Aerobic Culture Methods Research Articles

PSXIV-27 Liver Abscesses in Feedlot Cattle: Further Studies on Etiology and Pathogenesis Liver Abscesses in Feedlot Cattle: Further Studies on Etiology and Pathogenesis

Abstract Liver abscesses (LA) are a polymicrobial infection and the causative agents include two subspecies of Fusobacterium necrophorum, necrophorum and funduliforme, and Trueperella pyogenes. Nucleic acid-based analysis of the purulent material of LA has indicated that Proteobacteria and Bacteroidetes were the dominant phyla, next to phylum Fusobacteria. The sporadic isolations of bacterial species of the Proteobacteria and Bacteroidetes in LA have been reported. An aspect of the pathogenesis that has not been investigated is whether bacterial pathogens in LA originate, besides the rumen, from the colon? Therefore, our objectives were to target detection and isolations of Salmonella enterica, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Bacteroides fragilis, in addition to routine isolations of F. necrophorum and T. pyogenes, from LA and also from ruminal and colonic epithelial tissues of the same animals. Liver abscesses, matched with ruminal and colonic epithelial tissue samples from 96 steers and heifers, originating from 15 feedlots, were collected at slaughter, transported to the laboratory and processed within 24 hours. Samples were subjected to anaerobic and aerobic culture methods, including enrichment and selective media for detection and isolation of S. enterica, E. coli, K. pneumonia, P. aeruginosa, and B. fragilis. Prevalence of bacterial species were shown in table 1. For each bacterium, two-sided Fisher's exact test was used to evaluate the association of its prevalence in LA with that in colon and rumen at 0.05 level. Overall, prevalence of subsp. necrophorum, subsp. funduliforme, T. pyogenes and S. enterica in liver abscesses were 86.4% (83/96), 21.8% (21/96), 35.4% (34/96) and 6.2% (6/96), respectively (Table 1). In ruminal tissue samples, prevalence of subsp. necrophorum, subsp. funduliforme, T. pyogenes and S. enterica were 6.6% (6/96), 40.6% (39/96), 11.4% (11/96) and 4.1% (4/96), respectively. Prevalence of subsp. necrophorum, subsp. funduliforme, T. pyogenes and S. enterica in colonic tissues were 18.7% (18/96), 36.4% (35/96), 0% (0/96) and 7.2% (7/96), respectively. Prevalence of E. coli, Klebsiella spp., and P. aeruginosa in LA samples were 70.8% (68/96), 92.7% (89/96), and 91.6% (88/96), respectively. Prevalence of E. coli, Klebsiella spp., and P. aeruginosa in rumen epithelial tissue samples were 17.7% (17/96), 50.0%, (48/96), and 15.6% (15/96), respectively. Prevalence of E. coli, Klebsiella spp., and P. aeruginosa in colonic tissue samples were 16.6% (16/96), 24.0% (26/96), and 12.5% (12/96), respectively. Prevalence of subsp. funduliforme in ruminal and colonic tissues was greater than subsp. necrophorum. None of the liver abscess samples yielded B. fragilis. In conclusion, E. coli was the second most dominant species detected and isolated from LA, next only to subsp. necrophorum. The greater frequencies of isolations of subsp. necrophorum and S. enterica from colonic epithelial than ruminal epithelial tissues suggest that hindgut could also be a source of pathogens involved in LA.

Development of a feed-forward control system for medium in shake-flask culture

Shake-flask culture is used in various applications and is one of the most widely used aerobic culture methods at the laboratory scale. Most shake-flask cultures used upstream of bioprocess development use a batch mode strategy, necessitating the expansion of culture conditions in upstream bioprocess development not limited to batch mode. Hence, the development of convenient small-scale fed-batch culture methods is necessary. The aim of this study was to develop a system that can provide a feed strategy for shaking cultures using an Erlenmeyer flask with a breathable culture stopper. The developed system comprises commercial products, is equipped with a sampling unit that does not interfere with the feeding strategy when collecting culture broth during shaking culture, and is applied to a shake-flask culture of Saccharomyces cerevisiae. The set values for bacterial yield and specific growth rate were fixed at 0.5 g-dry cell/g-D-glucose and 0.2 /h, respectively, whereas the measured values were observed to be 0.55 g-dry cell/g-D-glucose and 0.22 /h, respectively (batch mode: 0.22 g-dry cell/g-D-glucose and 0.45 /h, respectively). These results indicate that the developed system enables highly accurate feed-forward control of the feeding solution without changing the conventional components used in the shake-flask culture methods.

The impact of lens care solutions on corneal epithelial changes during daily silicone hydrogel contact lens wear as measured by in vivo confocal microscopy.

To assess corneal epithelial microstructure via confocal microscopy and determine if cellular changes are associated with lens care solutions during daily wear of silicone hydrogel contact lenses. Corneal in vivo confocal microscopy with the Nidek ConfoScan4 was performed at baseline and after 5 months of lotrafilcon A daily contact lens wear. Enrolled participants were randomized to use either a polyhexamethylene biguanide (PHMB) preserved multipurpose care solution (MPS) or a peroxide based solution system. Lens and storage case bioburden were assessed with aerobic culture methods. Univariate and multivariable analyses were done to evaluate the association between solution use, or solution-related clinical covariates, and morphologic differences (hyper-reflectivity) in the superficial epithelial cells and epithelial basal cell density. Data on 139 participants were available for analysis of superficial epithelial cells while data on 92 participants were available for epithelial basal cell density. Five months after randomization to the solution groups, 33% of participants had visible hyper-reflective cells. More participants using MPS had ≥1 hyper-reflective cells compared to peroxide users at 5 months (44% vs. 22%; p=0.006). Similarly at 5 months, more participants with solution-induced corneal staining (SICS) had ≥1 hyper-reflective cells compared to non-SICS participants (57% vs. 29%; p=0.010). The adjusted odds ratios (ORs) for risk of presenting with hyper-reflective cells in MPS users or SICS participants was 2.7 (95% CI; 1.27-5.65) and 3.4 (95% CI; 1.29-8.97), respectively. Basal cell density decreased by over 350 cells/mm2 over time (about 6%) in participants who had substantial bioburden on their lenses or in their storage case. The confocal microscope can detect epithelial cellular changes in vivo during contact lens wear. Hyper-reflective superficial epithelial cells are associated with a PHMB preserved solution and decreases in basal epithelial cell density may be associated with bacterial bioburden.

Bacteria in sputum of patients with chronic chest lesions in chest department of Beni-Suef University Hospital

Pulmonary infection in chronic chest lesions (CCL) is poly-microbial and it is possible that anaerobic bacteria that are not detected by routine aerobic culture methods may be present in the airways mucus.

Combination of microbiological culture and multiplex PCR increases the range of vaginal microorganisms identified in cervical cancer patients at high risk for bacterial vaginosis and vaginitis.

Bacterial vaginosis (BV) and vaginitis in cervical cancer patients might becaused by mixed aerobic, anaerobic, and atypical bacteria. Since genital tract infections can be complicated, early and accurate identification of causal pathogens is vital. The purpose of this study was i) to determinate if currently used aerobic culture methods are sufficiently sensitive to identify pathogens that can appear in the cervix of women after cancer treatment; ii) to investigate if molecular methods can improve the diagnostic process of BV and vaginitis, as well as broaden the range of detectable pathogens that would otherwise be difficult to cultivate. A one-year hospital-based study was conducted in 2011/2012. Cervical swabs from 130 patients were examined by microbiological culture and multiplex PCR. Swab samples were positive for 107 and 93 women by microbiological culture and multiplex PCR, respectively The most common bacteria isolated from culture were: Escherichia coli, Enterococcus faecalis, Streptococcus agalactiae, and Staphylococcus aureus, and using the molecular technique were: Gardnerella vaginalis, Bacteroides fragilis, Ureoplasma ureoliticum/parvum, Mobiluncus curtisii and Atopobium vaginae. Multiplex PCR might contribute to the diagnosis of genital tract infections and it broadens the number of detectable microorganisms responsible for BV. Combination of these two methods may become the basis for standardized diagnosis of BV and vaginitis.

Clinical identification of bacteria in human chronic wound infections: culturing vs. 16S ribosomal DNA sequencing

BackgroundChronic wounds affect millions of people and cost billions of dollars in the United States each year. These wounds harbor polymicrobial biofilm communities, which can be difficult to elucidate using culturing methods. Clinical molecular microbiological methods are increasingly being employed to investigate the microbiota of chronic infections, including wounds, as part of standard patient care. However, molecular testing is more sensitive than culturing, which results in markedly different results being reported to clinicians. This study compares the results of aerobic culturing and molecular testing (culture-free 16S ribosomal DNA sequencing), and it examines the relative abundance score that is generated by the molecular test and the usefulness of the relative abundance score in predicting the likelihood that the same organism would be detected by culture.MethodsParallel samples from 51 chronic wounds were studied using aerobic culturing and 16S DNA sequencing for the identification of bacteria.ResultsOne hundred forty-five (145) unique genera were identified using molecular methods, and 68 of these genera were aerotolerant. Fourteen (14) unique genera were identified using aerobic culture methods. One-third (31/92) of the cultures were determined to be < 1% of the relative abundance of the wound microbiota using molecular testing. At the genus level, molecular testing identified 85% (78/92) of the bacteria that were identified by culture. Conversely, culturing detected 15.7% (78/497) of the aerotolerant bacteria and detected 54.9% of the collective aerotolerant relative abundance of the samples. Aerotolerant bacterial genera (and individual species including Staphylococcus aureus, Pseudomonas aeruginosa, and Enterococcus faecalis) with higher relative abundance scores were more likely to be detected by culture as demonstrated with regression modeling.ConclusionDiscordance between molecular and culture testing is often observed. However, culture-free 16S ribosomal DNA sequencing and its relative abundance score can provide clinicians with insight into which bacteria are most abundant in a sample and which are most likely to be detected by culture.

Relationship of Bacteremia to Toothbrushing in Patients with Periodontitis

The purpose of this research was to investigate the occurrence of bacteremia after tooth- and gingival brushing. Conventional aerobic culture methods were used, as well as prereduced anaerobic culture methods with a new adaptation of anaerobic agar culture medium to quantitate anaerobic bacteria in blood samples. Thirty patients with periodontitis were selected for the brushing study. As a base-line study, nine patients who were having extractions participated. Bacteria found in cultures of blood samples taken from the brushing group were compared with the bacteria found in cultures of samples taken from the extraction group. Bacteremia was found in five of the 30 individuals after brushing and in all nine patients after extractions. No microorganisms were detected in the prebrushing or presurgical blood culture control samples. The results indicate that the incidence of bacteremia after brushing in patients with periodontitis may be of serious consideration in the management of high-risk patients such as those with a history of rheumatic fever or congenital cardiac defects, or those who have intracardiac and vascular prostheses.