Surveys on the rates of healthy carriers of Neisseria meningitidis and charaterization of circulating strains

BACKGROUND: During the epidemic season of 1996-97, the increase in the incidence of Meningococcal Disease caused by N. Meningitidis serogroup C led to the initiation of vaccination programmes and to the performance of a number of studies, among which, two were designed to ascertain the prevalence of healthy carriers and are presented here. METHODS: Healthy carriers in the population at large: cross survey performed between March and May 1998, among residents in Extremadura. We took two age groups: 0-19 years of age, vaccinated (n = 1,140) and 20 years of age and over (n = 1,193), unvaccinated. Healthy carriers in a military barracks: cross survey on a military base in May 1998 (n = 619), taking two groups: < 20 years of age (n = 453) vaccinated, and 20 years of age and over (n = 166) unvaccinated. RESULTS: Healthy carrier in the population at large. The percentage of carriers for all of the serogroups was: 0-19 years of age 7.98, 20 years of age and older 3.32, total 4.60, for serogroup B: 4.43, 2.25 and 2.84; for C: 0.04, 0.10 and 0.08 respectively. The differences between the two age groups in serogroup B and the total are statistically significant, as well as the greater prevalence of B over C. The subtype of the three samples with isolation of serogroup C was: one strain NT:P1.6, another strain 2b:P1.2, and one that could not be sub-typed. A strain that could not be classified into a serogroup was sub-typed as 2b:P1.5. Healthy carriers in a military barracks. The percentage of carriers for all of the serogroups was: < 20 years 8.43, 20 years of age and over 6.84, total 7.27, for serogroup B: 4.82, 3.75 and 4.04; and for C: 0.60, 0.00 and 0.16 respectively. The higher prevalence obtained in military subjects in comparison with the population at large revealed statistically significant differences. Also, the prevalence of serogroup B was significantly higher than C. The only isolated C strain was sub-typed as: p1.2,5. CONCLUSIONS: The prevalence of healthy carriers of N. meningitidis in the population at large was 4.60%, being higher in the lower age group and the barracks. Very low prevalence of serogroup C. Impossible to conclude that the strain N. meningitidis serogroup C was circulating during the 1997/98 season.     

Antibiotic sensitivities of Neisseria meningitidis isolates from patients and carriers in Greece.

Usage of antibiotics in southern Europe is less well regulated than in northern countries. The proportion (48%) of meningococci in Spain insensitive to pencillin (MIC greater than or equal to 0.1 mg/l) prompted this investigation of antibiotic sensitivities of isolates from Greek patients with meningitis (31) and carriers (47 school-children and 472 recruits). The agar dilution method was used to determine MIC to penicillin G (PN), sulphamethoxazole (SU), rifampicin (RF), cefaclor (CF) and ciprofloxacin (CP). The proportion of isolates insensitive to PN was 48% for isolates from patients, 19% from school-children and 36.6% from recruits. Resistance to SU (MIC greater than or equal to 16 mg/l) was found in 16% of those from patients, 10.6% from children and 40% from recruits. None of the isolates from patients was resistant to RF (greater than or equal to 1 mg/l) but 6% of those from carriers were. Resistance to CF (greater than or equal to 4 mg/l) was found in 9.2% of patient isolates, 6.4% from children and 23.7% from recruits. All isolates except one were sensitive to CP (MIC range less than 0.0015-0.125 mg/l). Resistances to PN, SU and RF were analysed by serogroup, serotype and subtype of the bacteria. The proportion of resistant isolates showed some variation between different areas of Greece, but it was not statistically significant.     

Sero/subtyping of Neisseria meningitidis isolated from patients in Spain.

To know the types of meningococcal strains in Spain, we serotyped and subtyped 743 Neisseria meningitidis isolates recovered between 1990 and 1992 from patients. A great number of serogroup B, serogroup C and non-groupable meningococci reacted with the serotyping reagents while many serogroup C and non-groupable isolates did not react with the serosubtyping reagents (78.2% and 54.8% respectively); only 8.9% of serogroup B meningococci were non-subtypeable (NST). Distribution of serotypes was similar in serogroup C and in non-groupable strains. Isolates showed great variability in antigenic phenotypes (71 in serogroup B, 20 in serogroup C and 25 in non-groupable meningococci). The most frequent antigenic combinations were 4:P1.15 (39.8%) in serogroup B, 2b:NST (55.8%) in serogroup C and 2b:NST (35.6%) in non-groupable meningococci.     

Antimicrobial sensitivity patterns of hospital and non-hospital strains of Staphylococcus aureus isolated from nasal carriers.

The nasal carriage rate of Staphylococcus aureus was significantly higher in hospitalized persons (children, adult females and staff) - 53.8%, - than in similar persons at a local clinic - 29.8% (P less than 0.001) - in Ile-Ife, Nigeria. However, unlike studies carried out elsewhere, a higher proportion of S. aureus strains obtained from persons at the clinic were resistant to commonly used antimicrobial agents than were strains isolated in the hospital. This has been attributed to the ease at which these drugs can be obtained by the general population and used unsupervised and indiscriminately. Methicillin was the most effective antimicrobial agent against pathologic staphylococci (2.2% resistance), followed by erythromycin (16.5% resistance), co-trimaxozole (28.0% resistance), chloramphenicol (76.9% resistance), tetracycline (78.6% resistance) and penicillin and ampicillin (97.8% resistance). The widespread resistance of S. aureus to penicillin and ampicillin (and other antimicrobial agents) is of clinical significance in the treatment of post-operative infections, since carriers are reportedly more prone to such infections than are non-carriers.     

海南省脑膜炎奈瑟菌多位点序列分型研究

目的 了解海南省脑膜炎奈瑟菌（Nm）的分子分型特征。方法 采用多位点序列分析（MLST）技术,对2005-2015年海南省流行性脑脊髓膜炎（ECM）病人、密切接触者和健康带菌者样本中分离到的16株Nm和1份脑脊液样本进行核酸序列分析。结果 17份样本共分为11种不同的Nm ST型别,分属于ST-4821、ST-11、ST-5、ST-175、ST-364克隆群和5个无序列群分类（UA）,其中前3个克隆群为高致病性克隆群,分别占29.41%（5株）、17.65%（3株）、5.88%（1株）。ST-4821克隆群有ST-4821型和ST-3200型。ST-4821型来自3例C群ECM病例和1株不可分群密切接触者。ST-3200型来自2005年的C群健康带菌者。ST-11、ST-5克隆群分别只有W135群的ST-11型和不可分群的ST-7型,均来自健康带菌者。B群5株有5种ST,其中ST-11127型和ST-11134型为新发现的ST,2015年海口市首例B群病人是ST-7962型,与2010年分离自儋州市ECM密切接触者的B群ST-11127型同源,均为UA,其他不同基因群序列型相互间进化关系较远。结论 海南省Nm分子型别具有基因多样性,Nm C群ST-4821型是优势序列群。健康人群中携带有高致病性克隆群菌株。     

The enterotoxigenicity of strains of Escherichia coli isolated from the faeces of healthy people and cattle.

In this study 197 strains of Escherichia coli isolated from cowpats and the faeces of healthy humans were examined for the presence of enterotoxins. Six strains representing five different serotypes were found to be enterotoxigenic. Four of these strains produced the heat labile enterotoxin and two, the Vero cell cytotoxin.     

Comparison of various characters and antigenic structure in S. aureus strains cultivated in hospitalized patients and in healthy carriers]

A comparison has been done between various characters of 170 non epidemic strains cultivated from hospitalized patients and 29 strains originated from healthy carriers without any hospital contact and antibiotic treatment since 6 months. Following characters have been tested: M.I.C. of 13 antibiotics, heterogenous methicillin resistance, enzymatic antibiotic resistance, macrolide inducible or constitutive type resistance, mercuric chloride susceptibility; phage types; enzymes and toxins production. Antigenic structure has been studied, in particular production of protein A, A beta teichoc acid and type antigens. Significant differences have been observed between hospital and healthy carriers strains; these later strains are antibiotic susceptible, produce few toxins and enzymes, are not frequently phage typable. Their antigenic structure shows also significant differences: A beta-teichoic acid is less frequently detected; type antigens are less frequent and different. Role of these surface antigens in virulence is discussed.     

小牛血清培养基用于人群脑膜炎奈瑟菌带菌调查研究

目的建立一种新型的正常人群脑膜炎奈瑟菌检验方法。方法配制一种小牛血清“双抗”培养基作为脑膜炎奈瑟菌的保菌增菌培养基,用于现场咽拭子采样,带回实验室增菌后再接种平板培养基,分离脑膜炎奈瑟菌,并以常规检测方法作配对比较。结果两次试验新方法检出脑膜炎奈瑟菌14株,常规方法仅在第2次试验时检出脑膜炎奈瑟菌1株。结论应用小牛血清“双抗”培养基建立的新方法适用于A、B、C群脑膜炎奈瑟菌检测,且检测效果明显优于常规的咽拭子直接接种法。     

江西省2005-2008年C群脑膜炎奈瑟菌分子分型分析

对2005-2008年江西省流脑暴发、常规监测中分离的79株C群脑膜炎奈瑟菌进行脉冲场凝胶电泳(PFGE)和多位点测序(MLST)分析,描述江西省C群脑膜炎奈瑟菌的菌型分布和变迁,从分子水平了解其流行特征.     

江西省2005-2008年C群脑膜炎奈瑟菌分子分型分析

对2005-2008年江西省流脑暴发、常规监测中分离的79株C群脑膜炎奈瑟菌进行脉冲场凝胶电泳(PFGE)和多位点测序(MLST)分析,描述江西省C群脑膜炎奈瑟菌的菌型分布和变迁,从分子水平了解其流行特征.     

An experimental outer membrane vesicle vaccine from N. meningitidis serogroup B strains that induces serum bactericidal activity to multiple serogroups

A trivalent native outer membrane vesicle vaccine that has potential to provide broad based protection against Neisseria meningitidis serogroup B strains has been developed. Preliminary immunogenicity studies in mice showed that the vaccine was capable of inducing an effective broad based bactericidal antibody response against N. meningitidis serogroup B strains. These findings in mice have been repeated with a cGMP trivalent NOMV vaccine and extended to show that the bactericidal antibody response induced by the vaccine in mice is effective against strains belonging to serogroups C, Y, W135, X, and NadA-expressing serogroup A strains. Taken together these results suggest that this experimental vaccine may provide protection against both serogroup B and non-serogroup B N. meningitidis strains.