Research progress on the pathogenicity of Porphyromonas gingivalis clinical strains / 口腔疾病防治

@#Porphyromonas gingivalis (P. gingivalis) is closely related to the occurrence and development of periodontitis. It is considered to be one of the important pathogens leading to alveolar bone resorption. At present, research on P. gingivalis mostly adopts standard laboratory strains whose genetic characteristics have been confirmed, are guaranteed and are traceable, such as ATCC 33277. The virulence phenotypes (endotoxin, firmbria, etc.) of clinically extracted isolates are quite different from those of standard strains, and the pathogenic effects and ability of the host are also widely different. In addition, P. gingivalis is considered to have a significant correlation with a variety of systemic diseases, and the virulence characteristics and pathogenic ability of different strains will have different effects on systemic diseases. However, at present, there is a lack of research on clinical strains and standard strains, and there is a lack of systematic comparison between the two sources of bacteria. In this paper, the differences in the virulence phenotypes and pathogenic effects between clinical isolates and standard strains of P. gingivalis in the last 5-10 years are reviewed. The aim is to elucidate the important virulence gene loci in the P. gingivalis gene sequence, which will play an important role in improving therapeutic methods and the development of related drugs.

Fist report on fumagillin production by Aspergillus fumigatus sensu stricto gliotoxigenic strains recovered from raw cow milk and clinical samples in Argentina / Primer reporte en Argentina sobre la producción de fumagilina por cepas deAspergillus fumigatus sensu stricto productoras de gliotoxina, aisladas de lechecruda y de casos clínicos

Abstract In Argentina there are no reports on Aspergillus fumigatus fumagillin-producingstrains. In this study we describe the isolation and mycotoxin production capacity of ten A.fumigatus strains isolated from farm and clinical samples. Farm strains were isolated frommilk samples taken from dairy cows in Córdoba province, some of which were associated withsubclinical mastitis. A culture medium was defined to optimize fumagillin production and adetection method was developed by HPLC chromatography. It is known that in addition to thehost immune status, strain virulence is a fundamental characteristic that will determine itspathogenicity and, in this sense, fumagillin is considered to be among the virulence factors. Inthe present work, all the strains tested for the production of fumagillin were able to synthesizeit, highlighting that the strain A. fumigatus RC2243, from a milk sample from a cow with clinicalmastitis, was the most productive. The existence of fumagillin-producing strains represents apotential risk of mycotoxins being transferred to raw milk, constituting a public health risk.

Resumen En Argentina no existen reportes sobre cepas de Aspergillus fumigatus productoras de fumagilina. En este trabajo se describe el aislamiento y la producción de dicha micotoxina clínicaspor 10 cepas, provenientes del medioambiente rural y aisladas de muestras clínicas. Las cepasde origen rural fueron aisladas de vacas lecheras en tambos de la provincia de Córdoba, yalgunas de esas cepas se asociaron a casos de mastitis subclínica. Se definió la composición deun medio de cultivo para optimizar la producción de fumagilina y se desarrolló un método decromatografía HPLC para su determinación. Es conocido que, además del estado inmunitario delhuésped, la virulencia de la cepa es una de las características fundamentales que determinansu potencial patogénico y, en este sentido, la fumagilina es considerada un factor de virulencia. En el presente trabajo todas las cepas estudiadas fueron capaces de sintetizarla y la cepa A.fumigatus RC2243, proveniente de leche de una vaca con mastitis subclínica, se destacó comola cepa más productora. La existencia de cepas productoras de fumagillina representa un riesgopotencial por el pasaje de dicha micotoxina a la leche, lo cual constituye un problema para lasalud pública.

Use of Traditional Indian Plants in the Inhibition of Caries-Causing Bacteria - Streptococcus mutans

The aim of the study was to comparatively evaluate the antibacterial activity of six Indian plant extracts and 0.2% chlorhexidine against clinical strains of Streptococcus mutans, which were isolated from the plaque samples of 45 pediatric patients. Six plant extracts were prepared in three different forms, namely aqueous extracts, organic solvent-based extracts and crude (raw) extracts. The antimicrobial sensitivity testing was done by agar well diffusion method. Antimicrobial activity of the extracts was determined by measuring the mean zones of inhibition (mm) produced against the bacterial isolates. Results showed that crude garlic extract exhibited greater antibacterial activity than chlorhexidine. Aqueous extract of amla and organic solvent-based extract of ginger showed the maximum antibacterial activity against S. mutans, whereas aqueous extract of tulsi and organic solvent based extract of amla showed the minimum antibacterial activity. This study suggests that plant extracts like garlic in crude form, amla as aqueous infusion and ginger as alcoholic tincture have potential for the control of S. mutans. These extracts can be used as an alternative remedy for dental caries prevention or in the form of mouthwash, which is safe and economical.

O objetivo do estudo foi avaliar comparativamente a atividade antibacteriana de seis plantas indianas contra linhagens clínicas de Streptococcus mutans, que foram isoladas das amostras de biofilme dental de 45 pacientes pediátricos, com 0,2% de clorexidina. Seis extratos vegetais foram preparados em três formas diferentes, a saber, extratos aquosos, extratos à base de solventes orgânicos e extratos brutos. Os testes de sensibilidade antimicrobiana foram realizados por método de difusão em agar. A atividade antimicrobiana dos extratos foi determinada através da medição da zona de inibição, em milímetros, produzida contra os isolados bacterianos. Os resultados mostraram que o extrato de alho cru apresentou maior atividade antibacteriana do que a clorexidina. O extrato aquoso de amla e o extrato à base de solventes orgânicos de gengibre mostraram a máxima atividade antibacteriana contra S. mutans, enquanto o extrato aquoso de tulsi (manjericão) e o extrato à base de solventes orgânicos de amla mostraram mínima atividades antibacteriana. Este estudo sugere que extratos de plantas como o alho em forma bruta, amla como infusão aquosa e gengibre como tintura alcoólica tem um potencial para o controle de S. mutans. Estes extratos podem ser utilizados como uma via alternativa para a prevenção de cáries dentárias ou sob a forma de bochechos, que são seguros e econômicos.

Characterization of mercury-resistant clinical Aeromonas species

Mercury-resistant Aeromonas strains isolated from diarrhea were studied. Resistance occurs via mercuric ion reduction but merA and merR genes were only detected in some strains using PCR and dot hybridization. Results indicate a high variability in mer operons in Aeromonas. To our knowledge, this is the first report of mercury-resistant clinical Aeromonas strains.

Molecular Identification of Anginosus Group Streptococci Isolated from Korean Oral Cavities

Anginosus group streptococci (AGS) were classified based on the nucleotide sequences of the 16S rRNA gene (16S rDNA) and comprised Streptococcus anginosus, Streptococcus intermedius, and Streptococcus constellatus. It is known that AGS is a causative factor of oral and systematic diseases. The purpose of this study was to discriminate the 56 clinical strains of AGS isolated from Korean oral cavities using phylogenetic analysis of 16S rDNA and species-specific PCR at the species-level. The 16S rDNA of clinical strains of AGS was sequenced using the dideoxy chain termination method and analyzed using MEGA version 5 software. PCR was performed to identify the clinical strains using species-specific primers described in previous studies and S. intermedius-specific PCR primers developed in our laboratory. The resulting phylogenetic data showed that the 16S rDNA sequences can delineate the S. anginosus, S. intermedius, and S. constellatus strains even though the 16S rDNA sequence similarity between S. intermedius and S. constellatus is above 98%. The PCR data showed that each species-specific PCR primer pair could discriminate between clinical strains at the species-level through phylogenetic analysis of 16S rDNA nucleotide sequences. These results suggest that phylogenetic analysis of 16S rDNA and PCR are useful tools for discriminating between AGS strains at the species-level.

Antibiotic Resistance of Clinical Strains of Staphylococcus aureus Isolated in Xiangfan City / 中华医院感染学杂志

OBJECTIVE To investigate the antibiotic resistance status in clinical strains of Staphylococcus aureus (SAU) in Xiangfan and provide scientific evidence for reasonable use of antibiotics. METHODS Retrospective review was performed to analyzed the specimen source and the clinical distribution of 359 strains of SAU. BioMerieux Vitek 32 was used to identify the species of bacteria. Antibiotic susceptibility test was performed by K-B method and drug-resistance results were read according to CLSI2006. RESULTS Isolating rate of methicillin resistant S. aureus (MRSA) arrived at 54.9%. The results of susceptibility test showed that SAU had been resistant to the diverse antibiotics in different degree. The drug sensitivity rate of glycopeptide antibiotics and linezolid were all 100%. CONCLUSIONS The different grade hospitals should practically perform the management of antibiotics to postpone the resistance development and control outbreak and prevalence of nosocomial infections.

Nested PCR for Detection of Malassezia Species from Patient Skin Scales and Clinical Strains / 대한피부과학회지

BACKGROUND: Due to recent identification of new Malassezia (M.) species, M. dermatis, and M. equi, the genus Malassezia was revised into eleven species that have been isolated from human and animal skin. This has further substantiated the need for molecular techniques to distinguish the various Malassezia species. OBJECTIVE: We aimed to make the nested polymerase chain reaction (PCR) using species-specific primers with specificity and sensitivity as a diagnostic tool for differentiating the various Malassezia species from skin scales and fungal cells rapidly and accurately. In addition, we evaluated the common causative Malassezia species in the patients with seborreheic dermatitis, pityriasis versicolor or pityrisporum folliculitis. METHODS: Malassezia species-specific primers were designed based on DNA sequencing of the ribosomal RNA gene. The standard strains of eight members of the genus Malassezia such M. pachydermatis, M. furfur, M. sympodialis, M. globosa, M. obtuse, M. restricta, M. slooffiae, and M. dermatis were used for positive control. Each Malassezia species was cultured separately and two or three standard species were cultured together on Modified Leeming and Notman agar (MLNA) media plates. In addition, twenty-five clinical strains of Malassezia species isolated from the skin of patients with dermatological conditions and twenty-three samples of skin scale were used as well. RESULTS: The nested PCR assay with primers for all eight Malassezia species were species-specific since it amplified DNA only from the target Malassezia species, and could differentiate mixed, that is, the two or three Malassezia species of all standard strains grown on MLNA medium precisely. Detection of Malassezia species from clinical strains and patient skin scales using the nested PCR assay was 96% (24/25) and 87% (20/23), respectively. M. globosa, M. sympodialis, M. restricta were the most common causative Malassezia species in patients with pityriasis versicolor, pityrosporum folliculitis, seborrheic dermatitis, respectively. CONCLUSION: Nested PCR using species-specific primers is useful and reliable in the detection of various Malassezia species from patient skin scales as well as cultured fungal cells.

Multilocus microsatellite typing of clinical Cryptococcus neoformans var.grubii strains from China and Brazil / 第三军医大学学报

Objective To understand the genotype distribution of clinical Cryptococcus neoformans var.grubii strains from China and Brazil using multilocus microsatellite typing(MLMT) method and to study the difference in their MLMT genotyping.Methods DNA was extracted from the identified 69 clinical Cryptococcus neoformans var.grubii strains.DNA fragments covering microsatellite loci(CNG1,CNG2,and CNG3) were amplified by PCR and sequenced.The number of each motif repeats in 3 microsatellite regions("TA","GA",and "CAT" repeats for CNG1,CNG2,and CNG3,respectively) was calculated.The MLMT types of 69 clinical Cryptococcus neoformans var.grubii strains were determined according to the repeat number of different motifs.Data were analyzed using SPSS 11.5 software.Results Five genotypes were identified in 33 clinical strains from China.Of these strains,29 were MLMT-17,accounting for 87.88% of the total strains.Ten genotypes were identified in 36 clinical strains from Brazil.Of the 36 strains,19 were MLMT-13,accounting for 52.78% of the total strains.Conclusion The difference is great in major genotype distributions of the clinical Cryptococcus neoformans var.grubii strains from China and Brazil.The genotype of clinical strains from Brazil is diversely distributed.