Epidemiological and clinical characteristics of bacteraemia caused by Aeromonas spp. as compared with Escherichia coli and Pseudomonas aeruginosa

Epidemiology of Aeromonas Species Bloodstream Infection in Queensland, Australia: Association with Regional and Climate Zones

Aeromonas species can cause severe bloodstream infection (BSI) however, few studies have examined their epidemiology in non-selected populations. The objective of this study was to describe the incidence and determinants of Aeromonas species BSI in Queensland, Australia. A retrospective population-based cohort study was conducted during 2000-2019. Aeromonas species BSI were identified by laboratory surveillance and clinical and outcome information through data linkages to statewide databases. A total of 407 incident Aeromonas species BSI were identified with an age- and sex-standardized incidence of 5.2 per million residents annually. No trend in annual incidence rate during two decades of surveillance was demonstrated. Significant variable monthly occurrences were observed with highest rates during warmer, wetter months, and lowest rates during winter and dry periods. There was significant variability in incidence accordingly to region and climate zones, with higher rates observed in tropical north regions and lowest in southeastern corner. The highest incidence was observed in very remote and hot areas in Queensland. Cases were infrequent in children and risk was highest in elderly and males. Seventy-eight patients died within 30 days with a case-fatality rate of 19%. Older age, non-focal infection, higher Charlson score, and monomicrobial bacteremia were independent risk factors for death. Demographic and climatic changes may increase the burden of these infections in future years.

Clinical significance and outcome of aeromonas infection among 19 patients-a descriptive study from south India

We describe a series of 19 patients with Aeromonas infection in a tertiary hospital from South India. Bacteremia (n,9) and skin and soft tissue infection (n,9) were the common presentations, and one case of gastroenteritis. Twelve were male and seven were female. Comorbid conditions were seen with 52% cases. Among 18 patients hospitalized, 37% required intensive care. The infection was polymicrobial in 26%, mainly enteropathogens. Decreased susceptibility of beta lactams (94% to cefepime, 84% to ceftazidime and imipenem and 53% to piperacillin tazobactam) is a matter of concern. All but one patient with bacteremia survived the infection.

Clinical and microbiological characteristics of Aeromonas bacteremia in Turkey

We investigated the cases with Aeromonas bacteremia in terms of clinical and microbiological characteristics, underlying disease and mortality rates. Patients with positive blood cultures were included in this research. Aeromonas bacteremia was diagnosed as at least one positive blood culture for Aeromonas species. The bacteremia was defined as community origin if the onset was in the community or within 72 hours of hospital admission. The others were considered as nosocomial. All bacteria were defined as Aeromonas with conventional method. Species identification was verified by VITEK system. Antibiotic susceptibility tests were analyzed with the disc diffusion, E-test method or VITEK system. Thirty-three patients were diagnosed with bacteremia due to Aeromonas spp. Hematologic and solid tumors were the leading underlying conditions, followed by cirrhosis. Two patients (6%) had community-acquired infections. Aeromonas hydrophila was the most common isolated bacterium. The crude mortality rate was 36%. 12 patients died and 6 deaths and 4 deaths were detected in patients with bacteremia caused by A. hydrophila and Aeromonas sobria respectively. All strains were resistant to ampicillin and more than 90% of the strains were susceptible to trimethoprim-sulfamethoxazole, fluoroquinolone, third generation cephalosporins, and carbapenems. Aeromonas sp. is not a frequent cause of bacteremia however, it may lead to high mortality rates, especially in the immunocompromised hosts and patients with liver cirrhosis. Nosocomial Aeromonas bacteremia is not uncommon in these populations. Broad-spectrum cephalosporins, piperacillin-tazobactam, fluoroquinolones, and carbapenems remain as effective antimicrobial agents for therapy of Aeromonas bacteremia.

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.

Mortality analysis of Aeromonas hydrophila infection in hepato-biliary pancreatic surgery: Multicenter retrospective observational study

BACKGROUND/PURPOSE

Aeromonas hydrophila can cause lethal infectious complications after surgery. There have been no large cohort studies of this specific to the hepato-biliary-pancreatic (HBP) field. We investigate the postoperative influence of A hydrophila infection after HBP surgery.

METHODS

We retrospectively reviewed patients who underwent HBP surgery between 2008 and 2017 at eight university hospitals. Patients with A hydrophila isolation during perioperative management were extracted, and their postoperative courses were investigated.

RESULTS

Bacterial culture examination of 10 074 patients was performed as perioperative management. Among them, 76 patients (0.75%) had A hydrophila isolation, most of whom underwent pancreatoduodenectomy (n = 38) or hepatectomy with biliary reconstruction (n = 14). There were seven mortalities after these two procedures (13.5%), five within 3 days after the onset of infection. Bile (n = 48) and abdominal drainage fluid (n = 29) were major sites of A hydrophila isolation. Typical prophylactic antibiotics, cefazolin or flomoxef, were mostly resistant. There was no mortality among patients that received sensitive antibiotics prophylactically.

CONCLUSIONS

Isolation of A hydrophila was low in our cases of HBP surgery, but the condition of some patients deteriorated rapidly by this infection. Although there could be several bacterial infections during management of HBP surgery, A hydrophila should not be overlooked. Preparation of appropriate prophylactic antibiotics may prevent or reduce mortality.

Sexual dimorphism in bacterial infections

Background

Sex differences are important epidemiological factors that impact in the frequency and severity of infectious diseases. A clear sexual dimorphism in bacterial infections has been reported in both humans and animal models. Nevertheless, the molecular mechanisms involved in this gender bias are just starting to be elucidated. In the present article, we aim to review the available data in the literature that report bacterial infections presenting a clear sexual dimorphism, without considering behavioral and social factors.

Main body

The sexual dimorphism in bacterial infections has been mainly attributed to the differential levels of sex hormones between males and females, as well as to genetic factors. In general, males are more susceptible to gastrointestinal and respiratory bacterial diseases and sepsis, while females are more susceptible to genitourinary tract bacterial infections. However, these incidences depend on the population evaluated, animal model and the bacterial species. Female protection against bacterial infections and the associated complications is assumed to be due to the pro-inflammatory effect of estradiol, while male susceptibility to those infections is associated with the testosterone-mediated immune suppression, probably via their specific receptors. Recent studies indicate that the protective effect of estradiol depends on the estrogen receptor subtype and the specific tissue compartment involved in the bacterial insult, suggesting that tissue-specific expression of particular sex steroid receptors contributes to the susceptibility to bacterial infections. Furthermore, this gender bias also depends on the effects of sex hormones on specific bacterial species. Finally, since a large number of genes related to immune functions are located on the X chromosome, X-linked mosaicism confers a highly polymorphic gene expression program that allows women to respond with a more expanded immune repertoire as compared with men.

Conclusion

Notwithstanding there is increasing evidence that confirms the sexual dimorphism in certain bacterial infections and the molecular mechanisms associated, further studies are required to clarify conflicting data and to determine the role of specific hormone receptors involved in the gender bias of bacterial infections, as well as their potential as therapeutic targets.

Phenotypic and genotypic characteristics of ESBL and AmpC producing organisms associated with bacteraemia in Ho Chi Minh City, Vietnam

Background

Broad-spectrum antimicrobials are commonly used as empirical therapy for infections of presumed bacterial origin. Increasing resistance to these antimicrobial agents has prompted the need for alternative therapies and more effective surveillance. Better surveillance leads to more informed and improved delivery of therapeutic interventions, potentially leading to better treatment outcomes.

Methods

We screened 1017 Gram negative bacteria (excluding Pseudomonas spp. and Acinetobacter spp.) isolated between 2011 and 2013 from positive blood cultures for susceptibility against third generation cephalosporins, ESBL and/or AmpC production, and associated ESBL/AmpC genes, at the Hospital for Tropical Diseases in Ho Chi Minh City.

Results

Phenotypic screening found that 304/1017 (30%) organisms were resistance to third generation cephalosporins; 172/1017 (16.9%) of isolates exhibited ESBL activity, 6.2% (63/1017) had AmpC activity, and 0.5% (5/1017) had both ESBL and AmpC activity. E. coli and Aeromonas spp. were the most common organisms associated with ESBL and AmpC phenotypes, respectively. Nearly half of the AmpC producers harboured an ESBL gene. There was no significant difference (p > 0.05) between the antimicrobial resistance phenotypes of the organisms associated with community and hospital-acquired infections.

Conclusion

AmpC and ESBL producing organisms were commonly associated with bloodstream infections in this setting, with antimicrobial resistant organisms being equally distributed between infections originating from the community and healthcare settings. Aeromonas spp., which was associated with bloodstream infections in cirrhotic/hepatitis patients, were the most abundant AmpC producing organism. We conclude that empirical monotherapy with third generation cephalosporins may not be optimum in this setting.

Electronic supplementary material

The online version of this article (10.1186/s13756-017-0265-1) contains supplementary material, which is available to authorized users.

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.

Clinical and Therapeutic Implications of Aeromonas Bacteremia: 14 Years Nation-Wide Experiences in Korea

BACKGROUND

To elucidate the clinical presentation, antimicrobial susceptibility, and prognostic factors of monomicrobial Aeromonas bacteremia in order to determine the most effective optimal therapy.

MATERIALS AND METHODS

We reviewed the medical records of Aeromonas bacteremia patients for the period January 2000 to December 2013 in a retrospective multi-center study.

RESULTS

A total of 336 patient records were reviewed, with 242 having community-acquired bacteremia. The major clinical infections were of the hepatobiliary tract (50.6%) and peritonitis (18.5%), followed by primary bacteremia (17.9%). The infections usually occurred in patients with malignancy (42.3%), hepatic cirrhosis (39.3%), or diabetes mellitus (25.6%). High antimicrobial-resistance rates (15.5% for ceftriaxone, 15.5% for piperacillin/tazobactam) were noted. However, resistance to carbapenem and amikacin was only 9.8% and 3.0%, respectively. Aeromonas hydrophila (58.9%) was the most common pathogen, followed by Aeromonas caviae (30.4%). The severity of A. caviae bacteremia cases were less than that of A. hydrophila or Aeromonas veronii bacteremia (P <0.05). A. hydrophila showed higher antimicrobial resistance than did other Aeromonas species (P <0.05). Patients with hospital-acquired bacteremia were more likely to have severely abnormal laboratory findings and relatively high antimicrobial-resistance rates. Mortality was associated with metastatic cancer, shock, delayed use of appropriate antimicrobial agents, increased prothrombin time, and increased creatinine level (P <0.05).

CONCLUSIONS

Aeromonas species should be considered one of the causative agents of bacteremia in patients with intra-abdominal infections or malignancies. Although ceftriaxone-resistant Aeromonas bacteremia was not statistically related to mortality in this study, it was associated with severe clinical manifestations and laboratory abnormalities. Appropriate antibiotics, including carbapenem, should be administered early, especially in Aeromonas bacteremia patients with shock and impaired renal function.

A community-based gastroenteritis outbreak after Typhoon Haiyan, Leyte, Philippines, 2013

BACKGROUND

Three weeks after Typhoon Haiyan, an increasing number of acute gastroenteritis cases were reported in Kananga, Leyte, an area where evacuated residents had returned home two days after the disaster. An outbreak investigation was conducted to identify the source and risk factors associated with the increase of gastroenteritis.

METHODS

A case was defined as any person in Kananga who developed acute diarrhoea (≥ 3 times/24 hours) and any of the following symptoms: fever, nausea, vomiting or abdominal pain from 11 November 2013 to 10 December 2013. Active case finding was conducted by reviewing medical records, and a case-control study was conducted. Rectal swabs and water samples were tested for bacteriological examination.

RESULTS

One hundred and five cases were identified. Multivariate analysis revealed that consumption of untreated drinking-water was associated with illness (adjusted odds ratio: 18.2). Both rectal swabs and municipal water samples tested positive for Aeromonas hydrophila. On inspection of the municipal water system, breaks in the distribution pipes were found with some submerged in river water.

CONCLUSION

This acute gastroenteritis outbreak was most likely caused by Aeromonas hydrophila and transmitted through a contaminated water source. This study highlights that areas less damaged by a disaster that do not require ongoing evacuation centres can still have acute gastroenteritis outbreaks. All affected areas should be monitored during a disaster response, not just those with evacuation centres. Boiling or chlorinating of water should also be recommended for all areas affected by disaster.

A foodborne outbreak of Aeromonas hydrophila in a college, Xingyi City, Guizhou, China, 2012

BACKGROUND

On 12 May 2012, over 200 college students with acute diarrhoea were reported to the Guizhou Center for Disease Control and Prevention. We conducted an investigation to identify the agent and mode of transmission and to recommend control measures.

METHODS

A suspected case was a person at the college with onset of ≥ two of the following symptoms: diarrhoea (more than three loose stools in 24 hours), abdominal pain, vomiting or fever (> 37.5C) between 6 and 15 May 2012. A confirmed case also had a positive Aeromonas hydrophila culture from a stool sample. A retrospective-cohort study of 902 students compared attack rates (AR) by dining place, meals and food history. We reviewed the implicated premise, its processes and preparation of implicated food.

RESULTS

We identified 349 suspected cases (AR = 14%) and isolated Aeromonas hydrophila from three stools of 15 cases. Students who ate in cafeteria A were more likely to be ill compared to those eating in other places (relative risk [RR]: 3.1, 95% confidence interval [CI]: 2.0-4.8). The cohort study implicated cold cucumber (RR: 2.6, 95% CI: 2.0-3.3) and houttuynia dishes (RR: 1.8, 95% CI: 1.4-2.3). Environmental investigation showed that vegetables were washed in polluted water from a tank close to the sewage ditch, then left at 30 °C for two hours before serving. The Escherichia coli count of the tank was well above the standard for drinking-water.

CONCLUSION

This outbreak of Aeromonas hydrophila was most probably caused by salad ingredients washed in contaminated tank water. We recommended enhancing training of foodhandlers, ensuring tanks and sewerage systems comply with appropriate standards and adequate monitoring of drinking-water sources.

Infectious diseases in end-stage liver disease patients

Patients with chronic liver diseases sustain impairment to immune systems, which worsens over time. These defects in their host defense lead to risks of bacterial infections and increased morbidity. Providers should have heightened surveillance for infectious diseases and suspect one with any acute change in status. Patient history may reveal rare infections and allow initiation of early appropriate therapy. There should be a low threshold for obtaining diagnostic cultures and peritoneal fluid samples and discussing possible causes with an infectious diseases consultant or a microbiology laboratory. These maneuvers will maximize therapy in patients at high risk for death due to infectious disease.

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.

Different clinical characteristics between polymicrobial and monomicrobial Aeromonas bacteremia--a study of 216 cases

BACKGROUND

Part of Aeromonas bacteremia is polymicrobial infection. However, a clinical comparison of monomicrobial and polymicrobial Aeromonas bacteremia has not hitherto been reported.

METHODS

A retrospective analysis of medical records of patients with Aeromonas bacteremia at three large referral hospitals in Taiwan for an 8-year period (2001-2008) was conducted.

RESULTS

There were 154 patients with monomicrobial Aeromonas bacteremia and 62 patients with polymicrobial Aeromonas bacteremia. In the polymicrobial infections, E. coli was the most common combined pathogen (42%), followed by Klebsiella spp. (24%) and Enterobacter spp. (16%). Multivariate logistic regression analysis revealed solid cancer as the risk factor for polymicrobial Aeromonas bacteremia, with male gender and cirrhosis as risk factors for monomicrobial Aeromonas bacteremia. However, of all types of solid cancer, hepatoma was associated with monomicrobial Aeromonas bacteremia. APACHE II score was the most important prognostic factor in both groups.

CONCLUSION

Aeromonas bacteremia in patients with cirrhosis or male gender tended to be monomicrobial. Polymicrobial Aeromonas bacteremia was associated with solid cancers. In either polymicrobial or monomicrobial Aeromonas bacteremia, prognosis could be predicted according to disease severity measured by APACHE II score.

Surgical site infection due to Aeromonas species: report of nine cases and literature review

Gastrointestinal and wound infections are the most common clinical presentation of Aeromonas. Surgical site infections (SSIs) due to this microorganism are rare. We studied the clinical and microbiological characteristics of 9 cases that appeared at 2 Spanish hospitals and reviewed 15 cases available in the literature. All patients (including our cases) had gastrointestinal or biliary diseases. 21 patients (91.3%) developed SSIs after abdominal or pelvic surgery. The mean duration from surgery to the onset of wound infection was 2.2 d in our 9 patients. The infection was polymicrobial in 17 patients (77.2%) and 19 cases were nosocomial (95%). Clinical outcome of all cases was uniformly good after treatment except for 2 patients. Two patients were cured only with surgical drainage. In conclusion, SSIs due to Aeromonas species have a probable endogenous source after abdominal or pelvic surgery and the onset is rapid in most cases. Clinical outcome is good after antibiotic treatment but surgical drainage without antibiotic therapy can be sufficient to clear the infection in some cases.

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.

Nationwide study of invasive Pseudomonas aeruginosa infection in Norway: importance of underlying disease

OBJECTIVE

Pseudomonas aeruginosa is an opportunistic pathogen that may cause invasive disease. We describe the epidemiology of invasive P. aeruginosa infection in Norway and identify associated clinical factors.

METHODS

All patients with invasive P. aeruginosa and Pseudomonas not identified at the species level (Pseudomonas spp.) in Norway 1992-2002 were included. Detailed information was collected for all cases during 1999-2002. Population and health institution statistics were obtained from national databases.

RESULTS

In 1999-2002 the incidence rate was 3.16 per 100 000 person-years at risk or 0.20 per 1000 hospital stays. For hospital-acquired infection the rate was 671 per 100 000 person-years as compared with 1.13 for community-acquired infection, and 37 in nursing homes. The highest risk for invasive Pseudomonas disease was found in patients with malignant neoplasms of lymphoid and haematopoietic tissue (risk per 1000 hospital stays 1.9; 95% CI 1.5-2.3) and other diseases of blood and blood-forming organs (2.2; 95% CI 1.2-3.7). The case fatality rate was 35%.

CONCLUSIONS

The incidence of invasive P. aeruginosa infection in this population-based study was much lower than in most single-hospital studies. The nationwide study design and prudent antibiotic use may explain some of the difference. Infection risk is strongly associated with certain underlying diseases.

Clinical significance of spontaneous Aeromonas bacterial peritonitis in cirrhotic patients: a matched case-control study

BACKGROUND

Although Aeromonas species are known to cause bacteremia in patients with cirrhosis, less is known about spontaneous bacterial peritonitis (SBP) caused by Aeromonas species in these patients.

METHODS

We performed a retrospective, matched case-control study (1:2 ratio) consisting of patients presenting with SBP due to Aeromonas species from January 1997 through December 2006. Control subjects were patients with SBP caused by other organisms and were matched to the patients by age (+/- 1 year) and sex.

RESULTS

We identified 43 patients with SBP due to Aeromonas species, 40 (93%) of whom had Aeromonas hydrophila infection and 3 (7%) of whom had Aeromonas sorbia infection. There were 81 control subjects, of whom 38 (47%) were infected with Escherichia coli, 25 (31%) were infected with Klebsiella species, 12 (15%) were infected with Streptococcus species, and 6 (7%) were infected with other bacteria. Baseline Child-Pugh class and model for end-stage liver disease score did not differ between groups. A significant increase in the incidence of infection during the warm season (July-September) was observed in the group with SBP due to Aeromonas species, compared with the group with SBP due to other bacteria (63% vs. 25%; P < .001). Diarrheal episodes were significantly more frequent in the group with SBP due to Aeromonas species (26% vs. 6%; P = .002). There were no statistically significant differences between groups with regard to appropriateness of initial antibiotic therapy,3-day mortality, and 30-day cumulative survival. In the group with Aeromonas infection, the in-hospital mortality rate was 23%; septic shock was the only independent prognostic factor of in-hospital mortality (odds ratio, 34.5;95% confidence interval, 1.9-640.6; P = .02).

CONCLUSION

Aeromonas species should be considered to be a causative organism of SBP in cirrhotic patients presenting with diarrheal episodes during the warm season. Compared with SBP caused by other organisms, SBP due to Aeromonas species was not associated with more-advanced cirrhosis.

Relationship between the usage of carbapenem antibiotics and the incidence of imipenem-resistant Pseudomonas aeruginosa

Metallo-beta-lactamase (MBL)-producing Pseudomonas aeruginosa isolates are resistant to almost all broad-spectrum beta-lactams and carbapenems. We investigated 389 P. aeruginosa isolates, collected from 29 hospitals in the Tohoku area of Japan, to determine their susceptibilities to ten antimicrobial drugs, and the rates of MBL-producing P. aeruginosa among them. Two hundred and one P. aeruginosa strains were isolated from small (group S)hospitals that had adopted imipenem as a carbapenem antibiotic, and 188 were isolated from general (group G) hospitals, which employed three or four carbapenems. MBL genes were analyzed by polymerase chain reaction (PCR) in all isolates for which the sodium mercaptoacetic acid (SMA) disk method gave positive results. The antimicrobial agents tested were imipenem, meropenem, biapenem, panipenem, piperacillin, ceftazidime, sulbactam/cefoperazone, amikacin, arbekacin, and ciprofloxacin. Sixteen (8.0%) of the 201 isolates from group S hospitals and three (1.6%) of the 188 isolates from group G hospitals were MBL-producing P. aeruginosa. In this study, the proportion of MBL-producing P. aeruginosa in group S was significantly higher than that found in group G (P < 0.01). The use of only one agent as a carbapenem antibiotic may have been one of the factors contributing to the high detection rate of MBL-producing P. aeruginosa observed in group S hospitals.

Aeromonas veronii biovar sobria bacteraemia with septic arthritis confirmed by 16S rDNA PCR in an immunocompetent adult

An 81-year-old man developed septic arthritis and bacteraemia with Aeromonas veronii biovar sobria. Cultures of the joint wash-out fluid were negative; however, DNA matching that of Aeromonas veronii was identified by 16S rDNA PCR. The patient was successfully treated with a 4 week course of ciprofloxacin. No recognized risk factors were found.

Isolation and Characterization of Potentially Human Pathogenic, Cytotoxin-producing Aeromonas Strains from Retailed Seafood in Berlin, Germany

The presence of potentially human pathogenic strains of Aeromonas was investigated in 84 samples of seafood which were purchased from retail traders in Berlin, Germany in spring 2000. A total of 134 Aeromonas strains were isolated on selective [GSP agar and Aeromonas (Ryan) agar] and unselective (standard count agar and enterohaemolysin agar) media from 27 (32.1%) of the samples and were classified as Aeromonas hydrophila (67.9%), A. caviae (26.1%) and A. sobria (6.0%) by biotyping. Thirteen (48.1%) of the 27 positive samples contained more than one species of Aeromonas. Production of haemolysins on enterohaemolysin agar was found with 132 (98.5%) of the strains at 28 degrees C and with 130 strains (97.0%) at 37 degrees C growth temperature. Vero cytotoxins were produced by 99 (73.9%) of the strains when grown at 28 degrees C but only by 24 of the strains (17.9%) at 37 degrees C. The latter strains were identified as A. hydrophila (n = 22) and A. sobria (n = 2) which came from 17 (20.2%) samples of raw seafood and from ready-to-eat salted herring 'Matjes' products. Cytotoxin-encoding genes for aerolysin (aer) and haemolysin A (hlyA) were investigated by PCR. Aer and hlyA genes were detected in both, strains which produced toxins only at 28 degrees C and strains which produced toxins at 37 degrees C. Our data indicate that raw seafood and ready-to-eat fish products can harbour potential human pathogenic, cytotoxin producing Aeromonas strains.