strains of the bacterial fish pathogen Yersinia ruckeri were identified with the API 20E system and distinguished on the basis of whole cell agglutination with antisera, sorbitol fermentation and polymyxin B sensitivity. Strains which were shown to possess the virulence-associated heat-sensitive factor (HSF) were shown to grow preferentially on culture media containing sodium dodecyl sulphate (SDS) and to produce a creamy deposit around the colonies. By contrast, strains lacking this factor (HSF^-) grew poorly and without forming a deposit. Enhancement of the differentiation between the two types was shown by the incorporation of Coomassie brilliant blue dye into agar containing 1% SDS, and the uptake of Coomassie blue and Congo red was shown to be temperature-dependent. Most strains tested were shown to belong to serotype I, and were sensitive to polymyxin and did not ferment sorbitol. With the medium developed most serotype I strains but not those of other serotypes were shown to possess HSF. It is suggested that the medium is used in epidemiological studies of Y. ruckeri.     

Rapid Sulfonamide Disc Sensitivity Test for Meningococci

Minimal inhibitory concentrations (MIC) of 90 strains of Neisseria meningitidis were determined by a plate dilution technique that employed twofold changes in concentrations of sulfadiazine. The geometric mean of three MIC determinations on each strain was correlated with inhibition zones produced by a 300-mug sulfathiazole disc. The linear relationship between the logarithm of the geometric mean MIC values and the zone diameters was highly significant. Strains were separated into sensitive and resistant populations by both test procedures. Quantitative criteria for interpreting the sensitivity of a strain by the disc test were established.     

Identification of variable region differences in Neisseria meningitidis class 3 protein sequences among five group B serotypes

Strains of Neisseria meningitidis express one of two porin proteins. These porins have been identified as the class 2 and class 3 proteins, and express serotype-specific epitopes. The gene for the class 3 protein was amplified by the polymerase chain reaction from the DNA of a serotype 4 strain as a 1025 bp fragment. The nucleotide sequence of this gene was determined and compared with two recently published sequences. On the basis of this comparison we have identified two major variable regions in the translated protein sequence, VR1 and VR2, that may be associated with serotype specificity. Three other variable regions were also identified. The sequences in the VR1 and VR2 regions from five additional group B N. meningitidis strains of serotypes 1, 4, 8, 12, and 15, all expressing class 3 proteins, were determined. The VR1 and VR2 regions were variable and were flanked by highly conserved regions among eight different class 3 sequences. These two variable regions of 15 and 9 amino acids are predicted to be in surface-exposed loops.     

Sensitivity of Neisseria gonorrhoeae to antibiotics]

Since 1976 strains of Neisseria gonorrhoeae producing beta-lactamase have been isolated in many countries. Strains with high level resistance to tetracycline have been also described. The appearance of resistant strains implies a constant surveillance of the isolated gonococcus and the study of their antibiotics sensitivity.     

Serological Identification of a New Porcine Mycoplasma Species,M. Flocculare

In a preceding paper (Friis 1972), the so-called SAR (M. suipneumoniae antibody resistant) mycoplasma strains were described. As the reported findings indicated that these isolates belonged to a separate species, a representative cloned strain, Ms42, was selected for serological comparison with the known acid-producing mycoplasma species.     

Mechanism of Kasugamycin Resistance in <Emphasis Type="Italic">Escherichia coli</Emphasis>

Strains of Escherichia coli are resistant to the antibiotic kasugamycin due to the partial non-methylation of 16S ribosomal RNA. An RNA methylase activity, absent from resistant strains, is shown here to methylate in vitro the 16S RNA of resistant as well as sensitive strains.     

Characterization of monoclonal antibodies that recognize common epitopes located on O antigen of lipopolysaccharide of serotypes 1, 9 and 11 of Actinobacillus pleuropneumoniae

Abstract Seven murine monoclonal antibodies (mAbs) against serotype 1 of Actinobacillus (Haemophilus) pleuropneumoniae (reference strain Shope 4074) were produced and characterized. All hybridomas secreting mAbs were reactive with whole-cell antigens from reference strains of serotypes 1, 9 and 11, except for mAb 5D6 that failed to recognize serotype 9. They did not react with other taxonomically related Gram-negative organisms tested. The predominant isotype was immunoglobulin (Ig) M, although IgG_2a, IgG_2b, and IgG₃ were also obtained. The epitopes identified by these mAbs were resistant to proteinase K treatment and boiling in the presence of sodium dodecyl sulfate and reducing conditions; however, they were sensitive to sodium periodate treatment. Enhanced chemiluminescence-immunodetection assay showed that mAbs could be divided in two groups according to the patterns of immunoreaction observed. Group I (mAbs 3E10, 4B7, 9H5 and 11C3) recognized a ladder-like banding profile consistent with the O antigen of lipopolysaccharide (LPS) from smooth strains. Group II (mAbs 3B10 and 9H1) recognized a long smear of high molecular weight which ranged from 60 to 200 kDa. The mAbs were tested against 96 field isolates belonging to serotypes 1, 5, 9, 11 and 12, which had previously been classified by a combination of serological techniques based on polyclonal rabbit sera (counterimmunoelectrophoresis, immunodiffusion and coagglutination). The panel of mAbs identified all isolates of serotypes 9 and 11, but only 66% of those belonging to serotype 1. This may suggest the existence of antigenic heterogeneity among isolates of A. pleuropneumoniae serotype 1. These mAbs reacted with epitopes common to serotypes 1, 9 and 11 of Actinobacillus pleuropneumoniae which were located on the O antigen of LPS.     

Monoclonal antibodies with a high degree of specificity for Listeria monocytogenes serotype 4b.

Strains of Listeria monocytogenes serotype 4b account for a large fraction of sporadic listeriosis cases, as well as all major food-borne epidemics attributed to this pathogen. We have identified a set of three monoclonal antibodies which showed a high degree of specificity for strains of L. monocytogenes serotype 4b. Two of these antibodies (c74.33 and c74.180, isotypes immunoglobulin M [IgM] and IgG3, respectively) recognized all serotype 4b strains, whereas antibody c74.22 (isotype IgG1) failed to recognize certain epidemic-associated strains. The corresponding antigens were located on the surface of the bacteria and were expressed following bacterial growth in different media and over a wide range of temperatures (4, 22, and 37 degrees C). Heating L. monocytogenes cells at 80,90, or 100 degrees C abolished reactivity for c74.22 but not for c74.33 MAb. These MAbs were negative for all of the non-Listeria strains tested, including representatives of several gram-negative and gram-positive species. The surface antigen recognized by c74.22 appeared to be associated with the ability of the bacteria to enter (invade) mammalian cells in culture.     

Serratia marcescens: Biochemical, Serological, and Epidemiological Characteristics and Antibiotic Susceptibility of Strains Isolated at Boston City Hospital

The biochemical, serological, and epidemiological characteristics of 95 strains of Serratia marcescens isolated at the Boston City Hospital were examined. Several strains were shown to be endemic, and the majority of isolates were cultured from urine or respiratory secretions. Serratia species were highly resistant to polymyxin B and the cephalosporins, and various proportions were also resistant to other antibiotics including kanamycin, but all of the isolates were sensitive to gentamicin. The appearance of resistance to kanamycin and nalidixic acid among endemic strains was demonstrated. The nosocomial nature of Serratia infections, particularly those involving the urinary tract, was confirmed. Many clinical bacteriology laboratories currently fail to identify the nonpigmented strains.     

Survival, mutation and capacity to repair single-strand DNA breaks after gamma irradiation in different Exr? strains of Escherichia coli

Summary Strains of Escherichia coli K-12 and B/r made by transduction of the exrA allele from a B_s-2 derivative have been compared with Exr(W)^– strains derived from B_s-1 and B_s-2 by mutation (E.M. Witkin, 1967). Both transduced exrA and Exr(W)^– strains were almost unmutable by gamma radiation, but the former class were as sensitive to gamma radiation as recA strains and, like them, were unable to repair single-strand DNA breaks as detected by the McGrath-Williams technique. In contrast the Exr(W)^–strains were as resistant to gammaradiation as Exr(W)⁺ strains derived from them and were equally efficient in repairing single-strand breaks. The existence of Exr(W)^–strains suggests that the mutagenicity of single-strand breaks may depend entirely on the way in which they are repaired. The properties of the (Exr(W)^–strains cannot be ascribed solely to the transducable exrA allele.A large effect of diffuse daylight in lowering the molecular weight of DNA on alkaline sucrose gradients is described which, unless prevented, may lead to erroneous results in such experiments.     

The effects of deoxycholate and sodium dodecyl sulphate on the serological reactivity of antigens isolated from six Bacteroides reference strains

The detergents sodium dodecyl sulphate (SDS) and sodium deoxycholate (NaD) are frequently used as solvents for macromolecular polysaccharide complexes in immunochemical and serological techniques. The influence of the disaggregating surfactants on the serological reactivity of endotoxins isolated from six serotype specific reference strains of the Bacteroides fragilis group was investigated by comparing haemagglutinating and precipitating reactivities of antigen solutions in phosphate buffered saline (PBS), NaD and SDS. All antigens were phenol/water extracted endotoxins. Solutions of antigens isolated from serotypes A, B, C and D in PBS exhibited mainly serotype specificity and a few well known low-titer cross reactions; solutions in NaD showed additional cross reactivity, which was enhanced by solubilization of the antigens in SDS. In immunoelectrophoresis endotoxins isolated from serotypes A and C and dissolved in NaD or SDS showed additional precipitation lines compared to solutions of the same antigens in PBS. These changes in the serological reactivity are of relevance for investigations where the serological specificity of antigens is in question.     

Susceptibility of gram-negative bacteria to the synergistic bactericidal action of serum and polymyxin B nonapeptide

Polymyxin B nonapeptide was able to sensitize Escherichia coli strains and strains of Salmonella typhimurium, Klebsiella spp., Enterobacter cloacae, Pseudomonas aeruginosa, and Haemophilus influenzae to the bactericidal action of fresh normal human serum. The degree of sensitization varied significantly within the strains. Strains of Proteus mirabilis, Neisseria gonorrhoeae, and N. meningitidis remained resistant.     

Classification des souches du groupeBacillus thuringiensis par la détermination de l'antigène flagellaire

Summary The serological study of 26 new strains ofBacillus thuringiensis (of which the biochemical features are also given) makes it possible to classify these strains into: 1^o Strains which are in concordance with the six serotypes previously described. 2^o Strains which have a new H antigen. Here, we describe two new serotypes: serotype 7 (aizawai), serotype 8 (morrisoni). On the other hand, the serological study of five new strains ofB. thuringiensis belonging to serotype 4 shows that the H₄ antigen must be divided into ?sub-factors?: ?4 a, 4b? to be found in the strains sotto, dendrolimus, T.84-A, L (Grig) and ?4 a, 4 c? to be found in the strains Pil 94, 1748 and Rhodesia. Table 6 gives the present statute of theB. thuringiensis strains' classification by the flagellar agglutination technic.

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Avec la collaboration technique deM. Lechevallier etT. Le Borgne. Nous remercions vivement les collègues qui ont bien voulu nous adresser des cultures et nous nous tenons à la disposition de tous ceux qui seraient intéresés par la détermination de l'antigène H de leurs souches. Nous remercions également notre collègueLe Minor pour ses précieux conseils.     

淋病流行株外排系统与外膜通透性和多重耐药性的关系

探讨外排系统、外膜通透性与淋病流行株多重耐药性的关系。应用K—B法和琼脂稀释法从湛江地区分离出62株淋球菌多重耐药株。利用SDS—PAGE测定淋球菌外膜孔蛋白的表达;应用直接荧光法测定能量抑制剂加入前后淋球菌对抗生素的摄入和积累情况,比较耐药菌与敏感菌内膜泵蛋白表达的差异;利用煮沸法提取细菌DNA,PCR扩增mtrR基因,并对扩增产物测序,比较敏感株与多重耐药株的差异。结果5株多重耐药菌均有外膜孔蛋白表达的缺失或下降,同时伴有外排泵蛋白的表达;5株敏感淋球菌无mtrR的突变,10株多重耐药株均有mtrR基因的突变。表明外排系统、外膜通透性与淋病流行株的多重耐药性密切相关。     

Properties of Serratia marcescens strains isolated in septic diseases of newborn infants

As the result of the study of blood and liquor samples from 120 newborns, Serratia marcescens was isolated in 21 cases (17.5 %). 8 strains were isolated from the environment of these patients. Almost all strains isolated from both the patients and the environment (with the exception of one environmental strain) belonged to serotype 04. The isolated S. marcescens strains were resistant to penicillin, ampicillin, streptomycin, kanamycin, oxacillin, methicillin, ceporin and moderately sensitive to polymixin. 2 strains from the environment and 9 strains from the patients were mildly sensitive to gentamicin. In one hospital all isolated strains were found to have 2 transmissive R plasmids with the molecular weight 40 and 60 megadaltons. The presence of R plasmids with the same molecular weight in all S. marcescens strains isolated in this hospital, as well as their serological identity, suggest that in all patients infection originated from a common source.     

Serological response to chlamydial infection in sheep, studied by enzyme-linked immunosorbent assay and immunoblotting

Two enzyme-linked immunosorbent assays (ELISA) using highly purified elementary bodies (EB) of Chlamydia psittaci A/22 strain (ovine) or 6BC strain (psittacine) were set up for the detection of antichlamydial antibodies in sheep. No significant differences were observed between the two ELISAs, whereas these tests proved to be more sensitive than complement fixation test and showed a good correlation (r = 0.75) with immunofluorescence assay. The periodate treatment of chlamydial antigens modified the results of serological responses studied by ELISA, depending on the sera. The average reduction of ELISA values by periodate was 28%, ranging between 5% and 65%. The immunoblot analysis of sheep sera showed high cross reactivity between the polypeptides of A/22 and 6BC strains. However, some differences were observed. The major outer membrane protein (MOMP) of 6BC strain was recognized at different molecular weight position (40,000 kDa) in comparison with the MOMP of A/22 strain (38,000 kDa). In addition, a clear band of 97,000 kDa was detected by all sheep sera tested with A/22 strain. This band was undetectable in the blots performed with 6BC strain.