Search Results (125)

This study investigated tick species and spotted fever group rickettsiae (SFGR) infection rates in ticks from yaks in Jiulong County, Sichuan Province, China. Firstly, ticks collected from yaks were meticulously classified through morphological identification. Subsequently, the total DNA of ticks was extracted, and specific partial sequences of their ITS-2 region, as well as the ompA and ompB genes of SFGR, were amplified using PCR. The positive PCR products were sequenced and compared thoroughly against the NCBI database. A phylogenetic analysis was conducted for ITS-2, ompA, and ompB to determine the species of tick and the SFGR. The results revealed that a total of 585 ticks were collected, with the most abundant species being R. microplus, which accounted for 52.65% (308/585) of the total and was followed by I. ovatus (32.99%, 193/585), I. acutitarsus (8.89%, 52/585), and D. everestianus (5.50%, 32/585). Furthermore, SFGR was detected in 63.93% (374/585) of the ticks. Notably, the infection rate of SFGR in semi-agricultural and pastoral areas was significantly higher at 70.60%, compared to 45.10% in pastoral areas (p < 0.01). Overall, this study marks the first investigation into the prevalence of SFGR in Jiulong County and highlights the high infection rate of SFGR in ticks, with R. raoultii being the predominant species. Full article

Avian Pathogenic Escherichia coli (APEC) constitutes a major etiological agent of avian colibacillosis, which significantly hinders the development of the poultry industry. Conducting molecular epidemiological studies of APEC plays a crucial role in its prevention and control. This study aims to elucidate the molecular epidemiological characteristics of Avian Pathogenic Escherichia coli in Shanxi Province. In this study, 135 APEC strains were isolated and identified from 150 liver samples of diseased and deceased chickens exhibiting clinical symptoms, which were collected from farms in Shanxi Province between 2021 and 2023. The isolates were then analyzed for phylogenetic clustering, drug resistance, resistance genes, virulence genes, and biofilm formation capabilities. The results revealed that the proportions of the A, B1, B2, and D evolutionary subgroups were 26.67%, 32.59%, 17.78%, and 15.56%, respectively. The drug resistance testing results indicated that 92% of the isolates exhibited resistance to cotrimoxazole, kanamycin, chloramphenicol, amoxicillin, tetracycline, and other antibiotics. In contrast, 95% of the strains were sensitive to ofloxacin, amikacin, and ceftazidime. The most prevalent resistance genes included tetracycline-related (tetA) at 88.15%, followed by beta-lactam-related (bla-TEM) at 85.19%, and peptide-related (mcr1) at 12.59%. The virulence gene analysis revealed that ibeB, ompA, iucD, and mat were present in more than 90% of the isolates. The results revealed that 110 strains were biofilm-positive, corresponding to a detection rate of 81.48%. No significant correlation was found between the drug resistance genes, virulence genes, and the drug resistance phenotype. A moderate negative correlation was observed between the adhesion-related gene tsh and biofilm formation ability (r = −0.38). This study provides valuable insights into the prevention and control of avian colibacillosis in Shanxi Province. Full article

Vector-borne diseases, particularly those caused by Rickettsia species, pose a significant public health threat in Europe. Despite extensive research on tick-borne pathogens in various European countries, Luxembourg has yet not been studied for Rickettsia spp. in ticks infesting domestic animals. This study aimed to fill this gap by investigating the presence of Rickettsia spp. in Ixodes ricinus ticks collected from domestic dogs in Luxembourg between April 2023 and April 2024. A total of 61 ticks were examined using molecular techniques, including PCR amplification of the outer membrane protein B (ompB), outer membrane protein A (ompA), and citrate synthase (gltA) genes. Results revealed the presence of R. helvetica and R. conorii subsp. raoultii, with 4.9% of ticks testing positive for Rickettsia spp. Phylogenetic analysis confirmed the high genetic identity of the sequences obtained with previously described strains from Europe and Asia. This study highlights the potential risk of emerging tick-borne diseases in Luxembourg and emphasizes the need for ongoing surveillance to better understand the spread of Rickettsia spp. in Europe, particularly as climate change may facilitate the expansion of tick populations and their associated pathogens. Full article

Escherichia coli (E. coli) has the ability to induce clinical and subclinical mastitis in dairy cows, causing a huge loss for the dairy industry. In this study, 51 subclinical mastitis isolates and 36 clinical mastitis isolates from eight provinces of China between 2019 and 2021 were used to investigate the differences in their biological characteristics. The results showed that B1 (52.9%) and A (39.1%) were the predominant phylogroups; R1 (50.6%) was the predominant lipopolysaccharide (LPS) core type; and 44 STs (ST10 and ST58 were the most sequence-prevalent STs) and 2 new STs (ST14828 and ST14829) were identified; however, no significant difference was observed between the clinical and subclinical group strains. To compare the virulence gene differences between the clinical and subclinical mastitis-related isolates, 18 common virulence genes (including afaE, eaeA, papC, saa, sfa, ompA, aer, irp2, iucD, escV, sepD, east1, estB, stx2e, CNF1, cba, hlyA and traT) were determined using the PCR method. The results showed that the detection rates of traT, irp2 and iucD in clinical mastitis isolates were significantly higher than those in subclinical mastitis isolates (p ˂ 0.05). Meanwhile, subclinical-group E. coli had stronger biofilm formation abilities than the clinical group (p < 0.05) in 78 (89.7%) mastitis-related E. coli that could form biofilms. Furthermore, 87 mastitis-related E. coli showed severe resistance against tetracycline (37.9%), ampicillin (36.8%), streptomycin (34.5%) and cotrimoxazole (28.7%); their most prevalent resistance genes were blaCTX-M (33.3%), tetA (27.6%), sul2 (18.4%) and strB (28.7%). It was noteworthy that the clinical-group strains had a higher resistance against ampicillin and possessed higher amounts of the resistance gene blaCTX-M (p < 0.05) compared to the subclinical group. This study aims to provide references for preventing the E. coli isolates from inducing different types of mastitis. Full article

Multidrug-resistant Acinetobacter baumannii is a major concern in healthcare institutions worldwide. Several reports described the dissemination of A. baumannii high-risk clones that are responsible for a high number of difficult-to-treat infections. In our study, 19 multidrug-resistant A. baumannii strains from Budapest, Hungary, were investigated based on whole-genome sequencing (WGS). The obtained results were analysed together with data from 433 strains of A. baumannii from the Pathogenwatch database. WGS analysis of 19 A. baumannii strains detected that 12 belonged to ST2 and seven belonged to ST636. Among ST2 strains, 11 out of 12 carried either bla_OXA-23 or bla_OXA-58 genes; however, all strains of ST636 uniformly carried bla_OXA-72 gene. All strains of ST2 and ST636 carried bla_OXA-66 and bla_ADC-25 genes. Based on core genome multilocus sequence typing (cgMLST), 10 strains of ST2 belonged to cgMLST906, one strain to cgMLST458, and one strain to cgMLST1320; by contrast, all strains of ST636 belonged to cgMLST1178. Certain virulence determinants were present in all strains of both ST2 and ST636, namely, Ata, Bap, BfmRS, T2SS and PNAG. Interestingly, OmpA was present in all strains of ST2, but it was absent in all strains of ST636. Comparative analysis of 19 strains of this study and the collection of 433 isolates from Pathogenwatch database, proved a diverse clonal distribution of high-risk A. baumannii clones in Europe. The major clone in Europe is ST2, which is present all over the continent. However, ST636 has been mainly reported in Eastern Europe. Interestingly, cgMLSTs of ST2 correspond to the production of different beta-lactamases, namely, OXA-82 in cgMLST116, OXA-72 in cgMLST506, and cgMLST556, PER-1 in cgMLST456 and cgMLST1041. Our study demonstrates that the ST2 high-risk clone of A. baumannii is the most widespread in Europe; however, based on cgMLST analysis, a detailed detection of beta-lactamase production can be determined. Full article

Diarrheal diseases caused by Shigella and enterotoxigenic Escherichia coli (ETEC) are significant health burdens, especially in resource-limited regions with high child mortality. In response to the lack of licensed vaccines and rising antibiotic resistance for these pathogens, this study developed a recombinant Shigella flexneri strain with the novel incorporation of the eltb gene for the heat-labile enterotoxin B (LTB) subunit of ETEC directly into Shigella’s genome, enhancing stability and consistent production. This approach combines the immunogenic potential of LTB with the antigen delivery properties of S. flexneri outer membrane vesicles (OMVs), aiming to provide cross-protection against both bacterial pathogens in a stable, non-replicating vaccine platform. We confirmed successful expression through GM1-capture ELISA, achieving levels comparable to ETEC. Additionally, proteomic analysis verified that the isolated vesicles from the recombinant strains contain the LTB protein and the main outer membrane proteins and virulence factors from Shigella, including OmpA, OmpC, IcsA, SepA, and Ipa proteins, and increased expression of Slp and OmpX. Thus, our newly designed S. flexneri OMVs, engineered to carry ETEC’s LTB toxin, represent a promising strategy to be considered as a subunit vaccine candidate against S. flexneri and ETEC. Full article

Chlamydia psittaci is a bacterium that infects several species of birds and mammals. It is the causal agent of avian chlamydiosis and psittacosis in humans and it is globally distributed. Chlamydia psittaci is one of the main zoonotic pathogens transmitted by birds. In Argentina, there has been limited research on the prevalence and genetic variability of C. psittaci. The aim of this study was to detect and genotype C. psittaci using molecular techniques in birds living in Buenos Aires City, Argentina, during the period 2012–2015. A descriptive, observational, retrospective and cross-sectional study was carried out. A total of 983 bird samples submitted for diagnosis of avian chlamydiosis were analyzed. The frequency of C. psittaci was 12.54% and 7.89% in Psittaciformes and Columbiformes, respectively. A 348 bp region of the ompA gene was sequenced in positive samples. Molecular genotyping was performed through a Bayesian phylogenetic analysis. Of the 983 bird samples, 83 were positive for C. psittaci and 44 could be sequenced. The genotypes found were A, B, and E. Despite the high levels of host specificity, we found six psittacids with genotype B and one pigeon with genotype A, reflecting the affiliative interaction between Psittaciformes and Columbiformes. This study represents the first survey reporting the presence of C. psittaci in birds within the largest and most populous city in Argentina. Full article

Background/Objectives: A. baumannii is a prominent nosocomial pathogen due to its drug-resistant phenotype, representing a public health problem. In this study, the aim was to determine the effect of different antimicrobial combinations against selected multidrug-resistant (MDR) or extensive drug-resistant (XDR) isolates of A. baumannii. Methods: MDR or XDR A. baumannii isolates were characterized by assessing genes associated with drug resistance, efflux pumps, porin expression, and biofilm formation. The activities of antimicrobial combinations including tigecycline, ampicillin/sulbactam, meropenem, levofloxacin, and colistin were evaluated using checkerboard and time-to-kill assays on isolates with different susceptibility profiles and genetic characteristics. Results: Genetic characterization of MDR/XDR strains (n = 100) included analysis of OXA-24/40 gene carbapenemase (98%), genes encoding aminoglycoside-modifying enzymes (44%), and parC gene mutations (10%). AdeIJK, AdeABC, and AdeFGH efflux pumps were overexpressed in 17–34% of isolates. Omp33-36, OmpA, and CarO membrane porins were under-expressed in 50–76% of isolates; CarO was overexpressed in 22% of isolates. Isolates showed low biofilm production (11%). Synergistic activity was observed with levofloxacin-ampicillin/sulbactam and meropenem-colistin, which were able to inhibit bacterial growth. Conclusions: Genetic characteristics of A. baumannii were highly variable among the strains. Synergistic activity was observed with meropenem-colistin and levofloxacin-ampicillin/sulbactam combinations in the checkerboard method, but not in the time-to-kill assays. These discrepancies among both methods indicate that further studies are needed to determine the best therapeutic combination for treating infections by A. baumannii. Full article

To determine the etiological agents responsible for acute pneumonia in puppies in China, this study utilized bronchoalveolar lavage (BAL) fluid extraction to enable the isolation, culture, biochemical identification, and 16S rRNA PCR amplification of the pathogens. Following preliminary identification, the pathogens underwent analysis for antibiotic resistance phenotypes and resistance genes. Additionally, the study examined the presence of virulence genes, conducted multilocus sequence typing (MLST), and performed whole-genome sequencing (WGS). The findings revealed that all four isolated pathogens were characterized as extraintestinal pathogenic Escherichia coli (ExPEC). The examined ExPEC strains demonstrated resistance to cephalosporins, tetracyclines, and penicillins, while remaining susceptible to aminoglycosides, beta-lactamase inhibitors, carbapenems, chloramphenicols, and sulfonamides. An analysis of virulence genes identified the presence of eight genes, namely CNF-I, fyuA, fimC, papC, ompA, fimH, irp2, and iroN, which are implicated in their invasiveness and potential to inflict tissue damage. The MLST analysis revealed that all ExPEC strains were classified under either sequence type ST131 (Achtman database) or ST43 (Pasteur database). The study further determined that these strains were absent in the kennel’s drinking water source, thereby ruling out water contamination as a potential factor in the emergence of ST131-type ExPEC. This study offers a theoretical framework and empirical evidence for elucidating the potential pathogenic mechanisms and clinical therapeutic strategies of ExPEC in the etiology of acute pneumonia in puppies. Full article

Chlamydia trachomatis (CT) is a bacterium that causes one of the most common sexually transmitted infections (STIs) worldwide. In Panama, the prevalence of genital Chlamydia trachomatis (CT) among adolescents is 15.8%. However, no data describing circulating CT genotypes or evaluating molecular resistance are available. This study aims to determine the genotypes of genital CT infections and explore the macrolide resistance-associated mutations in this population to contribute to baseline information about CT circulating strains and antimicrobial resistance. Genomic analysis was performed on CT-positive, first-void urine specimens from school-going adolescents (14–19 years) in urban regions in Panama. The ompA gene was used for genotype and phylogenetic analysis, and the rplD, rplV, and 23S rRNA genes were used for molecular resistance analysis. Five genotypes were found: D, 15 (47%); F, 9 (28%); E, 4 (13%); Ia, 2 (6%); and Ja, 2 (6%) genotype Ja. A triple mutation (G52S, R65C, and V77A) was found in the rplV gene, though no mutations of interest were found for the rplD and 23S rRNA genes. The present study indicated CT genotype D had increased circulation within the population; mutations indicative of macrolide resistance were not found. Follow-up studies and implementation of active surveillance are necessary to understand the circulation of CT in Panama. Full article

Adhesive-invasive E. coli has been suggested to be associated with the development of Crohn’s disease (CD). It is assumed that they can provoke the onset of the inflammatory process as a result of the invasion of intestinal epithelial cells and then, due to survival inside macrophages and dendritic cells, stimulate chronic inflammation. In previous reports, we have shown that passage of the CD isolate ZvL2 on minimal medium M9 supplemented with sodium propionate (PA) as a carbon source stimulates and inhibits the adherent-invasive properties and the ability to survive in macrophages. This effect was reversible and not observed for the laboratory strain K12 MG1655. We were able to compare the isogenic strain AIEC in two phenotypes—virulent (ZvL2-PA) and non-virulent (ZvL2-GLU). Unlike ZvL2-GLU, ZvL2-PA activates the production of ROS and cytokines when interacting with neutrophils. The laboratory strain does not cause a similar effect. To activate neutrophils, bacterial opsonization is necessary. Differences in neutrophil NADH oxidase activation and ζ-potential for ZvL2-GLU and ZvL2-PA are associated with changes in membrane protein abundance, as demonstrated by differential 2D electrophoresis and LC-MS. The increase in ROS and cytokine production during the interaction of ZvL2-PA with neutrophils is associated with a rearrangement of the abundance of membrane proteins, which leads to the activation of Rcs and PhoP/Q signaling pathways and changes in the composition and/or modification of LPS. Certain isoforms of OmpA may play a role in the formation of the virulent phenotype of ZvL2-PA and participate in the activation of NADPH oxidase in neutrophils. Full article

Tick-borne rickettsioses are considered among the oldest known vector-borne zoonotic diseases. Among the rickettsiae, Rickettsia africae is the most reported and important in Africa, as it is the aetiological agent of African tick bite fever (ATBF). Studies describing the prevalence of R. africae in southern Africa are fragmented, as they are limited to small geographical areas and focused on Amblyomma hebraeum and Amblyomma variegatum as vectors. Amblyomma spp. ticks were collected in Angola, Mozambique, South Africa, Zambia and Zimbabwe during the sampling period from March 2020 to September 2022. Rickettsia africae was detected using the ompA gene, while characterisation was conducted using omp, ompA, ompB and gltA genes. In total, 7734 Amblyomma spp. ticks were collected and were morphologically and molecularly identified as Amblyomma eburneum, A. hebraeum, Amblyomma pomposum and A. variegatum. Low levels of variability were observed in the phylogenetic analysis of the R. africae concatenated genes. The prevalence of R. africae ranged from 11.7% in South Africa to 35.7% in Zambia. This is one of the largest studies on R. africae prevalence in southern Africa and highlights the need for the inclusion of ATBF as a differential diagnosis when inhabitants and travellers present with flu-like symptoms in the documented countries. Full article

Tick-borne rickettsioses (TBRs) are distributed worldwide and are recognized as important emerging vector-borne zoonotic diseases in Europe. The aim of this study was to identify tick-associated Rickettsia among ticks removed from humans, and to track how tick populations and their associated pathogens have changed over the years. For this purpose, we conducted a tick surveillance study in northwestern Spain between 2018 and 2022. Ticks were morphologically identified and analyzed for the presence of rickettsial pathogens through the amplification of the citrate synthase (gltA) and the outer membrane protein A (ompA) genes. PCR products were sequenced and subjected to phylogenetic analyses. We collected 7397 ticks, with Ixodes ricinus being the species most frequently isolated. Based on the PCR results, Rickettsia DNA was detected in 1177 (15.91%) ticks, and 10 members of Rickettsia were identified: R. aeschlimannii, R. conorii subsp. conorii, R. conorii subsp. raoultii, R. massiliae, R. monacensis, R. sibirica subsp. mongolitimonae, R. slovaca, R. helvetica, Candidatus R. barbariae, and Candidatus R. rioja. Some of these Rickettsia have gone previously undetected in the study region. There is clear geographic and seasonal expansion not only of tick populations, but also of the associated Rickettsia. The comparison of our data with those obtained years ago provides a clear idea of how the spatiotemporal distributions of ticks and their associated Rickettsiae have changed over the years. Full article

Background: Several Acinetobacter species live in different ecosystems, such as soil, freshwater, wastewater, and solid wastes, which has attracted considerable research interests in public health and agriculture. Methods: We assessed the distribution of Acinetobacter baumannii and Acinetobacter nosocomialis in three freshwater resources (Great Fish, Keiskemma, and Tyhume rivers) in South Africa between April 2017–March 2018. Molecular identification of Acinetobacter species was performed using Acinetobacter-specific primers targeting the recA gene, whilst confirmed species were further delineated into A. baumannii and A. nosocomialis. Similarly, virulence genes; afa/draBC, epsA, fimH, OmpA, PAI, sfa/focDE, and traT in the two Acinetobacter species were assessed. Results: Our finding revealed that 410 (48.58%) and 23 (2.7%) of the isolates were confirmed as A. baumannii and A. nosocomalis, respectively. Additionally, three hundred and eight (75.12%) A. baumannii and three (13.04%) A. nosocomialis exhibited one or more of the virulence genes among the seven tested. OmpA was the most prevalent virulence gene in A. baumannii in freshwater sources. Conclusions: The distribution of clinically important Acinetobacter species in the freshwater sources studied suggests possible contamination such as the release of hospital wastewater and other clinical wastes into the environment thereby posing a risk to public health. Full article

The Rickettsia species transmitted by ticks are mostly classified within the spotted fever group rickettsiae (SFGR), which causes tick-borne rickettsiosis. Although efforts have been made to investigate their prevalence in the Republic of Korea (ROK), research has been limited to certain areas. Furthermore, the pooling method for ticks does not fully reflect the exact infection rate. Therefore, we aimed to perform molecular identification of SFGR in ticks to elucidate the current prevalence of tick-borne rickettsiosis in the ROK. The SFGR of ticks was identified using polymerase chain reaction targeting the 17 kDa antigen, ompA, and gltA, followed by sequencing for species identification and phylogenetic analysis. In total, 302 ticks belonging to four species (Haemaphysalis flava, H. longicornis, Ixodes nipponensis, and Amblyomma testudinarium) were collected between April and November 2022. The overall SFGR infection rate was 26.8% (81/302 patients). Both adult and nymphal ticks and the SFGR infection rate increased during April–May, reaching their peaks in June, followed by a marked decline in August and July, respectively. Phylogenetic analysis revealed three species (R. monacensis, R. heilongjiangensis, and Candidatus R. jingxinensis) of SFGR. Thus, our results emphasize the importance of tick surveys for the prevention and management of tick-borne rickettsiosis. Full article