Study of the genetic diversity of Moraxella spp. isolates obtained from corneal abscesses / Estudio de la diversidad genética de aislamientos de Moraxella spp. a partir de abscesos corneales

Abstract This is the first study of the genetic diversity of Moraxella spp. Isolates were detected in an Eye Hospital in the City of Buenos Aires. Due to the high frequency of Moraxella spp. observed in corneal abscesses, we decided to validate their identification at the species level, determine their drug susceptibility and perform molecular subtyping. Seventeen (17) isolates obtained from corneal abscesses were evaluated. The identification was carried out using a combination of biochemical tests and MALDI-TOF mass spectrometry. Of these isolates, 88.2% were identified as Moraxella lacunata, and 11.8% as Moraxella nonliquefaciens. Molecular subtyping was performed using the pulsed-field gel electrophoresis (PFGE) technique. All isolates were typable and thirteen digestion patterns were identified. Based on the obtained results, the PFGE technique using the SmaI enzyme can be used for epidemiological studies of strains of these species.

Resumen En este trabajo se presenta el primer estudio de diversidad genética de aislamientos de Moraxella spp. detectados en un hospital de oftalmología de la Ciudad Autónoma de Buenos Aires. Debido a la observación de una elevada frecuencia de Moraxella spp. en abscesos corneales, se decidió confirmar su identificación a nivel de especie, conocer su sensibilidad y realizar la subtipificación molecular. Se analizaron 17 aislamientos provenientes de abscesos corneales. La identificación se realizó mediante una combinación de pruebas bioquímicas y espectrometría de masas, MALDI-TOF MS. El 88,2% fueron identificados como Moraxella lacunata y el 11,8% como Moraxella nonliquefaciens. La subtipificación molecular se realizó por la técnica de electroforesis en gel de campo pulsado (PFGE). Todos los aislamientos fueron tipificables y se identificaron 13 patrones de digestión. Nuestros resultados muestran que la técnica de PFGE con la enzima SmaI es útil para hacer estudios epidemiológicos en cepas de estas especies.

Molecular characteristics and drug resistance of non-O1non-O139 Vibrio cholerae in Zhongshan City, Guangdong Province / 中国热带医学

@#Abstract: Objective　To investigate the molecular characteristics and drug resistance of non-O1/non-O139 Vibrio cholerae in Zhongshan City, and to provide laboratory basis for cholera prevention and control. Methods　The strains of non-O1/non-O139 Vibrio cholerae isolated from sporadic patients and aquatic products from 2015 to 2021 in Zhongshan city were collected. The identification and cluster analysis of the strains were analyzed by matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS), the ctxA virulence gene of strains were detected by real-time fluorescence quantitative PCR, the cluster analysis of the strains was analyzed by pulsed-field gel electrophoresis (PFGE), and the drug resistance of the strains were analyzed by microbroth dilution method. Results　From 2015 to 2021, 33 strains of non-O1/non-O139 Vibrio cholerae were isolated from Zhongshan City, including 28 strains from sporadic patients and 5 strains from aquatic products. Through MALDI-TOF-MS identification, 33 strains of non-O1/non-O139 Vibrio cholera can be identified to the level of species, and the identification results were all Vibrio cholerae. Among 33 non-O1/non-O139 Vibrio cholerae strains, 1 strain carried the ctxA virulence gene. The drug-resistant strains accounted for 69.7% (23/33), and the multidrug resistant strains accounted for 18.2% (6/33). A total of 7 kinds of drug resistance spectrum were produced, including 3 kinds of multidrug resistant spectrum, and showed drug resistance to 8 antibiotics, among which the resistance rates to streptomycin, cefazolin and compound sulfamethoxazole were above 30%. The 33 strains of non-O1/non-O139 Vibrio cholerae were divided into 32 PFGE fingerprints with a similarity ranging from 61.7% to 100%. MALDI-TOF-MS cluster analysis divided 33 non-O1/non-O139 Vibrio cholerae strains into two clusters. Conclusions The results of molecular typing of non-O1/non-O139 Vibrio cholerae in Zhongshan City presented diversity, and no significant correlation was found between PFGE and MALDI-TOF-MS cluster analysis. The strains demonstrated various degrees of resistance to certain antibiotics, and there were multidrug-resistant and toxigenic strains. Therefore, it is necessary to alert to the harmfulness of non-O1/non-O139 Vibrio cholerae and enhance monitoring.

Epidemiological investigation of a foodborne illness outbreak caused by Vibrio parahaemolyticus contamination / 上海预防医学

ObjectiveIn this paper， the cause of an outbreak of foodborne disease in Huzhou City was analyzed， which may help avoid the recurrence of such incidents. MethodsThrough the field epidemiological investigation， the case definition was formulated and the questionnaire survey was carried out in the case group and the control group. In addition， the chi-square test and logistic regression method were used to identify the factors affecting the outbreak. The patient stool samples， food samples， environmental samples and water samples were collected and used for the laboratory test. The PFGE molecular typing was conducted on the isolated positive strains. ResultsThe number of people exposed during the same period was 410， and the number of possible cases was 18， with an incidence of 4.39%. Generally， the main symptoms were abdominal pain and diarrhea， accompanied by nausea， fatigue， fever and others. For case-control analysis， 17 of the 18 patients were included in the case group， and 19 non-patients were into control group. The results suggested that the risk factors were blanched deep-water shrimp（OR=19.42， 95%CI=1.06‒357.02， P=0.046）and steamed Ao Long （Australian lobster） with garlic and vermicelli （OR=22.01， 95%CI=1.24‒390.70， P=0.035）. According to the laboratory test results Vibrio parahaemolyticus （VP） was positive in 5 cases， and the serum type was is O10∶K4. In the reserved food， VP was positive in the samples of steamed Australian lobster with garlic vermicelli and lamb chops. The serum type was O5∶Kut. ConclusionThis incident was an outbreak of foodborne disease caused by the consumption of wedding food contaminated by VP. The dinner was served by Hotel B on September 17. Moreover， the suspicious foods include the blanched deep-water shrimp and steamed lobster with garlic vermicelli.

Molecular subtyping of Salmonella spp. strains in provincial abattoirs with no hazard analysis critical control point from Buenos Aires, Argentina / Subtipificación molecular de Salmonella spp. en frigoríficos provinciales sin análisisde peligros y puntos críticos de control ubicados en Buenos Aires, Argentina

Abstract We subtyped 32 Salmonella enterica strains isolated from carcasses (n = 10), theenvironment (n = 14), head meat (n = 1) and viscera washing and chilling water (n = 7) in provin-cial abattoirs with no Hazard Analysis Critical Control Point (HACCP) system from Buenos Aires,Argentina, before and after implementing improvement actions. Pulsed-field gel electrophore-sis (PFGE) was carried out using the XbaI restriction enzyme. Strains belonged to six serovars,from which 10 restriction patterns were obtained (five unique patterns and five clusters). Wefound different clones of S. enterica serovars in the same abattoir by XbaI-PFGE. In addition topromoting good hygiene practices, the implementation of an HACCP plan is necessary to meetthe zero-tolerance criteria for Salmonella on beef.

Resumen Subtipificamos en total 32 cepas de Salmonella enterica aisladas de carcasas(n = 10), medio ambiente (n = 14), carne de cabeza (n = 1) y agua de lavado y enfriamientode vísceras (n = 7) en frigoríficos provinciales de Buenos Aires (Argentina) sin análisis de peli-gros y puntos críticos de control (hazard analysis critical control point [HACCP]); la toma demuestras se efectuó antes y después de implementar acciones de mejora. Se llevó a cabo elec-troforesis en gel de campo pulsado (PFGE) utilizando la enzima de restricción XbaI. Las cepaspertenecían a 6 serovares y presentaron 10 patrones de restricción (5 patrones únicos y 5 clus-ters). Demostramos la presencia de diferentes serovares de S. enterica en un mismo frigorífico.

Phenotypic and genotypic characterization of oxacillin-susceptible and mecA positive Staphylococcus aureus strains isolated in Uruguay / Caracterización fenotípica y genotípica de cepas de Staphylococcus aureus sensibles a oxacilina y mecA positivas aisladas en Uruguay

Abstract The aim of this study was to characterize phenotypically and genotypically 27 mecApositive Staphylococcus aureus strains with oxacillin MICs of ≤2 g/ml by Vitek 2, isolated indifferent regions of Uruguay. Susceptibility to oxacillin and cefoxitin was studied by gradient dif-fusion, disk diffusion to cefoxitin, and Phoenix and MicroScan systems. PBP2a was determined.SCCmec typing was performed and the isolates were compared by PFGE. Twenty-six isolateswere susceptible to oxacillin; one strain was susceptible to cefoxitin by disk diffusion and 3strains by gradient diffusion. Phoenix and MicroScan panels detected methicillin resistance in25 and 27 strains, respectively. Twenty-six strains tested positive for PBP2a. Twenty-six strainscarried SCCmec V and 24 belonged to pulsotype A. One strain carried SCCmec IV and did notbelong to pulsotype A. Cefoxitin disk diffusion test and PBP2a detection correctly identified 26of these 27 strains as MRSA. PFGE results suggest the dissemination of a cluster of MRSA carryingSCCmec V.

Resumen El objetivo de este estudio fue caracterizar fenotípicamente y genotípicamente 27 cepas de Staphylococcus aureus positivas para mecA y con CIM de oxacilina <2 pg/ml según Vitek 2, obtenidas en diferentes regiones del país. La sensibilidad frente a la oxacilina y la cefoxitina se estudió por difusión en gradiente, por disco-difusión (cefoxitina) y por los sistemas Phoenix y MicroScan. Se analizó la portación de PBP2a, se realizó la tipificación de SCCmec y las cepas se compararon mediante PFGE. Resultaron sensibles a oxacilina por difusión en gradiente 26 cepas; una fue sensible a cefoxitina por disco-difusión y 3 lo fueron por difusión en gradiente. Los sistemas Phoenix y MicroScan detectaron resistencia a meticilina en 25 y 27 cepas, respectivamente. Asimismo, 26 cepas portaban PBP2a y 26 cepas mostraron presencia de SCCmec V, 24 correspondieron al pulsotipo A. Una portaba SCCmec IV y no perteneció al pulsotipo A. La prueba de disco-difusión con cefoxitina y la detección de PBP2a identificaron 26 de 27 cepas como MRSA. La PFGE sugiere la diseminación de un grupo MRSA con SCCmec V. © 2022 Asociación Argentina de Microbiología. Publicado por Elsevier Espana, S.L.U. Este es un artículo Open Access bajo la licencia CC BY-NC-ND (https://creativecommons.org/licenses/by-nc-nd/4.0/).

Macrolide resistance, molecular characteristics and PFGE types of Bordetella pertussis strains / 中华微生物学和免疫学杂志

Objective:To analysis the macrolide resistance, molecular characteristics and plused-field gel electrophoresis(PFGE) type of Bordetella pertussis ( Bp), explore the possible resistance mechanism and the relationship between PFGE types and macrolide resistance profiles. Methods:Erythromycin, azithromycin and clarithromycin susceptibility of clinical isolates during 2016 to 2018 was determined by E-test. PCR was used to detect the drug-resistant genes and mutation sites. PFGE were employed to do molecular typing for the strains.Results:Thirty-five strains were isolated, of which 27 strains were resistant to all three antibiotics, two strains were resistant to erythromycin and azithromycin, and six strains were sensitive to all three antibiotics. Partial macrolide resistant strains carried the methylase gene ermA (27.6%, 8/29) and ermB (31.0%, 9/29); A2047G site mutation was detected in macrolide-resistant strains, while no drug-resistant genes or mutation sites were found in sensitive strains. Resistant strains were classified into BPSR23 and BPFINR9 types, while sensitive strains were other profiles. Conclusions:The clinical isolated Bp were seriously resistant to erythromy and showed signs of resistance to other macrolides. The acquisition of methylase gene and mutation of A2047G site might be the main mechanism of resistance. The macrolide resistance might have has a certain correlation with PFGE profile.

Macrolide-lincosamide-streptogramin B resistance phenotypes and their associated genotypes in Staphylococcus aureus isolates from a tertiary level public hospital of Uruguay / Fenotipos de resistencia a macrólidos lincosamidas-estreptograminas B y sus genotipos asociados en Staphylococcus aureus aislados en un hospital público de nivel terciario en Uruguay

Abstract This study was undertaken to investígate the resistance phenotypes to macrolide-lincosamide-streptogramin B (MLSb) antibiotics and their associated genotypes in isolates of Staphylococcus aureus. We analyzed one hundred, consecutive, non-duplicate isolates (methicillin-susceptible MSSA, n = 53 and methicillin-resistant MRSA, n =47) obtained from var-ious clinical samples between July 2012 to December 2013. The resistance profile to MLSb antibiotics was determined by phenotypic methods and the resistance genes were detected by PCR assays. All of the isolates were subjected to pulsed-field gel electrophoresis (SmaI-PFGE). The overall prevalence of resistance to MLSb antibiotics was 38% and the resistance phenotype distribution was as follows: cMLSb, 22%; iMLSB, 10%; MSb, 5% and L, 1%. We detected ermA, ermC, ermB and mrsA/B genes in these resistant isolates. The single ermA gene was commonly observed mainly in those with a cMLSb R phenotype, whereas the combination ermA and ermC was more commonly observed in isolates with inducible expression. The patterns of SmaI-PFGE suggest a great genetic diversity in both MRSA and MSSA resistant to MLSb antibiotics. The results demonstrate the local presence of S. aureus resistant to MLSb antibiotics and its most frequently described responsible genes. Some of these isolates, especially those with the iMLSB phenotype, may be associated with therapeutic failure. Therefore, efforts should be directed to the correct detection of all MLSb resistant isolates using appropriate laboratory tests. PFGE results reveal a wide spread of resistance genes rather than the circulation of S. aureus clones resistant to MLSb antibiotics.

Resumen Los objetivos de este estudio fueron investigar en Staphylococcus aureus la presencia de fenotipos resistentes a los antibióticos macrólidos, lincosamidas y estreptograminas tipoB (MLSb) y conocer sus genotipos responsables. Analizamos 100 aislamientos consecutivos, no duplicados (53 sensibles a meticilina [MSSA] y 47 resistentes a meticilina [MRSA]), obtenidos entre 2012 y 2013 a partir de diferentes muestras clínicas. El perfil de resistencia a los antibióticos MLSb fue determinado por métodos fenotípicos y los genes de resistencia se detectaron por PCR. Todos los aislamientos fueron comparados por SmaI-PFGE. La prevalencia global de resistencia a los antibióticos MLSB fue del 38% y la distribución de los fenotipos de resistencia fue la siguiente: cMLSB, 22%; iMLSB, 10%; MSB, 5%; L, 1%. Se detectaron los genes ermA, ermC y mrsA/B en los aislamientos resistentes. El gen ermA se observó, sobre todo, en aislamientos con fenotipo resistente constitutivo R (cMLSB), mientras que la combinación ermA y ermC se detectó principalmente en aislamientos con resistencia inducible (iMLSB). Los patrones de Smal-PFGE sugieren una gran diversidad genética en los aislamientos resistentes a los antibióticos MLSb, tanto MRSA como MSSA. Los resultados demuestran la presencia local de S. aureus resistentes a los antibióticos MLSB y de sus genes responsables más frecuentemente descritos. Estos cultivos, especialmente aquellos con fenotipo resistente iMLSB, pueden asociarse con fallas terapéuticas. Por lo tanto, los esfuerzos deben dirigirse a la correcta detección de todos los cultivos resistentes a MLSB utilizando pruebas de laboratorio adecuadas. Los resultados de Smal-PFGE sugieren una amplia diseminación de genes de resistencia, más que la circulación de clones resistentes a los antibióticos MLSB.

Antibiotic resistance, serotype and molecular typing of Listeria monocytogenes from foods in Shandong Province from 2013 to 2016 / 中华疾病控制杂志

Objective To understand the main serotypes, antibiotic resistance profiles and molecular typing characteristics of Listeria monocytogenes（LM) isolated from foods in Shandong Province from 2013 to 2016. Methods The antibiotic sensitivity of LM was tested by broth microdilution method. The serotypes were determined by slide agglutination and PCR, and the molecular typing was carried out by pulsed field gel electrophoresis (PFGE) and multilocus sequence typing(MLST) . Results Most of 191 LM strains were sensitive to the eight antibiotics tested. Tetracycline resistance was most prevalent (15/191, 7.85%). There was no significant difference in the 8 antibiotic resistance monitored for 4 years (P=1.000). The serotype 1/2a, 1/2b and 1/2c accounted for 38.82% (66/170), 18.82% (32/170), and 42.36% (72/170), respectively. The patterns of SDSRZXDZ016, S2014L031 and SDSRZX030, totally accounted for 33.78%, were the dominant types. The main ST types were ST9, ST8 and ST121, which accounted for 81.18% (69/85). The clinical common types, ST3, ST7 and ST87 accounted for 8.23% (7/85), mainwhile new ST type was not found. Conclusion The LM strains isolated in Shandong Province from 2013 to 2016 were sensitive to most antibiotics, but some strains were resistant to tetracycline and erythromycin. The dominant serotypes were 1/2c and 1/2a. Serotype 4b, prone to outbreaks of listeriosis, was not found. The main PFGE types were SDSRZXDZ016, S2014L031 and SDSRZX030, which were continuously found from 2013 to 2016. The main ST types were ST8, ST9 and ST121. The clinical types, ST3, ST7 and ST87 were isolated from food and should be paid seriously attention to.

Investigation on a food poisoning caused by Vibrio parahaemolyticus and its etiology / 公共卫生与预防医学

Objective To find out the causes of food poisoning in a school banquet and identify the pathogenic bacteria, so as to provide evidence for the treatment of food poisoning. Methods A field epidemiological survey was conducted to search for cases, find suspicious poisoning meals and food, and collect cases and food samples for laboratory testing, to determine pathogenic pathogens and virulence genes. The pulsed field gel electrophoresis (PFGE) was applied to identify the homology of the pathogens. Results A total of 92 poisoning cases were found, and the incidence rate was 46.94%. The main clinical manifestations were diarrhea (93.48%), abdominal pain (86.96%), nausea (39.13%), vomiting (34.78%) and fever (17.39%). The median of onset latency was 17 hours. Vibrio parahaemolyticus was detected in samples from 3 patients (2 stools and 1 anal swab). The virulence gene trh was positive and the similarity coefficient of PFGE banding was 97.4%. Pathogenic bacteria were not detected in 10 food samples. The results of the case-control study showed that six types of food were suspicious (OR values were 15.75, 10.14, 8.44, 5.93, 5.56 and 4.71 respectively, P1), including couple lung slices and California bass with extremely high risk of exposure (OR values>10). Conclusion 　The food poisoning resulted from this enrollment banquet was caused by trh-positive Vibrio parahaemolyticus and no suspicious food was identified (the possibility of contamination by couples' lung slices and California sea bass was high). It is suggested that the supervision and management of catering units and food safety publicity and education should be strengthened to reduce the occurrence of food-borne diseases from the source.

Brote de intoxicación alimentaria en un jardín de infantes de la provincia de Buenos Aires / Food poisoning outbreak in a kindergarten in the Province of Buenos Aires, Argentina

Resumen El 27 de noviembre de 2008 ocurrió un brote de intoxicación alimentaria asociado al consumo de salpicón de ave en un jardín de infantes de Hurlingham, provincia de Buenos Aires. Treinta y siete niños y 10 adultos presentaron síntomas gastrointestinales. Cinco niños fueron internados con signos de deshidratación, y uno de ellos requirió cuidados intensivos. Se aisló Staphylococcus aureus subsp. aureus del alimento involucrado, de 4/5 muestras de materia fecal de pacientes y de 3/5 manipuladores (nariz del manipulador 1, manos de manipuladores 2 y 3). Las cepas aisladas portaban los genes que codifican las enterotoxinas SEA y SED. Por electroforesis de campo pulsado con la enzima SmaI, los patrones de macrorrestricción presentaron 100% de similitud. La investigación oportuna del brote permitió identificar al agente causal de la intoxicación, determinar las fallas en la elaboración del alimento e implementar las medidas correctivas correspondientes.

Abstract On November 27, 2008, a foodborne disease outbreak associated with the consumption of chicken salad occurred in a kindergarten in the District of Hurlingham, Province of Buenos Aires. Thirty-seven children and 10 adults with gastrointestinal symptoms were affected. Five children were hospitalized with signs of dehydration, one of them requiring intensive care. Staphylococcus aureus subsp. aureus was isolated from the mentioned food in 4 out of 5 stool specimens from the patients, and in 3 out of 5 food handlers (nose of food handler #1, hands of food handlers #2 and 3). The isolates carried the genes coding for enterotoxins SEA and SED. The macrorestriction patterns showed 100% similarity by pulsed-field gel electrophoresis using the SmaI enzyme. A timely outbreak investigation allowed us to identify the causative agent of the food poisoning as well as the failures in food processing and to implement corrective measures.

Comparación de tres técnicas para subtipificación molecular de Listeria monocytogenes / Comparison of three molecular subtyping techniques for Listeria monocytogenes

Abstract Listeria monocytogenes is a foodborne pathogen. The recent alert for L. monocytogenes in vegetables from Argentina warns about the importance of reinforcing its isolation, characterization and subtyping in food, clinical and environmental samples. The aim of the present study was to compare the discriminatory power of enterobacterial repetitive interpower; genic consensus polymerase chain reaction (ERIC-PCR), automated ribotyping and pulsed-field gel electrophoresis (PFGE) to subtype strains of L. monocytogenes isolated from Argentine meat and environmental samples. Simpson's Diversity Index (DI) was calculated on the basis of based on the dendrograms obtained in the by cluster analysis, showing the following discriminatory power: ApaI-PFGE (0.980), AscI-PFGE (0.966), ribotyping (0.912), ERIC-PCR (0.886). The ID values between ApaI- and AscI-PFGE and between ribotyping and ERIC-PCR were not significantly different. Of the three techniques evaluated, PFGE showed the highest discriminatory power. However, the subtyping techniques should be accompanied by effective food monitoring strategies and reliable clinical and epidemiological studies.

Resumen Listeria monocytogenes es un patógeno alimentario. La reciente alerta por la presencia de L. monocytogenes en vegetales en Argentina advierte sobre la importancia de reforzar el aislamiento, la caracterización y la subtipificación de esta bacteria en muestras clínicas de alimentos y ambientales. El objetivo del presente estudio fue comparar el poder discriminatorio de enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR), la ribotipificación automatizada y la pulsed-field gel electrophoresis (PFGE) para subtipificar cepas de L. monocytogenes aisladas de carne y de muestras ambientales en Argentina. El índice de diversidad (ID) de Simpson, calculado a partir de los dendrogramas obtenidos en el análisis de agrupamiento, mostró los siguientes resultados: Apal-PFGE (0,980), AscI-PFGE (0,966), riboti-pado (0,912), ERIC-PCR (0,886). Los valores obtenidos no fueron significativamente diferentes al comparar entre Apal- y AscI-PFGE, ni entre ribotipadoy ERIC-PCR. De las técnicas evaluadas, la PFGE presentó el mayor poder discriminatorio. Sin embargo, las técnicas de subtipificación deberían acompañarse de estrategias de control de los alimentos efectivas y de estudios clínicos y epidemiológicos confiables.

Caracterización genética de cepas de Listeria monocytogenes aisladas durante los años 2007-2014 en Chile / Genetic characterization of Listeria monocytogenes strains isolated during 2007-2014 in Chile

Resumen Introducción: Listeria monocytogenes es un patógeno transmitido por alimentos que causa listeriosis, una enfermedad que puede presentarse como gastroenteritis febril o en una forma invasora que tiene altas tasas de mortalidad. Hasta el momento, ha sido poco estudiada la diversidad genética de cepas de L. monocytogenes aisladas desde pacientes, alimentos y fuentes ambientales en Chile. Objetivo: Caracterizar genéticamente cepas de L. monocytogenes de estos tres orígenes recibidas por el Instituto de Salud Pública de Chile (ISP) entre los años 2007 y 2014. Material y Métodos: Se seleccionaron 94 cepas de L. monocytogenes correspondientes a 94 pulsotipos diferentes identificados por electroforesis en gel de campo pulsado (PFGE), se extrajo ADN y se realizó serotipificación mediante reacción de polimerasa en cadena (RPC) y tipificación de secuencias multilocus (MLST). Resultados: El serotipo más común fue 4b (55,3%), seguido de 1/2a (25,5%), 1/2b (17%) y 1/2c (2,2%). Se identificaron 32 secuencias tipo (ST), de las cuales cuatro fueron nuevas, y las predominantes fueron ST1 (28,7%) y ST2 (13,8%). La totalidad de las cepas se agrupó en los Linajes I y II. Conclusiones: Se observó una gran variabilidad genética en las cepas de L. monocytogenes analizadas, siendo predominantes las secuencias tipo ST1 y ST2, ambas pertenecientes al Linaje I. Nuestros resultados contribuyen a conocer la estructura poblacional de este patógeno en Chile y su presencia en muestras clínicas, alimentos y el medio ambiente.

Background: Listeria monocytogenes is a foodborne pathogen that causes listeriosis, a disease that can present as febrile gastroenteritis or as an invasive form that has high mortality rates. So far, the genetic diversity of strains of L. monocytogenes isolated from patients, foods and environmental sources in Chile has been poorly studied. Aim: To characterize genetically L. monocytogenes strains received by the Institute of Public Health of Chile (ISP) between 2007 and 2014. Methods: We selected 94 strains of L. monocytogenes corresponding to 94 different pulsotypes identified by pulsed field gel electrophoresis (PFGE), DNA was extracted and serotyping was performed by polymerase chain reaction (PCR) and multilocus sequence typing (MLST). Results: The most common serotype was 4b (55.3%), followed by serotypes 1/2a (25.5%), 1/2b (17%) and 1/2c (2.2%). 32 sequence-type (ST) were identified, of which 4 were new, and the predominant ones were ST1 (28.7%) and ST2 (13.8%). All the strains of L. monocytogenes were grouped in Lineages I and II. Conclusions: A great genetic variability was observed in the strains of L. monocytogenes analyzed, being predominant the ST1 and ST2, both belonging to Lineage I. Our results contribute to know the population structure of this pathogen in Chile and its presence in clinical samples, food and the environment.

Infecciones por Escherichia coli productora de toxina Shiga O121: H19 en pacientes atendidos en Mar del Plata / Infections caused by Escherichia coli producing Shiga O121: H19 toxin in patients treated in Mar del Plata

Escherichia coli productora de toxina Shiga (STEC) O157:H7 es el serotipo más frecuentemente identificado como agente causal de colitis hemorrágica y síndrome urémico hemolítico (SUH), aunque se han descripto más de 100 serotipos con potencial patogénico similar. El objetivo del trabajo fue describir casos de enfermedad humana asociados a la infección por STEC O121:H19, atendidos en la ciudad de Mar del Plata y establecer la relación genética de los aislamientos mediante técnicas de epidemiología molecular. Se observó un amplio espectro en la severidad clínica de los ocho casos estudiados: dos fueron asintomáticos (contactos de SUH), un paciente tuvo diarrea sanguinolenta, y cinco presentaron SUH. Uno de los pacientes con SUH falleció. Las cepas O121:H19 portadoras del genotipo stx2a/eae/ehxA fueron sensibles a los antibióticos ensayados y presentaron por electroforesis en gel de campo pulsado (Xbal-PFGE) distintos patrones de macrorrestricción, con similitud del 84,25%. El patrón AREXKX01.0072, detectado en un SUH y en su contacto, es nuevo en la Base de Datos Nacional de STEC no-O157 de la Argentina. La utilización de métodos estandarizados de detección y tipificación de STEC permite a los laboratorios de referencia monitorear la frecuencia temporal y la distribución geográfica de las cepas circulantes para la prevención y control de estos patógenos asociados a enfermedad humana.

Shiga toxin-producing Escherichia coli (STEC) O157:H7 is the most frequent serotype identified as causative agent of sporadic cases and outbreaks of diarrhea with or without blood, hemorrhagic colitis and hemolytic uremic syndrome (HUS), although more than 100 serotypes have been described of similar pathogenic potential. The aim of the study was to describe cases of human disease associated with STEC O121:H19 infections, assisted in Mar del Plata City, and to establish the genetic relationship of the isolates by molecular epidemiology techniques. A wide spectrum was observed in the clinical severity of the eight cases studied: two were asymptomatic (contacts of HUS), one patient had bloody diarrhea, and five cases presented HUS. One HUS case died. All STEC O121:H19 strains carried the stx2a/eae/ehxA genotype, were sensitive to all antibiotics tested and showed different macrorestriction patterns by pulsed-field gel electrophoresis (Xbal-PFGE), with 84.25% similarity. The pattern AREXKX01.0072, detected in a HUS case and in his contact, is new in the Argentine National Database of non-O157 STEC. The use of standardized methods for detection and typing of STEC allows reference laboratories to monitor the temporal frequency and geographical distribution of circulating strains for the prevention and control of these pathogens associated with human diseases.

Escherichia coli produtora de toxina Shiga (STEC) O157:H7 é o sorotipo mais frequentemente identificado como o agente causador de colite hemorrágica e síndrome hemolítica urêmica (SHU), embora tenham sido descritas mais de 100 sorotipos com potencial patogênico semelhantes. O objectivo foi o de descrever os casos de doença humana associadas com a infecção por STEC O121:H19, assistido, na cidade de Mar del Plata e estabelecer relação genética de isolados utilizando epidemiologia molecular. Um amplo espectro foi observado na severidade clínica dos oito casos estudados, dois eram assintomáticos (contacto SHU), uma paciente teve diarreia com sangue, e cinco tiveram SHU. Um caso de SHU faleceu. As cepas O121:H19 portaram o genótipo stx2a/eae/ehxA, foram sensíveis aos antibióticos testados e apresentaram, por eletroforese em gel de campo pulsado (Xbal-PFGE), diferentes padrões de macrorestrição, com similaridade de 84,25%. O padrão AREXKX01.0072 detectado em SHU e em seu contato, é novo para a Base de Dados Nacional de STEC não-O157 na Argentina. O uso de métodos padrão de detecção e tipagem de STEC permite os laboratórios de referência monitorar frequência temporal e distribuição geográfica de estirpes circulantes para a prevenção e controlo destes agentes patogénicos associados com a doença humana.

Salmonella Panama: genetic diversity of the isolates collected from human and non-human sources

Abstract INTRODUCTION Salmonella enterica serovar Panama belongs to the D1 serogroup and is frequently associated with nontyphoidal salmonellosis in humans. This study aimed to characterize isolates collected from Northeast Brazil by phenotypic and molecular methods. METHODS Forty four S. Panama strains were examined for antimicrobial susceptibility, virulence genes, and pulsed field gel electrophoresis (PFGE) types. RESULTS All strains were susceptible to antibiotics (except for streptomycin), presented classical virulence factors, and could be clustered into four groups and 18 pulsotypes. CONCLUSIONS This work calls for continuous surveillance for the emergence of antibiotic resistance and new clones in a geographical area.

Molecular typing, virulence genes and drug resistance of Salmonella typhimurium in Longyan city / 中华微生物学和免疫学杂志

Objective@#To analyze the molecular typing characteristics by pulsed field gel electrophoresis (PFGE), drug resistance and virulence genes of Salmonella typhimurium in Longyan city in order to provide reference for the prevention and control.@*Methods@#A total of 79 Salmonella typhimurium strains were isolated from sporadic cases of diarrhea and food poisoning and raw poultry meat samples during 2010 to 2017. PFGE was performed to measure the minimum inhibitory concentrations (MIC) of 15 commonly used drugs against them. PCR was used to detect nine virulence genes (sopB, invA, sifA, sscA, sseE, spvB, pefA, spvR, spvC) in 55 strains.@*Results@#The 79 Salmonella typhimurium strains belonged to 61 PFGE types. There were 10, three and four strains of P1, P3 and P21 types, respectively. Seven P1 type strains were isolate from one food poisoning event. According to the 85% classification standard, 79 Salmonella typhimurium strains could be divided into five predominant gene clusters (G1-G5). Drug susceptibility test showed that the 79 strains had the highest resistance rate to ampicillin (88.61%), followed by that to tetracycline (87.34%) and streptomycin (73.41%). Multidrug resistant bacteria resistant to three or more antibacterial drugs accounted for 84.81% (67/79). All of the 55 strains carried invA, sopB, sseE and sscA genes. The other five genes, sifA, spvC, spvB, spvR and pefA, were detected in 54, 31. 10, 11 and 12 strains, respectively. There were 76.4% (42/55) of the strains carrying five or six virulence genes and all were positive for invA, sopB, sseE, sscA and sifA, and negative for spvB, spvR and pefA. The strains carrying all of the nine virulence genes accounted for 18.2% (10/55).@*Conclusions@#Salmonella typhimurium strains isolated in Longyan city had a diverse PFGE type. P1, P3 and P21 types were the three predominant PFGE types. In the food poisoning event, PFGE molecular typing could quickly alert the outbreak and traceability of Salmonella typhimurium. Attention should be paid to the multidrug resistance in Salmonella typhimurium. Monitoring of multidrug-resistant strains and supervision on antibacterial drug usage should be strengthened. Salmonella typhimurium had high virulence as it carried many virulence genes.

Methicillin-resistant Staphylococcus aureus isolated from an intensive care unit in Minas Gerais, Brazil, over a six-year period

ABSTRACT To characterize methicillin-resistant Staphylococcus aureus isolates from an intensive care unit of a tertiary-care teaching hospital, between 2005 and 2010. A total of 45 isolates were recovered from patients admitted to the intensive care unit in the study period. Resistance rates higher than 80% were found for clindamycin (100%), erythromycin (100%), levofloxacin (100%), azithromycin (97.7%), rifampin (88.8%), and gentamycin (86.6%). The SCCmec typing revealed that the isolates harbored the types III (66.7%), II (17.8%), IV (4.4%), and I (2.2%). Four (8.9%) isolates carried non-typeable cassettes. Most (66.7%) of the isolates were related to the Brazilian endemic clone from CC8/SCCmec III, which was prevalent (89.3%) between 2005 and 2007, while the USA100/CC5/SCCmec II lineage emerged in 2007 and was more frequent in the last few years. The study showed high rates of antimicrobial resistance among methicillin-resistant S. aureus isolates and the replacement of Brazilian clone, a well-established hospital lineage, by the USA100 in the late 2000s, at the intensive care unit under study.

Characteristics of drug resistance and molecular typing of Salmonella enteritidis isolated in Shanxi Province / 中华微生物学和免疫学杂志

Objective@#To investigate the antimicrobial resistance status and pulsed field gel electrophoresis (PFGE) patterns of Salmonella enteritidis (S.enteritidis) in Shanxi Province in order to provide references for the treatment of Salmonella infection and for tracing the source of outbreaks of foodborne diseases.@*Methods@#Sixty-four S. enteritidis strains were collected by monitoring sites for foodborne diseases from April 2015 to March 2018. Biochemical identification system and serotyping analysis were used for bacterial identification. Drug susceptibility patterns were analyzed with micro-broth dilution method. PFGE was used for molecular typing.@*Results@#The antimicrobial resistance rate of 64 S. enteritidis strains to nalidixic acid (95.31%) was the highest, followed by that to ampicillin (90.63%) and to ampicillin/sulbactam (81.25%). They had lower resistance rates to cefazolin, cefotaxime, tetracycline, ceftazidime, trimethoprim/sulfamethoxzole and ciprofloxacin (3.13%-23.44%) and were all sensitive to chloramphenicol, cefotaxime, azithromycin, imipenem and gentamicin. No statistically significant difference in drug resistance rates was found between the sporadic strains and the outbreak strains (P>0.05). All 64 S. enteritidis strains digested with XbaⅠwere divided into 33 molecular patterns by PFGE. The numbers of bacteria contained in each pattern ranged from 1 to 10 strains. The similarity among patterns was between 54.6% and 100%.@*Conclusion@#More attention should be paid to the drug resistance status of S. enteritidis in Shanxi Province. It is necessary to strengthen the standardized administration of antibiotics. The PFGE patterns of S. enteritidis reveal the presence of significant genetic polymorphism. PFGE is of great significance in analyzing the genetic relationship among S. enteritidis strains and in identifying and tracing the source of outbreaks of foodborne diseases.

A multicenter study of hospital infection with carbapenem-resistant Acinetobacter baumannii / 中华传染病杂志

Objective@#To investigate the epidemiologic features of interhospital, intrahospital, interdepartmental and intradepartmental infections of carbapenem-resistant Acinetobacter baumannii (CRAB) isolated from clinical specimens. @*Methods@#From September 2015 to September 2016, 540 non-repetitive strains of Acinetobacter baumannii were clinically isolated from 38 tertiary hospitals in Anhui Province, of which 460 strains were confirmed by antimicrobial resistance surveillance in Anhui Province. Agar plate dilution method was used to determine the MIC of 16 antibiotics and to select 312 CRAB isolates for drug sensitivity test. Pulsed field gel electrophoresis (PFGE) was used to analyze homology of 145 strains. PCR and clonal sequencing were used to determine the corresponding genotypes. @*Results@#All the 312 CRAB strains were multiple antibiotic resistant strains. The drug resistance rates to imipenem and meropenem were 67.9% and 70.6%, respectively. All the 145 strains were divided into 80 different types (PT1-PT80) by PFGE. Only one strain was found in the 60 types and two or more strains were found in the other 20 types. Genotype blaOXA-51 was detected in 145 strains (100%), genotype blaOXA-23 was detected in 134 of strains (92.41%), genotype blaOXA-24 was detected in 1 strain (0.69%), and subtype of blaIMP-4 was detected in 4 strains (2.76%). Genotype blaOXA-58, blaVIM, blaSIM, blaNDM and blaKPC were undetectable. @*Conclusions@#Homologous analysis indicates that all 145 strains of CRAB exhibit the interhospital, intrahospital, interdepartmental and intradepartmental transmission. Genotype blaOXA-51 is the inherent drug resistant associated gene in the chromosome of AB and genotype blaOXA-23 is the most common carbapenemase gene in Anhui Province and the main genotypes of resistance transmission.

Molecular Typing and Drug Resistance of Salmonella Typhimurium in Yunnan Province / 昆明医科大学学报

Objective To understand the molecular typing and drug resistance of Salmonella typhimurium in Yunnan Province, to provide scientific basis for preventing and controlling diseases caused by Salmonella typhimurium. Methods Molecular typing was carried out according to Salmonella PFGE typing technology published by Pulse Net China. The MIC value of the drug sensitive plate was obtained from the analysis of the instructions, and the results of S, I and R were obtained according to the corresponding standards of CLSI.Results The 68 strains salmonella typhimurium in Yunnan Province showed 53 types of PFGE. The drug resistance rate of the 68 strains of salmonella typhimurium was the highest for the compound sulfonamide (SXT), 45.59％, and the most sensitive to imipenem (IMP), among which one strain was resistant to 11 of the14 antibiotics. Conclusion The molecular typing of salmonella typhimuriumin in Yunnan province is diverse.Compound sulfonamide is the most resistant antibiotic of Salmonella typhimurium in this region. Multiple drug resistance of Salmonella typhimurium in this region is atypical.

Detection, genetic diversity and antibiotic resistance profiles of Bacillus cereus isolated from sago processing plants in Malaysia

Aims@#Bacillus cereus is a Gram-positive, rod-shaped and spore-forming bacterium. It is a ubiquitous bacterium which is widely distributed in several environments such as soil and plants and is commonly isolated from food and its processing environment. This study was aimed to determine the genetic diversity and antibiotic resistance of B. cereus isolated from sago processing in Sarawak. @*Methodology and results@#Out of 120 samples, 42 B. cereus isolates were detected with the presence of hly gene of B. cereus by using specific polymerase chain reaction (PCR). Twenty B. cereus isolates were randomly selected and further characterized by pulsed-field gel electrophoresis (PFGE) of chromosomal DNA digested with NotI to examine the genetic diversity. The result of the PFGE analysis confirmed that the B. cereus strains in sago processing were genetically diverse. Based on the dendrogram generated, B. cereus strains were grouped into two major clusters and these clusters were grouped together based on sources of isolation. The investigation on the antibiotic resistance of B. cereus strains revealed that the B. cereus strains were uniformly highly resistant to penicillin and ampicillin and highly susceptible to imipenem and norfloxacin. @*Conclusion, significance and impact of study@#The results of this study suggest that the B. cereus isolated from sago processing derived from a mixture of sensitive and resistant strains with diverse genetic contents.