Cystitis caused by Aeromonas caviae

Multidrug-resistant aeromonas caviae causing cystitis in a renal failure patient

A 49-year-old female with multiple myeloma complicated by renal failure had dysuria. The urine culture revealed multidrug-resistant aeromonas caviae during her hospital stay. Her symptoms and signs significantly improved after receiving a seven-day course of piperacillin-tazobactam treatment. She had no history of urinary tract infections(UTIs). On follow-up, she felt clinically well. Aeromonas caviae is a rare cause of UTI. We review previous cases of aeromonas caviae UTIs. The purpose of this case report is to assist in the diagnosis and management of aeromonas caviae cystitis.

Plasmid-Mediated Fluoroquinolone Resistance Genes in Quinolone-Susceptible Aeromonas spp. Phenotypes Isolated From Recreational Surface Freshwater Reservoir

Aeromonas spp. are recognized as opportunistic pathogens causing diseases. Infections in humans can result mainly in gastrointestinal and wound diseases with or without progression to septicemia. Although Aeromonas spp. are not known uropathogens and they rarely cause urinary tract infection, we hypothesize that the presence of these bacteria in the water and the contact during, e.g., recreational and bathing activity can create the conditions for the colonization of the human body and may result to diseases in various locations, including the urinary tract. Our study presents the occurrence of aeromonad fluoroquinolone-susceptible phenotypes with the presence of plasmid-mediated fluoroquinolone resistance (PMQR) genes in a natural freshwater reservoir occasionally used for recreational activities. Sixty-nine isolates collected during the bathing period were identified by mass spectrometry and screened for the presence of fluoroquinolone-resistant phenotypes and genotypes. Fluoroquinolone susceptibility was determined as minimal inhibitory concentration values. PMQR qnr genes were detected by PCR. Isolates comprising eight species, namely, mainly Aeromonas veronii (50.7% isolates) and Aeromonas media (24.6% isolates) and rarely Aeromonas eucrenophila, Aeromonas caviae, Aeromonas bestiarum, Aeromonas ichthiosmia, and Aeromonas hydrophila, were selected. All isolates were phenotypically susceptible either to ciprofloxacin or levofloxacin. Unexpectedly, at least one to three of the PMQR genes were detected in 42.0% of the fluoroquinolone-susceptible Aeromonas spp. phenotypes. Mainly the qnrS (34.8% isolates) and qnrA (14.5% isolates) determinants were detected. In conclusion, the freshwater reservoir occasionally used for bathing was tainted with aeromonads, with a high occurrence of opportunistic pathogens such as A. veronii and A. media. MALDI‐TOF MS is a powerful technique for aeromonad identification. Our data reveals the mismatch phenomenon between fluoroquinolone-susceptible aeromonad phenotypes and the presence of plasmid-mediated qnr resistance genes. It suggests that phenotypically susceptible bacteria might be a potential source for the storage and transmission of these genes. The exposure during, e.g., a recreational activity may create the potential risk for causing infections, both diagnostically and therapeutically difficult, after expressing the resistance genes and quinolone-resistant strain selection.

Microbial community origin and fate through a rural wastewater treatment plant

Conventional wastewater treatment relies on a complex microbiota; however, much of this community is still to be characterised. To better understand the origin, dynamics and fate of bacteria within a wastewater treatment plant: untreated primary wastewater, activated sludge, and post-treatment effluent were characterised. From 3,163 Exact Sequence Variants (ESVs), 860 were annotated to species-level. In primary wastewater, 28% of ESVs were putative bacterial species previously associated with humans, 14% with animals and 5% as common to the environment. Differential abundance analysis revealed significant relative reductions in ESVs from potentially humans-associated species from primary wastewater to activated sludge, and significant increases in ESVs from species associated with nutrient cycling. Between primary wastewater and effluent, 51% of ESVs from human-associated species did not significantly differ, and species such as Bacteroides massiliensis and Bacteroides dorei increased. These findings illustrate that activated sludge increased extracellular protease and urease-producing species, ammonia and nitrite oxidizers, denitrifiers and specific phosphorus accumulators. Although many human-associated species declined, some persisted in effluent, including strains of potential health or environmental concern. Species-level microbial assessment may be useful for understanding variation in wastewater treatment efficiency as well as for monitoring the release of microbes into surface water and the wider ecosystem. This article is protected by copyright. All rights reserved.

Infections caused by Aeromonas species in hospitalized patients: A case series

The Aeromonads are ubiquitous Gram-negative bacilli that cause community acquired, and healthcare associated infections. In this retrospective study we analysed clinical and microbiological characteristics of thirty-six culture proven Aeromonas infections. The most common species isolated was A.hydrophila. Clinical presentation included syndromes like skin and soft tissue infections (SSTI), urinary tract infections, and central line associated bloodstream infections (CLABSI). Most of the isolates were sensitive to aminoglycosides [97.2%], followed by 3 rd generation cephalosporins, quinolones and carbapenems. Overall mortality was 13.88% (5 out of 36 patients). A high index of suspicion is required for diagnosis and better outcomes.

Urinary tract infection due to Aeromonas species: An uncommon causative agent

BACKGROUND

Members of the genus Aeromonas are Gram-negative bacilli, belonging to family Aeromonadaceae, and are widely found in various aquatic environments. The most common species associated with human infections are A. hydrophila, A. caviae, and A. veronii biovar sobria. Aeromonas species are recognized as emerging opportunistic pathogens in humans mainly causing gastrointestinal infections and wound infections with or without progression to septicaemia. Aeromonas organisms rarely cause urinary tract infection (UTI) and are not known uropathogens.

CASE

We report a series of UTI due to Aeromonas species in three adult patients, specifically identified as A. veronii biovar sobria in two patients and A. hydrophila in one patient. Two patients had history of occupational exposure to aquatic environment.

CONCLUSIONS

The cases highlight another expanded range of infections caused by Aeromonas spp. that can be encountered in a community setting and indicate that infections with Aeromonas spp. should be kept in mind while investigating for the etiology of UTI, especially in adult patients with occupational exposure to aquatic ecosystems.

An Update on the Genus Aeromonas: Taxonomy, Epidemiology, and Pathogenicity

The genus Aeromonas belongs to the Aeromonadaceae family and comprises a group of Gram-negative bacteria widely distributed in aquatic environments, with some species able to cause disease in humans, fish, and other aquatic animals. However, bacteria of this genus are isolated from many other habitats, environments, and food products. The taxonomy of this genus is complex when phenotypic identification methods are used because such methods might not correctly identify all the species. On the other hand, molecular methods have proven very reliable, such as using the sequences of concatenated housekeeping genes like gyrB and rpoD or comparing the genomes with the type strains using a genomic index, such as the average nucleotide identity (ANI) or in silico DNA–DNA hybridization (isDDH). So far, 36 species have been described in the genus Aeromonas of which at least 19 are considered emerging pathogens to humans, causing a broad spectrum of infections. Having said that, when classifying 1852 strains that have been reported in various recent clinical cases, 95.4% were identified as only four species: Aeromonas caviae (37.26%), Aeromonas dhakensis (23.49%), Aeromonas veronii (21.54%), and Aeromonas hydrophila (13.07%). Since aeromonads were first associated with human disease, gastroenteritis, bacteremia, and wound infections have dominated. The literature shows that the pathogenic potential of Aeromonas is considered multifactorial and the presence of several virulence factors allows these bacteria to adhere, invade, and destroy the host cells, overcoming the immune host response. Based on current information about the ecology, epidemiology, and pathogenicity of the genus Aeromonas, we should assume that the infections these bacteria produce will remain a great health problem in the future. The ubiquitous distribution of these bacteria and the increasing elderly population, to whom these bacteria are an opportunistic pathogen, will facilitate this problem. In addition, using data from outbreak studies, it has been recognized that in cases of diarrhea, the infective dose of Aeromonas is relatively low. These poorly known bacteria should therefore be considered similarly as enteropathogens like Salmonella and Campylobacter.

Microbiological quality of trahira fish (Hoplias malabaricus) from Baixada Maranhense, municipality of São Bento, MA

ABSTRACT: Fish are considered rich sources of nutrients. Health care throughout its production chain aims to ensure quality, minimizing the risks of transmission of foodborne diseases. In order to evaluate the microbiological quality of trahira fish (H. malabaricus), 40 samples were analysed for Most Probable Number (MPN) of coliforms at 45ºC, counts of aerobic mesophilic bacteria and Staphylococcus spp., identification of E. coli, Salmonella spp. and Aeromonas spp.. Analyses were conducted according to official methods, procedures, and recommendations. Microbiological results showed coliform values at 45 °C ranging from <3 to > 1.1 × 103 MPN/g, presence of E. coli in 14 (35%) samples, counts of mesophilic aerobic bacteria from 9 × 102 to 109 CFU/g and absence of coagulase positive Staphylococcus aureus. Salmonella spp. was detected in 2 (5%) samples, which is in disagreement with the standards required by the RDC Nº 12 of January, 2001 (ANVISA) regarding Aeromonas spp. In total, 36 (90%) samples were contaminated, 7 (19.4%) by A. cavie and 29 (80.6%) by A. hidrophila. The results of this research showed unsatisfactory hygienic and sanitary conditions of fish from the municipality of São Bento (MA), exposing consumers to the risk of foodborne diseases.

Collection of mullet fish (Mugil cephalus) from west coast of India: evaluation of its quality with relation to food safety

The present study focuses on bacterial and selected heavy metal contaminations of economically important mullet fish (Mugil cephalus) collected from West coast of Gujarat, India. Molecular identification using 16S rRNA sequencing revealed the presence of Aeromonas veronii, A. mollusorum, A. cavae, A. bivalvum, and V.alginolyticus in the gill and the intestine along with some other non-pathogenic bacteria. Pathogenicity of different Aeromonas species was confirmed by hemolysin assay. Apart from pathogenicity, multidrug resistance pattern was also reported against some commonly used antibiotics. Heavy metal analysis of different parts such as ventral and dorsal muscles as well as gills of M. cephalus revealed maximum concentration of Pb (24.08 ± 4.40 mg/kg), Cd (8.25 ± 3.04 mg/kg), and Cu (33.67 ± 5.34 mg/kg), which were higher than the permissible limit. To the best of our knowledge, this is the first study analyzing different heavy metals and associated bacteria in M. cephalus fish in India. Further, the distribution of heavy metals in M. cephalus fish from other countries was also compared.

Aeromonas in Arab countries: 1995-2014

The aim of this review is to provide information on the prevalence, clinical syndromes, and antimicrobial resistance and therapy of Aeromonas spp. infections in Arab countries. The data were obtained by an English language literature search from 1995 to 2014 of Medline and PubMed for papers using the search terms "Aeromonas+name of Arab country (i.e. Algeria, Egypt, etc.)". Additional data were obtained from a Google search using the aforementioned terms. The organisms have been reported from diarrheal children, patients with cholera-like diarrhea, an outbreak of acute gastroenteritis and from different types of animals, foods and water source in several Arab countries in the Middle East and North Africa with predominance of A. hydrophila, A. caviae and A. sobria. Using molecular techniques few studies reported genes encoding several toxins from aeromonads isolated from different sources. Among the antimicrobials examined in the present review third generation cephalosporins, fluoroquinolones and aminoglycosides showed excellent activity and can be employed in the treatment of Aeromonas-associated human infections in Arabic countries. Whenever possible, treatment should be guided by the susceptibility testing results of the isolated organism. In the future, studies employing molecular testing methods are required to provide data on circulating genospecies and their modes of transmission in the community, and on their mechanisms of resistance to antimicrobials. Microbiology laboratories and research centers are encouraged to look for these organisms in clinical, food and water sources to attain a better understanding of the public health risks from these organisms in Arab countries.

Insight into the mobilome of Aeromonas strains

The mobilome is a pool of genes located within mobile genetic elements (MGE), such as plasmids, IS elements, transposons, genomic/pathogenicity islands, and integron-associated gene cassettes. These genes are often referred to as “flexible” and may encode virulence factors, toxic compounds as well as resistance to antibiotics. The phenomenon of MGE transfer between bacteria, known as horizontal gene transfer (HGT), is well documented. The genes present on MGE are subject to continuous processes of evolution and environmental changes, largely induced or significantly accelerated by man. For bacteria, the only chance of survival in an environment contaminated with toxic chemicals, heavy metals and antibiotics is the acquisition of genes providing the ability to survive in such conditions. The process of acquiring and spreading antibiotic resistance genes (ARG) is of particular significance, as it is important for the health of humans and animals. Therefore, it is important to thoroughly study the mobilome of Aeromonas spp. that is widely distributed in various environments, causing many diseases in fishes and humans. This review discusses the recently published information on MGE prevalent in Aeromonas spp. with special emphasis on plasmids belonging to different incompatibility groups, i.e., IncA/C, IncU, IncQ, IncF, IncI, and ColE-type. The vast majority of plasmids carry a number of different transposons (Tn3, Tn21, Tn1213, Tn1721, Tn4401), the 1st, 2nd, or 3rd class of integrons, IS elements (e.g., IS26, ISPa12, ISPa13, ISKpn8, ISKpn6) and encode determinants such as antibiotic and mercury resistance genes, as well as virulence factors. Although the actual role of Aeromonas spp. as a human pathogen remains controversial, species of this genus may pose a serious risk to human health. This is due to the considerable potential of their mobilome, particularly in terms of antibiotic resistance and the possibility of the horizontal transfer of resistance genes.

Ocorrência de Aeromonas spp. em alimentos de origem animal e sua importância em saúde pública

Aeromonas spp. são bactérias Gram negativas, opor-tunistas, de natureza ubíqua, isoladas principalmente de amostras de água. Até o presente momento foram reconhecidas 31 espé-cies, sendo as de maior importância médica Aeromonas hydrophila, Aeromonas caviae e Aeromonas veronii. A patogenicidade do gênero é considerada multifatorial, sendo este produtor de diversos tipos de toxinas e com envolvimento de outros fatores capazes de facilitar a penetração e o estabelecimento do agente no hospedeiro, causando doença. O objetivo desta revisão é elucidar o papel dos alimentos de origem animal como fontes de contaminação de bactérias do gênero Aeromonas para o ser humano. Isolamentos de aeromonas de diversos produtos de origem animal têm sido relatados, como carne, leite e seus derivados, além de frutos do mar, e em ambientes de processamento, como abatedouros, frigorífcos e laticínios. Tem-se buscado determinar fontes de contaminação dos alimentos, e a água foi definida como o principal disseminador. Aeromonas já foi defnida como sendo a causadora de diversas enfermidades, desde afecções gastrointestinais até casos de meningite e morte. Considerando os alimentos de origem animal como importantes veículos de transmissão para o ser humano e o reconhecimento da água como fonte de disseminação do agente, torna-se imprescindível o tratamento adequado da água utilizada nos estabelecimentos processadores de alimentos para a segurança alimentar.

Quorum sensing activity of Aeromonas caviae strain YL12, a bacterium isolated from compost

Quorum sensing is a well-studied cell-to-cell communication method that involves a cell-density dependent regulation of genes expression mediated by signalling molecules. In this study, a bacterium isolated from a plant material compost pile was found to possess quorum sensing activity based on bioassay screening. Isolate YL12 was identified using matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry and molecular typing using rpoD gene which identified the isolate as Aeromonas caviae. High resolution tandem mass spectrometry was subsequently employed to identify the N-acyl homoserine lactone profile of Aeromonas caviae YL12 and confirmed that this isolate produced two short chain N-acyl homoserine lactones, namely C4-HSL and C6, and the production was observed to be cell density-dependent. Using the thin layer chromatography (TLC) bioassay, both AHLs were found to activate C. violaceum CV026, whereas only C6-HSL was revealed to induce bioluminescence expression of E. coli [pSB401]. The data presented in this study will be the leading steps in understanding the role of quorum sensing in Aeromonas caviae strain YL12.

Aeromonas spp. clinical microbiology and disease

Members of the genus Aeromonas inhabit various aquatic environments and are responsible for, and are implicated in, a number of intestinal and extra-intestinal infections in humans as well as other animals. This review focuses on invasive human infection and disease and summarizes available findings regarding the microbiology and detection of Aeromonas spp., with emphasis on successful identification and diagnosis, and the control of disease in the population. Antimicrobial resistance and therapy of Aeromonas spp. is also discussed.

Emergence of CTX-M-3, TEM-1 and a new plasmid-mediated MOX-4 AmpC in a multiresistant Aeromonas caviae isolate from a patient with pneumonia

Aeromonas species rarely cause pulmonary infection. We report, for what is believed to be the first time, a case of severe pneumonia in a cancer patient caused by Aeromonas caviae. Detailed microbiological investigation revealed that this isolate carried three beta-lactamase-encoding genes (encoding MOX-4, CTX-M-3 and TEM-1) conferring resistance to all beta-lactams but imipenem. The beta-lactamase with a pI of 9.0 was transferred by conjugation and associated with a 7.3 kb plasmid, as demonstrated by Southern blot hybridization. Analysis of the nucleotide and amino acid sequences showed a new ampC gene that was closely related to those encoding the MOX-1, MOX-2 and MOX-3 beta-lactamases. This new plasmid-mediated AmpC beta-lactamase from China was named MOX-4. This is believed to be the first report of MOX-4, CTX-M-3 and TEM-1 beta-lactamases in a multiresistant A. caviae.

The genus Aeromonas: taxonomy, pathogenicity, and infection

Over the past decade, the genus Aeromonas has undergone a number of significant changes of practical importance to clinical microbiologists and scientists alike. In parallel with the molecular revolution in microbiology, several new species have been identified on a phylogenetic basis, and the genome of the type species, A. hydrophila ATCC 7966, has been sequenced. In addition to established disease associations, Aeromonas has been shown to be a significant cause of infections associated with natural disasters (hurricanes, tsunamis, and earthquakes) and has been linked to emerging or new illnesses, including near-drowning events, prostatitis, and hemolytic-uremic syndrome. Despite these achievements, issues still remain regarding the role that Aeromonas plays in bacterial gastroenteritis, the extent to which species identification should be attempted in the clinical laboratory, and laboratory reporting of test results from contaminated body sites containing aeromonads. This article provides an extensive review of these topics, in addition to others, such as taxonomic issues, microbial pathogenicity, and antimicrobial resistance markers.

The genus Aeromonas: taxonomy, pathogenicity, and infection

Over the past decade, the genus Aeromonas has undergone a number of significant changes of practical importance to clinical microbiologists and scientists alike. In parallel with the molecular revolution in microbiology, several new species have been identified on a phylogenetic basis, and the genome of the type species, A. hydrophila ATCC 7966, has been sequenced. In addition to established disease associations, Aeromonas has been shown to be a significant cause of infections associated with natural disasters (hurricanes, tsunamis, and earthquakes) and has been linked to emerging or new illnesses, including near-drowning events, prostatitis, and hemolytic-uremic syndrome. Despite these achievements, issues still remain regarding the role that Aeromonas plays in bacterial gastroenteritis, the extent to which species identification should be attempted in the clinical laboratory, and laboratory reporting of test results from contaminated body sites containing aeromonads. This article provides an extensive review of these topics, in addition to others, such as taxonomic issues, microbial pathogenicity, and antimicrobial resistance markers.

Clinical relevance of the recently described species Aeromonas aquariorum

Twenty-two human extraintestinal isolates (11 from blood) and three isolates recovered from patients with diarrhea were genetically characterized as Aeromonas aquariorum, a novel species known only from ornamental fish. The isolates proved to bear a considerable number of virulence genes, and all were resistant to amoxicillin (amoxicilline), cephalothin (cefalotin), and cefoxitin. Biochemical differentiation from the most relevant clinical species is provided.

High frequency of hemolytic and cytotoxic activity in Aeromonas spp. isolated from clinical, food and environmental in Rio de Janeiro, Brazil

Molecular study of aerolysin and cytotonic enterotoxin genes by PCR and colony blot hybridization was performed in 117 strains of Aeromonas spp. isolated from different sources. Homogeneous distribution of these genes in A. hydrophila complex strains was observed. For A. caviae and A. sobria complex strains, aerolysin genes were more frequent than cytotonic enterotoxins genes. Of 64 A. caviae complex strains, only one (1.5%) amplified the 451 bp product for the aer gene, however, the same primers detected a 400 bp product in 50 (78%) strains. This product was sequenced and had two short regions with homology to several hemolysin genes. The genotype aer (+)/aerA(+)/hly (+)/ast (+)/alt (+) was detected in six A. hydrophila strains from food and environmental source. The most common genotype found in A. hydrophila strains was hly (+) (85%) and aerA(+) (78.7%), while in A. caviae complex strains was aerA(+) (32.8%). All A. veronii complex sobria strains were aer (+)/aerA(+). All A. caviae and A. hydrophila were positive when tested with aer probe using the colony blot test. Thirty-seven percent of A. hydrophila and 53% of A. caviae tested were positive for ast probe. Eighty-nine percent of samples were cytotoxic in Vero cells. Our data demonstrated that Aeromonas spp. can harbor and express virulence genes and reinforce the potential of Aeromonas as a human pathogen.

Lectin-binding properties of Aeromonas caviae strains

The cell surface carbohydrates of four strains of Aeromonas caviae were analyzed by agglutination and lectin-binding assays employing twenty highly purified lectins encompassing all sugar specificities. With the exception of L-fucose and sialic acid, the sugar residues were detected in A. caviae strains. A marked difference, however, in the pattern of cell surface carbohydrates in different A. caviae isolates was observed. Specific receptors for Tritricum vulgaris (WGA), Lycopersicon esculentum (LEL) and Solanum tuberosum (STA) (D-GlcNAc-binding lectins) were found only in ATCC 15468 strain, whereas Euonymus europaeus (EEL, D-Gal-binding lectin) sites were present exclusively in AeQ32 strain, those for Helix pomatia (HPA, D-GalNAc-binding lectin) in AeC398 and AeV11 strains, and for Canavalia ensiformes (Con A, D-Man-binding lectin) in ATCC 15468, AeC398, AeQ32 and AeV11 strains, after bacterial growing at 37°C. On the other hand, specific receptors for WGA and EEL were completely abrogated growing the bacteria at 22°C. Binding studies with (125)I- labeled lectins from WGA, EEL and Con A were performed. These assays essentially confirmed the selectivity, demonstrated in the agglutination assays of these lectins for the A. caviae strains.