Aeromonas spp. isolated from ready-to-eat seafood on the Norwegian market: prevalence, putative virulence factors and antimicrobial resistance.

AIMS: We aim to investigate the prevalence, putative virulence factors and antimicrobial resistance of mesophilic Aeromonas isolated from ready-to-eat (RTE) seafood available on the Norwegian market, and to assess the potential risks by consuming RTE seafood to consumers. METHODS AND RESULTS: The prevalence of mesophilic Aeromonas in 148 RTE seafood was investigated and the highest prevalence was found in retail sushi (17%), followed by oysters (10%), fresh salmon loins (10%) and scallops (4%). Among 43 Aeromonas isolates, 75% of them were identified as A. media, 23% as A. salmonicida and 2% as A. bestiarum based on partial gryB gene sequencing. Aeromonas isolates were potentially pathogenic due to the presence of four virulence genes: alt (73%), hylA (22%), aerA (17%) and act (6%). In addition, all isolates were resistant to ampicillin and erythromycin. Most of the isolates (98%) were multidrug resistant. CONCLUSIONS: The occurrence of potentially pathogenic and multidrug-resistant Aeromonas strains in RTE seafood implies a potential risk to consumers. Our finding suggests that RTE seafood could be a potential vehicle for the transfer of virulent and multidrug-resistant Aeromonas. SIGNIFICANCE AND IMPACT OF THE STUDY: To our knowledge, this is the first study to report multiple antibiotic resistance in Aeromonas associated with RTE seafood in Norway.

Growth and spoilage metabolites production of a mesophilic Aeromonas salmonicida strain in Atlantic salmon (Salmo salar L.) during cold storage in modified atmosphere.

AIMS: The aim of the study was to quantify the growth kinetic parameters and spoilage-associated metabolites of an inoculated strain of Aeromonas salmonicida in pre-rigor filleted Atlantic salmon (Salmo salar L.) stored in vacuum (VP) or modified atmosphere (MAP 60/40% CO2 /N2 ) at 4 and 8°C. METHODS AND RESULTS: The maximum growth rate of A. salmonicida in VP salmon stored at 4°C was 0·56 ± 0·04 day-1 with no detectable lag-phase and the concentration of Aeromonas reached 8·33 log CFU per g after 10 days. The growth rates and maximum population density of Aeromonas in MAP salmon were lower but the applied atmosphere did not inhibit the growth. A selection of metabolites associated with fish spoilage were quantified using 1 H nuclear magnetic resonance (NMR) spectroscopy. The concentration of trimethylamine (TMA) was significantly affected by storage time and temperature, packaging atmosphere and inoculation with A. salmonicida (General Linear Model (GLM), P < 0·001 for all factors). CONCLUSION: The study presents preliminary results on A. salmonicida as a potential spoilage organism in vacuum-packaged salmon during cold storage. The combination of refrigeration and a packaging atmosphere consisting of 60/40 % CO2 /N2 did not completely inhibit the growth but prevented the formation of TMA. SIGNIFICANCE AND IMPACT OF THE STUDY: Little information is available on the spoilage potential of Aeromonas spp. in minimally processed salmon products under different packaging conditions. The study clearly demonstrates the importance of hurdle technology and provides data to further elucidate the significance of Aeromonas spp. as a spoilage organism.

Effects of storage temperature on bacterial growth rates and community structure in fresh retail sushi.

AIMS: This study was conducted to assess the effects of different storage temperatures (4-20°C), on bacterial concentrations, growth rates and community structure in fresh retail sushi, a popular retail product with a claimed shelf life of 2-3 days. METHODS AND RESULTS: The maximum specific growth rate based on aerobic plate count (APC) at 4°C was 0·06 h-1 and displayed a sixfold increase (0·37 h-1 ) at 20°C. Refrigeration resulted in no growth of hydrogen sulphide (H2 S)-producing bacteria, but this group had the strongest temperature response. The bacterial community structure was determined by PCR/DGGE (denaturing gradient gel electrophoresis). Multivariate analysis based on Bray-Curtis similarities demonstrated that temperature alone was not the major determinant for the bacterial community structure. The total concentration of aerobic bacteria was the variable that most successfully explained the differences between the communities. The dominating organisms, detected by sequencing of DNA bands excised from the DGGE gel, were Brochothrix thermosphacta and genera of lactic acid bacteria (LAB). CONCLUSION: The relationship between growth rates and storage temperatures clearly demonstrates that these products are sensitive to deviations from optimal storage temperature, possibly resulting in loss of quality during shelf life. Regardless of the storage temperature, the bacterial communities converged towards a similar structure and density, but the storage temperature determined how fast the community reached its carrying capacity. SIGNIFICANCE AND IMPACT OF THE STUDY: Little information is available on the microbial composition of ready-to-eat food that are prepared with raw fish, subjected to contamination during handling, and susceptible to microbial growth during cold storage. Moreover, the data are a good first possibility to simulate growth of APC, H2 S-producing bacteria and LAB under different temperature scenarios that might occur during production, distribution or storage.

Hemiarthroplasty for proximal humerus fracture and consequences of a comminuted greater tubercle fragment.

BACKGROUND: A prerequisite for a satisfying functional result in the treatment of comminuted fractures of the proximal humerus with hemiarthroplasty is anatomical reduction, fixation and healing of the tuberculi around the prosthetic neck in order to restore normal function of the rotator cuff. PURPOSE: This was a retrospective study to examine the outcome after hemiarthroplasty using a prosthetic stem designed to optimise re-attachment and healing of the tuberculi (Aequalis; Tornier and Global Fx, DePuy). A special emphasis was on the effect on outcome a comminuted greater tubercle might have. MATERIALS AND METHODS: At follow-up, clinical results were evaluated using the Constant score and WOOS index. All patients had radiographs taken of the injured shoulder. Quality of tubercle healing and prosthetic height were estimated; acromiohumeral distance was registered as well as greater tubercle comminution and resorption. RESULTS: Thirty-four patients with 35 hemiarthroplasties were included. Mean age was 71 years (range 47-88) at the time of injury. At follow-up (mean 38 months, range 23-67), the mean Constant score was 44 points (range 18-87). The mean WOOS index was 58 (range 15-96). A comminuted tubercle was associated with tubercle resorption and superior migration of the arthroplasty. Also, there was a correlation for the functional Constant score, but for the WOOS index, there was none. CONCLUSION: Like several other studies, we generally saw a group of patients with limited pain but poor range of movement in the shoulder. Our hypothesis was that comminution of the greater tubercle would correlate with both rotator cuff arthropathic radiographical features and more detrimental functional scores than average. Thus, a subtype of fracture could be identified at the time of injury and perhaps be allocated to a different treatment than hemiarthroplasty. Due to a limited number of patients in this study, we are unable to make any strong statistically supported conclusions regarding this hypothesis. LEVEL OF EVIDENCE: Level 4 evidence.

Multiple myeloma in central and northern Norway 1981-1982: a follow-up study of a randomized clinical trial of 5-drug combination therapy versus standard therapy.

In a randomized study of 92 previously untreated patients with multiple myeloma, the intention was to document the possible beneficial effect of combination chemotherapy including vincristine, carmustine, alkylating agents and prednisone, as compared to conventional therapy with melphalan and prednisone. Major prognostic factors did not differ significantly between the treatment groups. With the 2-drug therapy and 5-drug combination therapy, 48 and 54% of the patients achieved remission, respectively. Median survival for patients treated with the 2-drug regimen and 5-drug regimen was 29 and 33.5 months, respectively. No significant difference was found between the survival curves for stage III patients treated with the two regimens. After 12 months, patients who had achieved remission were randomized to have treatment discontinued or to have maintenance treatment. The numbers of relapses, remission duration and survival of the two groups were similar.