Person: Weitzel, Thomas
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Publication Campylobacter spp. Prevalence in Santiago, Chile: A Study Based on Molecular Detection in Clinical Stool Samples from 2014 to 2019(2023) Porte, Lorena; Pérez, Caricia; Barbé, Mario; Varela, Carmen; Vollrath, Valeska; Legarraga, Paulette; Weitzel, ThomasCampylobacter spp. is an emerging cause of infectious diarrhea worldwide. In South American countries such as Chile, its prevalence is underestimated due to inadequate detection methods. Gastrointestinal multiplex PCR panels (GMP) permit rapid and sensitive detection of bacterial pathogens and provide important epidemiological information. This study aimed to analyze Campylobacter epidemiology using the results of molecular methods and to compare molecular detection results to those of culture methods. We performed a retrospective, descriptive analysis of Campylobacter spp. detected in clinical stool samples between 2014-2019 by GMP and culture. Within 16,582 specimens examined by GMP, Campylobacter was the most prevalent enteropathogenic bacteria (8.5%), followed by Salmonella spp. (3.9%), Shigella spp./enteroinvasive Escherichia coli (EIEC) (1.9%), and Yersinia enterocolitica (0.8%). The highest Campylobacter prevalence occurred in 2014/2015. Campylobacteriosis affected more males (57.2%) and adults from 19-65 years (47.9%) and showed a bimodal seasonality with summer and winter peaks. In 11,251 routine stool cultures, Campylobacter spp. was detected in 4.6%, mostly C. jejuni (89.6%). Among 4533 samples tested by GMP and culture in parallel, GMP showed a superior sensitivity (99.1% versus 50%, respectively). The study suggests that Campylobacter spp. is the most frequent bacterial enteropathogen in Chile.Publication Whole-genome sequencing reveals changes in genomic diversity and distinctive repertoires of T3SS and T6SS effector candidates in Chilean clinical Campylobacter strains(2023) Katz, Assaf; Porte, Lorena; Weitzel, Thomas; Varela, Carmen; Muñoz, Cristina; Ugalde, Juan; Grim, Christopher; González, Narjol; Blondel, Carlos; Bravo, VerónicaCampylobacter is the leading cause of bacterial gastroenteritis worldwide and an emerging and neglected pathogen in South America. This zoonotic pathogen colonizes the gastrointestinal tract of a wide range of mammals and birds, with poultry as the most important reservoir for human infections. Apart from its high morbidity rates, the emergence of resistant strains is of global concern. The aims of this work were to determine genetic diversity, presence of antimicrobial resistance determinants and virulence potential of Campylobacter spp. isolated from patients with acute gastrointestinal disease at 'Clinica Alemana', Santiago de Chile. The study considered the isolation of Campylobacter spp., from stool samples during a 20-month period (January 2020 to September 2021). We sequenced (NextSeq, Illumina) and performed an in-depth analysis of the genome sequences of 88 Campylobacter jejuni and 2 Campylobacter coli strains isolated from clinical samples in Chile. We identified a high genetic diversity among C. jejuni strains and the emergence of prevalent clonal complexes, which were not identified in our previous reports. While ~40% of strains harbored a mutation in the gyrA gene associated with fluoroquinolone resistance, no macrolide-resistance determinants were detected. Interestingly, gene clusters encoding virulence factors such as the T6SS or genes associated with long-term sequelae such as Guillain-Barré syndrome showed lineage-relatedness. In addition, our analysis revealed a high degree of variability regarding the presence of fT3SS and T6SS effector proteins in comparison to type strains 81-176, F38011, and NCTC 11168 and 488. Our study provides important insights into the molecular epidemiology of this emerging foodborne pathogen. In addition, the differences observed regarding the repertoire of fT3SS and T6SS effector proteins could have an impact on the pathogenic potential and transmissibility of these Latin American isolates, posing another challenge in characterizing the infection dynamics of this emergent and neglected bacterial pathogen.Publication Infecciones por helmintos intestinales en Chile: Análisis retrospectivo en Santiago, años 2015-2019(2023) Ahumada, María; Haecker, Felipe; Porte, Lorena; Weitzel, ThomasIntroducción: Existe escasa evidencia epidemiológica actual sobre helmintos intestinales en Chile. Objetivo: Describir la prevalencia de infecciones por helmintos intestinales en un centro de salud en Santiago, Chile. Métodos: Análisis retrospectivo de helmintos intestinales diagnosticados en muestras parasitológicas de rutina en el Laboratorio de Microbiología de Clínica Alemana de Santiago, entre los años 2015 y 2019. Las pruebas diagnósticas se seleccionaron según la solicitud médica. Los datos se obtuvieron de los sistemas informáticos del laboratorio y se analizaron de manera anonimizada. Resultados: Se detectaron 127 infecciones por helmintos en 11.809 muestras estudiadas (1,1%). Estas infecciones fueron: 78 (61,4%) Enterobius vermicularis, 25 (19,6%) Dibothriocephalus/Adenocephalus spp., 9 (7,1%) Taenia spp., 6 (4,7%) Pseudoterranova spp., 5 (3,9%) Strongyloides stercoralis y 4 (3,1%) Ascaris lumbricoides. Enterobius vermicularis predominó en niños y adolescentes; Dibothriocephalus/ Adenocephalus spp. predominó en adultos. Conclusión: El estudio proporciona información epidemiológica actual sobre la distribución de helmintos intestinales en muestras clínicas en Santiago, Chile. Enterobius vermicularis fue prevalente, seguido de helmintos transmitidos por alimentos mientras que los transmitidos por el suelo solo se detectaron ocasionalmente. El surgimiento de difilobotriasis y anisakidosis (pseudoterranoviasis), es relevante y posiblemente se relacione con cambios en las condiciones de vida y la cultura alimentaria en Chile. Background: Epidemiological information on the current prevalence of intestinal helminths in Chile is scarce. Aim: To describe the prevalence of different intestinal helminth infections in a healthcare center in Santiago, Chile. Methods: We performed a retrospective analysis of intestinal helminths diagnosed in routine parasitological samples in the microbiological laboratory of Clínica Alemana Santiago, Chile, between 2015 and 2019. Diagnostic tests were applied according to the sender's request. Data were obtained from laboratory information systems and analyzed in an anonymized manner. Results: Among 11,809 samples, 127 (1.1%) helminth infections were detected, of those, 78 (61.4%) were Enterobius vermicularis, 25 (19.6%) Dibothriocephalus/Adenocephalus spp., 9 (7.1%) Taenia spp., 6 (4.7%) Pseudoterranova spp., 5 (3.9%) Strongyloides stercoralis, and 4 (3.1%) Ascaris lumbricoides. Enterobius vermicularis was predominant among children and adolescents, while Dibothriocephalus/Adenocephalus spp. was the most frequent helminth in adults. Conclusion: The study provides updated epidemiological information on distribution of helminth infections in clinical samples in Santiago, Chile. After E. vermicularis, food-borne helminths were second most prevalent, while soiltransmitted helminths were very rarely detected. The emergence of diphyllobothriasis and anisakidosis (pseudoterranoviasis) is noteworthy and possibly related to changes in living conditions and food culture in Chile.Publication Head-to-head comparison of CAMPYAIR aerobic culture medium versus standard microaerophilic culture for Campylobacter isolation from clinical samples(2023) Levican, Arturo; Varela, Carmen; Porte, Lorena; Weitzel, Thomas; Briceño, Isabel; Guerra, Francisco; Mena, Benjamín; Hinton Jr, ArthurCampylobacter spp. are considered the most frequent cause of acute gastroenteritis worldwide. However, outside high-income countries, its burden is poorly understood. Limited published data suggest that Campylobacter prevalence in low- and middle-income countries is high, but their reservoirs and age distribution are different. Culturing Campylobacter is expensive due to laboratory equipment and supplies needed to grow the bacterium (e.g., selective culture media, microaerophilic atmosphere, and a 42°C incubator). These requirements limit the diagnostic capacity of clinical laboratories in many resource-poor regions, leading to significant underdiagnosis and underreporting of isolation of the pathogen. CAMPYAIR, a newly developed selective differential medium, permits Campylobacter isolation without the need for microaerophilic incubation. The medium is supplemented with antibiotics to allow Campylobacter isolation in complex matrices such as human feces. The present study aims to evaluate the ability of the medium to recover Campylobacter from routine clinical samples. A total of 191 human stool samples were used to compare the ability of CAMPYAIR (aerobic incubation) and a commercial Campylobacter medium (CASA, microaerophilic incubation) to recover Campylobacter. All Campylobacter isolates were then identified by MALDI-TOF MS. CAMPYAIR showed sensitivity and specificity values of 87.5% (95% CI 47.4%-99.7%) and 100% (95% CI 98%-100%), respectively. The positive predictive value of CAMPYAIR was 100% and its negative predictive value was 99.5% (95% CI 96.7%-99.9%); Kappa Cohen coefficient was 0.93 (95% CI 0.79-1.0). The high diagnostic performance and low technical requirements of the CAMPYAIR medium could permit Campylobacter culture in countries with limited resources.Publication Notes from the Field: Scrub Typhus Outbreak - Los Lagos Region, Chile, January-February 2023(2023) Weitzel, Thomas; Martínez, Constanza; Acosta, Gerardo; Abarca, KatiaDuring January 14–February 14, 2023, a total of 36 cases of suspected scrub typhus were reported from the Los Lagos Region in southern Chile. Scrub typhus is a bacterial disease caused by one of three Orientia spp. and transmitted through bites from infected chiggers (larval mites).Publication Eco-epidemiology of rodent-associated trombiculid mites and infection with Orientia spp. in Southern Chile(2023) Silva, María; Pérez, Caricia; Martínez, Constanza; Pérez, Ruth; Vial Cox, María Cecilia; Stekolnikov, Alexandr; Abarca, Katia; Thomas Weitzel; Weitzel, Thomas; Acosta, GerardoBackground: Scrub typhus is a potentially severe infection caused by bacteria of the genus Orientia, endemic in Asia-Pacific and recently discovered in southern Chile. The presented study aimed to determine the prevalence and species richness of rodent-associated trombiculid mites and their infection with Orientia spp. in different areas of two regions in southern Chile. Methodology/principal findings: During summer 2020, trombiculid mites were collected from rodents captured in three areas in southern Chile known to be endemic for scrub typhus (Cochamó and Chiloé Island in the Los Lagos Region and Tortel in the Aysén Region). A total of 132 rodents belonging to five species were captured using Sherman-like traps; 89.4% were infested with trombiculids. Mite specimens were morphologically identified and subsequently tested by Orientia-specific qPCR. Six mite species were identified. Among chigger-infested rodents, 33.9% carried Orientia-positive mites; this rate was higher in Tortel (63.8%) than in Cochamó (45.0%) and Chiloé Island (2.0%). The analysis of individual mites (n = 901) revealed that 31.2% of Herpetacarus antarctica samples (n = 202) were positive for Orientia DNA; the prevalence was 7.0% in Paratrombicula neuquenensis (n = 213), 6.9% in Herpetacarus eloisae (n = 144), 3.6% in Argentinacarus expansus (n = 55), and 0% in Paratrombicula goffi (n = 110) and Quadraseta chiloensis (n = 177). The southernmost site (Tortel) showed the highest rates of trombiculid infestation, trombiculid load, and Orientia infection in the captured rodents. Conclusions/significance: Our study provides new insights into the trombiculid fauna and prevalence of Orientia in mites collected from wild rodents in southern Chile. Orientia DNA was detected in four of the six mite species. Rates of infestation, mite loads, and Orientia prevalences differed geographically and were highest in the Aysén Region. Our data improve our knowledge on possible vectors of scrub typhus and their distribution in Chile.