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Neisseria lactamica is a nonpathogenic commensal bacterium that is potentially associated with the development of natural immunity against N. meningitidis. However, the genetic variation present in natural populations of N. lactamica has not been fully investigated. To better understand its epidemiology and genetic variation, we studied N. lactamica carriage in 1200 students aged 11-19 years old in Salvador, Brazil. The carriage prevalence was 4.5% (54/1200), with no statistical difference among sex and age, although we observed a trend towards higher carriage prevalence among 11-year-old individuals. Whole genome sequence analysis revealed a high genetic diversity among the isolates, with the presence of 32 different STs, 28 (87.5%) of which were new. A total of 21/50 (42%) isolates belonged to three different clonal complexes. While none of the isolates contained nadA or fHpb alleles, we detected 21 FetA variants, 20 NhbA variants and two variants of PorB. The data provide detailed information on circulating N. lactamica isolates in adolescents in Brazil and are complementary to studies in other countries.

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Neisseria lactamica está envolvida na aquisição da imunidade natural contra Neisseria meningitidis, causadora da doença meningocócica. Vesículas de membrana externa (OMV) de N. lactamica são antígenos potenciais contra N. meningitidis. Analisou-se a cinética de biomassa, de produção de OMV, da fonte de carbono (lactato), e dos metabólitos, para maximizar a produção de OMV. Realizaram-se ensaios em biorreator, em batelada simples, batelada alimentada com lactato, com ou sem pulsos de aminoácidos e extrato de levedura (YE). Utilizou-se o meio de Catlin (MC) como meio mínimo, e analisaram-se efeitos das concentrações do lactato, aminoácidos e YE. Lactato foi consumido e citrato e acetato produzidos. Os melhores resultados obtidos foram no meio com adição de 2 g/L de YE e concentrações dobradas de lactato e 5 aminoácidos constitutivos do MC, em batelada alimentada com pulsos. O lactato apresentou efeito positivo sobre o rendimento de OMV e o YE sobre a biomassa. Os 5 aminoácidos constitutivos do MC foram necessários para obtenção de biomassa e rendimento de OMV.

Neisseria lactamica is involved with the acquisition of natural immunity to Neisseria meningitidis. N. lactamica outer membrane vesicles (OMV) are potential antigens against N. meningitidis, the pathogen of meningococcal disease. The objective of this work was to analyze the kinetics of bacterial growth, OMV production, the carbon source (lactate), and products of metabolism, to improve growing conditions and OMV production. Groups were studied in batch process, fed-batch process with lactate, fed-batch process with pulses of amino acids and YE. MC was considered as minimal medium and it was analyzed the effect of lactate, amino acids and YE. Lactate was consumed and citrate and acetate increased in the medium. The best results were in fed-batch with pulses, in MC with the double concentrations of lactate and amino acids, added with 2 g/L of YE. The lactate had a positive effect over OMV yield and YE had a positive effect over biomass. 5 amino acids of MC were necessary to obtain biomass and OMV yield.

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The aim of the present study was to investigate the immune response to native outer membrane vesicles (NOMVs) of Neisseria lactamica with and without Bordetella pertussis (BP) as adjuvant in intranasal (i.n./i.m) immunization. N. lactamica NOMVs delivered intranasally (i.n) to BALB/c mice in a final volume of 5microl that was gradually introduced with a micropipette, Animals received 1, 2, 3, or 4 doses of antigens at 3, 7, 9 and 12 days after birth. On the 35th day, the animals were immunized intramuscularly (i.m.) with (NOMV) of N. lactamica. The prime-booster strategy using NOMV of N. lactamica with BP as adjuvant in the primer (i.n.) and booster (i.m.) is an effective immunization protocol for inducing humoral immune responses producing IgG antibodies of intermediate to high avidity.

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Abstract Neisseria lactamica, a commensal bacterium that is non-pathogenic to humans and is usually found in the upper respiratory tract of children, is closely related to the pathogenic species Neisseria meningitidis. Colonization by Neisseria lactamica can be responsible for the development of natural immunity to meningococcal infection in childhood, when rates of meningococcal carriers are low. These features suggest that N. lactamica components can be key elements in the production of a new vaccine for N. meningitidis. The production of monoclonal antibodies for N. lactamica is an important tool in the selection of new antigens for the preparation of a vaccine for N. meningitidis B.

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Se determinó la prevalencia de N meningitidis y N lactamica, así como su relación con las variables edad y sexo enindividuos de tres grupos de riesgo diferentes (círculo infantil, escuela primaria y escuela universitaria), a los que se les realizó exudado de la nasofaringe posterior. Se identificaron los marcadores epidemiológicos de las cepas de N meningitidis aisladas y se analizó la presencia de otros microorganismos de la familia Neisseriaceae. La identificación de las cepas obtenidas se realizó por el sistema APINH (bioMérieux), el seroagrupamiento de N meningitidis se determinó por aglutinación en lámina portaobjetos con antisueros específicos y los sero/subtipos e inmunotipos se identificaron por un ensayo inmunoenzimático de células enteras con anticuerpos monoclonales. El10,9 por ciento de los sujetos investigados fue portador de N meningitidis, cifra que aumentó con la edad. La prevalencia de portadores tuvo el siguiente comportamiento: Grupo 1: niños de 0-6 años (4,3 por ciento); Grupo 2: niños de 5-12 años (6,9 por ciento) y Grupo 3: adultos jóvenes de 17-22 años (25,1 por ciento). No hubo diferencias significativas respecto al sexo (p > 0,05). En el Grupo 1 predominó el fenotipo NA:NT:P1.6:L3, 7,9 (71,5 por ciento), mientras que, en los Grupos 2 y 3, prevaleció laasociación NA:NT:P1.NST:L3,7,9 (36,4 y 25 por ciento, respectivamente). El predominio de cepas no epidemiogénicas avalan el impacto de la inmunización en Cuba con VA-MENGOC-BC. El aislamiento de cepas de N. lactamica disminuyó a medida que aumentó la edad: Grupo 1 (47,5 por ciento), Grupo 2 (29,8 por ciento) y Grupo 3 (3 por ciento)(AU)

Prevalence of N meningitidis and N lactamica, as well as their relationship to age and sex variables in individuals of three different risk groups (day care centers, primary school and universities) was determined by performing an exudate of uppernaso-pharynx. Epidemiological markers of the isolated N meningitidis strains were identified and the presence of othermicroorganisms of Neisseriaceae family was identified. Identification of the strains obtained was carried out by API NH (bioMérieux) system; sero-grouping of N meningitidis was determined by agglutination in slides with specific antisera and sero/subtypes and immunotypes were identified by an immuno-enzymatic assay of whole cells with monoclonal antibodies. The 10.9 percent of investigated subjects was carrier of N meningitidis, which increased with age. Prevalence of carriers had the following behavior: Group 1: children from 0-6 years old (4.3 percent); Group 2: children from 5-12 years old (6.9 percent) and Group3: young adults from 17-22 years old (25.1 percent). No significant differences were observed with respect ot sex (p > 0.05). In Group 1, phenotype NA:NT:P1.6:L3.7.9 (71.5 percent) predominated while in Groups 2 and 3, the association NA:NT:P1.NST:L3.7.9 (36.4 and 25 percent, respectively) prevailed. Predominance of non-epidemiogenic strains support the impact of immunization in Cuba with VA-MENGOC-BC. Isolation of strains of N. lactamica decreased with the increaseof age: Group 1 (47.5 percent), Group 2 (29.8 percent) and Group 3 (3 percent)(AU)

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We describe a case of an adult organ recipient patient with a pulmonary cavitary lesion due to Neisseria lactamica, a harmless commensal organism that rarely causes human infection. To our knowledge, this is the first report of pulmonary disease caused by this organism and the second case of N. lactamica infection in an adult patient.

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The muscosal delivery of vaccines has many advantages including ease of administration and the induction of a mucosal immune response at the natural site of infection for many pathogens. Mice were immunised with outer membrane vesicles (OMV) prepared from Neisseria lactamica or Neisseria meningitidis by subcutaneous (SC) or intranasal (IN) routes, or live cells of N. lactamica given IN or by SC injection. A systemic IgG and mucosal IgA response was demonstrated and N. lactamica OMV induced antibodies cross-reactive with N. meningitidis; however, a cross-reactive response following IN administration was only evident after three doses of vaccine. OMV from both organisms were also an effective intranasal adjuvant for a co-administered model antigen, hepatitis B surface antigen (HBsAg), inducing systemic IgG against HBsAg and IgA in lung and vaginal washes. IN administration of N. meningitidis OMV elicited serum antibodies that were bactericidal for meningococci and provided passive protection in an infant rat model of meningococcal bacteraemia. The antibody response to N. lactamica OMV given IN was only weakly bactericidal but still afforded passive protection. Thus, OMV from N. lactamica given IN elicit immune responses cross-reactive with N. meningitidis and act as an effective mucosal adjuvant.

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Na pesquisa de portadores de Neisseria meningitidis, a distinção da Neisseria lactamica é da maior importância, pois esta apresenta um perfil antigênico semelhante ao da Neisseria meningitidis o que ocasiona reações cruzadas freqüentes. Em pesquisa realizada em 1.983 voluntários, foram encontradas 431 amostras de Neisséria que se comportaram sorologicamente como Neiseeria meningitidis. Estas cepas foram estudadas em relação ao ataque à lactose (1% em meio C.T.A., Difeo) e quanto à hidrólise do O.N.P.G. (ortho-nitrophenyl-j3-D-galactopyranoside) pela ação da Beta-galactosidase. Das 431 amostras, 70 foram O.N.P.G. positivas e destas apenas 42 atacaram a lactose, após 48 horas (tempo máximo de observação foi de 15 dias). O ataque da lactose revelou o encontro da Neisseria lactamica em apenas 60% das oportunidades e, assim mesmo, após observação por 48 horas na grande maioria dos casos. Em vista destes achados, os autores recomendam a introdução do teste da Beta-galactosidase na rotina da pesquisa de Neisseria. meningitidis pois, além de ser um método simples e rápido, evita erros diagnósticos decorrentes de reações antigênicas cruzadas. Este fato assume maior relevância, pois esta bactéria já foi responsabilizada por um caso de meningite purulenta (AU).

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