Comparative performance of isolation methods using Preston broth, Bolton broth and their modifications for the detection of Campylobacter spp. from naturally contaminated fresh and frozen raw poultry meat

Current methodologies and future direction of Campylobacter isolation and detection from food matrices, clinical samples, and the agricultural environment

Campylobacter spp. are the leading cause of bacterial foodborne infections in both developed and developing countries. The food commodities primarily attributed to campylobacteriosis include raw milk, poultry, seafood, and fresh produce. Furthermore, insects, animal/bird fecal material, and agricultural water have been shown to be the sources of Campylobacter contamination in these commodities. Both established and emerging species of Campylobacter have been recovered from food and environmental sources. Therefore, optimal detection and isolation of Campylobacter spp., including the emerging species, is critical for improved surveillance, prevention, and traceback of Campylobacter outbreaks. This review focuses on the existing variability in Campylobacter enrichment and isolation procedures used by researchers and regulatory agencies worldwide, for various matrices. Additionally, the challenges associated with developing and validating new culture, molecular, and immunological methods for rapid and sensitive Campylobacter detection are discussed.

Bactericidal and anti-biofilm effects of uncharged and cationic ultrasound-responsive nitric oxide microbubbles on Pseudomonas aeruginosa biofilms

Bacterial biofilms are a major and ongoing concern for public health, featuring both inherited genetic resistance traits and a conferred innate tolerance to traditional antibiotic therapies. Consequently, there is a growing need for novel methods of drug delivery, to increase the efficacy of antimicrobial agents. This research evaluated the anti-biofilm and bactericidal effects of ultrasound responsive gas-microbubbles (MBs) of either air or nitric oxide, using an in vitro Pseudomonas aeruginosa biofilm model grown in artificial wound medium. The four lipid-based MB formulations evaluated were room-air MBs (RAMBs) and nitric oxide MBs (NOMBs) with no electrical charge, as well as cationic (+) RAMBs⁺ and NOMBs⁺. Two principal treatment conditions were used: i) ultrasound stimulated MBs only, and ii) ultrasound stimulated MBs with a sub-inhibitory concentration (4 µg/mL) of the antibiotic gentamicin. The total treatment time was divided into a 60 second passive MB interaction period prior to 40 second ultrasound exposure; each MB formulation was tested in triplicate. Ultrasound stimulated RAMBs and NOMBs without antibiotic achieved reductions in biofilm biomass of 93.3% and 94.0%, respectively. Their bactericidal efficacy however was limited, with a reduction in culturable cells of 26.9% and 65.3%, respectively. NOMBs with sub-inhibitory antibiotic produced the most significant reduction in biofilm biomass, corresponding to a 99.9% (SD ± 5.21%); and a 99.9% (SD ± 0.07%) (3-log) reduction in culturable bacterial cells. Cationic MBs were initially manufactured to promote binding of MBs to negatively charged biofilms, but these formulations also demonstrated intrinsic bactericidal properties. In the absence of antibiotic, the bactericidal efficacy of RAMB⁺ and NOMB⁺ was greater that of uncharged counterparts, reducing culturable cells by 84.7% and 86.1% respectively; increasing to 99.8% when combined with antibiotic. This study thus demonstrates the anti-biofilm and bactericidal utility of ultrasound stimulated MBs, and specifically is the first to demonstrate the efficacy of a NOMB for the dispersal and potentiation of antibiotics against bacterial biofilms in vitro. Importantly the biofilm system and complex growth-medium were selected to recapitulate key morphological features of in vivo biofilms. The results us offer new insight for the development of new clinical treatments, for example, in chronic wounds.

Prevalence of Campylobacter spp. in Chicken Carcasses in Slaughterhouses from South of Brazil

Campylobacteriosis has become common cause of diarrhea in humans and is associated with Guillain-Barré Syndrome, Reactive Arthritis and Irritable Bowel Syndrome is caused mainly by contaminated food and water intake in which the majority occurs from manipulation, preparation and consumption of poultry meat. The aim of this study was to estimate the prevalence of Campylobacter in chicken carcasses from slaughterhouses located in the states of Parana, Santa Catarina and Rio Grande do Sul in the South of Brazil. The samples were analyzed for Campylobacter enumeration using the ISO method 10272-2 and the species C. jejuni and C. coli, important for public health, were identified through Maldi-TOF mass spectrometry. From July 2017 to July 2018, 816 samples were analyzed, indicating the prevalence of 35.84%, with higher occurrence of C. jejuni (78.47%). No difference in prevalence was observed in relation to the size of the slaughterhouses. However, significant differences were noted among the three states in the southern region of the country, with the lowest prevalence being observed in Parana. The results reinforce the need to advance in the implementation of strategies to control this pathogen in the country, in order to safeguard consumer's health and contribute for the maintenance of Brazil's position in the international poultry meat market.

Research Note: A baseline survey of thermotolerant Campylobacter in retail chicken in southern Brazil

Chicken is a leading source of thermotolerant Campylobacter, which triggers human foodborne enteritis. This study evaluated thermotolerant Campylobacter contamination of retail chicken in southern Brazil, using qualitative and quantitative analyses. Selective enrichment in Bolton broth for 24 and 48 h after plating onto modified charcoal-cefoperazone-deoxycholate (mCCD) agar and Preston agar was assessed. The combined results of the detection and enumeration methods revealed a frequency of 70% occurrence of thermotolerant Campylobacter in chicken samples. Campylobacter was enumerated in 60% of the samples, whereas 46% of the samples were positive in the qualitative analysis. Quantitative analysis showed average counts of 3.10 ± 0.15 log₁₀ CFU/sample. Higher numbers of Campylobacter-positive samples were found using 24-h enrichment before plating onto Preston agar (46%) than onto mCCD agar (2%). The majority of isolated strains were identified as Campylobacter jejuni, and Campylobacter coli was also found but to a lesser extent. Subtyping revealed a clear distinction between strains isolated from different chicken sources. The enriched samples plated onto mCCD agar showed extensive spreading of nonproducing extended-spectrum β-lactamases Proteus mirabilis that hampered the identification of Campylobacter colonies. P. mirabilis strains showed resistance to cefoperazone, trimethoprim, and polymyxin B present in broth and plate media used and were inhibited by rifampicin present in Preston agar. The results underline the effect of the spread of contaminant strains on Campylobacter cultures, which might be prevented using a recently revised International Organization for Standardization method for qualitative analysis of chicken.

Electrochemical and Optical Biosensors for the Detection of Campylobacter and Listeria: An Update Look

Foodborne safety has aroused tremendous research interest in recent years because of a global public health problem. The rapid and precise detection of foodborne pathogens can reduce significantly infection diseases and save lives by the early initiation of an effective treatment. This review highlights current advances in the development of biosensors for detection of Campylobacter spp. and Listeria monocytogenes that are the most common causes of zoonosis. The consumption of pathogen contaminated food is responsible for humans hospitalization and death. The attention focused on the recognition elements such as antibodies (Ab), DNA probes and aptamers able to recognize cells, amplicons, and specific genes from different samples like bacteria, food, environment and clinical samples. Moreover, the review focused on two main signal-transducing mechanisms, i.e., electrochemical, measuring an amperometric, potentiometric and impedimetric signal; and optical, measuring a light signal by OLED (Organic Light Emitting Diode), SPR (Surface Plasmon Resonance), and Optical fiber. We expect that high-performance of devices being developed through basic research will find extensive applications in environmental monitoring, biomedical diagnostics, and food safety.