Distribution of Biofilm-associated Genes among Acinetobacter baumannii by in-silico PCR

Background: Acinetobacter baumannii is a coccobacillus that is Gram negative, non motile, non fermentative and oxidase negative. It is the most common and successful nosocomial pathogen recognised by WHO. This dreadful pathogen causes urinary tract infections, ventilator associated pneumonia (VAP), bacteremia, etc., These infections are most common in hospital wards especially Intensive Care Unit (ICU). The infections are due to biofilm formation by the virulent genes of A. baumannii, and the common biofilm-associated genes of A. baumannii were bap, csuE, fimH, epsA, bfmS, ptk, pgaB, ompA, blaPER-1. Among these, bap, epsA and ompA genes are highly prevalent among the clinical strains of A. baumannii. Aim: To detect the three vital biofilm-associated genes of A. baumannii by in-silico PCR analysis. Materials and Methods: 19 isolates of A. baumannii were selected and 3 target genes, namely epsA, ompA and bap gene were used for the amplification process through in-silico PCR simulation tools. Evolutionary analysis was done for the ompA gene. Results: The epsA gene was expressed in 10.52% of the total strains selected with the highest occurrence of ompA gene as 57.89%. bap gene was not observed from the study strains included. From evolutionary analysis based on ompA distributed strains, the Acinetobacter baumannii SDF and Acinetobacter baumannii BJAB0715 might be the parental strains where the evolution of strains would have started. Through successive generations, the Acinetobacter baumannii MDR-ZJ06 and Acinetobacter baumannii TYTH-1 had become the multidrug resistant strains present in the environment. Conclusion: The findings of the study confirms the distribution of epsA and ompA genes among the 19 different strains of A. baumannii. The study suggests periodical monitoring of biofilm based virulence genes among the clinical strains and to curtail the A. baumannii infections.

Identification and Genetic Diversity Analysis of Rickettsia in Dermacentor Nuttalli Within Inner Mongolia, China

Background The pathogen genus Rickettsia contains the linages spotted fever group, typhus group, transitional group, and the ancestral group, of which the spotted fever group Rickettsia (SFGR) is transmitted by ticks. Dermacentor nuttalli is considered the main vector carrying SFGR. Studying the genetic diversity and population structure of Rickettsia is essential for developing effective control strategies and predicting evolutionary trends of the pathogens. Methods We collected 408 Dermacentor nuttalli in the Inner Mongolia Autonomous region in 2019, detected Rickettsia infection, and characterized the haplotypes. The extracted Rickettsia DNA of the gltA and ompA genes were amplified and sequenced. Result In this study, 10 haplotypes of the gltA gene and 22 haplotypes of the ompA gene were obtained. In the two resulting phylogenetic trees, the haplotypes G1-G7 and G9 of the gltA gene clustered with Rickettsia raoultii, while G8 and G10 clustered with Rickettsia sibirica. Haplotypes O1-O15, O18 and O20-O22 of the ompA gene clustered with Rickettsia raoultii, while O16 and O19 clustered with Rickettsia sibirica. The average haplotype diversity was 0.3 for gltA and 0.7 for ompA, while the average nucleotide diversity was greater than 0.05. Neutrality tests were insignificant for Tajima’s D results and Fu’s Fs results. The fixation index values (FST) showed that the degree of genetic differentiation between most sampled populations was small (FST<0.05), while others were medium (FST>0.05) and large (FST>0.15). Analysis of molecular variance (AMOVA) revealed that the variation within populations was greater than that between populations. The mismatch analysis of Rickettsia showed double peaks. Conclusion We found two genotypes of Rickettsia: Rickettsia raoultii and Rickettsia sibirica. The high genetic diversity of Rickettsia allows for easy adaption to different environments; furthermore, genetic differentiation between populations is small and Rickettsia populations do not show a pedigree geographical structure. The high rates of retention and infestation of Rickettsia in Dermacentor nuttalli together with the animal husbandry exchange in China gradually lead to the genetic characteristics of Rickettsia harmonizing across various regions. Overall, the significant genetic diversity and geographic structure of Rickettsia in Dermacentor nuttalli are critical for SFGR control.

Molecular Characteristics of Rickettsia in Ticks Collected along the Southern Border of Mongolia

Tick-borne infections are a significant threat to public health, particularly in regions where individuals frequently enter tick habitats. Roughly 26% of the population in Mongolia practice nomadic pastoralism and are considered at high risk of exposure to ticks and the diseases they carry. This study tested ticks from Mongolia’s southern border for Rickettsia spp. to better understand the epidemiology of tick-borne diseases in the region. Dermacentor nuttalli and Hyalomma asiaticum ticks (n = 4022) were pooled and tested for Rickettsia spp. by real-time PCR. Melt-curve analyses and Sanger sequencing were used to identify Rickettsia species. Approximately 64% of the 786 tick pools tested positive for Rickettsia bacteria. Melt curve analyses identified four different Rickettsia species circulating in these tick pools. Amplicon sequencing of the ompA gene identified Rickettsia spp. that closely resembled R. raoultii and R. sibirica. Dermacentor nuttalli ticks from Govi-Altai had the highest maximum likelihood estimation infection rate 48.4% (95% CI: 41.7–56.5%), while Hyalommaasiaticum collected in Omnogovi had a rate of 7.6% (95% CI: 6.2–9.2%). The high detection of Rickettsia suggests a substantial risk of infection in southern Mongolia. Further studies are necessary to investigate the clinical burden of tick-borne diseases in Mongolia.

Detection and identification of Chlamydia spp. from pigeons in Iran by nested PCR and sequencing

Background and Objectives: Chlamydia psittaci, an obligate intracellular, Gram-negative zoonotic pathogen, has eight serovars and nine genotypes isolated from avian species with higher frequency in parrots and pigeons. The aim of this study was to characterize Chlamydia spp. using nested PCR and sequencing. Materials and Methods: A total of 270 pharyngeal swab samples collected randomly from asymptomatic pigeons of 30 pigeon aviaries in Tehran province. DNA was extracted with specific kit and amplified by specific primers in the first PCR and outer membrane protein A (ompA) gene in the second PCR. Positive samples were sequenced and phylogenetic tree analyzed based on the ompA gene. Results: Records showed that 16 of 30 (53%) pigeon aviaries were positive for Chlamydia spp. Phylogenetic tree analysis revealed that 15 of 16 (93.7%) positive samples, belonged to C. psittaci genotype B whereas the other sample belonged to C. avium. C. psittaci detected in 50% of pigeon aviaries that is high rate in Tehran province. Conclusion: As C. psittaci is a zoonosis and life threaten pathogen for human being, these results indicate the significance of it detection in asymptomatic pigeons. Also, this is the first report of Chlamydia avium presence in Iranian pigeons which its zoonotic potential is still unknown.

Molecular Characteristics of Rickettsia in Ticks Collected Along the Southern Border of Mongolia

Introduction: Tick-borne infectious dDermacentor and iseases represent a significant threat to public health, particularly in regions where individuals frequently enter tick habitats. This is especially true in Mongolia, where 26% of the population are pastoral herders whose lifestyle results in high risk of tick-borne diseases, which include Rickettsial diseases. In this study, ticks collected along Mongolia’s southern border were tested for the presence of Rickettsia spp. DNA to better understand the risk of this bacterial infection in the region. Methods: Dermacentor and Hyalomma ticks (n = 4,022) collected across southern Mongolia (aimags Bayankhongor, Dornogovi, Govi-Altai, Khovd, and Omnogovi) were pooled and tested for Rickettsia spp. by real-time PCR. Subsequent melt-curve analyses and Sanger sequencing were used to identify specific Rickettsia species. Results: Approximately 64% of the 786 tick pools tested positive for Rickettsia bacteria. Melt curve analyses identified between four and six different Rickettsia species circulating in these tick pools. Amplicon sequencing of the ompA gene from selected positive samples identified Rickettsia spp. that closely resembled R. raoultii and R. sibirica. Detection rates varied greatly by sampling region and tick genus. Dermacentor ticks from the Govi-Altai region had the highest maximum likelihood estimation (MLE) infection rate of 48.4% (95% CI: 41.7-56.5%) while Hyalomma ticks collected in Omnogovi had an MLE rate of 7.6% (95% CI: 6.2-9.2%). Conclusions: Multiple Rickettsia species were found to circulate at high rates within native tick species in southern Mongolia. Further studies are required to investigate the clinical burden of disease associated with these Rickettsia spp. in exposed Mongolian populations.