[Clinical analysis of children with pertussis and significance of respiratory virus detection in the combined diagnosis].

Objective: To analyze the clinical data of children with pertussis and explore the necessity of respiratory virus detection in the combined diagnosis so as to improve the clinician's understanding and standardize the diagnosis and treatment of pertussis in children. Method: Clinical data and laboratory examination of 195 suspected pertussis children between Jan. 2015 and Dec. 2016 in Children's Hospital Affiliated to Capital Institute of Pediatric were analyzed retrospectively. Result: The nasopharyngeal secretions were collected from 195 suspected pertussis children, PCR was employed to detect the nucleic acid of Bordetella pertussis. Meanwhile, 172 of 195 cases were screened for antigens of 7 common respiratory viruses by direct immunofluorescence (DIF) (respiratory syncytial virus(RSV), adenovirus(ADV), influenza virus A and B, parainfluenza viruses type Ⅰ-Ⅲ). (1) Eighty cases were positive in pertussis nucleic acid detection (positive rate was 41.0%), 47 males and 33 females, age ranged from one month to ten years, all of them had paroxysmal cough (100.0%), 50 cases with spasmodic cough (62.5%), 9 cases with vomiting after cough(11.2%), 22 cases with cyanosis after cough(27.5%), 13 cases with roaring after cough(16.2%), 4 cases with dyspnea(5.0%), 18 cases were diagnosed as pneumonia by chest radiography(22.5%) and 1 case was diagnosed as pertussis encephalopathy(1.2%); (2) 172 cases of respiratory virus DIF detection were completed and 69 of them were positive(positive rate was 40.1%), including 32 cases positive for RSV(18.6%), 29 cases for PIVⅢ(16.8%); (3) In 80 confirmed pertussis children, 66 cases of respiratory virus DIF detection were completed and 9 were positive(9/66, 13.6%), including 7 cases positive for PIVⅢ. The clinical manifestations were cyanosis after cough(6 cases), dyspnea(2 cases) and pneumonia were diagnosed by chest radiography in 3 cases, the clinical symptoms of these children were more prominent than children with general pertussis; (4) Patients were divided into three groups according to the pathogens: 57 cases in single pertussis group, 32 cases in RSV infection group, 22 cases in single PIVⅢ infection group.The cases of spasmodic cough in Pertussis group was 35 (61.4%), RSV infection group was 7(21.9%), single PIVⅢ infection group was 8(36.4%), compared with the other two groups, the incidence of spasmodic cough were higher in Pertussis group (χ(2) =12.850, 4.013, P<0.05). The cases of roaring in Pertussis group was 11 (19.3%), RSV infection group was 1(3.1%), single PIVⅢ infection group was 0, and the incidence were higher in Pertussis group (χ(2)=4.596, 4.932, P<0.05). The cases of dyspnea in Pertussis group was 2 (3.5%), RSV infection group was 11(34.4%), single PIVⅢ infection group was 0, and the incidence was higher in RSV infection group (χ(2)=15.654, 9.487, P<0.01). Conclusion: Pertussis is common in children, especially in unvaccinated or incompletely vaccinated infants. The typical clinical manifestation is paroxysmal spasmodic cough; complicated with PIVⅢ infection is a risk factor for sever pertussis. Early detecting of Bordetella by PCR is helpful for the diagnosis of pertussis, RSV and PIVⅢ are the main pathogen for Pertussis-like syndrome. The detection of respiratory virus is helpful for differential diagnosis and medication guidance.

Differential regulation of type III secretion and virulence genes in Bordetella pertussis and Bordetella bronchiseptica by a secreted anti-σ factor.

The BvgAS phosphorelay regulates ∼10% of the annotated genomes of Bordetella pertussis and Bordetella bronchiseptica and controls their infectious cycles. The hierarchical organization of the regulatory network allows the integration of contextual signals to control all or specific subsets of BvgAS-regulated genes. Here, we characterize a regulatory node involving a type III secretion system (T3SS)-exported protein, BtrA, and demonstrate its role in determining fundamental differences in T3SS phenotypes among Bordetella species. We show that BtrA binds and antagonizes BtrS, a BvgAS-regulated extracytoplasmic function (ECF) sigma factor, to couple the secretory activity of the T3SS apparatus to gene expression. In B. bronchiseptica, a remarkable spectrum of expression states can be resolved by manipulating btrA, encompassing over 80 BtrA-activated loci that include genes encoding toxins, adhesins, and other cell surface proteins, and over 200 BtrA-repressed genes that encode T3SS apparatus components, secretion substrates, the BteA effector, and numerous additional factors. In B. pertussis, BtrA retains activity as a BtrS antagonist and exerts tight negative control over T3SS genes. Most importantly, deletion of btrA in B. pertussis revealed T3SS-mediated, BteA-dependent cytotoxicity, which had previously eluded detection. This effect was observed in laboratory strains and in clinical isolates from a recent California pertussis epidemic. We propose that the BtrA-BtrS regulatory node determines subspecies-specific differences in T3SS expression among Bordetella species and that B. pertussis is capable of expressing a full range of T3SS-dependent phenotypes in the presence of appropriate contextual cues.

Epidemiologia genômica de Bordetella pertussis no Brasil / Genomic epidemiology of bordetella pertussis in Brazil

A coqueluche, ou pertússis, é uma doença do trato respiratório causada principalmente pela bactéria Bordetella pertussis. Após 50 anos de vacinação, pertussis reemergiu, passando a ser a doença imunoprevinível mais frequente mesmo em países desenvolvidos. Várias são as hipóteses para a reemergência de pertússis, uma delas é a adaptação do patógeno frente à vacinação. Linhagens contemporâneas de B. pertussis diferem de linhagens do período pré-vacinal, especialmente em genes codificadores de proteínas usadas na produção de vacinas acelular. Esta re-emergência também tem sido observada no Brasil, assim, realizamos a caracterização genética por MLST baseado nesses genes, de 26 isolados B. pertussis de surtos de três regiões brasileiras (Norte, Sul e Nordeste). Foram identificados dois perfis alélicos, em 24 isolados: prn2-ptxS1A-fim3B-ptxP3, de surtos (2008-2013) de Alagoas, Pernambuco e Rio Grande do Sul - e o perfil prn2-ptxS1A-fim3A-ptxP3 , em dois isolados de Pará/2004. Análises filogenéticas agruparam esses perfis com isolados do período pós vacinal de outras partes do globo. Deste conjunto, três do perfil mais frequente e um do perfil menos frequente, tiveram seus genomas sequenciados na plataforma GS 454 Junior. A comparação desses genomas com outros genomas de B. pertussis disponíveis em dados públicos não identificou SNPs ou genes únicos que caracterizassem os isolados do Brasil. Este estudo desenvolveu uma metodologia que permitiu definir a posição da IS481 nos genomas, e uma delas corresponde a um gene relacionado a regulação da transcrição da família MarR, Análise filogenômica, baseada em 826 SNPs, demonstrou que os isolados recentes do Brasil da linhagem pandêmica que presente em todos os continentes, exceto a África...

Pertussis more commonly referred as whooping cough is respiratory tract diseasemainly caused by the bacteria B. pertussis. After 50 years of vaccination pertussisremerged, becoming the most frequent vaccine preventable disease in developedcountries. Many hypotheses have been proposed for the re-emergence of pertussis,one being the pathogen adaptation in a vaccinated environment. Current pertussisstrains are different than those from the prevaccination era, especially in genes thatcode for proteins used in acelluar pertussis vaccines. This re-emergence is alsoobserved in Brazil, therefore we characterized 26 isolates from 3 regions of Brazil(North,South,Northeast) using an MLST approach based on these genes. We identifiedtwo allelic profiles, 24 isolates from the states of Rio Grande do Sul (2008-2009),Alagoas (2008-2009), Pernambuco (2013) and Pará (2004) presented the prn2-ptxS1A-fim3B-ptxP3 allelic profile, while 2 isolates from Pará (2004) presented theprn2-ptxS1A-fim3A-ptxP3 allelic profile. Phylogenetic analysis branch these two allelicprofiles along with other post vaccination isolates around the globe. Four isolates, threefrom the dominant profile and one from the less frequent profile, had their genomescompleted sequenced on the GS 454 Junior Platform. We compared these genomeswith others available in public databases and no SNP or unique genes were identifiedin the Brazilian genomes. This study also developed a methodology that identifies thelocation of the repetitive region IS481, and what genes it interrupted. One of them wasthe MarR transcriptional regulator gene. Phylogenomic analysis based on 826 SNPsrevealed that Brazilian B. pertussis lineages are part of the current pandemic linagepresent in all continents, except Africa...

Hospitalisations due to pertussis in New Zealand in the pre-immunisation and mass immunisation eras.

AIM: Pertussis disease burden in New Zealand in recent decades has been large compared with other developed countries. However, these comparisons use data from relatively short time periods given the long epidemic cycle of pertussis. To better understand the current disease burden, this study examined pertussis hospitalisation data in New Zealand in both the pre-immunisation and mass immunisation eras. METHODS: Hospital discharge data and population data from 1873 to 2004 were used to estimate average pertussis hospital discharge rates per decade. Rates were compared using relative risks and 95% confidence intervals (CI). RESULTS: Average annual pertussis hospitalisation rates per 100000 were less than two from 1873 to 1919, increased to 12 in the 1940s, decreased to less than four in the 1960s and have increased since then with the rate in the current decade being 5.8. Compared with the 1960s (3.8 per 100000) the average annual rate has been significantly greater in the 1980s (RR=1.11, 95% CI 1.03, 1.21), 1990 s (RR=1.33, 95% CI 1.23, 1.44) and 2000s (RR=1.55, 95% CI 1.42, 1.68). Since 1960 hospitalisation rates have increased for those less than one year old, one to four years old and five years and older. The increases have been most marked for infants (RR 2000s vs. 1960s=2.87, 95% CI 2.59, 3.18). CONCLUSION: After an initial decline following mass immunisation, pertussis hospitalisation rates in New Zealand have subsequently increased steadily. To reduce pertussis disease burden improved immunisation coverage and timeliness is required and consideration given to spreading the pertussis vaccine schedule over a wider age range.

[Molecular evidence for the lysogenic state of microorganisms belonging to the genus Bordetella and characterization of Bordetella parapertussis temperate bacteriophage 66(2.2)].

A new bacteriophage phiK of microorganisms belonging to the genus Bordetella was isolated from cells of the earlier characterized strains 66(2-2) (1 and 2) obtained upon phage conversion of B. parapertussis 17903 cells by B. pertussis bacteriophage phi134. Bacteriophage phiK is identical to previously described Bordetella bacteriophages phiT, phi134, and phi214 in morphology and some biological properties but has a permuted genome different from all other phages. DNA of bacteriophage phiK is not integrated in the chromosome of B. parapertussis 17903, similar to DNA of bacteriophages phiT, phi134, and phi214 that are not integrated into B. pertussis and B. bronchiseptica chromosomes, but may be present in a small part of the bacterial population as linear plasmids. Sequences homologous to DNA of bacteriophage phiK were detected in the chromosome of strain 66(2-2) (1 and 2) and in chromosomes of all tested strains B. pertussis and B. bronchiseptica. Prophage integration in chromosomes of microorganisms of the genus Bordetella may vary in different bacterial strains and species. An assumption about abortive lysogeny of B. parapertussis bacteria for phiK phage and of B. bronchiseptica for closely related phages phiT, phi134, and phi214 has been advanced. The possibility of involvement of B. pertussis insertion sequences in the formation of the chromosomal structure in 66(2-2) convertants and in phage genomes is considered.