Evaluation of a novel Clostridioides difficile-selective growth broth under aerobic conditions.

A newly developed Clostridioides difficile-selective growth broth, which can be cultured under aerobic conditions, was found to have a sensitivity/specificity (98%/89%) comparable to conventional anaerobic culture methods. This might be a powerful tool for diagnosing Clostridioides difficile infection in resource-limited regions and health care settings in the future.

Degradation characteristics of polyethylene film by microorganisms from lake sediments.

Polyethylene (PE) exists widely in many habitats as a persistent organic pollution and poses a major threat to the ecological environment. In this study, bacterial communities in freshwater lake sediments were exposed to culture media using PE films as the sole carbon source in aerobic and anaerobic microculture environments, and they were able to adhere and adapt to the PE films for a longer period of time. The results demonstrated that the pH value of the medium in the two cultural conditions was distinct, as were the rates of films weight loss and surface functional group alterations. We also concluded the certain bacterial genera from freshwater lake sediments who may be able to degrade PE films under either aerobic or anaerobic conditions. Simultaneously, the dominating bacterial communities between the medium and the film differed significantly under two cultural settings, as did the community composition, while metabolism was the primary function.

Intraoperative Surgical Wound Contamination May Not Lead to Surgical-Site Infection in Patients Undergoing Clean Orthopaedic Procedures.

Objectives Surgical-site infections (SSIs) can complicate virtually any surgical procedure. While SSI can result from numerous causes, contamination of the surgical field can also contribute to it. Intraoperative bacterial contamination during clean orthopaedic procedures can be detected using perioperative cultures. We hypothesized that perioperative cultures could be used to predict possibility of development of SSI in patients undergoing clean orthopaedic surgeries. Materials and Methods We conducted a prospective cohort study at a tertiary care hospital over a 2-year period. Intraoperative surgical wound lavage fluid and closed suction drain tip obtained in the postoperative period were sent for aerobic culture. All patients were followed up to look for the development of SSI for a period of at least 30 days for those undergoing nonimplant surgery, and 90 days for those with implant surgery. Statistical Analysis Means with standard deviation of the continuous data were calculated. Fisher's exact test and chi-square test were used for the analysis of the categorical variables. Relative risk and odds ratio were calculated to evaluate the association of the parameters under study with SSI. Results A total of 384 patients satisfying the inclusion and exclusion criteria were included. Perioperative cultures detected surgical wound contamination in 39 patients (10.1%). Forty-five patients (11.7%) developed SSI during the follow-up period. Skin commensals constituted 59% of perioperative contaminants and accounted for 20% of the SSIs. The relative risk of developing SSI with perioperative contamination was 0.41 (95% confidence interval: 0.09-1.63). Conclusion Intraoperative surgical-site contaminants could be detected using perioperative cultures. However, these contaminants did not lead to SSI. Timely treatment of perioperative contamination with appropriate antibiotics and local wound care probably helped in the reduction of SSI.

Growth of various obligate and facultative anaerobic intestinal bacteria in cell culture medium under aerobic and anaerobic culture conditions.

Eight bacterial strains were used in this study to examine the survival of intestinal bacteria in immune cell cultures under aerobic and anaerobic culture conditions. With the addition of penicillin G and streptomycin, viable Clostridium clostridioforme and Fusobacterium varium cells did not decrease after 6 or 24 hr, even under aerobic conditions. Without antibiotics, eight bacterial strains did not decrease until 4 or 6 hr later, under both aerobic and anaerobic conditions. Escherichia coli numbers increased by more than 10 times under both conditions. In order to examine the effects of live gut bacteria on various immune cells, the viability of bacteria should be checked in cell culture media and under different conditions.

Pseudomonas aeruginosa Bacterioferritin Is Assembled from FtnA and BfrB Subunits with the Relative Proportions Dependent on the Environmental Oxygen Availability.

Ferritins are iron storage proteins assembled from 24 subunits into a spherical and hollow structure. The genomes of many bacteria harbor genes encoding two types of ferritin-like proteins, the bacterial ferritins (Ftn) and the bacterioferritins (Bfr), which bind heme. The genome of P. aeruginosa PAO1 (like the genomes of many bacteria) contains genes coding for two different types of ferritin-like molecules, ftnA (PA4235) and bfrB (PA3531). The reasons for requiring the presence of two distinct types of iron storage protein in bacterial cells have remained largely unexplained. Attempts to understand this issue in P. aeruginosa through the recombinant expression of the ftnA and bfrB genes in E. coli host cells, coupled to the biochemical and structural characterization of the recombinant 24-mer FtnA and 24-mer BfrB molecules, have shown that each of the recombinant molecules can form an Fe3+-mineral core. These observations led to the suggestion that 24-mer FtnA and 24-mer BfrB molecules coexist in P. aeruginosa cells where they share iron storage responsibilities. Herein, we demonstrate that P. aeruginosa utilizes a single heterooligomeric 24-mer Bfr assembled from FtnA and BfrB subunits. The relative content of the FtnA and BfrB subunits in Bfr depends on the O2 availability during cell culture, such that Bfr isolated from aerobically cultured P. aeruginosa is assembled from a majority of BfrB subunits. In contrast, when the cells are cultured in O2-limiting conditions, the proportion of FtnA subunits in the isolated Bfr increases significantly and can become the most abundant subunit. Despite the variability in the subunit composition of Bfr, the 24-mer assembly is consistently arranged from FtnA subunit dimers devoid of heme and BfrB subunit dimers each containing a heme molecule.

Characterization of a polysaccharide hydrogel with high elasticity produced by a mutant strain Sphingomonas sanxanigenens NX03.

Microbial polysaccharides as renewable bioproducts have attracted lots of attention in various industries. Hesan (Highly elastic Sanxan), an exopolysaccharide produced by a plasma mutagenic strain Sphingomonas sanxanigenens NX03, was characterized. It possessed the same monosaccharide composition as the original polysaccharide Sanxan produced from wild-type strain NX02, but significantly reduced acetyl and glyceryl contents. Textural analysis showed the springiness and cohesiveness of Hesan gel was much higher than Sanxan gel, and rheological behaviors indicated it possessed a lower loss factor, and its conformational transition temperatures at different concentrations were obviously lower than Sanxan gel and high-acyl gellan gel, which suggested that Hesan gel was highly elastic and temperature-sensitive. Additionally, Hesan gel could be efficiently produced through micro-aerobic static culture in shallow (10.46 ± 0.30 g/L) and deep liquids (3.21 ± 0.32 g/L), which was significantly different from the fermentation of other water-soluble polysaccharides. In short, this study characterizes a new mutant strain and its polysaccharide products.

Cultivation of gut microorganisms of the marine ascidian Halocynthia roretzi reveals their potential roles in the environmental adaptation of their host.

It has long been known that abundant symbiotic bacteria exist in the tunic and gut of marine ascidians, and that these play crucial roles in host development, physiological metabolism, and environmental adaptation. However, the identity, roles and functions of these symbiotic bacteria are known for only a few strains. In this study, we isolated and cultivated 263 strains of microorganisms from the intestine of the marine ascidian Halocynthia roretzi through a combination of aerobic and anaerobic culture approaches. Most cultivated species, both aerobic and anaerobic, from ascidian stool samples belonged to the genus Bacillus based on 16S rDNA sequencing identification and phylogenetic assays. The distribution of cultured bacteria varied with seasonal changes in environmental conditions. To explore the functions of cultured bacteria, we screened out a strain of Serratia sp. whose extracts showed high antibacterial activity against aquatic pathogens. These findings revealed the potential roles of gut microorganisms in ascidian defense and environmental adaptation, thus providing insights into the interaction and co-evolution between gut bacteria and their hosts. Supplementary Information: The online version contains supplementary material available at 10.1007/s42995-022-00131-4.

Effect of Peri-Operative Hyperoxygenation on Surgical Site Infection in Patients Undergoing Emergency Abdominal Surgery: A Randomized Controlled Trial.

Background: The rationale for hyperoxygenation in controlling surgical site infection (SSI) has been described in many studies yet has not been defined clearly. Some studies in colorectal surgery have reported beneficial effects, whereas studies in gynecologic surgery have reported either no effect or a deleterious effect. This study assessed the effectiveness of hyperoxygenation on the reduction of SSI in patients undergoing emergency abdominal surgery. Patients and Methods: Eligible patients were assigned randomly to two groups (study group, 80% oxygen or control group, 30% oxygen). The patients in the study group received 80% oxygen and the patients in the control group received 30% oxygen intra-operatively and for two hours after surgery. Arterial blood gas analysis was done after resuscitation, at the end of the surgery, and at two hours after extubation. All patients were assessed for SSI, post-operative nausea and vomiting, and respiratory complications. Patients were followed post-operatively for 14 days. Surgical site infection was diagnosed according to U.S. Centers for Disease Control and Infection (CDC) criteria and by aerobic wound cultures. Results: After exclusion, 85 patients in the control group and 93 patients in the study group were analyzed. There was no difference for baseline, intra-operative, and post-operative characteristics between the two groups, except for higher oxygen saturation at closure and two hours post-operatively, in the 80% group (p = 0.01). Surgical site infection occurred in 29 patients (34.11%) in 30% fraction of inspired oxygen (FIO2) group and in 19 patients (20.43%) in 80% FIO2 group (p = 0.04). The risk of SSI was 59% lower in the 80% FIO2 group (adjusted odds ratio, 0.41; 95% confidence interval [CI], 0.19-0.88 vs. the 30% FIO2 group). There were no differences in post-operative nausea and vomiting and respiratory complications between the two treatment groups. Conclusions: Administration of 80% peri-operative hyperoxygenation in emergency abdominal surgery reduces SSI and is a cost-effective method.

Factors associated with clinical interpretation of tracheal wash fluid from dogs with respiratory disease: 281 cases (2012-2017).

BACKGROUND: Clinicians face several dilemmas regarding tracheal washes (TWs) for the diagnosis of respiratory disease, including method and prediction of bacterial growth from cytology results. OBJECTIVE: To compare cytology and culture of endotracheal and transtracheal washes and identify factors associated with discordancy and bacterial growth. ANIMALS: Two hundred forty-five dogs with respiratory disease. METHODS: Retrospective study. Tracheal wash submissions were included if cellularity was sufficient for cytologic interpretation and aerobic cultures were performed. Collection technique, cytology, bacterial growth, and antibiotic history were analyzed. RESULTS: Fewer transtracheal specimens (9/144, 6.3%) were excluded for hypocellularity than endotracheal (28/174, 16.1%); otherwise, results were similar and were combined. Of 281 specimens with cellularity sufficient for interpretation, 97 (34.5%) had bacteria on cytology and 191 (68.0%) had bacterial growth. Cytology positive/culture negative discordancy was uncommon (8/97, 8%). Cytology negative/culture positive discordancy was frequent (102/184, 55.4%), but occurred less often (28/184, 14.2%) when only 1+ growth or greater was considered positive. Oropharyngeal contamination was associated with bacterial growth, but not discordancy. No association was found between antibiotic administration and bacterial growth. CONCLUSIONS AND CLINICAL IMPORTANCE: Endotracheal wash fluid, in particular, should be screened for gross mucus or turbidity to maximize the likelihood of an adequate specimen. Otherwise, endotracheal and transtracheal specimens were similar. Presence of bacteria on cytology was a good predictor of any growth, while their absence was a good predictor of the absence of growth of 1+ or more. Recent antibiotic usage should not discourage TW culture if there is compelling reason to avoid delay.

Analysis and effect of conventional flasks in shaking culture of Escherichia coli.

The circulation direct monitoring and sampling system (CDMSS) is used as a monitoring device for CO2 and O2 concentrations of bypass type in shake-culture flask. The CDMSS could measure kLa, an index for evaluating the performance of aerobic culture incubators, and kG, an indicator of the degree of CO2 ventilation in the flask gas phase. We observed that cylindrical flasks provided a different culture environment, yielded a much higher kG than the Erlenmeyer and Sakaguchi flasks, and yielded kLa equivalent to that by Erlenmeyer flask by setting the ring-type baffle appropriately. Baffled cylindrical flask used for Escherichia coli K12 IFO3301 shake culture maintained lower CO2 concentrations in the headspace than conventional flasks; therefore, CO2 accumulation in the culture broth could be suppressed. Cell growth in baffled cylindrical flask (with kLa equivalent to that of the Erlenmeyer flask) was about 1.3 and 1.4 times that in the Erlenmeyer and Sakaguchi flasks, respectively. This study focused on the batch culture at the flask scale and designed the headspace environment with low CO2 accumulation. Therefore, we conclude that redesign of flasks based on kLa and kG may contribute to a wide range of fields employing microorganism culture.

Twelve year analysis of aerobic-only blood cultures for routine detection of bacteraemia.

Sampling practices determine the accuracy of blood culture in diagnosing bloodstream infection. The main acute hospital in this study introduced aerobic-only routine blood cultures aiming to increase the volume and number of aerobic samples. At the smaller acute site, aerobic-anaerobic pairs were sent routinely. Culture yield and sampling practices were compared at these two sites and it was found that anaerobic cultures increased the yield of pathogens including facultative anaerobes. Volume cultured and number of samples sent fell short of national recommendations. The aerobic-only policy did not result in more blood being cultured. Based on these findings, the main acute hospital is reintroducing aerobic-anaerobic pairs for routine culture.

Bacteriological Profile of Aerobic and Anaerobic Isolates of Trophic Ulcer in Leprosy: A Study from Eastern India.

INTRODUCTION: Trophic ulcer is a dreaded complication of leprosy. Secondary infection compounds the damage to the already neglected ulcer. AIMS: To find out the bacterial pathogens in the isolates from trophic ulcers of leprosy and to find the drug sensitivity of the aerobic isolates so as to start a suitable antibiotic therapy. METHODOLOGY: An institution-based, cross-sectional study done over a period of 2 years. Swab was taken from the deeper part of the ulcer. It was put on a suitable culture media. Bacteriological profile was determined and antibiogram was done subsequently. RESULTS: Sixty patients with trophic ulcer secondary to leprosy were screened, among which all were screened for aerobic isolates and 38 were screened for anaerobic isolates. Among the aerobic isolates, 88% of patients were culture-positive. The most common organism was Staphylococcus aureus (37.7%), followed by Pseudomonas aeruginosa (22.64%), Proteus mirabilis (15.09%), Escherischia coli (13.2%), Klebsiella (9.43%). Maximum overall sensitivity was seen with amikacin (93.1%) and linezolid (89.65%). Maximum overall resistance was noted with cotrimoxazole (58.62%) and coamoxiclav (51.72%). Among the 38 patients cultured for anaerobic isolates, 17 were culture-positive for anaerobic organisms. Isolates showing Peptococcus were 6 (15.7%), purely Peptostreptococcus were 4 (10.5%), purely bacteroides were 3 (7.8%), and mixed growths were 4 (10.5%). CONCLUSION: Secondary bacterial infection is quite common in leprosy trophic ulcers. The most common organism was Staphylococcus aureus. Isolates were mostly sensitive to amikacin and linezolid and resistant to cotrimoxazole and coamoxiclav. Anaerobic isolates were not uncommon, with Peptococcus being the most common among them.

Conjunctival bacterial flora and antimicrobial susceptibility of captive and free-living sea turtles in Brazil.

PURPOSE: To describe the aerobic conjunctival bacterial flora of 3 especies of free-living and under human care sea turtles and determine its antimicrobial susceptibility in vitro. METHOD: Thirty-six sea turtles (72 eyes), juveniles and adults, 7 free-living Chelonia mydas and 8 Chelonia mydas, 4 Caretta caretta, 11 Eretmochelys imbricata, and 6 Lepidochelys olivacea under human care, were evaluated. Conjunctival cultures were collected for identification of aerobic bacteria and antimicrobial susceptibility testing for ciprofloxacin, chloramphenicol, gentamicin, neomycin, oxacillin, polymyxin B, tetracycline, and tobramycin using antibiotic disks. Bacterial strains showing no sensitivity to 4 or more antimicrobials were considered multiresistant to this panel. RESULTS: Bacterial growth was observed in 12/14 (85.71%) samples in the free-living sea turtles, and there was growth in 100% (58/58) of the samples from captive animals. There were 94 strains isolated and 15 species identified. There was a predominance of Gram-positive bacteria in free-living Chelonia mydas, most of which were Bacillus and Staphylococcus. The most commonly isolated Gram-negative species were enterobacteria for free-living and under human care animals. The strains were predominantly sensitive to ciprofloxacin and tobramycin, and less sensitive to oxacillin or polymyxin B. Ten multiresistant strains were isolated. Yeast were identified in 13.89% (10/72) of the samples. CONCLUSIONS: These results, showing differences in the conjunctival bacterial flora of free-living and captive animals, may be helpful for diagnosis and treatment of ocular disorders in sea turtles.

Effect of intermittent opening of breathable culture plugs and aeration of headspace on the structure of microbial communities in shake-flask culture.

In this study, we found that opening breathable culture plugs for 30 s during periodic and aseptic sampling affects the community structure of cultured soil microbes. Similar effects were observed using an automatic aeration flask system that mimics aseptic opening of the breathable culture plug during sampling, but without interruption in shaking. Thus, the observed changes in the microbial consortia appear to be due exclusively to the intermittent ventilation of the flask headspace. To elucidate the mechanism driving this phenomenon, we monitored CO2 and O2 concentrations in both headspace and culture broth using the new system termed as circulation direct monitoring and sampling system. The data show that the CO2 concentration in the culture broth temporarily decreased with the CO2 concentration in the headspace, strongly suggesting that the effect of intermittent ventilation of the headspace on the microbial consortia depends on CO2. Importantly, the data also imply that environmental variables during shake flask culture, especially CO2 concentration, is important for screening aerobic microorganisms.

Direct Production of (R)-3-Hydroxybutyric Acid of High Optical Purity by Halomonas sp. OITC1261 Under Aerobic conditions.

The chiral compound (R)-3-hydroxybutyric acid (R-3HB) has some important physiological functions in the human body and can also be applied as a functional material for industrial products. A novel Halomonas sp. OITC1261 isolated from a coastal sediment is selected for efficient production of R-3HB. This strain secreted R-3HB of high optical purity into the extracellular medium while maintaining poly(3-hydroxybutyric acid) (PHB) inside the microbial cell under aerobic conditions. There is a possibility that R-3HB is generated independently of PHB. Under aerobic cultivation, 58 g L-1 (0.65 g L-1 h-1 ) of R-3HB was produced simultaneously with 27 g L-1 (0.30 g L-1 h-1 ) of PHB. This direct production method of R-3HB contributes to the improvement of mass production technology.

Isolation, culture and identification of bacterial strains from tree shrews feces / 中国比较医学杂志

Objective Study the fecal flora diversity of the tree shrew , to provide a basis data of fecal bacteria of feeding the tree shrew .Methods Ten tree shrews were used in this study .The Stools of the animals were respectively cultured with oxygen and without oxygen to isolate the bacterial .Then the PCR-amplified 16S rRNA of the bacterial was sequenced and analyzed .Results 25 bacterial strains belonging to ten bacterial species were isolated by anaerobic incubation , and 25 bacterial strains belonging to twelve bacterial species were isolated by aerobic incubation .Proteus vulgaris, Enterococcus faecalis, Escherichia fergusonii, Enterococcus faecium, Shigella flexneri, Shigella sonnei, Staphylococcus aureus , Aeromonas salmonicida subsp .masoucida , Rahnella aquatilis , Exiguobacterium aquaticum , Raoultella terrigena , and Escherichia coli were identified in this study .Conclusions There is a fecal flora diversity of the tree shrew, and the Proteus vulgaris , Escherichia fergusonii and Enterococcus faecium may be the major parasitic flora .