Processing of cardiovascular allografts: effectiveness of European Homograft Bank (EHB) antimicrobial treatment (cool decontamination protocol with low concentration of antibiotics)

To assess the effectiveness of antimicrobial treatment by using cool decontamination protocol with low concentration of antibiotics during processing of cardiovascular allografts, 948 allografts processed during a 2-year period were analysed. Five hundred and fourty one donors aged <62 years were classified in: multiorgan donors (MOD) with non-transplantable hearts; recipients of cardiac transplantation (RHT); and non-beating heart cadavers with a warm ischemic time of less than 6 h (NBHD). During processing three samples for bacteriology testing were taken A (sampling before decontamination); B (sampling after decontamination); C (sampling on the final product). Samples A were positive in 348 cases (36.4%), respectively 36% for MOD, 21.6% for RHT and 78.1% for NBHD. All the allografts were immersed in a cocktail of four antibiotics at 4 °C. After exposure to antibiotics the rate of decontamination of those with A positive was 90.4, 92.5, 82.5% respectively for MOD, RHT, NBHD. At the end of processing, 57 allografts (6%) were positive in B and/or C, 15 allografts remained contaminated with the same bacteria as in A, 42 were contaminated during processing. The overall rate of sterility in the end of processing is 94% and for each group this is: 95.4% for MOD, 96.8% for RHT and 86.3% for NBHD. Analysis shows that there is no influence of time of exposure in AB in the rate of decontamination for MOD and RHT. The most predominant germ in contamination is Coagulase Negative Staphylococcus (CNS) (53.4% alone, 8.9% with other bacteria). 83.3% of MOD; 88.5% of RHT were contaminated with one germ, while 40.4% of NBHD were contaminated with more than one. This revised version was published online in July 2006 with corrections to the Cover Date.     

Bacteriology testing of cardiovascular tissues: comparison of transport solution versus tissue testing

Bacteriology testing is mandatory for quality control of recovered cardiovascular allografts (CVA). In this paper, two different bacteriology examinations (A tests) performed before tissue antibiotic decontamination were compared: transport solution filtration analysis (A1) and tissue fragment direct incubation (A2). For this purpose, 521 CVA (326 heart and 195 artery tissues) from 280 donors were collected and analyzed by the European Homograft Bank (EHB). Transport solution (A1) tested positive in 43.25 % of hearts and in 48.21 % of arteries, whereas the tissue samples (A2) tested positive in 38.34 % of hearts and 33.85 % of arteries. The main species identified in both A1 and A2 were Staphylococcus spp. in 55 and 26 % of cases, and Propionibacterium spp. in 8 and 19 %, respectively. Mismatches in bacteriology results between both initial tests A1 and A2 were found. 18.40 % of the heart valves were identified as positive by A1 whilst 13.50 % were considered positive by A2. For arteries, 20.51 % of cases were positive in A1 and negative in A2, and just 6.15 % of artery allografts presented contamination in the A2 test but were considered negative for the A1 test. Comparison between each A test with the B and C tests after antibiotic treatment of the allograft was also performed. A total decontamination rate of 70.8 % of initial positive A tests was obtained. Due to the described mismatches and different bacteria identification percentage, utilization of both A tests should be implemented in tissue banks in order to avoid false negatives.     

Banking of the human heart valves and the arteries at the European homograft bank (EHB) – Overview of a 14-year activity in this International Association in Brussels<Superscript>*</Superscript>

Processing of the human heart valves and arteries has been carried out at the European Homograft Bank (EHB) in Brussels since 1989 and 1991, respectively. Heart valve donors of 0–65 years were classified in (1) Beating heart donors (BHD), of which recipients of heart transplantation (RHT) and multiorgan donors (MOD) after brain death, and (2) non-beating heart donors (NBHD) with warm ischaemic time (WIT) of less then 6 h. Past history of the donors has been checked for malignant and chronic diseases, as well as biology for transmissible and infectious diseases. Perfect collaboration has been established with the transplant coordinators and transplant teams of the implanting centres. Dissection, decontamination, cryopreservation and storing in fluid nitrogen has been carried out in accordance with the Belgian and European Standards of cardiovascular allografts. During this period, a total of 2.828 hearts, 28 predissected valves and 616 batches of arteries arrived in the EHB. 3.537 valves and 1.137 different arteries were accepted for implantation. The main reasons for tissue rejection were morphology, contamination and cuts during the tissue retrieval or dissection. A huge network of different hospitals in Belgium and elsewhere in Europe and Switzerland were included in this process. Pulmonary allografts were not sent for implantation in the left ventricular outflow tract after 1998, since the early and mid-term results after 76 implantations were disappointing. The number of implanted aortic and pulmonary allografts remains stable from year to year, however the number of the allografts used for Ross operation is still increasing. Since the results of the follow up were disappointing, we still only require the implantation and immediate postoperative results, whereas the follow-up information only for specific study purposes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Decontamination of heart valve and arterial allografts in the European Homograft Bank (EHB): comparison of two different antibiotic cocktails in low temperature conditions

The aim of the study was to compare the efficiency of two different antibiotic cocktails in the cardiovascular allograft decontamination. Low temperature, low-concentration antibiotic cocktail with Cefoxitin, Lincomycin, Polymixin B and Vancomycin was decontamination protocol in EHB for many years. The modified cocktail doesn't contain Cefoxitin. The study had two steps. First step: cardiovascular allografts from 80 donors are incubated in classical (group 1) or modified cocktail (group 2). Second step: 184 and 182 allografts of group 1 and group 2 are incubated in the modified and classical antibiotic cocktail, respectively. The bacteriological examination is performed in three steps: A-transport solution, B-decontamination solution and C-cryopreservation solution. During the first step 23.75% of the tissues were initially contaminated mainly with Staphylococcus (78.95%). 93.75% of the allografts of group 1 and 100% of group 2 were sterile after incubation (p = 0.058). 25.54% and 30.77% of group 1 and 2, respectively were contaminated in A-examination during the second step. Staphylococci were isolated in 82.98% and 69.64% in group 1 and 2, respectively. About 4.35% of group 1 and 5.5% of group 2 were contaminated in A, B, and C whereas 5.4% of group 1 and 4.4% of group 2 were contaminated in B or C after being sterile in A. Finally 9.78% of the tissues were rejected and 90.22% cryopreserved in the modified, whereas 9.89% rejected and 90.11% accepted in the classical group (p = 0.1). The difference was non-significant in the level of decontamination between the two cocktails. Contamination of some tissues with low growing, low-pathogen germs that appeared in B or C examination, couldn't be explained. This issue needs complementary investigation.     

The use of real-time PCR for quantitative determination of some propionic bacteria inhabiting the human skin

A test system has been developed for determination of propionic bacterial species inhabiting the human skin. This system developed in the real time PCR format is applicable for quantitative determination and also detection of genomes of the following Propionibacterium species: P. acnes, P. granulosum, and P. avidum. This system was used for analysis of wash samples from the skin of 17 pentathlon sportsmen and 16 students. All three species of propionic bacteria were found in all skin wash samples. However, contamination with P. acnes was two times higher in the control group than in the group of pentathlon sportsmen.     

The diversity and host interactions of Propionibacterium acnes bacteriophages on human skin

The viral population, including bacteriophages, is an important component of the human microbiota, yet is poorly understood. We aim to determine whether bacteriophages modulate the composition of the bacterial populations, thus potentially playing a role in health or disease. We investigated the diversity and host interactions of the bacteriophages of Propionibacterium acnes, a major human skin commensal implicated in acne pathogenesis. By sequencing 48 P. acnes phages isolated from acne patients and healthy individuals and by analyzing the P. acnes phage populations in healthy skin metagenomes, we revealed that P. acnes phage populations in the skin microbial community are often dominated by one strain. We also found phage strains shared among both related and unrelated individuals, suggesting that a pool of common phages exists in the human population and that transmission of phages may occur between individuals. To better understand the bacterium–phage interactions in the skin microbiota, we determined the outcomes of 74 genetically defined Propionibacterium strains challenged by 15 sequenced phages. Depending on the Propionibacterium lineage, phage infection can result in lysis, pseudolysogeny, or resistance. In type II P. acnes strains, we found that encoding matching clustered regularly interspaced short palindromic repeat spacers is insufficient to confer phage resistance. Overall, our findings suggest that the prey–predator relationship between bacteria and phages may have a role in modulating the composition of the microbiota. Our study also suggests that the microbiome structure of an individual may be an important factor in the design of phage-based therapy.     

Residual Antibiotics in Decontaminated Human Cardiovascular Tissues Intended for Transplantation and Risk of Falsely Negative Microbiological Analyses

We investigated the presence of antibiotics in cryopreserved cardiovascular tissues and cryopreservation media, after tissue decontamination with antibiotic cocktails, and the impact of antibiotic residues on standard tissue bank microbiological analyses. Sixteen cardiovascular tissues were decontaminated with bank-prepared cocktails and cryopreserved by two different tissue banks according to their standard operating procedures. Before and after decontamination, samples underwent microbiological analysis by standard tissue bank methods. Cryopreserved samples were tested again with and without the removal of antibiotic residues using a RESEP tube, after thawing. Presence of antibiotics in tissue homogenates and processing liquids was determined by a modified agar diffusion test. All cryopreserved tissue homogenates and cryopreservation media induced important inhibition zones on both Staphylococcus aureus- and Pseudomonas aeruginosa-seeded plates, immediately after thawing and at the end of the sterility test. The RESEP tube treatment markedly reduced or totally eliminated the antimicrobial activity of tested tissues and media. Based on standard tissue bank analysis, 50% of tissues were found positive for bacteria and/or fungi, before decontamination and 2 out of 16 tested samples (13%) still contained microorganisms after decontamination. After thawing, none of the 16 cryopreserved samples resulted positive with direct inoculum method. When the same samples were tested after removal of antibiotic residues, 8 out of 16 (50%) were contaminated. Antibiotic residues present in tissue allografts and processing liquids after decontamination may mask microbial contamination during microbiological analysis performed with standard tissue bank methods, thus resulting in false negatives.     

Analysis of potential factors affecting allografts contamination at retrieval

The microbiological contamination of retrieved tissues has become a very important topic and it is a critical aspect in the safety of allografts, especially from multi-tissue donors whose tissues are frequently contaminated as a consequence of retrieval. We analysed a total of 10,107 tissues, 8178 musculoskeletal and 1929 cardiovascular tissues, retrieved from 978 multi-tissue donors. Of these, 159 heart-beating donors (HBD) were also organ donors, while the remaining 819 non-heart-beating donors (NHBD) were tissue donors only. A multivariate logistic model was used to determine the factors affecting contamination risk during retrieval. In the model, the dependent variable was the presence/absence of contamination while the covariates included were: gender, type of donor, age of donor, cause of death, previous skin donation, cadaver time, number of people attending the retrieval, number of tissues retrieved. Moreover, a second log-linear model was used to determine the number of strains isolated per tissue. Tissue contamination was statistically correlated with gender, type of donor, cadaver time, number of people attending the retrieval and season. In conclusion, to minimize the risk of bacterial contamination, aseptic techniques should be used at retrieval, with the number of retrieval team members kept to a minimum. In addition, cadaver time should be as short as possible and the donor should be refrigerated within a few hours after death.     

Heart valve allograft decontamination with antibiotics: impact of the temperature of incubation on efficacy

Heart valve allografts are typically processed at 4°C in North America, including the step of antibiotic decontamination. In our own experience with heart valve banking, we often observe persistent positive cultures following decontamination at wet ice temperature. We hypothesized that warmer temperatures of incubation might increase the efficacy of the decontamination procedure. In a first series of experiments, 12 different bacterial species were grown overnight, frozen in standardized aliquots and used directly to inoculate antibiotic cocktail aliquots at 10⁵ colony-forming units (CFU)/ml. The antibiotic cocktail contains vancomycin (50 μg/ml), gentamicin (80 μg/ml) and cefoxitin (240 μg/ml) in Dulbecco’s Modified Eagle’s Medium. Inoculated aliquots were incubated at 4, 22 and 37°C and CFUs were determined at regular intervals up to 24 h post-inoculation. In a second set of experiments, 10 heart valves were spiked with 5000 CFU/ml and incubated with antibiotics at 4 and 37°C for 24 h. The final rinse solutions of these heart valves were filtered and tested for bacterial growth. After 24 h of incubation, CFUs of all 12 bacterial species were reduced by a factor of only one to two logs at 4°C whereas log reductions of 3.7 and 5.0 or higher were obtained at 22 and 37°C, respectively. Most microorganisms, including Staphylococcus epidermidis, Lactococcus lactis lactis and Propionibacterium acnes survived well the 24-h antibiotic treatment at 4°C (<1 Log reduction). All 10 heart valves that were spiked with microorganisms had positive final rinse solutions after antibiotic soaking at 4°C, whereas 8 out of 10 cultures were negative when antibiotic decontamination was done at 37°C. These experiments show that a wet ice temperature greatly reduces the efficacy of the allograft decontamination process as microorganisms survived well to a 24-h 4°C antibiotic treatment. This could explain the high rate of positive post-processing cultures obtained with our routine tissue decontamination procedure. Increasing the decontamination temperature from 4 to 37°C may significantly reduce the incidence of post-disinfection bacterial contamination of heart valves.     

Bioburden in transport solutions of human cardiovascular tissues: a comparative evaluation of direct inoculation and membrane filter technique

All cardiac allograft tissues are under potential contamination, requiring a validated terminal sterilization process or a minimal bioburden. The bioburden calculation is important to determine the bacterial burden and further decontamination and disinfection strategies for the valve processing. The aim of this study was to determine the bioburden from transport solution (TS) of heart valves obtained from non-heart-beating and heart-beating donors in different culture methods. The bioburden from TS was determined in 20 hearts donated for valve allograft tissue using membrane filter (MF) and direct inoculation. Tryptic soy agar and Sabouraud plates were incubated and colonies were counted. Ninety-five percent of samples from this study were obtained from heart-beating donors. The warm ischemic time period for heart was 1.06?±?0.74 h and the cold ischemic time period was 25.66?±?11.16 h. The mean TS volume was 232.68?±?96.67 mL (48.5–550 mL). From 20 samples directly inoculated on TSA agar plates, 2 (10%) were positive. However, when MF was used, from 20 samples in TSA, 13 (65%) were positive with a mean count of 1.36?±?4.04 CFU/mL. In Sabouraud plates, the direct inoculation was positive in 5 samples (25%) with a mean count of 0.24?±?0.56 CFU/mL. The use of MF increased the positivity to 50% (10 samples from a total of 20) with a mean of 0.28?±?0.68 CFU/mL. The positivity was superior using MF in comparison with direct inoculation (p?<?0.05). The bioburden of TS is low and MF is the technique of choice due to higher positivity.     

Molecular testing of <Emphasis Type="Italic">Klebsiella pneumoniae</Emphasis> contaminating tissue allografts recovered from deceased donors

Microbiological screening of tissue allografts is crucial to prevent the transmission of bacterial and fungal infections to transplant recipients. Klebsiella was the most prevalent and resistant contaminating microorganism observed in our setting in the Iranian Tissue Bank. This study was conducted to determine the presence of extended-spectrum β-lactamase (ESBL) genes, antimicrobial resistance patterns of Klebsiella pneumoniae isolates, and their clonal relationships in allograft materials. K. pneumoniae contaminating bone and other tissue allografts recovered from deceased donors were identified and ESBL isolates were detected using a phenotypic confirmatory method. Antimicrobial susceptibility testing was carried out using the disk diffusion method. Distribution of ESBL genes and molecular typing were performed using polymerase chain reaction (PCR) and Repetitive-element (rep-PCR) methods. Of 3828 donated tissues, 51 (1.3%) were found contaminated by K. pneumoniae isolates. Compared to tissue allografts from brain-dead, heart-beating tissue donors, allografts from donors with circulatory cessation were associated with a higher risk of K. pneumoniae contamination [odds ratio (OR), 1.2 (CI 95% 0.9–2.3) (P value < 0.001)]. Half of the isolates produced ESBL, and the rate of susceptibility to cephalosporins was 51%. Among isolates, 22 (43.1%) harbored CTX-M, 31 (60.8%) SHV, and 9 (17.6%) harbored TEM types. The rep-dendrogram indicated that clones having identical or related strains with a similar antibiotype were isolated in the same period. This study provides evidence that a single clone of K. pneumoniae contaminated tissue allografts recovered from many different donors. A single clone found on tissues from several donors suggests contamination of tissues from a single source such as the tissue recovery process and environment. Genomic DNA testing and clonality of contaminating bacteria using molecular methods can focus the epidemiologic investigation on the tissue allograft recovery process including a search for contamination of the tissue recovery room environment, recovery staff, recovery equipment, reagents, solutions and supplies.     

Propionibacterium from Liver and Lung of Pigs and Guinea Pigs. 1: Physiological Identification

A total of 231 Propionibacterium strains originated from animals were identified based on key physiological properties. They comprised 218 strains derived from livers of pigs with or without milk spots, eight from lungs of pigs used in parasitic infection experiments (including controls), and three from livers and two from lungs of guinea pigs in experimental parasitic infection. All identification tests were performed in cysteine-containing media (reduced state) and incubated in an aerobic atmosphere, except the seed cultures used for inoculation and cultures for catalase test which were incubated under pure carbon dioxide. Among these strains, 212 isolates were clearly identified as P. acnes, Eleven asP. granulosum , seven as P. avidum and one as Propionibacteriu m species. For P. acnes, the key identification properties were maltose- and sucrose-negative at species level; and sorbitol-positive for type I and erythritol-positive for type II at subspecies level. All P. acnes type II strains were sorbitol-negative, but some type I strains also showed the same reaction. The P. acnes type I strains showed growth on the surface of semi-solid sugar medium and type II strains showed deep growth in the same medium. These growth modes provided an important tool for type differentiation. By summarizing all the results of adonitol–mannitol–sorbitol (AMS) reaction pattern; erythritol–trehalose (ET) reaction pattern, gelatin liquefaction, indole production and the growth mode, 34 differential patterns were established. As a result, 139 strains were classified as type I (130 from pig liver, six from pig lung, one from guinea-pig liver, two from guinea-pig lung), 68 strains as type II (64 from pig liver, 2 from pig lung, 2 from guinea-pig liver), and five strains as untypable. The two species; P. granulosum and P. avidum were first characterized by being melezitose-, maltose- and sucrose-positive. Then they were differentiated by aesculin and gelatin reactions. P. granulosum was negative for both and P. avidum was positive. One strain of Propionibacterium sp. had a unique pattern different from the other species.     

Analysis of the effectiveness of Sodium Hypochlorite decontamination of cadaveric human tissues at retrieval

Bacterial contamination of tissues retrieved from cadaveric donors is a common feature worldwide, and every tissue bank, albeit using different methods, conducts decontamination to guarantee safe tissues suitable for clinical use. The effectiveness of the methods used to eradicate pathogens differs. In order to reduce the tissue bioburden at retrieval, we have introduced a new method involving rinsing tissues in a sodium hypochlorite solution. To test its effectiveness we analyzed two comparable groups of tissues: Group A: 1881 tissues, all rinsed with isotonic saline solution after retrieval, and Group B: 1968 tissues immersed in an isotonic saline solution containing sodium hypochlorite (final concentration 0.1 %) for different lengths of time and subsequently rinsed with isotonic saline. The rinsing solution of each tissue was then sampled for microbiological cultures in both groups. The resultant overall contamination rate was 40.5 % for Group A and 6.7 % for Group B, with an 82.8 % difference in the reduction of contamination between the two groups. This was especially the case for commensal skin bacteria in musculoskeletal tissue, which accounted for over half the overall contamination. Our data highlighted that decontamination with sodium hypochlorite was helpful in reducing the bacterial bioburden in tissues retrieved from cadaveric donors.     

Modalités de la contamination d'une chaine trophique marine benthique par l'argent 110 m: 4. Influence du mode de contamination sur l'élimination du radionucléide

The elimination of ^110mAg by Navicula incerta Grunow ex Van Heurck, Navicula biskanteri Hustedt, Scrobicularia plana (da Costa) and Carcinus maenas (L.) depends upon the duration of contamination or the number of intakes of radioactive food. The longer the contamination occurred, the slower will be the climination.The decontamination is slower after (chronic) ingestion of radioactive food than after immersion in contaminated water. The physico-chemical forms of ^110mAg likely play a rôle in elimination kinetics. So, external organs, whose contamination results mainly from adsorption, get rid of ^110mAg faster than the digestive gland in which silver seems to be retained in a hardly exchangeable form.Consequently, the total radiation dose for contaminated organisms will depend greatly upon the way and the duration of the contamination.     

Comparison of contamination and growth of Mycobacterium avium subsp. paratuberculosis on two different media

AIMS: The purpose of the study was to compare the growth of Mycobacterium avium subsp. paratuberculosis (Map) and the degree of contamination on Herrold's egg yolk medium (HEYM) and modified L?wenstein-Jensen medium (LJ). METHODS AND RESULTS: Culture of 2513 faecal samples from dairy cows was performed on each of the two media. The media were read after 5, 8 and 12 weeks of incubation. Overall, the proportion of contaminated samples was significantly higher on LJ (14.2%) than on HEYM (13.2%) after 12 weeks but the degree of contamination was slightly less on LJ. After 8 weeks of incubation, only 1.0% of the samples were Map positive in LJ with 4.9% on HEYM. After 12 weeks of incubation, 3.3% of the samples were Map positive in LJ whereas 6.9% were positive in HEYM. All suspect and culture positive samples were confirmed by IS900 PCR. CONCLUSIONS: HEYM supported growth of Map significantly better and faster than LJ, however it could not be determined conclusively which of the two media that provided the highest degree of decontamination when the incubation time was also included. SIGNIFICANCE AND IMPACT OF THE STUDY: HEYM should be the primary medium rather than LJ for detection of Map in cattle.     

Combined chlorhexidine and PVP-I decontamination of human donor eyes prior to corneal preservation

The aim of this study was to report the efficacy of adding chlorhexidine to the protocol for decontamination of human donor globes prior to excision of corneo-scleral rims for future keratoplasty procedures. In 2005, chlorhexidine was introduced by our eye bank as an additional step in the protocol for decontaminating human donor globes. After 5?years, we prospectively evaluated the number of contaminations. Out of 2,891 globes included in our study, 2,663 globes were processed, of which 36 (1.4%) were considered contaminated. Seventeen contaminations (0.6%) were detected by culturing limbal swabs, directly after decontamination, eight (0.3%) by visible discoloration of the culture medium carrying a corneo-scleral rim, and eleven (0.4%) after inoculation of the culture medium on blood agar plates. Importantly, after 4?weeks of incubation, none of the aerobic and anaerobic cultures taken from the secondary ??transport medium?? (dextran containing medium used to transport corneal tissue to the transplantation centre) showed microbiological growth. In conclusion, the combined use of 0.02% chlorhexidine and 0.5% povidone-iodine may allow decontamination of donor globes to a level at which the risk of tissue contamination at the time of transplantation is minimized, while corneal viability is preserved.     

Formaldehyde Solution Effectively Inactivates Spores of Bacillus anthracis on the Scottish Island of Gruinard

Gruinard Island was heavily contaminated with the spores of virulent Bacillus anthracis during biological weapons trials in World War II. However, an extensive survey in 1979 showed that most of the island was not contaminated. In the early 1980s, a more intensive survey revealed that the contamination was largely confined to the top 8 cm of the soil in a 2.6-ha area of the 211-ha island. Small-scale tests showed that the spores could be inactivated by drenching the soil with fluid biocides. A solution of 5% formaldehyde in seawater applied by surface spray to each square meter of ground was shown to be the most effective treatment and was utilized for large-scale decontamination of the affected areas. Following this treatment, extensive sampling revealed that most of the spores of B. anthracis had been inactivated. Isolated pockets of surviving spores were treated further. A flock of sheep was then allowed to graze over the entire island for 5 months; none contracted anthrax.     

Antimicrobial efficiency and stability of two decontamination solutions

Two decontamination solutions, commercially produced BASE?128 and laboratory decontamination solution (LDS), with analogous content of antibiotic and antimycotic agents, were compared in their antimicrobial efficiency and stability (pH and osmolarity). Both solutions were compared immediately after thawing aliquots frozen for 1, 3 or 6 months. Agar well diffusion method was used to test their antimicrobial efficiency against five human pathogens: Staphylococcus aureus, Pseudomonas aeruginosa, Proteus mirabilis, Escherichia coli and Enterococcus faecalis. The difference in the inhibition of growth between the two decontamination solutions was mostly not statistically significant, with few exceptions. The most pronounced difference between the LDS and BASE?128 was observed in their decontamination efficacy against E. coli and E. faecalis, where the LDS showed to be more efficient than BASE?128. The osmolarity value of LDS decreased with cold-storage, the osmolarity values of the BASE?128 could not be measured as they were below the range of the osmometer. Slight changes were found in pH of the less stable LDS solution, whose pH increased from initial value 7.36?±?0.07 to 7.72?±?0.19 after 6 m-storage. We verified that BASE?128 and LDS are similarly efficient in elimination of possible placental bacterial contaminants and may be used for decontamination of various tissues.     

Population Genetic Analysis of Propionibacterium acnes Identifies a Subpopulation and Epidemic Clones Associated with Acne

The involvement of Propionibacterium acnes in the pathogenesis of acne is controversial, mainly owing to its dominance as an inhabitant of healthy skin. This study tested the hypothesis that specific evolutionary lineages of the species are associated with acne while others are compatible with health. Phylogenetic reconstruction based on nine housekeeping genes was performed on 210 isolates of P. acnes from well-characterized patients with acne, various opportunistic infections, and from healthy carriers. Although evidence of recombination was observed, the results showed a basically clonal population structure correlated with allelic variation in the virulence genes tly and camp5, with pulsed field gel electrophoresis (PFGE)- and biotype, and with expressed putative virulence factors. An unexpected geographically and temporal widespread dissemination of some clones was demonstrated. The population comprised three major divisions, one of which, including an epidemic clone, was strongly associated with moderate to severe acne while others were associated with health and opportunistic infections. This dichotomy correlated with previously observed differences in in vitro inflammation-inducing properties. Comparison of five genomes representing acne- and health-associated clones revealed multiple both cluster- and strain-specific genes that suggest major differences in ecological preferences and redefines the spectrum of disease-associated virulence factors. The results of the study indicate that particular clones of P. acnes play an etiologic role in acne while others are associated with health.     

Bacterial contamination of amniotic membrane in a tissue bank from Iran

Human Amniotic Membrane (AM) transplantation can promote tissue healing and reduce inflammation, tissue scarring and neovascularization. Homa Peyvand Tamin (HPT) tissue bank has focused on manufacturing human cell and tissue based products including AM. The purpose of this study is to evaluate and identify bacterial contamination of AMs that is produced by HPT for several ophthalmic applications. From July 2006 to April 2011, 122 placentas from cesarean sections were retrieved by HPT after obtaining informed consent from the donors. Besides testing donor’s blood sample for viral markers, microbiological evaluation was performed pre and post processing. During tissue processing, decontamination was performed by an antibiotic cocktail including; Gentamicin, Ceftriaxone and Cloxacillin. Of 271 cesarean section AM donors who were screened as potential donors, 122 were accepted for processing and assessed for microbiological contamination. Donors’ age were between 21 and 41 years (Mean = 27.61 ± 0.24). More than 92 % of mothers were in their first or second gravidity with full term pregnancies. The most prevalent organisms were Staphylococci species (72.53 %). After processing, contamination rates markedly decreased by 84.62 % (p value = 0.013). According to our results, most of bacterial contaminations were related to donation process and the contamination pattern suggests procurement team as a source. Therefore we recommend that regular training programs should be implemented by tissue banks for procurement staff. These programs should focus on improved donor screening and proper aseptic technique for tissue retrieval. We also suggest that tissue banks should periodically check the rate and types of tissue contaminations. These data help them to find system faults and to update processing methods.