Can Humidifier Reservoir Bacteria Colonize the Circuit During Mechanical Ventilation?

Background:Although the circuit condensate, an ideal bacterial reservoir, may flow into the humidifier reservoir (HR), no study has investigated if HR-colonized bacteria colonize other circuit locations with airflow. Therefore, the objective of this study was to explore if bacterial growth in the HR leads to bacterial colonization in the ventilator circuit. Methods: A randomized controlled experiment was performed in a public tertiary hospital in Guangdong Province, China. In vitro mechanical ventilation models (n = 60), divided into sterile water samples (n = 30) and broth samples (n = 30), were established. Sterile water was used for humidification in the ventilation models. The sterile water group contained either Acinetobacter baumannii (n = 15) or Pseudomonas aeruginosa (n = 15) in humidifier water. The broth group was similar to the sterile water group, but brain heart infusion broth was added to the HR. After 24, 72, and 168 h of continuous ventilation, bacteria in the humidifier water and at different circuit locations were sampled and cultured, and the results were analyzed by the Chi-square test. The difference in bacterial concentration at the HR outlet was analyzed by the F test, and P < 0.05 was considered statistically significant.Results:Bacterial culture results of the sterile water samples were negative. Bacteria in the humidifier water continued to proliferate in the broth group, and the bacterial concentration at different times was not significantly different (P > 0.05). With prolonged ventilation, the bacterial concentration at the HR outlet increased (P < 0.05). During continuous ventilation, no bacterial growth occurred at 10 cm from the HR outlet and the Y-piece of the ventilator circuit. The bacterial concentration at the HR outlet was higher in the P. aeruginosa group than in the A. baumannii group (P < 0.05).Conclusions:Sterile water in the HR was not conducive to bacterial growth. Although bacteria grew in the HR and could reach the HR outlet, colonization of other circuit locations was unlikely.

Thermophilic and non-thermophilic Campylobacter species Emits Distinct Volatile Organic Compounds in Different Culture Media and Growth Phases

Bacteria emits a multitude of volatile organic compounds (VOCs) into the headspace as a mean of interactions with the environments, as well as intra- and interkingdom communication for survival and persistence in the nature and within their hosts. Campylobacter, which is often found in poultry and ruminants, has shown great persistence in aquatic environments, making it one of the world's most dangerous foodborne pathogens, killing thousands of people annually. In this study, the VOCs emitted by both thermophilic (C. jejuni, C. coli and C. lari) and non-thermophilic Campylobacter (C. fetus) of clinical concerns, impacted by nutrients composition (media) and growth phase were identified. Most thermophilic Campylobacter were shown to release volatile alcohols and ketones (1s,4R,7R,11R-1,3,4,7-Tetramethyltricyclo [5.3.1.0(4,11)] undec-2-en-8-one and Isophorone) during early stationary and stationary phases using active sampling with active charcoal adsorbent and GC-MS analysis. C. jejuni cultured in the Brain Heart Infusion had 1-Heptadecanol in its headspace gas, but not in Bolton Broth. The non-thermophilic C. fetus did not produce alcohols or ketones, but rather a variety of unidentified chemicals that will require further investigation in the future. Overall, PCA analysis revealed that the five Campylobacter strains studied created distinct volatilomes, allowing for future Campylobacter identification based on VOCs.

Isolation of Shewanella putrefaciens GRD 03 from Fish and Explication of Biofilm Adherence Potency on Different Substrates

Foodborne pathogens are the main threat and cause of food poisoning. The majority of food infections have been related to the biofilm formation of foodborne pathogens in the food industry. Shewanella putrefaciens (KX355803, GRD 03), a Gram-negative pathogen isolated from mackerel fish, was identified and recognized as a food spoilage bacterium and a strong biofilm producer. The adhesion or attachment ability of Shewanella putrefaciens was determined on steel, plastic, glass, PVC and wood. NB (Nutrient broth), LB (Luria-Bertani broth), TSB (Tryptic soy broth) and BHI (Brain heart infusion broth) were enriched with glucose and shows optimum for bacterial adhesion. In the microtiter plate method (MTP), the strong attachment was observed at 48 and 72 hours of incubation and significant differences were obtained at p < 0.05. As the incubation period increases, the OD value (Optical density) of samples also increase. Biofilm formation is the major cause cross-contamination, and shows resistance to certain disinfectants, which leads to environmental stress tolerance. This study suggested with optimum biofilm production of isolate from fish by using glucose enriched media on different substrates, also comparing different growth media provide a detailed idea about biofilm-forming ability at different incubation time intervals.

Avaliação da população bacteriana em superfícies e equipamentos da sala de emergência do Hospital Universitário da Universidade Federal do Vale do São Francisco

As infecções hospitalares (IH), atualmente denominadas IRAS, elevam consideravelmente os custos no cuidado do paciente, além de aumentar o tempo de internação, morbidade e mortalidade nos serviços de saúde. O objetivo deste trabalho foi avaliar o perfil bacteriano das superfícies e equipamentos da Sala de Emergência de um hospital universitário. Trata-se de um estudo exploratório com abordagem quantitativa, o qual foi realizado na Sala de Emergência do Hospital Universitário da Universidade Federal do Vale do São Francisco (HU-UNIVASF/EBSERH). A coleta foi realizada em cinco leitos onde foram analisados o ventilador mecânico, os botões de comando do monitor cardíaco, a mesa da cabeceira, o diafragma do estetoscópio, a haste metálica do soro e a parede ao redor de cada leito. Os swabs foram passados nas superfícies e equipamentos e armazenados em tubos com 5ml meio líquido BHI (Brain Heart Infusion). Para isolamento dos microrganismos, as amostras foram semeadas em Ágar Sangue (AS) e incubadas a 37º por 24 horas. Após a incubação foi realizada a coloração de Gram, provas bioquímicas e o antibiograma. Os dados foram digitados em arquivos no formato de planilhas e gráficos e realizada análise descritiva. Obteve-se um total de trinta amostras dos cinco leitos resultando em um total de quarenta e três isolados bacterianos, entre elas, Staphylococcus coagulases negativa, bacilos gram positivo e duas possíveis espécies bacterianas causadores de infecções relacionadas à assistência à saúde, Escherichia vulneralis e Pseudomonas pseudoalcaligenes. Foram isoladas apenas duas espécies possíveis causadoras de infecções que se apresentaram sensíveis a todos os antibióticos testados.

Effects of different shrimp extracts on Vibrio parahaemolyticus growth and virulence

Vibrio parahaemolyticus is the main causative agent of acute hepatopancreatic necrosis disease (AHPND) in shrimp. This study aimed to investigate how shrimp extracts affect the growth and virulence of an AHPND-causative strain known as V. parahaemolyticus XN9. To this end, the bacteria was cultured in media containing 3% extract of each of five shrimp types and their growth kinetics were compared against that from bacteria grown in brain-heart infusion (BHI) media. Eight-hour growth curves were constructed using the plate-counting method. The activity of five extracellular enzymes that contribute to bacterial virulence was examined using the agar-based method. The results showed that V. parahaemolyticus XN9’s growth was strongly enhanced in all five shrimp extract media with the highest increase (25% greater than the BHI medium) found in the giant tiger prawn extract. Additionally, all the shrimp extracts boosted the extracellular enzymatic activity of V. parahaemolyticus XN9, although to different extents. In summary, the shrimp extracts, particularly that from the prawns, not only promoted the viability and growth of V. parahaemolyticus XN9 but also its extracellular enzymatic activities.

Peracetic Acid: A Practical Alternative to Formalin for Disinfection of Extracted Human Teeth

Extracted human teeth provide the closest approximation to teeth in situ and play important roles in dental education and materials research. Since extracted teeth are potentially infectious, the Centers for Disease Control recommend their sterilization by autoclaving or disinfection by formalin immersion to ensure safe handling. However, autoclaving is not recommended for teeth with amalgam fillings and formalin is hazardous. The goal of the present study was to investigate the potential of peracetic acid (PA) as an alternative method to achieve reliable disinfection of freshly extracted teeth. A total of 80 extracted teeth were collected for this study. Whole teeth were incubated in one of four solutions for defined periods of time: sterile water (2 weeks), formalin (2 weeks), PA 1000 ppm (2 weeks), and PA 2000 ppm (1 week). After sectioning, the crown and root fragments were transferred into separate tubes containing brain–heart infusion broth and incubated at 37 °C under anaerobic conditions for 72 h. Absence of broth turbidity was used to assess effectiveness of disinfection. No turbidity was observed in any of the formalin-treated or peracetic acid-treated samples, signifying complete disinfection. Our results indicate that PA can effectively disinfect extracted human teeth, providing a reliable alternative to formalin and autoclaving.

Low-Temperature Plasma Short-Exposure to Decontaminate Peri-Implantitis-Related Multispecies Biofilms on Titanium Surfaces

Peri-implantitis is a bacteria-initiated infection that as yet has no effective treatment. A novel approach to treat peri-implantitis is the use of low-temperature plasma (LTP). LTP disrupts the biofilm while conditioning the surrounding host environment for bone growth around the infected implant. The goal of this study was to evaluate the antimicrobial properties of LTP on newly formed (24-h) and mature (7-days) peri-implant-related biofilms. Biofilm was composed of Actinomyces naeslundii (ATCC 12104), Porphyromonas gingivalis (W83), Streptococcus oralis (ATCC 35037), and Veillonella dispar (ATCC 17748). They were cultivated in brain heart infusion supplemented with 1% yeast extract, hemin (0.5 mg/mL), and menadione (5 mg/mL) and kept at 37⁰C in anaerobic conditions for 24-h. The species were mixed for a final concentration of ~105 colony forming units (CFU)/mL (OD=0.01), and the bacterial suspension was transferred to 24-well plates containing titanium specimens. Biofilms were treated with LTP for 1, 3, and 5 min at 3 or 10 mm from plasma-tip to sample. Controls were no treatment (Negative control=NC) and argon-flow at the same LTP conditions. Positive controls were 14 g/mL amoxicillin and 140 µg/mL metronidazole individually or combined, and 0.12% chlorhexidine. Biofilms were evaluated by CFU, confocal laser scanning microscopy (CLSM), and Fluorescence in situ Hybridization (FISH). Wilcoxon Signed-Rank and Wilcoxon Rank Sum tests were applied (α = 0.05). Bacterial growth was observed in all no-treatment groups corroborated by FISH. LTP treatment significantly reduced all bacteria species when compared to the NC in both tested periods and in all treatment combinations (p≤0.016), these results were corroborated by CLSM. There were no significant differences during biofilm development, between 24-h, 3, and 7 days within each LTP treatment, or among the bacteria within each LTP treatment (p≥0.05). LTP application is effective to reduce peri-implantitis-related multispecies biofilms on titanium surfaces.

Avaliação da microbiota bacteriana conjuntival de cães hígidos atendidos no Hospital Veterinário da Universidade de Marília

A microbiota conjuntival dos cães é formada por uma associação de micro-organismos normalmente não patogênicos, que interagem com o sistema imune do animal e possui função de atuar como barreira natural contra entrada de agentes patogênicos. O presente trabalho foi delineado para investigar os micro-organismos presentes na conjuntiva de cães sadios. Foram utilizados 25 cães sadios da rotina clínico cirúrgica do hospital veterinário da Unimar e após instilar uma gota de colírio anestésico em cada olho colheu-se amostra conjuntival superior e inferior de ambos os olhos com swab etéril, preservando a amostra em meio Stuart e logo após cultivada em meios BHI (Brain Heart Infusion), Ágar sangue de carneiro 6%, Ágar MacConkey e Ágar TSA. Após o crescimento bacteriano foi realizada a identificação dos micro-organismos cultivados por meio de testes de triagem bioquímica como oxidase e catalase, além da análise da morfologia bacteriana em lâmina, padrão e coloração de crescimento em ágar. Houve crescimento bacteriano em amostras colhidas de 20 animais das quais 38% dos isolados foram compatíveis com S. intermedius; 30% de Bacilo sp. e 10% S. aureus. A espécie Staphylococcus sp. é natural de membranas mucosas, não sendo patogênica ao animal. Foi, portanto, constatada a predominância de S. intermedius nas amostras da microbiota do olho dos cães sadios examinados.

In Vitro Comparison of MTA and BC RRM-Fast Set Putty as Retrograde Filling Materials

Background: To compare, in vitro, the bioceramic materials (MTA and BC RRM-fast set putty) capacity to prevent microleakage of Enterococcus faecalis over time. Methods: An experimental design was made with forty extracted human teeth, coronally cut, and prepared to be placed in a leakage system under sterile conditions. They were randomly divided into an experimental group: thirty teeth (fifteen for retrograde filling material MTA and BC RRM-fast set putty, respectively) and a control group: ten teeth (five positive control, five negative control). The 3 mm root-ends were submerged in a brain-heart infusion broth with a red phenol indicator. The coronal access of each sample was inoculated with E. faecalis every seven days to maintain bacterial viability. The lower chamber was evaluated daily for 30 days to observe the turbidity of the culture medium and establish the presence and day of the filtration. Calculation of the colony-forming units (CFU) was performed for each leaked sample. Results: Of the total samples prepared for each type of bioceramic material, leaked 60.0% (9/15) of the MTA group and 40.0% (6/15) of the BC RRM-fast set putty group. All positive controls filtered on the first day of evaluation, while 20% (1/5) of the negative control leaked in the second week. There was no significant difference in leakage between the bioceramic material types, nor concerning the bacterial count and the type of cement used (p = 0.101). Conclusions: This study suggests that BC RRM-fast set putty and MTA have a similar sealing capacity when used as a retrograde filling material in vitro.

Design of a Low-Power Radio Frequency Unit and Its Application for Bacterial Inactivation under Laboratory Conditions

A lab-scale low-power free-running radio frequency (RF) oscillator operating at a frequency of 27.12 ± 0.50 MHz was developed to be suitable for fundamental microbiological research topics. Calibration and validation were conducted for two common foodborne pathogens in relevant microbiological growth media, i.e., Salmonella Typhimurium and Listeria monocytogenes in Tryptic Soy Broth and Brain–Heart Infusion broth, respectively. The evolution of temperature, frequency, and power consumption was monitored during treatments, both with and without bacterial cells. The setup operated within the predefined frequency range, reaching temperatures of 71–76 °C after 15 min. The average power consumption ranged between 12 and 14 W. The presence of bacteria did not significantly influence the operational parameters. The inactivation potential of the RF setup was validated, demonstrating the absence of viable cells after 8 and 10 min of treatment, for S. Typhimurium and L. monocytogenes, respectively. In future studies, the setup can be used to conduct fundamental microbiological studies on RF inactivation. The setup can provide added value to the scientific field, since (i) no consensus has been reached on the inactivation mechanisms of RF inactivation of pathogens in foods and (ii) most commercial RF setups are unsuitable to adopt for fundamental studies.