Pathogenic characterization of Aeromonas salmonicida subsp. masoucida turbot isolate from China.

Aeromonas salmonicida is a gram-negative bacterium that is the causative agent of furunculosis. An A. salmonicida strain was isolated from diseased turbot (Scophthalmus maximus) with the sign of furunculosis from North China. Based on vapA gene, the strain was further classified as A. salmonicida subsp. masoucida RZ6S-1. Culturing RZ6S-1 strain at high temperature (28°C) obtained the virulence attenuated strain RZ6S. Genome sequence comparison between the two strains revealed the loss of the type IV secretion system (T4SS) and type III secretion system (T3SS) from the native plasmid pAsmB-1 and pAsmC-1 of wild-type strain RZ6S-1, respectively. Further study demonstrated that the wild-type strain RZ6S-1, but not its derivative mutant RZ6S, can stimulate apoptosis. Elevated protein level of cleaved caspase-3 was detected from epithelioma papulosum cyprinid (EPC) cells infected with wild-type strain RZ6S-1 as compared with that infected with RZ6S strain. Meanwhile, the invasion of the mutant strain RZ6S was about 17-fold higher than the wild-type strain RZ6S-1, suggesting that some protein(s) from A. salmonicida subsp. masoucida RZ6S-1 suppress its invasion. The RZ6S mutant strain was attenuated, since its LD50 is over 10,000 times higher compared to the wild-type strain as revealed in the turbot infection model.

Distribution and Potential Effects of 17ß-Estradiol (E2) on Aeromonas Diversity in Wastewater and Fish Samples.

BACKGROUND AND OBJECTIVE: Recently, there has been evidence for the accumulation of steroid hormones in the water environment with negative consequences on fish and humans. However, there is paucity of information on how the steroid hormones influence the microbial community in environmental waters. The objective of this study was to determine the occurrence of 17ß-estradiol (E2) and its potential influence on the diversity of Aeromonas spp. MATERIALS AND METHODS: Wastewater samples were obtained from sewage treatment plants in northern South Africa and fish samples were collected from the Nandoni dam. Aeromonas spp. were isolated using microbiological methods and PCR protocols were used for their identification. A commercial Elisa kit was used for measuring the concentration of 17ß-estradiol (E2) from the wastewater samples as well as the fish samples. RESULTS: 17ß-estradiol (E2) was found in high concentration in sewage samples varying from 0.32-348.6 pg mL-1 while in fish samples, it ranged from 1.1-73.6 pg mL-1. There was a tendency of samples with high E2 concentrations to have higher diversity of Aeromonas spp., implying that steroid hormones may serve as nutrient for Aeromonas spp. Aeromonas hydrophila was the most prevalent species (71%), followed by A. sobria with (68%). CONCLUSION: The presence of Aeromonas spp. in environmental waters and fish that is consumed by the local community poses a serious health concern. The high content of E2 in treated wastewater is of serious concern as well. For the first time, the present study showed a positive impact of E2 on Aeromonas growth.

Taxonomy, virulence genes and antimicrobial resistance of Aeromonas isolated from extra-intestinal and intestinal infections.

BACKGROUND: Clinical characteristics (taxonomy, virulence genes and antimicrobial resistance ) of Aeromonas in isolated from extra-intestinal and intestinal infections were investigated to describe epidemiology, associated virulence factors and optimal therapy options. METHODS: Clinical samples (n = 115) of Aeromonas were collected from a general hospital in Beijing between the period 2015 and 2017. Taxonomy was investigate by Multilocus phylogenetic analysis (MLPA), 10 putative virulence factors by use of polymerase chain reaction (PCR) and antimicrobial resistance to 15 antibiotics by use of the microbroth dilution method. RESULTS: The most common species of Aeromonas detected in samples of intestinal tract included; A. caviae (43.9%), A. veronii (35.7%), and A. dhakensis (12.2%). Prevalent species of Aeromonas collected from extra-intestinal infections included; A. hydrophila (29.4%), A. caviae (29.4%), and A. dhakensis (23.5%). A. hydrophila were detected in 1% of stool samples and 29.4% (5/17) of extra-intestinal infections. A. hydrophila strains in extra-intestinal infections were related to malignancy. The most common medical conditions among patients with Aeromonas infections included malignancy and liver-transplant related cholecystitis. Multiple drug resistance (MDR) was prevalent in extra-intestinal isolates (82.3%, 14/17) and was greater than the prevalence in intestinal isolates (30.6%, 30/98) (P < 0.05). Resistant rates of extra-intestinal isolates were 70.6, 35.3, 23.5 and 5.9% for ceftriaxone, ciprofloxacin, gentamicin and imipenem, respectively, and were higher than found in previous studies. Despite differences in the number and type of virulence genes among samples of Aeromonas, no significant correlation was found between invasion and virulent genes in intestinal or extra-intestinal infections. CONCLUSIONS: Overall results of this study support a role for Aeromonas spp. as a potential causative infectious agent of gastroenteritis, and malignancy, liver cirrhosis, post liver transplantation in immunocompromised patients. A. hydrophila was more prevalent in samples of extra-intestinal infections when compared to samples of intestinal infections, and was especially prominent in samples of patients presenting with malignancy. Aeromonas isolates from extra-intestinal samples had high rates of drug resistance but 3rd generation cephalosporins, fluoroquinolones and aminoglycosides remain as options to treat severe diarrhea. However, increasing MDR of extra-intestinal infection samples warrants monitoring.

Detecção de Aeromonas spp. e do gene de virulência aerolisina em tilápias do Nilo (Oreochromis niloticus) com a técnica de mPCR / Detection of Aeromonas spp. and virulence gene aerolysin in Nile tilapia (Oreochromis niloticus) using PCR technique

As infecções causadas por bactérias do gênero Aeromonas estão entre as doenças mais comuns em peixes cultivados em todo o mundo, com ocorrência de aeromoniose em todos os países que possuem cultivo de tilápia do Nilo (Oreochromis niloticus). O presente trabalho descreve o desenvolvimento de uma nova multiplex PCR (mPCR) para diagnóstico de Aeromonas spp. e identificação do gene aerolisina (aerA). Para padronização da mPCR foram utilizadas cepas de referência de várias espécies do gênero Aeromonas e de outros gêneros. Também foram usadas cepas de campo de A. hydrophila oriundas de cultivos de peixes pacamãs (Lophiosilurus alexandri) e Aeromonas spp. de tilápias do Nilo. Os primers foram desenhados com base na região 16S rRNA e aerA. Para verificar a melhor temperatura de anelamento foram utilizados gradientes entre 59°C a 61°C com 40ng de DNA molde. Os produtos da amplificação da região 16S rRNA e do gene aerA apresentaram 786 e 550pb, respectivamente. A mPCR apresentou melhor temperatura de anelamento a 57,6°C com limite de detecção das concentrações de DNA em ambos genes (16S rRNA and aerA) de 10-10g/μL. A mPCR padronizada é rápida, sensível e específica no diagnóstico de Aeromonas spp. e identificação do gene aerolisina. Esta metodologia apresenta vantagens quando comparada aos métodos de diagnóstico convencionais, podendo ser utilizada em cultivos comerciais de tilápias do Nilo ou outros peixes. A identificação do gene aerolisina é uma importante ferramenta na determinação do potencial patogênico dos isolados de Aeromonas spp. estudados.(AU)

Infections caused by bacteria of the genus Aeromonas are among the most common diseases in fish farming systems worldwide, and this disease occurs in all countries which have Nile tilapia (Oreochromis niloticus) farmed. The present work describes the development of a new multiplex PCR (mPCR) technique that diagnosis the genus Aeromonas and detects aerolysin gene (aerA). Reference strains of several Aeromonas species and other genera were used for standardization of mPCR. Strains of A. hydrophila from "pacaman" fish (Lophiosilurus alexandri) and Aeromonas spp. from Nile tilapia from farming systems were used too. Primers were designed based on the 16S rRNA region and aerA (aerolysin toxin). To verify a better annealing temperature were used gradients between 59°C and 61°C with 40ng of the DNA template. The 16S rRNA gene and the aerA gene amplification products showed 786 and 550 bp, respectively. The mPCR showed better annealing temperature at 57.6°C, and the detection limit for both genes (16S rRNA and aerA) was 10-10g/μL of the DNA. The standardized mPCR is quick, sensitive, and specific for Aeromonas spp. diagnosis and to detect aerolysin gene. This method showed advantages when compared to the conventional diagnostic methods and can be used in Nile tilapia or other fish farming systems. The detection of aerolysin gene is an important tool to determine the potential pathogenicity of Aeromonas spp. isolates.(AU)

Reclassification of Aeromonas sharmana to a new genus as Pseudaeromonas sharmana gen. nov., comb. nov., and description of Pseudaeromonas pectinilytica sp. nov. isolated from a freshwater stream.

A Gram-reaction-negative, rod-shaped, facultatively anaerobic, motile bacterium, designated strain AR1T, was isolated from a freshwater stream in Jeonju, South Korea. Strain AR1T showed highest 16S rRNA gene sequence similarity (96.83 %) and also formed a separate clade with Aeromonas sharmana GPTSA-6T in the phylogenetic tree reconstructed among the members of the family Aeromonadaceae. Major cellular fatty acids are summed feature 3 (C16 : 1ω7c/C16 : 1ω6c) and C16: 0. Diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol are the predominant polar lipids. The genomic DNA G+C content was found to be 54.7 mol%. However, earlier studies on 16S rRNA gene, gyrB, rpoD and universal target region of cpn60 sequences of the members of the genus Aeromonas recommended the transfer of Aeromonas sharmana to a new genus. Hence, based on the comparative polyphasic data obtained during the present study and also on the previous recommendations, it is proposed that Aeromonas sharmana be transferred to a novel genus as Pseudaeromonas sharmana gen. nov., comb. nov. with strain GPTSA-6T (=DSM 17445T=MTCC 7090T=CIP 109378T=CCUG 54939T) as the type strain of the type species of the genus. Also, it is proposed that strain AR1T be designated as a representative of a novel species of this new genus, namely Pseudaeromonas pectinilytica sp. nov. The type strain is AR1T (=KCTC 42754T=JCM 31503T).

Distribution of Aeromonas species in environmental water used in daily life in Okinawa Prefecture, Japan.

OBJECTIVES: The genus Aeromonas is known to causes diseases such as food poisoning, sepsis, and wound infection. However, the mode of Aeromonas transmission from environment to humans is not clearly understood. To evaluate the health risks of Aeromonas spp. in environmental freshwater, the number, proportion and putative virulence factors of Aeromonas species were investigated in Okinawa Prefecture, Japan. METHODS: Environmental freshwater samples were collected from three dams, two springs and three private wells. Aeromonas strains were identified by the biochemical method and the viable count was calculated. The production of extracellular enzymes and the virulence genes were investigated for possessing putative virulence factors using representative isolates. RESULTS: At least seven species of already-known Aeromonas isolates as well as unidentified Aeromonas spp. with/without arginin dehydrolase (ADH) exist in water at these sites. Aeromonas spp. was found to exist at over 1000 CFU/100 ml in one spring and two wells. A. veronii biovar sobria and A. jandaei were the predominant species in dams, and A. hydrophila and/or A. eucrenophila were predominant in wells. Almost all the sampled Aeromonas species produced protease, gelatinase, lipase, esterase and DNase, but A. caviae, A. caviae-like bacteria, and A. eucrenophila had low hemolytic activity. Most sampled A. hydrophila strains possessed both aerolysin gene (aer) and hemolysin gene (hlyA), but A. caviae and A. eucrenophila strains did not possess either gene. CONCLUSIONS: Since these results indicated that several Aeromonas species having potential pathogenicity exist in environmental water in Okinawa, surveys are recommended as a public health measure.

Aeromonas lusitana sp. nov., Isolated from Untreated Water and Vegetables.

During previous studies to evaluate the phylogenetic diversity of Aeromonas from untreated waters and vegetables intended for human consumption, a group of isolates formed a unique gyrB phylogenetic cluster, separated from those of all other species described so far. A subsequent extensive phenotypic characterization, DNA-DNA hybridization, 16S rRNA gene sequencing, multi-locus phylogenetic analysis of the concatenated sequence of seven housekeeping genes (gyrB, rpoD, recA, dnaJ, gyrA, dnaX, and atpD; 4705 bp), and ERIC-PCR, were performed in an attempt to ascertain the taxonomy position of these isolates. This polyphasic approach confirmed that they belonged to a novel species of the genus Aeromonas, for which the name Aeromonas lusitana sp. nov. is proposed, with strain A.11/6(T) (=DSMZ 24095(T), =CECT 7828(T)) as the type strain.

Aeromonas aquatica sp. nov., Aeromonas finlandiensis sp. nov. and Aeromonas lacus sp. nov. isolated from Finnish waters associated with cyanobacterial blooms.

Three groups of Aeromonas strains isolated from Finland lakes experiencing cyanobacterial blooms could not be assigned to any known species of this genus on the basis of 16S rRNA and rpoD gene sequences. The Multilocus Phylogenetic Analysis (MLPA) of the concatenated sequence of seven genes (gyrB, rpoD, recA, dnaJ, gyrA, dnaX and atpD; 4093bp) showed that the three groups of strains did not cluster with any known Aeromonas spp. and formed three independent lineages. This was confirmed by performing the analysis with their closest relatives using 15 genes (the latter 7 and cpn60, dnaK, gltA, mdh, radA, rpoB, tsf, zipA; 8751bp). Furthermore, ANI results between the genomes of the type strains of the three potential new species and those of their close relatives were all <96% which is the previously proposed cutoff value for differentiating species within this genus. The in silico DDH values of the three type strains of the new species also showed a similarity<70% with the most closely related species indicating they belong to different taxa. The three groups of strains could be differentiated from each other and from other known Aeromonas species on the basis of several phenotypic characters. This polyphasic study revealed that the 3 groups of strains represent 3 novel Aeromonas species for which the names Aeromonas aquatica sp. nov. (type strain AE235T=CECT 8025T=LMG 26712T), Aeromonas finlandiensis sp. nov. (type strain 4287DT=CECT 8028T=LMG 26709T) and Aeromonas lacus sp. nov. (type strain AE122T=CECT 8024T=LMG 26710T) are proposed.

Clinical implications of species identification in monomicrobial Aeromonas bacteremia.

BACKGROUND: Advances in Aeromonas taxonomy have led to the reclassification of aeromonads. Hereon, we aimed to re-evaluate the characteristics of Aeromonas bacteremia, including those of a novel species, Aeromonas dhakensis. METHODOLOGY/PRINCIPAL FINDINGS: A retrospective study of monomicrobial Aeromonas bacteremia at a medical center in southern Taiwan from 2004-2011 was conducted. Species identification was based on rpoB sequencing. Of bacteremia of 153 eligible patients, A. veronii (50 isolates, 32.7%), A. dhakensis (48, 31.4%), A. caviae (43, 28.1%), and A. hydrophila (10, 6.5%) were the principal causative species. A. dhakensis and A. veronii bacteremia were mainly community-acquired and presented as primary bacteremia, spontaneous bacterial peritonitis, or skin and soft-tissue infection, whereas A. caviae was associated with hospital-onset bacteremia. The distribution of the AmpC ß-lactamase and metallo-ß-lactamase genes was species-specific: bla(AQU-1), bla(MOX), or bla(CepH) was present in A. dhakensis, A. caviae, or A. hydrophila, respectively, and bla(CphA) was present in A. veronii, A. dhakensis, and A. hydrophila. The cefotaxime resistance rates of the A. caviae, A. dhakensis, and A. hydrophila isolates were higher than that of A. veronii (39.5%%, 25.0%, and 30% vs. 2%, respectively). A. dhakensis bacteremia was linked to the highest 14-day sepsis-related mortality rate, followed by A. hydrophila, A. veronii, and A. caviae bacteremia (25.5%, 22.2%, 14.0%, and 4.7%, respectively; P = 0.048). Multivariate analysis revealed that A. dhakensis bacteremia, active malignancies, and a Pitt bacteremia score ≥ 4 was an independent mortality risk factor. CONCLUSIONS/SIGNIFICANCE: Characteristics of Aeromonas bacteremia vary between species. A. dhakensis prevalence and its associated poor outcomes suggest it an important human pathogen.

Biodegradation of Methyl Orange by alginate-immobilized Aeromonas sp. in a packed bed reactor: external mass transfer modeling.

Azo dyes are recalcitrant and xenobiotic nature makes these compounds a challenging task for continuous biodegradation up to satisfactorily levels in large-scale. In the present report, the biodegradation efficiency of alginate immobilized indigenous Aeromonas sp. MNK1 on Methyl Orange (MO) in a packed bed reactor was explored. The experimental results were used to determine the external mass transfer model. Complete MO degradation and COD removal were observed at 0.20 cm bead size and 120 ml/h flow rate at 300 mg/l of initial dye concentration. The degradation of MO decreased with increasing bead sizes and flow rates, which may be attributed to the decrease in surface of the beads and higher flux of MO, respectively. The experimental rate constants (k ps) for various beads sizes and flow rates were calculated and compared with theoretically obtained rate constants using external film diffusion models. From the experimental data, the external mass transfer effect was correlated with a model J D = K Re (-(1 - n)). The model was tested with K value (5.7) and the Colburn factor correlation model for 0.20, 0.40 and 0.60 bead sizes were J D = 5.7 Re (-0.15), J D = 5.7 Re (-0.36) and J D = 5.7 Re (-0.48), respectively. Based on the results, the Colburn factor correlation models were found to predict the experimental data accurately. The proposed model was constructive to design and direct industrial applications in packed bed reactors within acceptable limits.

Aeromonas hydrophila and Aeromonas veronii predominate among potentially pathogenic ciprofloxacin- and tetracycline-resistant aeromonas isolates from Lake Erie.

Members of the genus Aeromonas are ubiquitous in nature and have increasingly been implicated in numerous diseases of humans and other animal taxa. Although some species of aeromonads are human pathogens, their presence, density, and relative abundance are rarely considered in assessing water quality. The objectives of this study were to identify Aeromonas species within Lake Erie, determine their antibiotic resistance patterns, and assess their potential pathogenicity. Aeromonas strains were isolated from Lake Erie water by use of Aeromonas selective agar with and without tetracycline and ciprofloxacin. All isolates were analyzed for hemolytic ability and cytotoxicity against human epithelial cells and were identified to the species level by using 16S rRNA gene restriction fragment length polymorphisms and phylogenetic analysis based on gyrB gene sequences. A molecular virulence profile was identified for each isolate, using multiplex PCR analysis of six virulence genes. We demonstrated that Aeromonas comprised 16% of all culturable bacteria from Lake Erie. Among 119 Aeromonas isolates, six species were identified, though only two species (Aeromonas hydrophila and A. veronii) predominated among tetracycline- and ciprofloxacin-resistant isolates. Additionally, both of these species demonstrated pathogenic phenotypes in vitro. Virulence gene profiles demonstrated a high prevalence of aerolysin and serine protease genes among A. hydrophila and A. veronii isolates, a genetic profile which corresponded with pathogenic phenotypes. Together, our findings demonstrate increased antibiotic resistance among potentially pathogenic strains of aeromonads, illustrating an emerging potential health concern.

Reclassification of Aeromonas hydrophila subsp. dhakensis Huys et al. 2002 and Aeromonas aquariorum Martínez-Murcia et al. 2008 as Aeromonas dhakensis sp. nov. comb nov. and emendation of the species Aeromonas hydrophila.

Previous studies indicate that Aeromonas aquariorum and Aeromonas hydrophila subsp. dhakensis are the same taxon and suggest that they should be synonymized. Using a polyphasic approach, the phenotypic and phylogenetic relationship of A. aquariorum with the 3 defined A. hydrophila subspecies (i.e. dhakensis, hydrophila, ranae) was investigated. Phylogenetic trees derived from the 16S rRNA, rpoD or gyrB genes and a multilocus phylogenetic analysis (with the concatenated sequences of gyrB, rpoD, recA, dnaJ and gyrA) confirmed that both A. aquariorum and A. hydrophila subsp. dhakensis are a unique taxon, different from the other A. hydrophila subspecies, corroborating the phenotypic and DNA-DNA hybridization (DDH) results. A formal synonymization of A. aquariorum and A. hydrophila subsp. dhakensis and a reclassification of both as Aeromonas dhakensis sp. nov. comb nov. is therefore proposed.

Biliary tract infections caused by Aeromonas species.

This study investigated the clinical and microbiological characteristics of patients with Aeromonas infections of the biliary tract. Patients with bile cultures positive for Aeromonas species during the period July 2004 to December 2011 were identified from a computerized database of a hospital in Taiwan. Patients with Aeromonas infections of the biliary tract were further identified. During the study period, a total of 1,142 isolates of Aeromonas species were obtained from 750 patients. Of those patients, 91 (12.1 %) had Aeromonas infections of the biliary tract. The annual incidence (episodes per 10,000 patient-days) of biliary tract infections caused by all Aeromonas species was 0.31 in 2007, 0.12 in 2010, and 0.27 in 2011. A. hydrophila was the most common species isolated (n = 41, 45.1 %), followed by A. caviae (n = 30, 33.0 %), A. veronii biovar sobria (n = 15, 16.5 %), and A. veronii biovar veronii (n = 5, 5.5 %). The majority of patients (n = 77, 84.6 %) had polymicrobial infections. Hepatobiliary stones (n = 50, 54.9 %) and hepatobiliary cancer (n = 38, 41.8 %) were the most common underlying diseases, followed by diabetes mellitus (n = 29, 31.9 %) and liver cirrhosis (n = 7, 7.7 %). The in-hospital mortality rate was 8.8 %. Infection-related mortality was associated with underlying immunocompromised condition (p = 0.044) and use of mechanical ventilation (p = 0.004), but was not associated with inappropriate antibiotic usage or concomitant bacteremia (n = 8, 8.8 %). In conclusion, biliary tract infections caused by Aeromonas species are not uncommon and can develop in both immunocompromised and immunocompetent patients; however, patients with underlying hepatobiliary diseases are particularly susceptible to these infections.

Aeromonas cavernicola sp. nov., isolated from fresh water of a brook in a cavern.

Aeromonas P2973 was isolated from the water of a brook in a cavern in the Czech Republic. This isolate could not be biochemically identified at the species level, considering all updated species descriptions. Subsequent extensive phenotypic characterisation, DNA-DNA hybridisation, 16S rRNA gene sequencing and a Multi-Locus Phylogenetic Analysis (MLPA) of the concatenated sequence of 7 housekeeping genes (gyrB, rpoD, recA, dnaJ, gyrA, dnaX and atpD; 4705 bp) was employed in an attempt to ascertain the taxonomy of this isolate. Based on this polyphasic approach, we describe a novel species of the genus Aeromonas, for which the name Aeromonas cavernicola sp. nov. is proposed, with strain CCM7641(T) (DSM24474(T), CECT7862(T)) as the type strain.

Characterization of Aeromonas strains isolated from Indian foods using rpoD gene sequencing and whole cell protein analysis.

Aeromonas are responsible for causing gastroenteritis and extra-intestinal infections in humans. Twenty-two Aeromonas strains isolated from different food sources were re-identified up to species level using rpoD gene sequence analysis. Biochemical tests and 16S rRNA gene sequencing were insufficient to identify Aeromonas till species level. However, incorporation of additional biochemical tests lead to correct identification of 95.5 % strains up to species level. The 16S rRNA gene sequencing was useful to identify Aeromonas isolates at the genus level only. Sequences of the rpoD gene showed greater discriminatory power than 16S rRNA gene and provided conclusive discrimination of the strains for which the phenotypic species identification was uncertain. All these 22 strains were accurately identified up to species level by rpoD gene as A. salmonicida (6), A. veronii bv. veronii (4), A. caviae (3), A. hydrophila (2), A. veronii bv. sobria (2), A. jandaei (1), A. trota (1), A. sobria (1), A. allosaccharophila (1) and A. bivalvium (1). All these strains were also characterized using whole cell protein (WCP) analysis by gradient SDS-PAGE and showed different whole cell protein (WCP) profile [22-28 polypeptide bands (~10 to >97 kDa)], indicating high genetic diversity. The present work emphasizes the use of molecular methods such as rpoD gene sequencing along with comprehensive biochemical tests for the rapid and accurate identification of Aeromonas isolates till species level. The WCP profile can be subsequently used to characterize Aeromonas isolates below species level.

Aeromonas aquariorum septicemia and enterocolitis in a cirrhotic patient.

Aeromonas aquariorum is a recently described Aeromonas species. We present a cirrhotic patient with septicemia and bloody diarrhea in whom A. aquariorum was isolated from the blood and stool. The species identification was based on sequence analysis of the partial rpoB and rpoD genes. The A. aquariorum isolates carried genes encoding hemolysin, aerolysin, and the cytotonic enterotoxin Alt. Significant A. aquariorum-induced cytotoxicity in intestinal epithelial cells was also demonstrated.

Aeromonas spp asociada a enfermedad diarreica aguda en Cuba: estudios de casos y controles / Aeromonas spp asociated to acute diarrheic disease in Cuba: case-control study

The members of the genus Aeromonas are currently considered important gastrointestinal pathogens in different geographical areas. From February 1985 to January 2005 several case-control studies were coordinated by the National Reference Laboratory for Diarrheal Diseases from the Pedro Kouri Institute. The study purpose was to analyze a possible pathogenic role for Aeromonas spp in Cuban children with acute diarrhea. In that period 2,322 children less than 5 years old with acute diarrhea were studied for diarhoeal pathogens and another group of 2,072 non hospitalized children without diarrhea during the similar time from the same geographical areas and matched by ages were recruited. In the group of children with diarrheas (cases), Aeromonas spp. was isolated in 166 (7.15%) and in the control group the microorganism was found in only 35 (1.76%). When Aeromonas isolation rates were compared between both groups, we found that probability to isolate this specie was significantly higher in cases than in controls (OR = 4.48, 95% IC: 3.05-6.60; P < 0.001). The Aeromonas species more frequently isolated were A. caviae, A. hydrophila, and A. veronii bv sobria. Other enteric pathogens detected in children with diarrhea were: Shigella spp in 418 (18%) (P < 0.0001), Salmonella spp in 53 (2.3%) (P < 0.01), and enteropathogenic E. coli in 58 (2.49%) (P < 0.05).

Los miembros del género Aeromonas son considerados patógenos importantes del tracto gastrointestinal en diferentes áreas geográficas. De febrero de 1985 a enero de 2005 se realizaron estudios de casos y controles en el Laboratorio Nacional de Referencia de Enfermedades Diarreicas Agudas del Instituto Pedro Kourí con el objetivo de conocer el comportamiento de los microorganismos pertenecientes al género Aeromonas en niños con diarreas en Cuba. La muestra estuvo constituida por 2.322 niños bajo 5 años de edad, ingresados por enfermedad diarreica aguda y como grupo control se estudió un total de 2.072 niños con edades y áreas geográficas similares que acudieron a los hospitales correspondientes en ese mismo período de tiempo. En el grupo de niños que presentaron diarreas, Aeromonas spp fue aislada en 166 (7,15%), y en los controles fue encontrada en 35 (1,76%). Al comparar la positividad para Aeromonas entre ambos grupos, la probabilidad de diagnosticar este microorganismo fue 4,28 veces mayor en los casos que en los controles (OR = 4,28; IC al 95%: 2,96-6,20; P < 0,001). Las especies más frecuentemente aisladas fueron A. caviae, A. hydrophila, y A. veronii bv sobria. Otros enteropatógenos aislados en niños que presentaban diarrea fueron: Shigella spp. en 418 (18%) (P < 0,0001, Salmonella spp en 53 (2,3%) (P < 0,01),) y E. coli enteropatógena en 58 (2,49%) (P < 0,05).

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.

Caracterización fenotípica de cepas de Aeromonas aisladas de pacientes con enfermedad diarreica aguda / Phenotypic characterization of Aeromonas isolated from patients with acute diarrheal diseases

INTRODUCCIÓN: las enfermedades diarreicas agudas constituyen una de las principales causas de morbilidad y mortalidad en los niños menores de 5 años y en la población general, esto ocasiona una gran demanda de atención en los servicios de salud. La situación se agrava por el abuso de los antimicrobianos y el desarrollo de resistencia bacteriana, suceso que hoy día constituye un problema emergente de salud en diversas regiones del mundo. Entre los microorganismos causantes de enfermedades diarreicas agudas se encuentran los pertenecientes al género Aeromonas, los cuales han sido reconocidos como patógenos emergentes de riesgo II. OBJETIVOS: determinar las especies de Aeromonas más frecuentemente aisladas a partir de muestras de heces de pacientes con enfermedades diarreicas agudas y su susceptibilidad antimicrobiana. MÉTODOS: se determinó la susceptibilidad mediante el método de Bauer-Kirby frente a diferentes antimicrobianos a 100 aislamientos remitidos desde los centros provinciales de higiene y epidemiología del país durante 2007-2008. RESULTADOS: En 67 por ciento de los aislamientos se logró la identificación hasta especie, se observó el predominio de A. caviae (33 por ciento) y A. hydrophila (29 por ciento). Se demostró que 100 por ciento de los aislamientos resultaron resistentes al menos a un antimicrobiano de los investigados. El porcentaje más elevado de resistencia se observó frente a la cefalotina, las sulfonamidas y el ácido nalidíxico. CONCLUSIONES: se propone a la tetraciclina y el cloranfenicol como fármacos de elección para el tratamiento de las infecciones intestinales producidas por estos microorganismos en Cuba.

INTRODUCTION: the acute diarrheal diseases are one of the main causes of morbidity and mortality in children aged under 5 years and in the general population; this demands a great deal of care in the healthcare services. The situation worsens due to the overuse of antimicrobials and the development of bacterial resistance, being the latter an emerging health problem in different areas of the world. Among the causative microorganisms of acute diarrheal diseases are those of Aeromonas genus, recognized as second risk emerging pathogens. OBJECTIVES: to determine the most frequently isolated Aeromonas species in fecal samples from acute diarrheal patients and their antimicrobial susceptibility. METHODS: the Bauer-Kirby´s method allowed identifying the susceptibility to several antimicrobials of 100 isolated samples coming from the provincial hygiene and epidemiology centers during 2007 and 2008. RESULTS: identification of the species was accomplished in 67 percent of isolates, being A. caviae (33 percent) y A. hydrophila (29 percent) the predominant species. It was demonstrated that 100 percent of isolates got resistant to at least one of the studied antimicrobials. Drug resistance to cefalotine, sulfonamides and nalidixic acid showed the highest percentages. CONCLUSIONS: tetracycline and chloramphenicol are recommended as the drugs of choice for treating intestinal infections caused by these microorganisms in Cuba.