Arcobacter Isolation from Minced Beef Samples in Costa Rica

Improving the Shelf Life and Quality of Minced Beef by Cassia Glauca Leaf Extracts during Cold Storage

Minced beef is a popular meat product due to its low price and superior nutritional value. The contamination of minced beef is a significant risk for the worldwide meat market. Both natural and synthetic preservatives are used to expand the shelf life and improve the quality properties of meat. The harmful effects of synthetic preservatives make natural preservatives more appealing. Therefore, this research was performed to study the impact of different concentrations of Cassia glauca leaf extract (CGE) on increasing the shelf life of minced beef. Seventy-two minced beef samples were divided into control, 0.25, 0.5, and 1% w/w CGE treated groups. The control and treated samples were kept at 3 ± 1 °C in the refrigerator for 15 days. Minced beef samples’ sensory, chemical, and microbiological properties were assessed every three days. The gained results showed that the CGE addition effectively decreased the microbial count and maintained the minced beef’s sensory and chemical quality. Additionally, CGE extended the shelf life of minced meat up to 15 days under the proper refrigeration condition compared to the control group, which decomposed after the sixth day of refrigeration. Our study suggested that CGE could be used as a natural preservative for refrigerated minced meat.

Genetic characteristics, antimicrobial resistance, and prevalence of Arcobacter spp. isolated from various sources in Shenzhen, China

Arcobacter spp. is a globally emerging zoonotic and foodborne pathogen. However, little is known about its prevalence and antimicrobial resistance in China. To investigate the prevalence of Arcobacter spp. isolated from various sources, 396 samples were collected from human feces, chicken cecum, and food specimens including chicken meat, beef, pork, lettuce, and seafood. Arcobacter spp. was isolated by the membrane filtration method. For 92 strains, the agar dilution method and next-generation sequencing were used to investigate their antimicrobial resistance and to obtain whole genome data, respectively. The virulence factor database (VFDB) was queried to identify virulence genes. ResFinder and the Comprehensive Antibiotic Resistance Database (CARD) were used to predict resistance genes. A phylogenetic tree was constructed using the maximum likelihood (ML) method with core single-nucleotide polymorphisms (SNPs). We found that 27.5% of the samples (n = 109) were positive for Arcobacter spp., comprising Arcobacter butzleri (53.0%), Arcobacter cryaerophilus (39.6%), and Arcobacter skirrowii (7.4%). Chicken meat had the highest prevalence (81.2%), followed by seafood (51.9%), pork (43.3%), beef (36.7%), lettuce (35.5%), chicken cecum (8%), and human fecal samples (0%, 0/159). Antimicrobial susceptibility tests revealed that 51 A. butzleri and 40 A. cryaerophilus strains were resistant to streptomycin (98.1, 70%), clindamycin (94.1, 90%), tetracycline (64.7, 52.5%), azithromycin (43.1%, 15%), nalidixic acid (33.4, 35%), and ciprofloxacin (31.3, 35%) but were susceptible to erythromycin, gentamicin, chloramphenicol, telithromycin, and clindamycin (≤10%). A. skirrowii was sensitive to all experimental antibiotics. The virulence factors tlyA, mviN, cj1349, ciaB, and pldA were carried by all Arcobacter spp. strains at 100%, and the following percentages were cadF (95.7%), iroE (23.9%), hecB (2.2%), hecA, and irgA (1.1%). Only one A. butzleri strain (F061-2G) carried a macrolide resistance gene (ereA). One A. butzleri and one A. cryaerophilus harbored resistance island gene clusters, which were isolated from pork and chicken. Phylogenetic tree analysis revealed that A. butzleri, A. cryaerophilus, and A. skirrowii were separated from each other. To our knowledge, this is the first report of the isolation of Arcobacter spp. from vegetables and seafood in China. The resistance island gene cluster found in pork and chicken meat and the presence of virulence factors could be a potential risk to human health.

The ability of Aliarcobacter butzleri strains isolated from foods of animal origin in Costa Rica to form biofilm

Aliarcobacter butzleri is a zoonotic emerging food and waterborne pathogen widely distributed in nature. It is present in food processing environments and can easily be spread through the food industry because of its ability to form biofilm. The aim of this work was to determine the ability of strains isolated in Costa Rica from different food matrixes of animal origin to form biofilm. Thirty-eight A. butzleri strains previously isolated and identified from animal origin products were analyzed using the method described by Stepmovic et al. (2000), in three culture broths, brain heart infusion broth, Boer broth and Houf broth. Results showed that 67% of poultry origin strains, 62.5% of meat origin strains and just 8% of milk origin strains showed ability to form biofilm. The findings of this study confirm the adherence ability of A. butzleri to form biofilm, a characteristic that can promote dispersion and cross contamination along food industry processing lines.

Sensitivity to Oxygen in Microbial Electrochemical Systems Biofilms

The formation and bioelectric performance of anode biofilms in microbial electrochemical systems (MESs) are sensitive to oxygen. Investigating the temporal-spatial structure of anode biofilms will help elucidate the interfaces between oxygen and bacteria, thereby facilitating the applications of MESs in wastewater treatment and energy recovery. Here, use of optical coherence tomography, frozen sections, and a microsensor revealed that the aerobic biofilms exhibited a multilayered sandwich structure with a sparse gap between the aerobe- and amphimicrobe-enriched outer layer and the dense exoelectrogen-enriched inner layer, whereas the anaerobic biofilm consisted of only a single dense layer. Our results showed that the inner layer of aerobic anode biofilms performed electricity generation, whereas the outer layer only consumed oxygen. In this case, electron donor diffusion through the outer layer became the limiting factor in electricity generation by the bioanode. Consequently, as the anode biofilms matured, current generation decreased.

First isolation report of Arcobacter cryaerophilus from a human diarrhea sample in Costa Rica

Arcobacter cryaerophilus is an emerging enteropathogen and potential zoonotic agent transmitted by food and water. In Costa Rica, this bacterium has not been associated with cases of human gastroenteritis, even though it has been isolated from farm animals, especially poultry. This paper reports the first isolation of A. cryaerophilus from a human case of bloody watery diarrhea and the virulence genes associated with this isolate.