Bacterial Contamination Of Platelet Research Articles

Evaluation of riboflavin concentrations and light intensities on bacteria reduction in platelets using visible light

Bacterial contamination in platelets has been a major concern over the years. In this study, we showed that treatment with 420 nm visible light with various concentrations of riboflavin in platelets reduced E. coli and S. aureus by 0–1.56 and 0.3–2.02 logs (50 mW/cm2), 2.24–4.77 and 0.73–3.26 logs (75 mW/cm2), and ≥ 5.14 and ≥ 5.27 logs (100 mW/cm2). Treatment with high-intensity light (100 mW/cm2) and high concentrations of riboflavin (400 µM and 500 µM) effectively reduced both bacteria in platelets by over 4 logs. The study also found a positive correlation between bacterial reduction and light intensity, as well as riboflavin concentration in a dose-dependent manner. These results demonstrate the potential of using riboflavin and visible light to reduce the risk of bacterial contamination in platelets, and support the need for further exploration of pathogen reduction using 420 nm visible light and riboflavin.

Bacterial Contamination of Blood Products Stored at Room Temperature on Agitator in Lagos State, Nigeria

Abstract BACKGROUND: The relevance of some plasma-based medicinal products, especially platelet concentrates in modern medical care, is confirmed by their inclusion in the World Health Organization Essential Medicines. Therefore, this study characterized bacterial contamination in blood donor’s platelet concentrates in Lagos State. METHODS: A total number of 10 units of screened blood were collected and platelet concentrates were serially sampled following an aseptic procedure and stored for a period of 8 days (day 1 to day 8). The samples were incubated at 37°C on a daily basis for 7 days in brain–heart infusion growth medium and thioglycolate broth, respectively. The identities of the isolated organisms were determined by following standard microbiological techniques. The resistance pattern of isolates to selected antimicrobial agents was also determined by disc diffusion method. RESULTS: The results obtained showed that the overall prevalence of bacterial contamination in platelet concentrates stored at room temperature was 20% (2/10), with the growth on the 1st day of culture. The pattern of the bacterial isolates was Staphylococcus aureus – 10% (1/10) and Staphylococcus epidermidis – 10% (1/10) from 10 platelet concentrates with agitation for 8 days with no evidence of co-bacterial contamination. The resistance pattern of the bacterial isolates to different selected antibiotics ranged from 50% to 100%. There was no significant difference in P value obtained in the comparative analysis of the proportions of S. aureus and S. epidermidis in platelet concentrates (P = 1.000; P > 0.05). The findings of this study also confirmed the presence of multidrug-resistant Gram-positive bacteria in the blood component for transfusion studied in Lagos; the organisms isolated were S. aureus and S. epidermidis. The resistance pattern of the bacteria to the antibiotics ranged from 50% to 100%. CONCLUSION: This work revealed evidence of bacterial contamination in platelet concentrates prepared for transfusion with an overall bacterial contamination of 20% (S. aureus – 10%; S. epidermidis – 10%) with no evidence of co-bacterial contamination but with evidence of S. aureus and S. epidermidis multidrug resistance, hence the need for proper storage and screening of platelet concentrates for bacterial contamination before transfusion to avoid platelet aggregation that may lead to fatal complications in the recipient.

Aerobic Bacterial Contamination In Platelet Concentrates At The Regional Blood Centre, Peshawar.

Platelet concentrates play a crucial role in transfusion medicine, aiding in the management of various medical conditions, including haemorrhage, thrombocytopenia, and platelet dysfunction. However, their storage conditions at 22° C present an optimal environment for bacterial growth, making them susceptible to contamination. Of particular concern is the transmission of microorganisms from the skin flora during the phlebotomy process, which can lead to the transfusion of contaminated platelet concentrates. Such contamination poses significant risks to patients, potentially resulting in morbidity and mortality. Determining the frequency and identifying causative organisms of bacterial contamination in platelet concentrates. It was a descriptive cross-sectional study conducted at the Institute of Pathology and Diagnostic Medicine, Khyber Medical University, and the Regional Blood Center in Peshawar from May to October 2021, spanning a duration of six months. The study included 500 participants aged between 18 and 50 years (mean: 28.13±7.67 years. A simple convenient sampling technique was employed. Blood products underwent screening for Hepatitis B, Hepatitis C, HIV, Syphilis, and Malaria. Leaked units were excluded from the study. Platelets were prepared using a Cryofuge and subsequently subjected to culture media. The mean age of the participants included in the study was 28.13±7.67 years, with an age range of 18 to 50 years. Out of the total sample size of 500, there were 483 (96.6%) male participants and 17 (3.4%) female participants. Among the collected samples, bacterial growth was observed in only 11 (2.2%) platelet concentrates. The isolated organisms were Staphylococcus epidermidis, found in 7 (1.4%) platelet concentrates, and Staphylococcus aureus, found in 4 (0.8%) platelet concentrates. Bacterial contamination of platelet bags is higher compared to developed countries. Therefore, implementing quality control procedures is necessary to reduce the risk of bacterial contamination in platelet concentrates. Additionally, employing enhanced skin disinfection techniques at the phlebotomy site can significantly minimize bacterial contamination.

Cold-stored Platelets for Bleeding Patients: Comment.

Cold-stored Platelets for Bleeding Patients: Comment.

Hemovigilance data: An effective approach for evaluating bacterial protection systems for platelet transfusions.

Septic transfusion reactions due to bacterial contamination in platelet concentrates (PCs) are continually reported to hemovigilance (HV) programs. Worldwide, blood centers use different systems to avoid transfusion-associated bacterial sepsis in PCs. Herein, national HV data were gathered to compare bacterial protection systems and to assess the risk of bacterial contamination. HV data with definite transfusion-associated bacterial sepsis in PCs were obtained from Australia, Canada, the United Kingdom (U. K.), and Switzerland between 2006 and 2016. These data were reviewed to evaluate bacterial protection systems including early small-volume (ESV), early large-volume (ELV), and delayed large-volume (DLV) bacterial culture screening and pathogen inactivation (PI) treatment. Implementation of DLV bacterial culture screening in the U. K. and PI treatment in Switzerland resulted in significant reductions (P < 0.05) in transfusion-associated bacterial sepsis for the period of 2011-2016 compared to the prior 4 years (2006-2010). Approximately 1.86 million DLV bacterial culture-screened PCs and 0.21 million PI-treated PCs were issued with no reported septic fatalities nor cases of life-threatening sepsis. In Australia, two life-threatening septic transfusion reactions (1.923 per million) were reported out of almost 1.04 million ELV bacterial culture-screened PCs, and no septic fatalities were reported. Meanwhile, in Canada, four life-threatening septic transfusion reactions (3.6/million) and one fatality (0.9/million) were observed in about 1.11 million ESV bacterial culture-screened PCs. DLV bacterial culture and PI treatment significantly reduced the incidence of septic reactions. The advantages and disadvantages of both systems merit further investigation before implementation.

Implementation strategy for complete pathogen reduction technology treated apheresis platelet inventory.

Bacterial contamination in platelets remain a major public health concern, which prompted the US Food and Drug Administration guidance for bacterial contamination mitigation. Pathogen reduction technology (PRT) is one mitigation strategy that has shown success in Europe over the last decade. Therefore, our center sought to transition from a dual system of bacterial culturing (BacT) and PRT to full PRT. A 1 month pilot study was conducted to simulate 100% PRT conditions. Our center also collected baseline data on key platelet production metrics in the 4 months prior to 100% PRT and compared it to the 4 months post-implementation. The pilot study showed no statistical differences in split rate, proportion of low-yield products, or proportion of single, double, and triple collections. The only observed difference was an 11 min increase in the average duration of double collections. Our baseline versus post-implementation monitoring showed no difference in split rate, discard rate, percentage of low-yield units, and average yield of low yield units. Statistical differences were detected in the proportion of single, double, and triple collections, as well as the average yield of full dose products. Roughly 20% of our inventory consisted of low-yield products. With suitable mitigation strategies, transitioning to a full PRT inventory may result in higher net margins while not adversely affecting overall platelet production. A pilot study is a good way to project potential effects of switching from a dual BacT and PRT inventory to full PRT, and can be adopted by other centers aiming to make the transition.

Transfusion outcomes between regular and low yield pathogen reduced platelets across different patient populations in a single institution.

Pathogen reduction technology (PRT) effectively mitigates bacterial contamination in platelets but is more likely to produce low yield units. Although low dose transfusion using conventional platelets has not been associated with increased bleeding, these findings have not been reproduced with PRT-treated platelets. Platelet transfusions in a tertiary adult hospital were retrospectively reviewed. Comparisons were made between PRT-treated regular (PRT-PR) and low (PRT-PL) yield platelets. Outcomes examined included the number of platelets and RBCs transfused, transfusion-free interval, and corrected count increment (CCI). Subgroup analyses were also performed on hematology-oncology inpatients and outpatients, as well as non-hematology-oncology patients. Platelet utilization per patient remained mostly unchanged (mean 2.9-4.3units per patient per month) even when the frequency of PRT-PL transfusion increased. Among 1402 patients examined, the number of platelets and RBCs transfused was not significantly different between patients first transfused with PRT-PR versus PRT-PL (mean number of platelet units=2.8 vs. 3.1, p=0.38; mean number of RBC units=4.8 vs. 4.3, p=0.93). Among 10,257 platelet transfusions examined, the transfusion-free interval (hazard ratio=1.05, 95% confidence interval 1.00-1.10) and CCI (10.2 vs. 11.0, p=0.70) were comparable between PRT-PR and PRT-PL units. Similar findings were observed in all subgroups, except for shortened transfusion-free intervals among hematology-oncology inpatients. PRT-PR and PRT-PL units may be used in an equivalent manner to maintain an adequate platelet inventory, since there was only a minor difference in time between transfusions.

Association of Staphylococcus aureus in platelet concentrates with skin diseases in blood donors: Limitations of cultural bacterial screening.

Bacterial contamination in platelet concentrates (PCs) is a major problem in transfusion medicine. Contamination with Staphylococcus aureus is occasionally missed, even with cultural screening. Donors implicated in S. aureus-contaminated PC were followed up. Skin and nasal swab specimens from six donors and S. aureus isolated from PCs related to these donors were subjected to multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) to determine the identity of bacteria. To evaluate the validity of the screening method using BacT/ALERT 3D, we spiked S. aureus and three other bacterial species as comparisons into PCs and investigated their growth pattern. S. aureus was isolated from all nasal specimens and from the arm skin specimens of three donors with atopic dermatitis. In all cases, the S. aureus strains isolated from the PC and those from the nasal and skin specimens of the same donor showed concordant results using MLST and PFGE. In the spiking study, S. aureus showed irregular detectability over 24 to 48 h post-spike periods, whereas the three other bacterial species were detected in all culture bottles after a 24-h post-spike period. The strain identity of S. aureus between donor and PC suggests that the contaminants were derived from those colonized in the donor. Furthermore, S. aureus yielded false-negative results using BacT/ALERT 3D.

Bacterial contamination of platelets and red blood cell concentrates: A regional transfusion center study in Pakistan

Bacterial contamination of platelets and red blood cell concentrates: A regional transfusion center study in Pakistan

Expanded validation of the effect and quality of a pathogen inactivation system based on riboflavin photochemistry on platelet bacterial contamination

BackgroundBacterial contamination still poses serious challenges to blood safety. Platelets have the highest bacterial contamination risk of all blood components.MethodsTwenty units of manual platelets were prepared from blood donated by our hospital, which were inoculated with Staphylococcus aureus and Escherichia coli suspensions. The riboflavin sodium phosphate solution was added into platelets, adjusted to a final concentration of 160 μmol/L. Platelets added into an illumination bag and placed in the inactivation system for riboflavin photochemistry at various doses. The inactivation effect of bacteria was evaluated on a Columbia blood agar plate by the plate counting method. Meanwhile, the blood routine, blood gas analysis, platelet aggregation test, and thromboelastogram of platelets before and after treatment were detected to evaluate the changes of platelet quality after treatment.Resultsthe inactivation effect of S. aureus and E. coli at the inactivation dose (16.9 J/cm2) could reach more than 4 logs. After treatment at 16.9 J/cm2, the blood routine results showed that the platelet count was significantly different (P<0.05), and the blood gas analysis showed that the oxygen partial pressure (pO2) and lactic acid concentration (cLac) were also significantly different (P<0.05). After 16.9 J/cm2 treatment, there was a significant difference between Arachidonic acid (AA) and Collagen (Cog) activator groups in the platelet aggregation experiment (P<0.05), but there was no significant difference in the main thrombelastogram (TEG) parameters (R value, K value, angle value, MA value) after treatment (P>0.05).ConclusionsThe inactivation effect of this set of blood component pathogen inactivation system on platelet bacterial contamination could be considered to meet actual clinical needs, with the inactivation treatment having little impact on platelet function.

Rapid Analysis of Bacterial Contamination in Platelets without Pre-Enrichment Using Pig Serum-Derived Antibodies.

As the shelf life of platelets collected from donated blood is very short, approximately 5 days, the determination of bacterial contamination in platelets has become necessary. In this study, rapid analysis of Gram-positive and Gram-negative bacterial contamination in platelet samples was presented without pre-enrichment using pig serum-derived antibodies against the outer membrane proteins (OMP) of Gram-negative bacteria and antibodies against lipoteichoic acid (LTA) on the surface of Gram-positive bacteria. The anti-OMP antibodies against Gram-negative bacteria were isolated using sequential incubation with (1) the modified Gram-negative bacteria ClearColi, which lacks lipopolysaccharide (LPS) on the outer membrane, and (2) the Gram-positive bacteriaBacillus subtilis to filter away nonspecifically bound proteins from ClearColi. The anti-lipoteichoic acid (LTA) antibodies against Gram-positive bacteria were isolated using sequential incubation with (1) the Gram-positive bacteriaB. subtilis and (2) the Gram-negative bacteria Escherichia coli BL21 to filter away nonspecifically bound proteins fromB. subtilis. The feasibility of using the antibodies isolated from pig serum against Gram-negative and Gram-positive bacteria was demonstrated using flow cytometry. Finally, detection of the contamination of platelets with Gram-negative and Gram-positive bacteria using the impedance immunosensor based on these isolated antibodies was successfully demonstrated.

Pathogen reduction technology for blood component: A promising solution for prevention of emerging infectious disease and bacterial contamination in blood transfusion services

With the rapid evolving of emerging pathogens and residual risk of bacterial contamination in platelets, they continue to pose a constant threat to the safety of blood supply despite effort implemented to mitigate such risk via conventional measures and testing. Three photochemical based advanced pathogen reduction technology (PRT) that utilize amotosalen, riboflavin and UVC only offer some of the unique advantages over conventional approaches. They have demonstrated superior pathogen reduction capability against various emerging viruses, bacteria, parasites and leukocytes, as well as acceptable safety and clinical efficacy based on reports, studies and clinical trials. Although concern related to cost and adverse transfusion reaction of PRT application remains, with further study and continue improvement, future PRT will continue to play a paramount role in assuring the safety of blood and blood products.

The PGDprime immunoassay for detection of bacterial contamination in platelet concentrates: sensitivity and specificity

The PGDprime immunoassay for detection of bacterial contamination in platelet concentrates: sensitivity and specificity

FDA guidance on bacterial contamination risk control strategies to enhance the safety and availability of platelets: advantages and limitations

: Bacterial contamination of platelets was first addressed by primary culture, introduced in US in 2004, which ameliorated but did not solve the problem. Guidance to further decrease bacterial contamination were published by the US Food and Drug Administration in September 2019; recommended implementation is by October 2021. These include three single-step strategies: (I) culture at ≥36 h of ≥16 mL (≥8 mL aerobic, ≥8 mL anaerobic) per split apheresis unit or whole-blood derived pool; 5 day outdate; (II) culture at ≥48 h of ≥16 mL (≥8 mL aerobic, ≥8 mL anaerobic) per split apheresis unit; 7 day outdate; (III) pathogen reduction of apheresis units performed within 24 h of collection (5-day outdate). Several two-step strategies are available: First step has two options: (I) culture ≥36 h of ≥16 mL as in single-step option 1 (5 day outdate); (II) culture at ≥24 h after collection of ≥16 mL (≥8 mL aerobic, ≥8 mL anaerobic) per apheresis collection or split unit, or whole-blood derived pool (3 day outdate). The second step has three options to extend these outdates: (I) secondary culture of each unit of ≥8 mL (aerobic) on ≥ day 3 (extends outdate to 5 days); (II) secondary culture of each unit of ≥16 mL as in step 1 on ≥ day 4 (extends outdate to 7 days); (III) rapid testing of each unit within 24 hours of transfusion on ≥ day 3 (extends outdate to 7 days). This review addresses advantages and limitations of these strategies based on evidence of their efficacy.

Retrospective Study of the Prevalence of Bacterial Contamination of Platelet Concentrates in Morocco

Objective: This retrospective study was conducted using data from the 2005 to 2012 archives at the Laboratory of Bacteriology Serology and Hygiene of Ibn Sina University Hospital Center in Rabat, Morocco. Its aim is to determine the prevalence of bacterial contamination of platelet concentrates produced by the Regional Center for Blood Transfusion of Rabat, after the implementation of the bacterial quality control of the platelet concentrates. Methods: A total of 3898 platelet concentrates, obtained after disinfection of the sampling site and diversion of the first milliliters of the blood donation, were cultured to study bacterial contamination between 2005 and 2012. The obtained bacterial colonies are tested by Gram staining and orientation tests such as: catalase, coagulase, oxidase, as well as the biochemical gallery for identification. This retrospective study was conducted over a period of six months using data from the archives of the Laboratory of Bacteriology Serology and Hygiene of Ibn Sina University Hospital Center in Rabat, Morocco. Results: This retrospective study concluded that the prevalence of bacterial contamination in platelet concentrates is 0.44 %. It also showed the presence of the following bacteria species: coagulase-negative Staphylococcus species and Bacillus sp each at 29.41%, Staphylococcus aureus, Streptocoque, E.coli and Enterobacter each were found at 5.9%. Other bacilli’s grams negative were present at 17.65 %. Conclusion: Even though, the prevalence of bacterial blood contamination found in this study was low, blood transfusion in Morocco has a long way to go before reaching the standards set and commonly accepted in developed countries.

A national survey of hospital-based transfusion services on their approaches to platelet bacterial risk mitigation in response to the FDA final guidance for industry.

Bacterial contamination of platelets is the leading infectious risk to the United States (US) blood supply. On 30 September 2019, the US Food and Drug Administration (FDA) published a Final Guidance for Industry to reduce the risk of transfusing platelets contaminated by bacteria. A national survey was undertaken to assess readiness, attitudes, and the potential impact on hospital-based transfusion services. A survey was distributed to transfusion services in all 50 US states. Summary statistics were performed along with review and categorization of email feedback and free text comments. Eighty-three transfusion services from 48 states participated in this survey study. Currently, the most common approach is primary culture performed at manufacturing (n = 49/83, 59%). Of the bacterial risk mitigation strategies provided by the FDA, the most frequently preferred are (a) pathogen reduced platelets (PRP) for up to 5-day storage (n = 36/77, 47%), (b) large volume delayed sampling (LVDS) ≥48 hours for up to 7-day storage (n = 16/77, 21%), and (c) primary culture ≥24 hours + secondary rapid testing for up to 7-day storage (n = 7/77, 9%). The main motivating factors for the survey participants' selected strategies to comply with FDA final guidance were product availability from supplier, reducing the risk of septic transfusion reactions (STR), and complexity of implementing and performing a new or additional test. While having platelets to transfuse and preventing STR are of the utmost importance, nationwide, the majority of transfusion services do not want to take on performing new or additional testing in their laboratories.

Evaluation of the Efficacy of Flow Cytometry in Detecting Bacterial Contamination in Platelets

Introduction: Bacterial contamination of platelet products is a major risk of infections in blood transfusion. Due to their storage conditions at room temperatures (22 to 24°C), cases of septicemia and even death caused by platelet injection have been reported. Therefore, use of appropriate diagnostic methods can improve the health of this product. In this study, flow cytometry was used to detect contaminated platelet units.&#x0D; Methods: This study was a diagnostic interventional type. 15 units of platelet concentrate was prepared at a minimum interval time after production. Staphylococcus epidermidis and Escherichia coli (E. coli) bacteria were each added to 6 platelet bags, with a concentration of 10 CFU / ml, while 3 bags were used as negative control. Platelets were stored in a shaking incubator at 22 - 24°C, for 0, 6, 24 and 48 hour-intervals after inoculation. Samples were then taken at 1 ml volume and evaluated by flow cytometry.&#x0D; Results: The sensitivity of the flow cytometry method to detect contaminated platelet units in infections with both Staphylococcus epidermidis and E. coli, in a 1 ml volume in all samples at 0, 6, 22 and 24 hours after inoculation, was 100%, and the number of bacteria increased in 24 hours of incubation, except for E. coli that decreased after 24 hours.&#x0D; Conclusion: This study shows that flow cytometry can be a useful method for detecting bacterial contamination in platelets, and can detect low concentrations (10 CFU / ml) of bacteria in small volumes of sample (ml) in a short time.

Surrogate markers and their correlation to bacterial contamination and other quality parameters in random-donor platelets by platelet-rich plasma method

Introduction: Bacterial contamination in platelet concentrates (PCs) occurs more frequently than other blood components because of several factors such as storage in oxygen permeable blood bags at 20°C–24°C with continuous agitation which facilitates bacterial growth compared to other blood components which are kept frozen or refrigerated which inhibits bacterial proliferation in them. The purpose of the study was to assess the incidence of bacterial contamination of random-donor PCs and factors associated with its contamination and see how well the surrogate markers such as pH and swirling correlate with the same. Methodology: This was a cross-sectional study which included randomly chosen 500 random-donor platelets (RDPs) in blood bank prepared by platelet-rich plasma method. The samples chosen for the study were from the RDPs on the 5th day of storage after their preparation. pH, platelet count, and swirling in platelets, which act as surrogate markers for bacterial contamination, were checked on the RDP units. About 1–3 ml of PCs was inoculated from the RDP units into labeled culture bottles (BD Bactec Peds Plus/F). Results: Among a total of 499 random-donor PCs that were cultured in the automated BACTEC system for the study, none of them were culture positive. Thirty RDP units in the study were visibly lipaemic whereas 93 RDP units were visibly reddish in appearance. PCs having volumes 70 ml did not affect the swirling, pH, and platelet counts. There was a statistically significant difference between mean pH with RDP units having swirling Grade 2 and 3 and platelet counts with RDP units having swirling Grade 1 and 2. Conclusion: Bacterial contamination though poses a significant risk is a very rare event in a meticulously prepared and stored PCs. Surrogate markers though useful in resource-constrained settings does not correlate optimally with the quality indicators.

Combining culture and microbead‐based immunoassay for the early and generic detection of bacteria in platelet concentrates

Despite current preventive strategies, bacterial contamination of platelets is the highest residual infectious risk in transfusion. Bacteria can grow from an initial concentration of 0.03-0.3 colony-forming units (CFUs)/mL up to 108 to 109 CFUs/mL over the product shelf life. The aim of this study was to develop a cost-effective approach for an early, rapid, sensitive, and generic detection of bacteria in platelet concentrates. A large panel of bacteria involved in transfusion reactions, including clinical isolates and reference strains, was established. Sampling was performed 24 hours after platelet spiking. After an optimized culture step for increasing bacterial growth, a microbead-based immunoassay allowed the generic detection of bacteria. Antibody production and immunoassay development took place exclusively with bacteria spiked in fresh platelet concentrates to improve the specificity of the test. Antibodies for the generic detection of either gram-negative or gram-positive bacteria were selected for the microbead-based immunoassay. Our approach, combining the improved culture step with the immunoassay, allowed sensitive detection of 1 to 10 CFUs/mL for gram-negative and 1 to 102 CFUs/mL for gram-positive species. In this study, a new approach combining bacterial culture with immunoassay was developed for the generic and sensitive detection of bacteria in platelet concentrates. This efficient and easily automatable approach allows tested platelets to be used on Day 2 after collection and could represent an alternative strategy for reducing the risk of transfusion-transmitted bacterial infections. This strategy could be adapted for the detection of bacteria in other cellular products.

Detection of bacterial contamination in platelet concentrates from Brazilian donors by molecular amplification of the ribosomal 16S gene.

The aim of our work was to establish a semi-automated high-throughput DNA amplification method for the universal screening of bacteria in platelet concentrates (PCs). Among cases of transfusion transmission of infectious agents, bacterial contamination ranks first in the number of events, morbidity and mortality. Transmission occurs mainly by transfused PCs. Automated culture is adopted by some blood banks for screening of bacterial contamination, but this procedure is expensive and has a relatively long turnaround time. PCs were spiked with suspensions of five different bacterial species in a final concentration of 1 and 10 colony-forming units (CFU) per millilitre. After incubation, the presence of bacteria was investigated by real-time polymerase chain reaction (PCR) and by the Enhanced Bacterial Detection System (eBDS, Pall) assay as a reference method. Real-time PCR amplification was performed with a set of universal primers and probes targeting the 16S rRNA gene. Co-amplification of human mitochondrial DNA served as an internal control. Using the real-time PCR method, it was possible to detect the presence of all bacterial species tested with an initial concentration of 10CFU mL-1 24 h after contamination, except for Staphylococcus hominis. The PCR assay also detected, at 24 h, the presence of Serratia marcescens and Enterobacter cloacae with an initial concentration of 1CFU mL-1 . The real-time PCR assay may be a reliable alternative to conventional culture methods in the screening of bacterial contamination of PCs, enabling bacterial detection even with a low initial concentration of microorganisms.