Tissues are valuable microbiological samples that have proved superiority over swabs. Culture of tissue samples is used in the diagnosis of a variety of infections. However, as well as factors such as the site of obtaining the sample, the number of samples, and previous antibiotic use, the method of tissue processing may have an important effect on sensitivity. Data from the literature comparing different tissue processing methods is very limited. This study aimed to compare different mechanical and chemical methods of tissue processing in terms of efficacy and retaining the viability of the bacteria in the tissues. Standard suspensions of Staphylococcus aureus and Escherichia coli were prepared and treated differently to test the effect of that treatment on bacterial viability. Artificially inoculated pork tissue and known infected human tissue samples were then processed by different methods prior to culture, and results were compared. Percentages of reduction in the number of viable bacteria compared to the control by homogenization was similar to 5-min dithiothreitol treatment but significantly lower than bead beating. Bacterial recovery from homogenized human tissues was significantly higher than from any other method of treatment. Although bead beating could be the most efficient method in obtaining a homogeneous tissue product, it significantly reduces the number of viable bacteria within tissues. Homogenization offers the most effective easily controllable retrieval of bacteria from tissue and retains their viability. Guidelines for diagnosing infections using tissue samples should include a standardized processing method.
Prosthetic joint infection is usually caused by staphylococci. Among the coagulase-negative staphylococci, Staphylococcus lugdunensis is important because it behaves as a pathogen similar to S aureus. It also develops biofilms, and the biofilm phenotype can appear as small-colony variants. Although genetically indistinguishable, they differ in size and antibiotic susceptibility from the parent strain and are responsible for chronic persistent infection and failure of antibiotic treatment. They can also lead to misinterpretation of results. The patient reported here underwent total knee replacement and 2 years later presented with prosthetic joint infection. Tissue samples and prosthesis taken at revision grew S lugdunensis, the majority of which were small-colony variants. Recommendations are made for their detection and identification.
False negative culture results in periprosthetic joint infection (PJI) are not uncommon particularly when patients have received long term antibiotics. Polymerase chain reaction (PCR) has a lower specificity partly due to detection of residual DNA from dead bacteria. Propidium monoazide (PMA) prevents DNA from dead bacteria from being amplified during the PCR. This study aimed to determine the role of PMA in PCR for diagnosis of PJI. Clinical samples were tested by PCR with and without prior treatment with PMA and compared to conventional microbiological culture. The PCR assay included genus-specific primers for staphylococci and enterococci and species-specific primers for Cutibacterium acnes. The validated conditions of PMA treatment used in this study were 20 μM concentration and 5 and 10 min of dark incubation and photo-activation respectively. 202 periprosthetic tissues and explanted prostheses from 60 episodes in 58 patients undergoing revision arthroplasties for either PJI or non-infective causes were tested, by culture, PCR, and PMA-PCR. 14 of the 60 episodes satisfied the Musculoskeletal Infection Society (MSIS) criteria for PJI and 46 did not. Sensitivity of culture, PCR, and PMA-PCR were 50%, 71%, and 79% respectively. Specificities were 98%, 72%, and 89% respectively. All figures were calculated for episodes rather than samples. PMA-PCR enhanced both the specificity and the sensitivity of PCR. It has the potential to detect residual bacterial viability prior to reimplantation in the two-stage revision for PJI.
Low-fat cake prepared by partial replacement of shortening with Maltodextrin or Simplesse were organoleptically evaluated and subjected to analysis for gross composition and caloric value. A nutrition experiment on rats was conducted to determine the effect of lowfat cake diet on growth parameters and serum lipid profile. The sensory evaluation results indicated that no significant difference (P≤ 0.05) was found among replacement treatments up to 50% replacement level and the full fat cake, and the panelists considered that, all treatments were acceptable up to 75% replacement level. The results of gross chemical composition and caloric value showed a significant decreased (P≤ 0.05) in fat content and caloric value by increasing fat replacement level. The final body weight, weight gain, feed efficiency ratio and the organ weight (% of body weight) of rats were not significantly (P≤ 0.05) affected by fat replacement. Triglycerides (T.G), total cholesterol and low density lipoprotein cholesterol (LDL-C) of serum were significantly (P≤ 0.05) decreased by replacement 50% or 75% of shortening using both fat replacers. The calculated Atherogenic Index was significantly decreased (P≤ 0.05) by fat replacement at ratio of 25%, 50% and 75% by using maltodextrin or at ratio of 50% and 75% by simplesse.
Background: Hepatocellular carcinoma (HCC0 is the most common primary hepatic malignancy worldwide [1] . It is the first cause of cancer mortality in Egypt [2] due tothe heavy burden of chronic HCV (14.7%). Among cirrhotic patients, 1-4% per year will develop HCC [3] . HCC patients evaluated for liver transplantation are often given exceptional MELD score, giving them a priority for liver transplantation. We aimed at determining the MELD score in HCC patients, its correlation with TNM tumour stage and tumour size. Also, we aimed at determining a cut off value of MELD score above which chronic HCV (CHC) cirrhotic patients have high chance to develop HCC. Aim of Work:To determine the actual MELD score in HCC patients, its correlation with TNM stage and tumour size. Also, we aimed at termining a cut off value of MELD score above which chronic HCV (CHC) cirrhotic patients have a high chance to develop HCC. Material and Methods:The study included 98 patients with CHC and HCC (group I) and 219 patients with CHC without HCC (group II). CHC was diagnosed by ELISA for HCV Antibody and serum HCV RNA. HCC diagnosis was based on EASL criteria i.e. focal hepatic lesion with arterial phase enhancement and washout in portal and delayed phases, obtained by contrast enhanced abdominal CT and/or MRI. HCC was staged according to the seventh edition TNM tumour staging system. MELD score was calculated using the following formula: MELD score=10 *[(0.957*In (Creatinine)] + [0.378*In (Bilirubin)] + [1.12*In (INR)] + 6.43. We used the MELD score calculator of the liver application of the EASL. We computed ROC curve for MELD score concerning the prediction of HCC. Stratum specific likelihood ratio (SSLR) was calculated as the pro-portion of diseased subjects (HCC) with a test result in a given range divided by the proportion of non-diseased subjects (non HCC) with a test result in the same range [4] .Results: MELD score was significantly higher in group I than group II. The score was 9.71 ±4.08 in group I versus 5.61 ±3.25 in group II (p≤ .000). In group I the MELD score ranged from 0.7 to 20.33. There was significant positive correlation between MELD score and TNM tumour stage (r=0.3 12, p=0.002) but the correlation was insignificant as regards the tumour size ( r=0. 041, p=0.687). The distribution of TNM tumour stage in group I was as follows: Stage I represented 19.3%, stage II represented 25.5%, stage IIIa represented 19.3%, stage IIIb represented 18.3%, stage IIIc represented 1%, stage IVa represented 8% and stage IVb represented 7%. The cut off value of MELD score above which there was a high risk of HCC development was ≥5.74.The area under the curve (AUC) was 78.3%, sensitivity was 87.8%, specificity was 56%, positive predictive value (PPV) of 46.7%, negative predictive value (NPV) of 91%, accuracy of 65.3% and positive likelihood ratio (LR) of 1.96. The SSLR for HCC presence by MELD score was 0.21 in score <5, 0.97 in score from 5 to 10 and 4.57 in score >10.Conclusion: MELD score has significant positive correlation with TNM tum...
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