Descripción de datos clínico-epidemiológicos de pacientes pediátricos con diarrea por Aeromonas spp. y estudio de la sensibilidad antibiótica de dicho agente / Epidemiological data description of pediatric patients with diarrhea by Aeromonas spp. and the antibiotic susceptibility of this agent

Resumen El objetivo de nuestro estudio fue describir las características clínico-epidemiológicas de los pacientes pediátricos con diarrea por Aeromonas spp. y estudiar lasensibilidad antibiótica de dicho agente, a partir del análisis de casos ocurridos en un períodode 7 anos. Aeromonas caviae fue identificada en 93 muestras de heces recuperadas de ninos,el 52,2% de ellos fueron varones y el 85,6% menores de 36 meses. La estación del ano conmenor cantidad de aislamientos fue el invierno (14,4%). Hubo coinfección con otros microorganismos diarreogénicos en el 31,1% de esas muestras. El mayor número de muestras procediódel servicio de urgencias de nuestro hospital (45,6%). El 43,3% de los pacientes presentaronfiebre; el 87,8%, diarrea (43% con productos patológicos) y el 67,8%, vómitos. El 73,3% de lospacientes no precisó ingreso hospitalario. Se encontró una sensibilidad superior al 87% frentea trimetoprima-sulfametoxazol, ciprofloxacina, cefotaxima y cefepime. Todos los pacientessuperaron el proceso infeccioso aun cuando el 63,3% no recibió ningún tratamiento antibiótico.Concluimos que el tratamiento antibiótico estaría indicado en casos seleccionados, cuandoexiste gravedad clínica.© 2019 Asociacion Argentina de Microbiologıa. Publicado por Elsevier Espana, S.L.U. Este es unartıculo Open Access bajo la licencia CC BY-NC-ND (https://creativecommons.org/licenses/by-nc-nd/4.0/).

Abstract The aim of our study was to describe the epidemiological features of pediatric patients with diarrhea caused by Aeromonas spp. and to study the antibiotic susceptibility of this agent during a seven-year period. Aeromonas caviae was identified in 93 stool samples from 52.2% males and 85.6% patients younger than 36 months. The season with the lowest number of isolates was winter (14.4%). Coinfection with other diarrheagenic microorganisms was observed in 31.1% of the cases. The largest number of isolates was obtained from Emergency Department samples (45.6%); 43.3% of the patients presented with fever, 87.8% with diarrhea (43% of these cases were associated with pathological products) and 67.8% with vomiting, while 73.3% of the patients did not require hospital admission. Susceptibility higher than 87% was observed to trimethoprim-sulfamethoxazole, ciprofloxacin, cefotaxime and cefepime. All the patients overcame the infectious process and 63.3% of them did not receive any antibiotic treat-ment during the process. A. caviae was the isolated species associated with intestinal infection. Antibiotic treatment would be specifically indicated in cases selected for their clinical severity. © 2019 Asociación Argentina de Microbiología. Published by Elsevier España, S.L.U. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/).

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.

Caracterización fenotípica y factores de virulencia en cepas de Aeromonas aisladas de pacientes con enfermedad diarreica aguda en Cuba / Phenotypic characteristics and virulence factors in Aeromonas strains isolated from patients with diarrheic disease in Cuba

Fifty four strains of Aeromonas spp were isolated from patients with acute diarrheic episodes by using Aerokey II and Aeroesquema methods. In vitro antimicrobial susceptibility and virulence factors were analyzed. The most frequently isolated specie was Aeromonas caviae. Over 75 percent of strains exhibited resistance to penicillins and ce-phalosporins; for the other antibiotic groups resistance was under 20 percent. Twenty six strains (48.1 percent) were multiresist-ant. At least one virulence factor among those evaluated in the study was present in 53 (98.1 percent) of the 54 strains.

Se identificaron 54 cepas de Aeromonas aisladas de pacientes con enfermedad diarreica aguda mediante los métodos Aerokey II y Aeroesquema. Se determinó la susceptibilidad antimicrobiana y algunos factores de virulencia. La especie encontrada en mayor frecuencia fue Aeromonas caviae. Se observaron valores de resistencia por sobre 75 por ciento para penicilinas y cefalotina; para el resto de los antimicrobianos estos valores se encontraron bajo 20 por ciento>; 26 cepas (48,1 por ciento) presentaron multi-resistencia. Al menos un factor de virulencia de los investigados estuvo presente en 53 (98,1 por ciento) de las 54 cepas analizadas.

Caracterização de Aeromonas spp isoladas de neonatos hospitalizados / Characterization of Aeromonas spp isolates from newborns hospitalized

Aeromonas spp é reconhecida como patogênica para o homem após o consumo de água e alimentos contaminados. Na presente investigação, foram avaliadas 2.323 amostras de swabs retais de neonatos hospitalizados no Rio de Janeiro objetivando o isolamento de Aeromonas. As amostras foram coletadas e enviadas ao Laboratório de Referência Nacional de Cólera e outras enteroinfecções bacterianas, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz. Os swabs foram submetidos ao enriquecimento em água peptonada alcalina adicionada de 1 por cento de cloreto de sódio (NaCl) e água peptonada alcalina adicionada de 3 por cento de NaCl (37ºC/18-24h) e semeadas em agar seletivo para Pseudomonas aeromonas (Agar GSP). Foram isoladas 56 cepas de Aeromonas assim distribuídas: Aeromonas caviae (42,8 por cento), Aeromonas media (25 por cento), Aeromonas veronii biogrupo sobria (10,7 por cento), Aeromonas hydrophila (9 por cento), Aeromonas veronii biogrupo veronii (5,3 por cento), Aeromonas sobria (1,8 por cento), Aeromonas jandaei (1,8 por cento), Aeromonas schubertii (1,8 por cento) e Aeromonas sp (1,8 por cento). Foi observada resistência a uma ou mais drogas antimicrobianas em 26,8 por cento das cepas. Considerando a relevância de Aeromonas torna-se urgente alertar sobre sua importância para o controle de infecções hospitalares.

Aeromonas spp is recognized as pathogenic to humans after consumption of contaminated water and food. In the present investigation, 2,323 rectal swab samples from newborns hospitalized in Rio de Janeiro were evaluated with a view to isolating Aeromonas. The samples were collected and sent to the national reference laboratory for cholera and other bacterial intestinal infections, at the Oswaldo Cruz Institute of the Oswaldo Cruz Foundation. The swabs were subjected to enrichment in alkaline peptonated water with the addition of 1 percent sodium chloride (NaCl) and alkaline peptonated water plus 3 percent NaCl (37°C/18-24h) and were streaked onto agar that was selective for Pseudomonas-Aeromonas (GSP Agar). Fifty-six Aeromonas strains were isolated, distributed as follows: Aeromonas caviae (42.8 percent), Aeromonas media (25 percent), Aeromonas veronii biogroup sobria (10.7 percent), Aeromonas hydrophila (9 percent), Aeromonas veronii biogroup veronii (5.3 percent), Aeromonas sobria (1.8 percent), Aeromonas jandaei (1.8 percent), Aeromonas schubertii (1.8 percent) and Aeromonas sp (1.8 percent). Resistance to one or more antimicrobial drugs was observed in 26.8 percent of the strains. Considering the importance of Aeromonas, there is an urgent need to warn about this in relation to nosocomial infection control.

Prevalence, pathogenesis, antibiotic susceptibility profiles, and in-vitro activity of selected medicinal plants against Aeromonas isolates from stool samples of patients in the Venda region of South Africa.

The prevalence, pathogenic indices, such as haemolytic and haemagglutinating activities, antibiograms, and in-vitro activities of local medicinal plants against Aeromonas isolates in Vhembe district of Limpopo province, South Africa, were studied using standard microbiological methods. In total, 309 diarrhoeic stool samples were collected from patients attending five health centres in the region during December 2004-May 2005. Aeromonas species were identified using the API 20E system. The haemagglutinating and haemolytic activities of isolates on human, sheep, pig and chicken red blood cells were investigated. Antibiotic susceptibility profiles of the isolates to several antibiotics and in-vitro activity of local medicinal plants were also ascertained using previously-reported schemes. Results showed that 104 (33.6%) of the 309 samples were positive for Aeromonas species, of which 89 (85.6%) were Aeromonas hydrophila, 12 (11.5%) A. sobria, and three (2.9%) A. caviae. All strains of A. hydrophila and A. caviae produced haemolysis on sheep blood, while eight of the 12 A. sobria strains were haemolytic on sheep blood. The haemolytic activities of the isolates were variable on other red blood cells tested. High level of resistance was observed to amoxicillin and ampicillin, followed by cefuroxime (79%), chloramphenicol (74%), and erythromycin (65%). The carbapenems were the most active drugs with only 7% resistance to meropenem and 11% to imipenem. About 12% of the isolates were resistant to ciprofloxacin. The extracts of three of seven medicinal plants tested showed inhibitory activity against all Aeromonas isolates; these included acetone and hexane extracts of Pterocarpus angolensis, Syzygium cordatum, and Zornia milneana. The results suggest a high prevalence of Aeromonas species in the region. The isolates demonstrated multiple resistant profiles to different antibiotics tested. Some local medicinal plants were inhibitory to Aeromonas isolates, indicating a potential role in the management of Aeromonas-related infections. Structural elucidation of the active components may pave the way for the discovery of candidate templates for eventual drug design. Most isolates possessed important virulence characteristics based on their haemolytic and haemagglutinating ability. However, the genetic characterization of the isolates will further confirm their pathogenicity and the origin of multiple antibiotic resistance.

The involvement of tetA and tetE tetracycline resistance genes in plasmid and chromosomal resistance of Aeromonas in Brazilian strains

This study analyzed the involvement of tetA and tetE genes in the tetracycline resistance of 16 strains of genus Aeromonas, isolated from clinical and food sources. Polymerase chain reactions revealed that 37.5 percent of the samples were positive for tetA, and also 37.5 percent were tetE positive. One isolate was positive for both genes. Only the isolate A. caviae 5.2 had its resistance associated to the presence of a plasmid, pSS2. The molecular characterization of pSS2 involved the construction of its restriction map and the determination of its size. The digestion of pSS2 with HindIII originated two fragments (A and B) that were cloned separately into the pUC18 vector. The tetA gene was shown to be located on the HindIII-A fragment by PCR. After transforming a tetracycline-sensitive strain with pSS2, the transformants expressed the resistance phenotype and harbored a plasmid whose size was identical to that of pSS2. The results confirmed the association between pSS2 and the tetracycline resistance phenotype, and suggest a feasible dissemination of tetA and tetE among strains of Aeromonas. This study suggests the spreading tetA and tetE genes in Aeromonas in Brazil and describes a resistance plasmid that probably contributes to the dissemination of the resistance.

Aeromonas spp. isolated from oysters (Crassostrea rhizophorea) from a natural oyster bed, Ceará, Brazil

Foram realizadas 30 coletas quinzenais, entre abril e outubro de 2002, de ostras (Crassostrea rhizophorea) de um criadouro natural, no estuário do rio Cocó (Fortaleza/Ceará/Brasil), objetivando-se isolar cepas de Aeromonas spp. As amostras de ostras foram submetidas aos métodos de plaqueamento direto (PD) e presença/ausência (P/A). Foram identificadas Aeromonas em 15 (50%) amostras analisadas pelo método PD e em 13 (43%) pelo método P/A. Foram isoladas: A. caviae, A. eucrenophila, A. media, A. sobria, A. trota, A. veronii bv. sobria, A. veronii bv. veronii e Aeromonas sp. A espécie predominate foi A. veronii (ambos biovars), identificada em 13 (43%) amostras, seguida de A. media em 11 (37%) e A. caviae em 7 (23%). Das 59 cepas identificadas, 28 (48%) apresentaram resistência a pelo menos um, dos oitos antibióticos testados.

Serogroups, K1 antigen, and antimicrobial resistance patterns of Aeromonas spp. strains isolated from different sources in Mexico

A total of 221 strains of Aeromonas species isolated in Mexico from clinical (161), environmental (40), and food (20) samples were identified using the automated system bioMérieux-Vitek®. Antisera for serogroups O1 to 044 were tested using the Shimada and Sakazaki scheme. The K1 antigen was examined using as antiserum the O7:K1C of Escherichia coli. Besides, we studied the antimicrobial patterns according to Vitek AutoMicrobic system. Among the 161 clinical strains 60 percent were identified as A. hydrophila, 20.4 percent as A. caviae, and 19.25 percent as A. veronii biovar sobria. Only A. hydrophila and A. veronii biovar sobria were found in food (55 and 90 percent respectively) and environmental sources (45 and 10 percent respectively). Using "O" antisera, only 42.5 percent (94/221) of the strains were serologically identified, 55 percent (121/221) were non-typable, and 2.5 percent (6/221) were rough strains. Twenty-two different serogroups were found, O14, O16, O19, O22, and O34 represented 60 percent of the serotyped strains. More than 50 percent of Aeromonas strain examined (112/221) expressed K1 encapsulating antigen; this characteristic was predominant among Aeromonas strains of clinical origin. Resistance to ampicillin/sulbactam and cephazolin was detected in 100 and 67 percent of Aeromonas strain tested for their susceptibility to antibiotics. In conclusion, antibiotic-resistant Aeromonas species that possess the K1 encapsulating antigen and represent serogroups associated with clinical syndrome in man are not uncommon among Aeromonas strains isolated from clinical, food and environmental sources in Mexico.

Prevalence, species differentiation, haemolytic activity, and antibiotic susceptibility of aeromonads in untreated well water

The use of untreated water for drinking and other activities have been associated with intestinal and extraintestinal infections in humans due to Aeromonas species. In the present study aeromonads were isolated from 48.7 percent of 1,000 water samples obtained from wells and other miscellaneous sources. Aeromonas species were detected in 45 percent of samples tested in spring, 34.5 percent in summer, 48 percent in autumn and 60 percent of samples tested in winter. Speciation of 382 strains resulted in 225 (59 percent) being A. hydrophila, 103 (27 percent) A. caviae, 42 (11 percent) A. sobria and 11 (3 percent) atypical aeromonads. Of 171 Aeromonas strains tested for their haemolytic activity, 53 percent, 49 percent, 40 percent and 37 percent were positive in this assay using human, horse, sheep and camel erythrocytes respectively. The results obtained indicate that potentially enteropathogenic Aeromonas species are commonly present in untreated drinking water obtained from wells in Libya (this may also apply to other neighbouring countries) which may pose a health problem to users of such water supplies. In addition, ceftriaxone and ciprofloxacin are suitable drugs that can be used in the treatment of Aeromonas-associated infections, particularly in the immunocompromised, resulting from contact with untreated sources of water

Aeromonas species isolated from pintado fish (Pseudoplatystoma SP): virulence factors and drug susceptibility

Aeromas has been described as an emergent foodborne pathogen of increasing importance. In this study, we report that 48(per cent) of 50 Pintado fish samples collected at the retail market of São Paulo city were positive for Aeromas sp, as detected by the direct plating method. When the presence/absence method was used, the positivity was 42(per cent). A caviae was the most frequent species, followed by A. hydrophila and A. sobria. Production of cytotoxic enterotoxin, observed in suckling mouse assay, was detected in 67(per cent) of A sobria strains, in 60(per cent) of A. hydrophila strains and in 40(per cent) of A. caviae strains. In vitro tests, performed with HEp-2 cells, showed that 88(per cent) of A. hydrophila, 27(per cent) of A. sobria and 13(per cent) of A. caviae strains were positive for this toxin. The in vivo production of cytotonic enterotoxin, tested after heating the filtrates at 56degreeC for 20 minutes, was detected in 17(per cent) of A. sobria, in 10(per cent) of A. caviae and in none of A. hydrophila strains in vivo. All analyzed strains did not alter HEp-2 cells. 20(per cent) and 16(per cent) of A. sobria and A. caviae isolates, respectively, presented capacity to adhere to HEp-2 cells. In counterpart, invasion of HEp-2 cells was not observed in any isolate. The Aeromonas isolates were sensitive to the majority of the antimicrobiol agents tested.

Prevalência de Aeromonas spp. em fezes diarréicas de crianças menores de 5 anos de idade na cidade de Goiânia, Goiás, no biênio 1995-1996 / The prevalence of Aeromonas spp. in the diarrheal feces of children under the age of 5 years in the city of Goiânia, Goiás in the 1995-1996 biennium

Foram analisadas 163 amostras de fezes de crianças com idade abaixo de 5 anos no período de 1995 a 1996, sendo 91 de fezes diarréicas e 72 de fezes não diarréicas. O material foi coletado em meio para transporte e submetido ao processo de enriquecimento a 4oC por 7 dias. Para o isolamento primário foi utilizado ágar amido ampicilina e incubado a 35oC por 18 a 24 horas. Foram isoladas 20 (21,9%) das seguintes espécies: Aeromonas A. caviae (7,7%), A. salmonicida salmonicida (6,6%), A. sobria (4,3%), A. hydrophila (2,2%) e Salmonicida achromogenes (1,1%). Nenhuma Aeromonas spp foi isolada dos 72 pacientes-controles. A susceptibilidade das amostras de Aeromonas spp aos antimicrobianos foi maior com a ciprofloxacina, diminuindo gradativamente com cloranfenicol, gentamicina, ampicilina e eritromicina.

From 1995 through 1996, 163 fecal specimens of children aged under 5 years were analysed, 91 being from diarrhea feces and 72 without diarrhea. The material was collected in transport medium and submitted to the enrichment procedure at 4 degrees C for 7 days. For the primary isolation starch ampicillin agar was used and incubated at 35 degrees C for 18 to 24 hours. Twenty (20.9%) from the following specimens were isolated: Aeromonas (A.) caviae (7.7%), A. salmonicida salmonicida (6.6%), A. sobria (4.3%), A. hydrophila (2.2%) and Salmonicida achromogenes (1.1%). No Aeromonas spp. was isolated from the 72 control subjects. The Aeromonas spp. susceptibility to antimicrobial was greater with ciprofloxacin, being this susceptibility gradually diminished with chloranphenicol, gentamicin, ampicillin and erythromycin.

Enterotoxicity, haemolytic activity and antibiotic susceptibility of Aeromonas eucrenophila strains isolated from water and infected fish.

Strains of A. eucrenophila isolated from fresh water (2 strains) and infected fish (4 strains) were tested for haemolytic activity and enterotoxicity and any correlation between them. Also, the resistance patterns of A. eucrenophila were tested especially in relation to ampicillin. None of the A. eucrenophila strains caused fluid accumulation in the initial tests, however, they did so only after one to four sequential passages through the gut of a susceptible host. All the strains of A. eucrenophila showed beta-haemolytic activities. Production of beta-haemolysin could be correlated with enterotoxicity. Since all the strains of A. eucrenophila were resistant to ampicillin, media containing this antibiotic may be used for their isolation from diverse sources.

Aeromonas species and Plesiomonas shigelloides in diarrhoea in Goa.

Sixty six strains (1.9%) of Aeromonas species and 7 strains (0.2%) of Plesiomonas shigelloides were isolated from 3484 stool/rectal swabs from cases of diarrhoea during the study period of four years from August 1986 to July 1990 in Goa. Although the selective medium (Ampicillin sheep blood agar) was not used for the isolation of Aeromonas, an increase in the rate of isolation of Aeromonas from 0.2% in the year 1986 to 6.0% in 1990 was observed. Stool samples from 100 controls (patients without diarrhoea) examined in the year 1989 did not yield either of the pathogens.

Susceptibilidad antimicrobiana en cepas italianas de Aeromonas / Antimicrobial susceptibility in Italian Aeromonas strains

Treinta y una cepas de Aeromonas spp. aisladas de heces humanas fueron sometidas al estudio de susceptibilidad antimicrobiana por el método de Kirby-Bauer. Todas las Aeromonas fueron suceptibles al mezlocilin, cefalosporina de segunda y tercera generación, aztrionan y aminoglucósidos (excepto para streptomycin) trimetropin-sulfametoxazol, ácido nalidíxico, rifampicina, norfloxaxin y colistin. Todas las cepas fueron resistentes a la ampicillina, carbanecillin y lincomicina. Todas menos 1 Aeromonas sobria fueron susceptibles al cefalotin. En conclusión, estos resultados mostraron que muchos aislamientos fueron sensibles a un amplio rango de agentes antimicrobianos

Aeromonas spp en niños con síndrome diarreico agudo / Aeromonas spp in children with acute diarrheal disease

El interés por el género Aeromonas es creciente, tanto como causante de enfermedades diarreicas como extraintestinales. Produce cuadros intestinales a través de acción citotóxica y enterotóxica. Empleando agar sangre con 30 mg/l de ampicilina (ASA) se aislaron Aeromonas spp en 8 de 400 niños diarreicos y en ninguno de 230 controles no diarreicos. El aislamiento fue muy inferior en los medios tradicionales del coprocultivo, agar lactosa y agar Shigella-Salmonella, así como agar sangre sin ampicilina, en el que hubo sobredesarrollo de flora entérica. Cinco cepas aisladas fueron A. hydrophila, 2 A. caviae y 1 A. veroni biotipo sobria. Cuatro de cinco cepas probadas resultaron enterotoxigénicas en asa de conejo. Todas las cepas fueron hemolíticas; 6 fueron Voges Proskauer (+), lisina decarboxilasa (+) y glucosa con gas (+), características que han sido relacionadas con la virulencia. Todos los aislados resultaron resistentes a las aminopenicilinas con o sin sulbactama y sensibles a cloranfenicol, colistin, gentamicina, neomicina y norfloxacina. Dos cepas resultaron resistentes a sulfametoxazol-trimetoprima

Cultural and Biochemical Characteristics of Clinical Isolates of Aeromonas hydrophila

Aeromonas hydrophila infection has been increasingly found, in particular among patients with various underlying diseases. Many characteristics of this organism are quite similar to those of Enterobacteriaceae and Vibrio, making an accurate identification difficult. In a period of 2 years, the authors obtained a total of 27 isolates of A. hydrophila from clinical materials, and their cultural and biochemical characteristics are herewith reported. Some of the most important clues to suspect this organism were a wide zone of complete hemolysis on blood agar, partially alkaline slant, acid butt, and small amount of gas in trip1e sugar iron agar (TSI), weak indole reaction, and negative ornithine decarboxylase in motility indole ornithine medium (MIO), and usually positive citrate utilization. It is concluded that the identification of this organism should be possible on the basis of deoxyribonuclease (DNase), oxidase, and a few other tests. Our isolates showed a similar antibiotic susceptibility to those reported in other countries; i.e., a11 were resistant to ampicillin and most were susceptible to other antibiotics, excluding cephalothin.