Bacillus licheniformis bloodstream infections associated with oral probiotic administration: Two case reports

Exploring the dark side of probiotics to pursue light: Intrinsic and extrinsic risks to be opportunistic pathogens

Probiotics, live microorganisms with multiple health benefits, have gained popularity for their roles in maintaining daily health and treating a variety of diseases. However, they have the potential to be opportunistic pathogens in some conditions. This review delves into the intrinsic and extrinsic risks associated with probiotics. Intrinsic risks involve the production of harmful substances, such as toxins and invasive factors, biofilm formation, bacteria emboli, antibiotic resistance with relevant genetic materials, genetic plasticity, and metabolic issues, while extrinsic risks include problems in regulatory oversight and public awareness, host health status and appropriately administration. It emphasizes the need for a balanced view of their therapeutic benefits and potential hazards, advocating for further research to understand the complex interactions between probiotics and the human microbiome, to optimize the safety and efficacy of probiotics.

Pseudo-outbreak of Bacillaceae species associated with poor compliance with blood culture collection recommendations

PURPOSE

This study describes a pseudo-outbreak of Bacillaceae spp. bloodstream infections that spanned five months starting in May 2023 and the infection prevention measures implemented to control it.

METHODS

This retrospective study was conducted at a tertiary infectious disease hospital in Bucharest, Romania. An observational audit of the blood culture collection practice in our hospital was performed, and the materials used during blood culture collection were sampled. Bacterial colonies were identified using MALDI Biotyper. The Bacillaceae blood culture positivity rates in the previous four years were compared using the Kruskal‒Wallis rank test.

RESULTS

Bacillaceae spp.-positive blood cultures were recovered from 60 patients over a five-month period. In the case of 58 patients, Bacillaceae spp.-positive blood cultures were considered contaminated. Two patients were treated for Bacillus spp. bacteraemia. The audit revealed significant variation during the preparation of the venipuncture site step and the use of nonsterile medical cotton wool. Medical cotton wool contaminated with species of Bacillaceae was found in 10 out of 12 wards. The control measures included repeated training on the blood culture collection procedure and the removal of Bacillaceae spp.-contaminated cotton wool.

CONCLUSIONS

The pseudo-outbreak was caused by the unjustified use of medical cotton wool for disinfection of the skin and blood culture bottle septums. The investigation of this pseudo-outbreak highlighted a gap in blood culture collection practices at our facility and thus allowed for its improvement.

Spore-forming bacteria in gelatin: Characterization, identification by 16S rRNA and MALDI-TOF mass spectrometry (MS), and presence of heat resistance and virulence genes

Gelatin, a versatile protein derived from collagen, is widely used in the food, pharmaceutical and medical sectors. However, bacterial contamination by spore-forming bacteria during gelatin processing represents a significant concern for product safety and quality. In this study, an investigation was carried out to explore the heat and chemical resistance, as well as the identification and characterization of spore-forming bacteria isolated from gelatin processing. The methodologies involved chemical resistance tests with drastic pH in microplates and thermal resistance tests in capillary tubes of various isolates obtained at different processing stages. In addition, phenotypic and genotypic analyses were carried out to characterize the most resistant isolates of spore-forming bacteria. The findings of this study revealed the presence of several species, including Bacillus cereus, Bacillus licheniformis, Bacillus sonorensis, Bacillus subtilis, Geobacillus stearothermophilus, and Clostridium sporogenes, with some isolates exhibiting remarkable chemical and heat resistances. In addition, a significant proportion of the most resistant isolates showed gelatinase activity (n = 19/21; 90.5 %) and the presence of heat resistance (n = 5/21; 23.8 %), and virulence genes (n = 11/21; 52.4 %). The results of this study suggest that interventions should be done in quality control practices and that process parameter adjustments and effective contamination reduction strategies should be implemented through gelatin processing.

Invited review: Role of Bacillus licheniformis in the dairy industry- friends or foes?

Bacillus licheniformis is one of the major spore-forming bacteria with great genotypic diversity in raw milk, dairy ingredients, final dairy products, and is found throughout the dairy processing continuum. Though being widely used as a probiotic strain, this species also serves as a potential risk in the dairy industry based on its roles in foodborne illness and dairy spoilage. Biofilm formation of B. licheniformis in combined with the heat resistance of its spores, make it impossible to prevent the presence of B. licheniformis in final dairy products by traditional cleaning and disinfection procedures. Despite the extensive efforts on the identification of B. licheniformis from various dairy samples, no reviews have been reported on both hazard and benefits of this spore-former. This review discusses the prevalence of B. licheniformis from raw milk to commercial dairy products, biofilm formation and spoilage potential of B. licheniformis, and its potential prevention methods. In addition, the potential benefits of B. licheniformis in the dairy industry were also summarized.

Recent Records on Bacterial Opportunistic Infections via the Dietary Route

This narrative review was aimed at identifying the opportunistic bacterial pathogens that can be transmitted by contaminated food and represent a current threat for patients particularly susceptible to infections because of underlying conditions or predisposing factors. The analysis was focused on recent case or outbreak reports and systematic reviews published in the years 2019 to 2023 and resulted in sorting 24 bacterial groups comprising the genera or species able to cause a variety of systemic or invasive infections if ingested with food or drinking water. These included both bacteria known to cause mild infections in immunocompetent persons and bacteria considered to be innocuous, which are used in food fermentation or as probiotics. No recent cases of infections transmitted through dietary routes were reported for the critical nosocomial pathogens widely found in food products, primarily Acinetobacter baumannii and Klebsiella pneumoniae. However, the very first sources of their introduction into the clinical environment still need to be established. In many instances, risky dietary habits, such as eating raw fish, seafood, raw meat, unpasteurized milk, and their derived products or the lack of control in fermentation processes, has led to the reported illnesses, pointing out the necessity to improve the hygiene of production and consumer awareness of the risks.