Aeromonas infection in acute suppurative cholangitis: review of 30 cases

Good Performance of Revised Scoring Systems in Predicting Clinical Outcomes of Aeromonas Bacteremia in the Emergency Department: A Retrospective Observational Study

BACKGROUND

Aeromonas species, Gram-negative, non-sporulating, facultative, and anaerobic bacilli, widely distributed in aquatic environments, derive various infections, including bacteremia. Most of these infections were opportunistic and found in patients with predisposing conditions. Among the infections, bacteremia remains with notable mortality, reported from 15% to 45%. However, predicting systems for assessing the mortality risk of this disease have yet to be investigated. We aimed to validate the performance of specific predictive scoring systems to assess the clinical outcomes of Aeromonas bacteremia and applied the revised systems to predict mortality risk.

METHODS

A retrospective observational study reviewed patients with bacteremia caused by Aeromonas spp. based on at least one positive blood culture sample collected in the emergency department from January 2012 to December 2020. The outcome was in-hospital mortality. We used seven predictive scoring systems to predict the clinical outcome. According to the effectiveness in predicting mortality, we revised three of the seven predictive scoring systems by specific characteristics to refine their risk-predicting performances.

RESULTS

We enrolled 165 patients with bacteremia caused by Aeromonas spp., including 121 males (73.3%) and 44 females (26.7%), with a mean age of 66.1 ± 14.9 years and an average length of hospital stay of 12.4 ± 10.9 days. The overall mortality rate was 32.7% (54/165). The non-survivors had significantly higher scores in MEDS (6.7 ± 4.2 vs. 12.2 ± 3.3, p < 0.001), NEWS (4.0 ± 2.8 vs. 5.3 ± 3.0, p = 0.008), and qSOFA (0.3 ± 0.6 vs. 0.6 ± 0.7, p = 0.007). Regarding mortality risk prediction, the MEDS demonstrated the best predictive power with AUC of ROC measured up to 0.834, followed by NEWS (0.626) and qSOFA (0.608). We revised the MEDS, NEWS, and qSOFA by hemoglobin and lactate. We found that the revised scores had better powerful performance, including 0.859, 0.767, and 0.691 of the AUC of ROC, if the revised MEDS ≥10, revised NEWS ≥8, and revised qSOFA ≥2, respectively.

CONCLUSIONS

MEDS, NEWS, and qSOFA were good tools for predicting outcomes in patients with Aeromonas spp. bacteremia. The revised MEDS, NEWS, and qSOFA demonstrated more powerful predicting performance than the original scoring systems. We suggested that patients with higher scores in revised MEDS (≥10), revised NEWS (≥8), and revised qSOFA (≥2) received early goal-directed therapy and appropriate broad-spectrum antibiotic treatment as early as possible to reduce mortality.

Enteric Aeromonas Infection: a Common Enteric Bacterial Infection with a Novel Infection Pattern Detected in an Australian Population with Gastroenteritis

Aeromonas species are emerging human enteric pathogens. However, they are currently not routinely detected in many diagnostic laboratories, and information regarding Aeromonas enteric infections detected using molecular methods is lacking. Here, we investigated the detection of Aeromonas species and four other enteric bacterial pathogens in 341,330 fecal samples from patients with gastroenteritis processed in a large Australian diagnostic laboratory between 2015 and 2019. These enteric pathogens were detected using quantitative real-time PCR (qPCR) methods. Furthermore, we compared the qPCR cycle threshold (CT) values obtained from fecal samples that tested positive for Aeromonas only by molecular detection with those of samples that tested positive by both molecular detection and bacterial isolation methods. Aeromonas species were found to be the second most common bacterial enteric pathogens among patients with gastroenteritis. We observed a unique pattern of three infection peaks for Aeromonas, which correlated with the age of the patients. Aeromonas species were the most common enteric bacterial pathogens in children younger than 18 months. Fecal samples that tested positive for Aeromonas only by molecular detection had significantly higher CT values than fecal samples that tested positive by both molecular detection and bacterial culture. In conclusion, our findings reveal that Aeromonas enteric pathogens exhibit an age-related three-peak infection pattern, distinguishing them from other enteric bacterial pathogens. Moreover, the high rate of Aeromonas enteric infection discovered in this study suggests that Aeromonas species should be routinely tested in diagnostic laboratories. Our data also show that combining qPCR with bacterial culture can enhance the detection of enteric pathogens. IMPORTANCE Aeromonas species are emerging human enteric pathogens. However, these species are currently not routinely detected in many diagnostic laboratories, and no studies have reported the detection of Aeromonas enteric infection using molecular methods. We investigated the presence of Aeromonas species and four other enteric bacterial pathogens in 341,330 fecal samples from patients with gastroenteritis using quantitative real-time PCR (qPCR) methods. Interestingly, we discovered that Aeromonas species were the second most common bacterial enteric pathogens in patients with gastroenteritis, exhibiting a novel infection pattern compared to those of other enteric pathogens. Furthermore, we found that Aeromonas species were the most prevalent enteric bacterial pathogens in children aged 6 to 18 months. Our data also revealed that qPCR methods exhibit higher sensitivity in detecting enteric pathogens compared to that of bacterial culture alone. Moreover, combining qPCR with bacterial culture enhances the detection of enteric pathogens. These findings emphasize the importance of Aeromonas species in public health.

Aeromonas and Human Health Disorders: Clinical Approaches

The genus Aeromonas comprises more than 30 Gram-negative bacterial species and naturally inhabitants from aquatic environments. These microorganisms, commonly regarded as pathogens of fish and several other animals, have been gaining prominence on medical trial due to its ability to colonize and infect human beings. Besides water, Aeromonas are widely spreaded on most varied sources like soil, vegetables, and food; Although its opportunistic nature, they are able to cause infections on immunocompromised or immunocompetent patients. Aeromonas species regarded as potential human pathogens are usually A. hydrophila, A. caviae, and A. veronii biovar sobria. The main clinical manifestations are gastrointestinal tract disorders, wound, and soft tissue infections, as well as septicemia. Regarding to antibiotic responses, the bacteria present a diversified susceptibility profile and show inherence resistance to ampicillin. Aeromonas, as an ascending genus in microbiology, has been carefully studied aiming comprehension and development of methods for detection and medical intervention of infectious processes, not fully elucidated in medicine. This review focuses on current clinical knowledge related to human health disorders caused by Aeromonas to contribute on development of efficient approaches able to recognize and impair the pathological processes.

Microbiological analysis of patients with first and recurrent episodes of acute cholangitis in a middle-sized hospital: A single-center retrospective study in rural North Kyoto, Japan

BACKGROUND

Knowledge of the bacterial spectrum involved in acute cholangitis is essential for adequate empiric antibiotic treatment. There is a lack of published data comparative data between patients with first and recurrent episodes of acute cholangitis. This study aimed to analyze the microbial spectrum in patients with first and second episodes of acute cholangitis.

METHODS

We retrospectively assessed 251 patients with first episodes of acute cholangitis between January 2014 to September 2020.

RESULTS

At the first episode of acute cholangitis, the predominant strains belonged to Escherichia coli (17.9%), followed by Klebsiella spp. (15.5%), Enterobacter spp. (6.4%), and Enterococcus spp. (5.6%). During follow-up, acute cholangitis recurred in 109 patients; at the second episode, the predominant strains belonged to Enterococcus spp. (35.8%), followed by Klebsiella spp. (27.5%), Enterobacter spp. (22.9%), and Escherichia coli (15.6%). Enterococcus spp. were the most common pathogen in patients with second episode of acute cholangitis, regardless of whether the cholangitis was caused by a malignant tumor or a benign disease.

CONCLUSIONS

Unlike in patients with a first episode of acute cholangitis, clinicians should consider empirical treatment with anti-enterococcal antibiotics in patients with recurrent episodes of acute cholangitis.

The Isolation of Aeromonas Species and Other Common Enteric Bacterial Pathogens from Patients with Gastroenteritis in an Australian Population

Aeromonas species are emerging human enteric pathogens. However, systematic analysis of Aeromonas species infection in human gastroenteritis in comparison with other enteric bacterial pathogens in the Australian population is lacking. Here we analysed the isolation of Aeromonas species and other bacterial pathogens in five consecutive years (2015–2019) from 375,842 stool samples of patients with gastroenteritis in a large Australian diagnostic laboratory and identified a subset (48 isolates) of Aeromonas isolates to species level, using multilocus phylogenetic analysis. Aeromonas species were the third most common bacterial pathogens, following Campylobacter and Salmonella species. Aeromonas infection rate was significantly correlated with increasing age (p < 0.001). Aeromonas species were more often isolated in warm seasons and in males than females (p < 0.001). Five Aeromonas species were identified. Most of the infections were from three species, namely Aeromonas veronii (52%), Aeromonas caviae (27%) and Aeromonas hydrophila (12.5%). The majority of patients with Aeromonas species infection did not have a documented overseas travel history. The findings from this study support the importance of Aeromonas species in human gastroenteritis and suggest that the sources of Aeromonas infection in Australian patients should be further investigated.

The Great ESKAPE: Exploring the Crossroads of Bile and Antibiotic Resistance in Bacterial Pathogens

Throughout the course of infection, many pathogens encounter bactericidal conditions that threaten the viability of the bacteria and impede the establishment of infection. Bile is one of the most innately bactericidal compounds present in humans, functioning to reduce the bacterial burden in the gastrointestinal tract while also aiding in digestion. It is becoming increasingly apparent that pathogens successfully resist the bactericidal conditions of bile, including bacteria that do not normally cause gastrointestinal infections. This review highlights the ability of Enterococcus, Staphylococcus, Klebsiella, Acinetobacter, Pseudomonas, Enterobacter (ESKAPE), and other enteric pathogens to resist bile and how these interactions can impact the sensitivity of bacteria to various antimicrobial agents. Given that pathogen exposure to bile is an essential component to gastrointestinal transit that cannot be avoided, understanding how bile resistance mechanisms align with antimicrobial resistance is vital to our ability to develop new, successful therapeutics in an age of widespread and increasing antimicrobial resistance.

Bacteriological, Clinical and Virulence Aspects of Aeromonas-associated Diseases in Humans

Aeromonads have been isolated from varied environmental sources such as polluted and drinking water, as well as from tissues and body fluids of cold and warm-blooded animals. A phenotypically and genotypically heterogenous bacteria, aeromonads can be successfully identified by ribotyping and/or by analysing gyrB gene sequence, apart from classical biochemical characterization. Aeromonads are known to cause scepticemia in aquatic organisms, gastroenteritis and extraintestinal diseases such as scepticemia, skin, eye, wound and respiratory tract infections in humans. Several virulence and antibiotic resistance genes have been identified and isolated from this group, which if present in their mobile genetic elements, may be horizontally transferred to other naive environmental bacteria posing threat to the society. The extensive and indiscriminate use of antibiotics has given rise to many resistant varieties of bacteria. Multidrug resistance genes, such as NDM1, have been identified in this group of bacteria which is of serious health concern. Therefore, it is important to understand how antibiotic resistance develops and spreads in order to undertake preventive measures. It is also necessary to search and map putative virulence genes of Aeromonas for fighting the diseases caused by them. This review encompasses current knowledge of bacteriological, environmental, clinical and virulence aspects of the Aeromonas group and related diseases in humans and other animals of human concern.

Aeromonas veronii biovar veronii and sepsis-infrequent complication of biliary drainage placement: A case report

BACKGROUND

Aeromonas species are uncommon pathogens in biliary sepsis and cause substantial mortality in patients with impaired hepatobiliary function. Asia has the highest incidence of infection from Aeromonas, whereas cases in the west are rare.

CASE SUMMARY

We report the case of a 64-year-old woman with advanced pancreatic cancer and jaundice who manifested fever, abdominal pain, severe thrombocytopenia, anemia and kidney failure following the insertion of a percutaneous transhepatic biliary drainage. Blood culture results revealed the presence of Aeromonas veronii biovar veronii (A. veronii biovar veronii). After antibiotic therapy and transfusions, the life-threatening clinical conditions of the patient improved and she was discharged.

CONCLUSION

This was a rare case of infection, probably the first to be reported in West countries, caused by A. veronii biovar veronii following biliary drainage. A finding of Aeromonas must alert clinician to the possibility of severe sepsis.

Biliary tract infections and their Microbiological Spectrum- A study from coastal region of Southern India

Objective: Biliary tract infections include cholangitis and cholecystitis. They are associated with high morbidity and mortality in elderly patients with co-morbid disease. The present study was undertaken to determine the microbial aetiology causing biliary tract infections and also to study their antimicrobial resistance profile.Materials & methods: A retrospective study was conducted from January 2011 to December 2016 at the Enteric Diseases Division, Kasturba Medical College Hospital, Manipal. Patients with biliary tract infections admitted in tertiary referral health care hospital, Manipal were included for the study. Aerobic and anaerobic bacteriological and fungal aetiology of biliary tract infections were recorded along with their antimicrobial resistance profile.Results: Out of 307 bile samples sent for aerobic culture and susceptibly testing 187 (60.91%) were positive for culture, of which Escherichia coli (44.4%) was the predominant aetiology followed by Klebsiella pneumoniae (27.3%). Among the 14 samples sent for anaerobic culture, 5 (35.75%) specimens showed growth, of which Bacteroides fragilis group was found to be the predominant anaerobe. Among the 201 bacterial pathogens tested for their antimicrobial susceptibility, 108 (53.73%) isolates were resistant, out of which 9 were PDR Enterobacteriaceae with 12 ESBL strains. All the Candida species were susceptible to fluconazole with the exception of C. glabrata and C. krusei. All the anaerobic isolates were found to be susceptible to Metronidazole.Conclusions: The high rate of bacterial infection particularly gram-negative bacteria was recorded. It is necessary that antimicrobial therapy be initiated when culture or the clinical conditions reports caution. Routine aerobic and anaerobic culturing of bile samples with biliary tract infections are imperatively necessary. With the emergence of multidrug resistant pathogens and change in the microbiological spectrum of biliary tract infections, there is a need for the empirical antimicrobial therapy in every clinical setting.

Clinical significance and outcome of Aeromonas spp. infections among 204 adult patients

The objectives of this investigation were to analyze the clinical patterns, risk groups, prognostic factors, and mortality of infections caused by Aeromonas spp. This was a retrospective study of adult patients with Aeromonas spp. isolates attended at the Hospital del Mar in Barcelona, Spain, between January 2006 and December 2012. Epidemiological data, antimicrobial susceptibility, clinical patterns, underlying illnesses, type of infection, admission to the intensive care unit (ICU), number of episodes, coinfection, antimicrobial therapy, and evolution were analyzed. A total of 221 clinical samples from 204 patients were positive for Aeromonas spp. The mean age of the patients was 67.6 years. The main clinical form of presentation was gastrointestinal (78.4%). Malignancy was the main risk group in 69 (33.8%) patients, and 48 (23.5%) were previously healthy. Twenty-one patients (10.3%) were admitted to the ICU. Infections were acquired in the hospital in 52.5% of the patients, and 28.9% were polymicrobial. The overall mortality (after 1 year of follow-up from the first positive culture) was 26.5%. Univariate analysis identified an association between increased mortality and the following variables: age ≥80 years, hospitalization, admission to the ICU, malignancy, extraintestinal infection, and appropriate antimicrobial therapy. In the multivariate analysis, age ≥80 years [odds ratio (OR), 4.37 [95% confidence interval (CI), 1.68-11.35; p = 0.002]], admission to the ICU (OR, 6.59 [95% CI, 2.17-19.99; p = 0.001]), and malignancy (OR, 3.62 [95% CI, 1.32-9.90; p = 0.012]) were significantly associated with mortality. Aeromonas infections are mainly gastrointestinal. The 1-year follow-up mortality rate was high. Old age (age ≥80 years), admission to the ICU, and malignancy were identified as independent risk factors for mortality.

Aeromonas species: an opportunistic enteropathogen in patients with inflammatory bowel diseases? A single center cohort study

BACKGROUND

The role of Aeromonas species as an enteropathogen in patients with and without inflammatory bowel disease (IBD) is still debated. The aim was to explore the significance of positive Aeromonas stool cultures in IBD and patients without IBD.

METHODS

Observational retrospective study including all patients with a stool culture positive for Aeromonas between January 2011 and October 2013 at the Leuven University Hospitals. Demographics, clinical, and endoscopic outcomes and laboratory results were analyzed.

RESULTS

A total of 77 patients (11 IBD) were identified. In 37 cases, Aeromonas caused a mild self-limited gastrointestinal infection. Among the 40 patients needing antibiotics, 22 presented a mild-to-moderate gastrointestinal infection; 4 suffered from extraintestinal complications; and 4 were coinfected by Campylobacter spp. A. veronii caused more frequently severe infection than the other species (25% versus 5%; P = 0.046). In 2 patients with ulcerative colitis, Aeromonas triggered a moderate-to-severe flare and 2 cases appeared in the context of de novo Crohn's disease. In contrast, in 1 patient with ulcerative colitis and 2 patients with Crohn's disease, Aeromonas caused a mild gastrointestinal infection not worsening the disease activity and in 4 patients with Crohn's disease, it presented in the context of active disease with no clear pathogenic role. Patients with IBD were treated more often with antibiotics (82 versus 41%, P = 0.012) and had more complications (46 versus 14%, P = 0.024).

CONCLUSIONS

Aeromonas caused mostly mild infections but also moderate and severe infections. A. veronii was more prevalent in patients with IBD and was associated with worse clinical outcomes. Aeromonas caused milder infections in patients without IBD. Other risk factors for severe infection were not found.

Caracterização de Aeromonas spp isoladas de amostras de ostras e água por método microbiológico e molecular

Objetivou-se isolar e identificar bactérias do gênero Aeromonas de amostras de ostras e de água, pelos métodos microbiológico e molecular. A identificação do gênero Aeromonas foi realizada pelo método convencional e pela técnica da PCR e a caracterização das espécies foi realizada pela chave de identificação Aerokey II e pela técnica de RFLP-PCR do 16S rDNA. Foram identificadas 59 (98,3%) amostras de ostras e 15 (75%) amostras de água contaminadas por bactérias do gênero Aeromonas. Dos 74 isolados de Aeromonas spp. obtidos pela análise microbiológica, 53 (71,62%), 38 (65,51%) de amostras de ostras e 15 (100%) de amostras de água, confirmaram a caracterização do gênero pela técnica molecular. Quanto a identificação bioquímica das espécies 59,3% (n=35) e 40,6% (n=24) dos isolados de Aeromonassp. obtidos das amostras de ostras foram classificados como A. hydrophila e A. caviae, respectivamente; e para os isolados obtidos das amostras de água, 60% (n=9) foram classificados como A. hydrophila e 40% (n=6) como A. caviae; entretanto, somente a A. hydrophila foi confirmadapelo sequenciamento genético. Quanto a classificação através da RFLP-PCR 16S rDNA, foram obtidos padrões de bandas inespecíficos, impossibilitando a identificação das espécies por esta técnica. O grande número de amostras de ostras contaminadas com Aeromonas spp. e a identificação da A. hydrophila demonstram que este molusco pode oferecer risco à saúde dos consumidores, principalmente por ser consumido in natura e se tratar de um micro-organismo potencialmente patogênico para o ser humano.

Pneumonia caused by Aeromonas species in Taiwan, 2004-2011

We investigated the clinical characteristics of patients with pneumonia caused by Aeromonas species. Patients with pneumonia caused by Aeromonas species during the period 2004 to 2011 were identified from a computerized database of a regional hospital in southern Taiwan. The medical records of these patients were retrospectively reviewed. Of the 84 patients with pneumonia due to Aeromonas species, possible Aeromonas pneumonia was diagnosed in 58 patients, probable Aeromonas pneumonia was diagnosed in 18 patients, and pneumonia due to Aeromonas was conclusively diagnosed in 8 patients. Most of the cases of Aeromonas pneumonia developed in men and in patients of advanced age. A. hydrophila (n = 50, 59.5 %) was the most common pathogen, followed by A. caviae (n = 24, 28.6 %), A. veronii biovar sobria (n = 7, 8.3 %), and A. veronii biovar veronii (n = 3, 3.6 %). Cancer (n = 37, 44.0 %) was the most common underlying disease, followed by diabetes mellitus (n = 27, 32.1 %). Drowning-associated pneumonia developed in 6 (7.1 %) patients. Of 47 patients who were admitted to the intensive care ward, 42 patients developed acute respiratory failure and 24 of those patients died. The overall in-hospital mortality rate was significantly associated with liver cirrhosis, cancer, initial presentation of shock, and usage of mechanical ventilation. In conclusion, Aeromonas species should be considered as one of the causative pathogens of severe pneumonia, especially in immunocompromised patients, and should be recognized as a cause of drowning-associated pneumonia. Cirrhosis, cancer, and shock as the initial presenting symptom are associated with poor outcome.

Skin and soft-tissue infections caused by Aeromonas species

This study investigated the clinical characteristics of patients with skin and soft-tissue infections (SSTIs) due to Aeromonas species. Patients with SSTIs caused by Aeromonas species during the period from January 2009 to December 2011 were identified from a computerized database of a regional hospital in southern Taiwan. The medical records of these patients were retrospectively reviewed. A total of 129 patients with SSTIs due to Aeromonas species were identified. A. hydrophila (n = 77, 59.7 %) was the most common pathogen, followed by A. veronii biovar sobria (n = 22, 17.1 %), A. veronii biovar veronii (n = 20, 15.5 %), A. caviae (n = 9, 7.0 %), and A. schubertii (n = 1, 0.8 %). The most common isolates obtained from patients with polymicrobial infections were Klebsiella species (n = 33), followed by Enterococcus spp. (n = 24), Enterobacter spp. (n = 21), Escherichia coli (n = 17), Staphylococcus spp. (n = 17), Streptococcus spp. (n = 17), and Acinetobacter spp. (n = 15). Liver cirrhosis and concomitant bacteremia were more common among patients with monomicrobial Aeromonas SSTIs than among patients with polymicrobial SSTIs. Nine (7 %) patients required limb amputations. The in-hospital mortality rate was 1.6 %. In conclusion, Aeromonas species should be considered as important causative pathogens of SSTIs, and most infections are polymicrobial. In addition, the clinical presentation differs markedly between patients with monomicrobial and those with polymicrobial Aeromonas SSTIs.

Comparative sequence analysis of a multidrug-resistant plasmid from Aeromonas hydrophila

Aeromonas hydrophila is a pathogenic bacterium that has been implicated in fish, animal, and human disease. Recently, a multidrug resistance (MDR) plasmid, pR148, was isolated from A. hydrophila obtained from a tilapia (Oreochromis niloticus) farm in Thailand. pR148 is a 165,906-bp circular plasmid containing 147 coding regions showing highest similarity to pNDM-1_Dok1, an MDR plasmid isolated from a human pathogen. pR148 was also very similar to other IncA/C plasmids isolated from humans, animals, food, and fish. pR148 contains a mercuric resistance operon and encodes the complete set of genes for the type 4 secretion system. pR148 encodes a Tn21 type transposon. This transposon contains the drug resistance genes qacH, bla(OXA-10), aadA1, and sul1 in a class 1 integron; tetA and tetR in transposon Tn1721; and catA2 and a duplicate sul1 in a locus showing 100% similarity to IncU plasmids isolated from fish. The bla(OXA-10) and aadA1 genes showed 100% similarity to those from the Acinetobacter baumannii AYE genome. The similarity of pR148 to a human pathogen-derived plasmid indicates that the plasmids were either transferred between different genera or that they are derived from a common origin. Previous studies have shown that IncA/C plasmids retain a conserved backbone, while the accessory region points to lateral gene transfer. These observations point out the dangers of indiscriminate use of antibiotics in humans and in animals and the necessity of understanding how drug resistance determinants are disseminated and transferred.

Infectious causes of chronic diarrhoea

Infections are an uncommon cause of chronic diarrhoea. Parasites are most likely, including protozoa like giardia, cryptosporidia and cyclospora. Bacteria are unlikely to cause chronic diarrhoea in immunocompetent individuals with the possible exception of Yersinia, Plesiomonas and Aeromonas. Infectious diarrhoea can trigger other causes of chronic diarrhoea, including inflammatory bowel disease, irritable bowel syndrome and "Brainerd-type" diarrhoea. A thorough evaluation should detect most infections causing chronic diarrhoea.

Empyema caused by Aeromonas species in Taiwan

Strains of Aeromonas species are prevalent bacteria in coastal areas of southern Taiwan. Aeromonad is known as a cause of epidemic diarrheal disease, and the most common clinical manifestation is acute gastroenteritis. Extra-intestinal infections by Aeromonas species, such as pleural cavity, are rare. Herein, we described the six patients who developed Aeromonas spp.-related empyema, and was successfully treated with antimicrobial agent and drainage.

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.

Emerging Aeromonas species infections and their significance in public health

Aeromonas species are ubiquitous bacteria in terrestrial and aquatic milieus. They are becoming renowned as enteric pathogens of serious public health concern as they acquire a number of virulence determinants that are linked with human diseases, such as gastroenteritis, soft-tissue, muscle infections, septicemia, and skin diseases. Proper sanitary procedures are essential in the prevention of the spread of Aeromonas infections. Oral fluid electrolyte substitution is employed in the prevention of dehydration, and broad-spectrum antibiotics are used in severe Aeromonas outbreaks. This review presents an overview of emerging Aeromonas infections and proposes the need for actions necessary for establishing adequate prevention measures against the infections.

Severe sepsis caused by Aeromonas hydrophila in a patient using tocilizumab: a case report

INTRODUCTION

Aeromonas species do not commonly cause disease in humans. However, when disease is seen, it often occurs in patients with underlying immunosuppression or malignancy and has a high fatality rate.

CASE PRESENTATION

A 72-year-old Japanese woman with rheumatoid arthritis treated with tocilizumab (which has an immunosuppressive effect) presented with severe epigastric pain. She had a fever with chills, hypotension and jaundice. She was diagnosed with acute suppurative cholangitis and treated with cefoperazone-sulbactam and an endoscopic drainage was performed. Jaundice was slightly improved, but the shock state and inflammatory reactions were prolonged as typical of septic shock. On the second day after admission, an electrocardiogram showed ST segment elevation and echocardiography showed ventricular wall dysfunction. Coronary arteries were patent in coronary angiography and she was diagnosed with stress-induced cardiomyopathy. Blood cultures showed Aeromonas hydrophila. A stool culture was negative for A. hydrophila. On day six, her white blood cell count and neutrophils were normalized and cefoperazone-sulbactam treatment was halted. Left ventricular function normalized on day twelve and a laparoscopic cholecystectomy for cholelithiasis was performed on the 16th day of hospitalization. A culture from the bile showed A. hydrophila. Eighteen days after surgery, tocilizumab treatment was restarted and there were no complications. Two months after restarting tocilizumab, our patient is stable without any serious events.

CONCLUSION

We present a rare case of A. hydrophila sepsis and acute suppurative cholangitis in an elderly patient with gallstones and rheumatoid arthritis using tocilizumab. This clinical course may suggest that preemptive treatment for cholelithiasis prior to using molecular-targeting agents might be feasible in elderly patients.

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.

Aeromonas spontaneous bacterial peritonitis: a highly fatal infectious disease in patients with advanced liver cirrhosis

BACKGROUND/PURPOSE

Aeromonas infections, rarely reported in Western countries, are not uncommon infectious diseases in Taiwan. The clinical manifestations and prognostic factors of Aeromonas spontaneous bacterial peritonitis (SBP) in patients with liver cirrhosis were investigated.

METHODS

We reviewed the medical charts and microbiological records of liver cirrhosis patients with Aeromonas SBP between January 1990 and December 2005, in a medical center in southern Taiwan.

RESULTS

Thirty-one liver cirrhosis patients developed Aeromonas SBP within a 16-year period. The majority (26, 84%) had concurrent Aeromonas bacteremia. A. sobria (55%) and A. hydrophila (45%) were the causative species. The predominant clinical manifestations included fever (84%), abdominal pain (74%), hypotension on admission (48%), altered mental status (45%), and acute renal failure (42%). Gram-negative bacilli were found in Gram staining of ascitic fluids in 27% of 26 patients, while aeromonads were isolated from ascitic fluids in 55% of 31 patients. The yield rate of ascitic fluid cultures decreased greatly, if paracentesis was performed at > 3 hours after the administration of antimicrobial therapy. All but one patient received in-vitro-active antimicrobial agents within 48 hours, but the all-cause mortality rate was 56%. Initial high Pitt's bacteremia score was independently associated with a fatal outcome in multivariate analysis.

CONCLUSION

Aeromonas SBP is a fatal disease, and must be included in the differential diagnosis of SBP in patients with advanced liver cirrhosis in endemic areas.

Prospective nationwide study of Aeromonas infections in France

We report a systematic prospective multicenter nationwide study of clinical Aeromonas infections in France. During 6 months (May to October 2006), 78 cases of aeromonosis were reviewed for risk factors and clinical, microbiological, and antimicrobial susceptibility data. They included wound infections (44%), bacteremia (26%), enteritis (19%), respiratory tract infections (6%), and miscellaneous (5%) infections.

Emerging infections of the gastrointestinal tract

Infections account for significant GI morbidity and mortality worldwide. New organisms are being identified, associated with diarrhoeal illness and some with other gastrointestinal illness as well. Among GI viruses, Sapovirus is now recognised to cause diarrhoea, especially in children. A hypervirulent strain of Clostridium difficile has caused epidemics in many countries. Newly identified bacterial species that may cause diarrhoea include Campylobacter concisus, Arcobacteria, Edwardsiella tarda, Aeromonas, Plesiomonas and Laribacter. Helicobacteria are reviewed, as well as the role of gastric acid suppression in predisposing to enteric infections.

Epidemiology and prognostic determinants of patients with bacteremic cholecystitis or cholangitis

OBJECTIVES

To compare mortalities in patients with sepsis due to biliary tract infections (BTIs) and due to infections from other sources, and to identify independent predictors of mortality in these patients.

METHODS

This study was part of a community-acquired bloodstream infection (BSI) study that prospectively collected comprehensive clinical, laboratory, and outcome data from 937 consecutive patients with microbiologically documented BSI in the emergency department. BTI was the confirmed source of 145 of the 937 BSIs. We determined the independent prognostic factors by evaluating the correlation between 30-day mortality and various factors, for example, comorbidity, clinical severity, related hepatobiliary complication, and decompressive procedures.

RESULTS

Patients with biliary sepsis had a high percentage of Gram-negative (88.3%), polymicrobial (26.9%), and anaerobic infections (6.9%). The 30-day overall mortality was 11.7%. Cox proportional hazard regression analysis disclosed five significant independent predictors: acute renal failure (hazard ratio, 95% confidence interval: 6.86, 6.02-25.5), septic shock (5.83, 4.36-15.64), malignant obstruction (4.35, 1.89-12.96), direct type hyperbilirubinemia (1.26, 1.1-1.42), and Charlson score > or =6 (1.57, 1.12-2.22). Compared with the remaining 792 patients in the source population, patients with bacteremic BTI had significantly better prognosis (log-rank test, P= 0.007). Adjusting for age, comorbidity, and clinical severity, BTI was still independently associated with better 30-day survival (0.25-0.76).

CONCLUSIONS

Though the mortality rate in patients with bacteremic BTI is substantial, survival is better than in those with bacteremia from other sources. The main prognostic factors identified in this study may help clinicians recognize patients at high risk for early mortality so that they can give prompt, appropriate treatment.

Acute suppurative necrotizing pancholangitis. A case report

OBJECTIVE

To present a case of ascending cholangitis with resulting necrosis of the biliary system with perforation.

CLINICAL PRESENTATION AND INTERVENTION

A 40-year-old male patient presented with upper abdominal pain, fever and jaundice assessed clinically and investigated by laboratory and radiological tests. Endoscopic retrograde cholangiogram and surgery were performed. However, because of extensive suppurative pancholangitis involving most of the intrahepatic radicles, sound surgical drainage could not be accomplished. Unfortunately, the patient died 2 days after surgery.

CONCLUSION

In this case of severe cholangitis, endoscopic and surgical interventions were not successful and might have contributed to the worsening of the condition.

Aeromonas infection of the hepatobiliary system: report of 15 cases and review of the literature

Aeromonas species cause both intestinal and extraintestinal disease. We reviewed hospital laboratory and medical records to identify patients with Aeromonas infection of the hepatobiliary or pancreatic system. Analysis of data from our hospital, as well as a review of the published literature, yielded a total of 41 episodes in 39 patients, and the features of these episodes are described. The most common manifestation of Aeromonas hepatobiliary infection among all reported cases was cholangitis (29 of 41 episodes). The majority of infections in our hospital occurred in patients with underlying immunosuppression or malignancy (13 of 15 patients), including 4 liver transplant recipients, and nosocomial infection was not infrequent (8 of 17 episodes). Infection occurred most commonly in patients with obstruction of the biliary tract due to stones, tumor, or stricture and was associated with a relatively high mortality rate (11.8%). Antibiotic susceptibility testing revealed that gentamicin, imipenem, and ciprofloxacin had the highest activity against the Aeromonas species isolated.

Aeromonas veronii biovar veronii septicaemia and acute suppurative cholangitis in a patient with hepatitis B

Gram-negative bacilli of the genus Aeromonas are widespread in aquatic environments and can be responsible for human infections. Although Aeromonas extraintestinal and systemic infections have been reported with growing frequency in recent years, Aeromonas septicaemia remains an uncommon finding, often associated with serious underlying disease and predominantly related to the species Aeromonas hydrophila, Aeromonas veronii biovar sobria and Aeromonas caviae. Here, a case of A. veronii biovar veronii septicaemia and acute suppurative cholangitis is reported in a patient with chronic hepatitis B.