How to accelerate antimicrobial susceptibility testing.

BACKGROUND: Antimicrobial susceptibility testing (AST) results are crucial for timely administration of effective antimicrobial treatment, and, thus, should be made available to clinicians as fast as possible. In particular, increasing rates of multidrug-resistant organisms emphasize the need for rapid AST (rAST). OBJECTIVES: This article aims to provide microbiologists and clinicians with a critical overview of the current state of possibilities to accelerate AST. We also intend to discuss technical and strategic aspects of rAST, which may be helpful to academic researchers and assay developers in the industry. SOURCES: We have reviewed literature on rAST methods and their implementation in routine diagnostics. CONTENT: Phenotypic rAST is universal, mechanism-independent and allows exact categorization, but it demands time for the microorganisms to start the growth and to express the response to antibiotics. Detection of selected resistance mechanisms is more rapid, but the interpretation of its clinical impact is limited. Technical challenges of phenotypic rAST include inoculum effect, delayed expression of resistance, lag phase and initial biomass increase in susceptible isolates. Criteria for a successful rAST assay are ease of use, random access, capacity for simultaneous testing of multiple specimens, affordability and financial attractiveness for industry. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS)-based AST seems to be particularly promising, as it can optimally be combined with MALDI-TOF MS identification. Direct testing from clinical specimens provides particularly early findings, with positive blood cultures being the most suitable specimen type. Polymicrobial samples and inoculum effect are serious obstacles for direct AST from other clinical specimens. Next to the technology improvement, optimization of pre-analytics and laboratory organization is essential. IMPLICATIONS: It appears feasible to generate an AST report within the same working shift; however, only affordable and easy-to-use rAST technologies have a chance to enter broad diagnostic routine. Efforts should be made by industry, authorities and academia to enable wide dissemination of rAST in clinical diagnostics.

Fungal prosthetic joint infection in total hip or knee arthroplasty: a retrospective single-centre study of 26 cases.

AIMS: Fungal prosthetic joint infections (PJIs) are rare and account for about 1% of total PJIs. Our aim was to present clinical and microbiological results in treating these patients with a two-stage approach and antifungal spacers. PATIENTS AND METHODS: We retrospectively reviewed our institutional database and identified 26 patients with positive fungal cultures and positive Musculoskeletal Infection Society (MSIS) criteria for PJI who were treated between 2009 and 2017. We identified 18 patients with total hip arthroplasty (THA) and eight patients with total knee arthroplasty (TKA). The surgical and antifungal treatment, clinical and demographic patient data, complications, relapses, and survival were recorded and analyzed. RESULTS: The median follow-up was 33 months. The success rate was 38.5% (10/26). Fluconazole resistance was found in 15%. Bacterial co-infection was common in 44% of patients for THA and 66% of patients with TKA. Mortality, reoperations, and treatment failure were common complications. CONCLUSION: Treatment with a two-stage exchange is a possible option for treatment, although fungal infections have a high failure rate. Therapeutic factors for treatment success remain unclear. Cite this article: Bone Joint J 2019;101-B:589-595.

Microbiological diagnostics of bloodstream infections in Europe-an ESGBIES survey.

OBJECTIVES: High-quality diagnosis of bloodstream infections (BSI) is important for successful patient management. As knowledge on current practices of microbiological BSI diagnostics is limited, this project aimed to assess its current state in European microbiological laboratories. METHODS: We performed an online questionnaire-based cross-sectional survey comprising 34 questions on practices of microbiological BSI diagnostics. The ESCMID Study Group for Bloodstream Infections, Endocarditis and Sepsis (ESGBIES) was the primary platform to engage national coordinators who recruited laboratories within their countries. RESULTS: Responses were received from 209 laboratories in 25 European countries. Although 32.5% (68/209) of laboratories only used the classical processing of positive blood cultures (BC), two-thirds applied rapid technologies. Of laboratories that provided data, 42.2% (78/185) were able to start incubating BC in automated BC incubators around-the-clock, and only 13% (25/192) had established a 24-h service to start immediate processing of positive BC. Only 4.7% (9/190) of laboratories validated and transmitted the results of identification and antimicrobial susceptibility testing (AST) of BC pathogens to clinicians 24 h/day. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry from briefly incubated sub-cultures on solid media was the most commonly used approach to rapid pathogen identification from positive BC, and direct disc diffusion was the most common rapid AST method from positive BC. CONCLUSIONS: Laboratories have started to implement novel technologies for rapid identification and AST for positive BC. However, progress is severely compromised by limited operating hours such that current practice of BC diagnostics in Europe complies only partly with the requirements for optimal BSI management.

Rapid detection of antibiotic resistance by MALDI-TOF mass spectrometry using a novel direct-on-target microdroplet growth assay.

OBJECTIVES: We aimed to develop a universal phenotypic method, which allows easy and rapid antimicrobial susceptibility testing independently of underlying resistance mechanisms. METHODS: We established a novel direct-on-target microdroplet growth assay for the detection of antibiotic resistance within a few hours, which is based on matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The microorganisms were incubated with and without meropenem in nutrient broth as microdroplets directly on MALDI-TOF MS target. Subsequently, broth was separated from microbial cells by contacting the microdroplets with an absorptive material. The microorganisms grown in the presence of antibiotic were detected by MALDI-TOF MS. A total of 24 Klebsiella pneumoniae and 24 Pseudomonas aeruginosa isolates were used to assess performance for detection of meropenem resistance. The microdroplet volumes investigated were 2, 4, 6, 8 and 10 µL. RESULTS: The best performance was achieved using 6-µL microdroplets. Applying this volume, all growth controls were successfully detected (definition of valid test), and all isolates were correctly categorized as susceptible or non-susceptible after an 18-h incubation. For K. pneumoniae, rate of valid tests, sensitivity and specificity all reached 100% after a 4-h incubation of 6-µL microdroplets. Using the same microdroplet volume for P. aeruginosa, incubation for 5 h resulted in 83.3% of valid tests with 100% sensitivity and 100% specificity. CONCLUSIONS: We demonstrated easy, rapid and accurate resistance detection using carbapenem-resistant Gram-negative bacteria as an example. Our technology is suitable for automatization and expandable to further applications, e.g. simultaneous testing of multiple antibiotics as well as resistance determination directly from clinical samples.

First description of an Anaerobiospirillum succiniciproducens prosthetic joint infection.

Anaerobiospirillum succiniciproducens belongs to the normal flora of cats and dogs and can rarely infect humans. Here, we report the first case of an A. succiniciproducens prosthetic joint infection.

Direct blood culturing on solid medium outperforms an automated continuously monitored broth-based blood culture system in terms of time to identification and susceptibility testing.

Pathogen identification and antimicrobial susceptibility testing (AST) should be available as soon as possible for patients with bloodstream infections. We investigated whether a lysis-centrifugation (LC) blood culture (BC) method, combined with matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) identification and Vitek 2 AST, provides a time advantage in comparison with the currently used automated broth-based BC system. Seven bacterial reference strains were added each to 10 mL human blood in final concentrations of 100, 10 and 1 CFU/mL. Inoculated blood was added to the Isolator 10 tube and centrifuged at 3000 g for 30 min, then 1.5 mL sediment was distributed onto five 150-mm agar plates. Growth was observed hourly and microcolonies were subjected to MALDI-TOF MS and Vitek 2 as soon as possible. For comparison, seeded blood was introduced into an aerobic BC bottle and incubated in the BACTEC 9240 automated BC system. For all species/concentration combinations except one, successful identification and Vitek 2 inoculation were achieved even before growth detection by BACTEC. The fastest identification and inoculation for AST were achieved with Escherichia coli in concentrations of 100 CFU/mL and 10 CFU/mL (after 7 h each, while BACTEC flagged respective samples positive after 9.5 h and 10 h). Use of the LC-BC method allows skipping of incubation in automated BC systems and, used in combination with rapid diagnostics from microcolonies, provides a considerable advantage in time to result. This suggests that the usefulness of direct BC on solid medium should be re-evaluated in the era of rapid microbiology.

Successful interdisciplinary radical treatment of Mycobacterium fortuitum infection in a lipotourist from Germany after abdominoplasty in Turkey.

We report a case of a 30-year-old woman who experienced recurrent infections of the abdominal wall after travelling to Turkey from Germany to undergo abdominoplasty for aesthetic reasons. The patient's Mycobacterium fortuitum infection was successfully treated by surgery and antibiotic therapy. Surgical tourism-in this case, lipotourism-is resulting in an increasing number of patients in Europe who may present uncommon disease patterns.

Rapid identification of microorganisms from positive blood cultures by MALDI-TOF mass spectrometry subsequent to very short-term incubation on solid medium.

Rapid identification of the causative microorganism is important for appropriate antimicrobial therapy of bloodstream infections. Bacteria from positive blood culture (BC) bottles are not readily available for identification by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Lysis and centrifugation procedures suggested for direct MALDI-TOF MS from positive BCs without previous culture are associated with additional hands-on processing time and costs. Here, we describe an alternative approach applying MALDI-TOF MS from bacterial cultures incubated very briefly on solid medium. After plating of positive BC broth on Columbia blood agar (n = 165), MALDI-TOF MS was performed after 1.5, 2, 3, 4, 5, 6, 7, 8, 12 and (for control) 24 h of incubation until reliable identification to the species level was achieved (score ≥2.0). Mean incubation time needed to achieve species-level identification was 5.9 and 2.0 h for Gram-positive aerobic cocci (GPC, n = 86) and Gram-negative aerobic rods (GNR, n = 42), respectively. Short agar cultures with incubation times ≤2, ≤4, ≤6, ≤8 and ≤12 h yielded species identification in 1.2%, 18.6%, 64.0%, 96.5%, 98.8% of GPC, and in 76.2%, 95.2%, 97.6%, 97.6%, 97.6% of GNR, respectively. Control species identification at 24 h was achieved in 100% of GPC and 97.6% of GNR. Ethanol/formic acid protein extraction performed for an additional 34 GPC isolates cultivated from positive BCs showed further reduction in time to species identification (3.1 h). MALDI-TOF MS using biomass subsequent to very short-term incubation on solid medium allows very early and reliable bacterial identification from positive BCs without additional time and cost expenditure.

[Successful treatment of Fusarium-associated keratitis with multiresistant pathogen and multimorbid patient]. / Erfolgreiche Therapie einer Fusarium-assoziierten Keratitis bei multiresistentem Erreger und multimorbidem Patienten.

A 75-year-old man (not a contact lens wearer) presented with Fusarium-associated hypopyon keratitis. After several weeks of empirical and subsequently targeted antimycotic treatment, no considerable improvement was observed. However, after sclerokeratoplasty (11.2 × 11.2 mm) combined with prolonged antimycotic therapy a good local result with relapse-free long-term follow-up was achieved.

Trends in antimicrobial non-susceptibility in methicillin-resistant Staphylococcus aureus from Germany (2004-2011).

We analysed trends in antimicrobial non-susceptibility in methicillin-resistant Staphylococcus aureus (MSRA) from Germany to assess the impact of the changing population structure of MRSA on antimicrobial resistance rates. During two large nationwide multicentre studies in 2004-2005 and 2010-2011, we collected consecutively spa-genotyped MRSA isolates. The increase in non-susceptibility rates for tetracycline and trimethoprim-sulphamethoxazole was associated with the spread of livestock-associated MRSA. A decrease in non-susceptibility rates for aminoglycosides and quinolones affected all major lineages (spa-clonal complexes 003, 008, and 032). All isolated remained susceptible to glycopeptides and linezolid.

Colorectal cancer in young patients in Israel: a distinct clinicopathological entity?

PURPOSE: This study was designed to characterize the entity of colorectal cancer (CRC) in young patients and to evaluate whether it has any unique epidemiological or clinicopathological features. METHODS: The study population consisted of all consecutive young (≤50 years old at diagnosis) patients with CRC who were diagnosed during the years 1997-2007 and were treated at our institution, and a matching group of patients (>50 years at diagnosis). The medical files of these patients were reviewed, and the epidemiological, clinical, and pathological features of both groups were compared. RESULTS: There were 406 patients: 203 in each group. The features of the older group were typical for patients with CRC, but the younger group showed female predominance, different ethnic composition, prevalence of family history of cancer and hereditary CRC syndromes, and lower incidence of polyps. The incidence of left-sided tumors and advanced stages (III-IV) at diagnosis was higher in the younger patients. Mucinous/signet ring histology, grade, stage, lymphatic and vascular invasion were all predictive of survival, whereas age was not. CONCLUSIONS: Colorectal cancer in young patients was found to display a cluster of unique characteristics but fewer than previously reported and young age by itself was not found to impact patient outcome.

The role of UFT in advanced gastric cancer.

BACKGROUND: Advanced gastric cancer has a poor prognosis, with a relative 5-year survival rate of 7%-27%. Chemotherapy, which improves overall survival (OS) and quality of life, is the main treatment option. Although numerous regimens have been investigated, there is no standard treatment. Combination chemotherapy, however, is associated with a significant survival benefit compared with monotherapy and i.v. 5-fluorouracil (5-FU) is one of the most widely used agents. UFT (tegafur-uracil) has similar efficacy to continuous infusion 5-FU with improved tolerability and is more convenient for patients. DESIGN: The efficacy and safety of UFT in the treatment of advanced gastric cancer have been demonstrated in a number of phase II studies. RESULTS: UFT with leucovorin (folinic acid) monotherapy shows overall response rates (ORRs) of 16%-29% and median OS of 5.8 months. Combination of UFT with cisplatin, etoposide, or paclitaxel shows ORRs of 35%-51% and median OS of 8.3-10.1 months. UFT-based three-drug combinations show ORRs of 41%-57% and median OS of 8.6-15 months. UFT-based combinations have a good tolerability profile, particularly a low incidence of myelosuppression, mucositis, and hand-foot syndrome. CONCLUSION: UFT represents a logical replacement for 5-FU in chemotherapy regimens for the treatment of advanced gastric cancer.

Irinotecan combined with bolus 5-fluorouracil and folinic acid for metastatic colorectal cancer: is this really a dangerous treatment?

Rothenberg et al called for caution in the palliative use of irinotecan, 5-fluorouracil (5-FU) bolus and leucovorin (IFL schedule), because of early treatment related deaths in C89803 and N9741 studies. The objective of our multicenter phase II study was to evaluate the efficacy and safety of the combination of 5-FU bolus, folinic acid (FA) and irinotecan as first-line chemotherapy for metastatic colorectal cancer. From December 1999 to June 2002 138 patients (pts) were treated. The chemotherapy regimen was as follows: irinotecan 125 mg/m2 i.v. over 90 min and 5-FU 500 mg/m2 preceded by FA 20 mg/m2, both given by bolus, weekly, for 4 weeks every 6 weeks. Treatment continued until disease progression or unacceptable toxicity. Total number of administered cycles was 404. Average dose intensity was 75%. 47 out of 131 evaluable pts achieved a complete (n = 6) or partial (n = 41) response, leading to an overall response rate (RR) of 36% [95% confidence interval (CI) 24% to 48%], stable disease was registered in 50 (38%). The estimated median time to progression and survival were 6.5 months (95% CI 5.2-9.4) and 16.6 months (95% CI 15.1-19.3) respectively. Two-year survival was 35%. Toxicity was well manageable. In 18 (13.8%) pts the chemotherapy was stopped because of toxicity. Treatment related death was not observed. Close clinical monitoring, early recognition of toxicity, immediate therapeutic intervention are recommended for pts receiving IFL. In our experience this regimen has manageable toxicity and appropriate level of dose intensity and seems to be a good option for first-line therapy in metastatic colorectal cancer.

Second neoplasms in patients with Merkel cell carcinoma.

BACKGROUND: Merkel cell carcinoma (MCC) has been associated with a high incidence of other skin tumors and hematological malignancies. The purpose of this study was to analyze data from the Israel Cancer Registry regarding the incidence of second neoplasms in patients with MCC and their impact on survival. METHODS: Sixty-seven patients in whom MCC was diagnosed between 1983 and 1999 were included. Data were collected on age, gender and ethnic origin, dates of diagnosis of MCC and any other neoplasm, and date and cause of death, if applicable. Comparison of MCC-specific survival, estimated by the Kaplan-Meier product limit method, between patients with no other neoplasm and those with second primary tumors was performed by log rank test. Age-specific standardized incidence ratio (SIR) was calculated using 5751 age- and ethnic-matched malignant melanoma patients as a control group. RESULTS: Seventeen patients (25%) had a second neoplasm before, concomitant with, or after the diagnosis of MCC; 2 of them also had a third primary tumor. The SIR was 2.8 (95% CI; range, 1.38-4.22), significantly higher than the control group. Almost half the tumors were squamous cell carcinomas, either skin or head and neck, and most of the remainder were hematological malignancies or breast and ovarian adenocarcinomas. On univariate analysis, the presence of another neoplasm, regardless of its chronology, was associated with higher MCC-specific mortality (65% vs. 40% for patients with MCC only; P = 0.022). Analysis of only those patients in whom a second neoplasm developed during follow-up after treatment for MCC yielded an estimated actuarial risk of developing a second primary of 2.1% for each year of observation. CONCLUSIONS: There is a high incidence of second neoplasms, including noncutaneous solid tumors, in patients with MCC. The presence of these neoplasms, whether they appear before, after, or simultaneously with MCC, is associated with a higher MCC-specific mortality.

The role of blood levels of soluble 53 kDa protein and CEA in monitoring colon cancer patients.

BACKGROUND: The usefulness of determining blood levels of the soluble p53 antigen and CEA was evaluated with respect to the monitoring colon cancer patients. METHODS: HPLC (high performance liquid chromatography) was used to measure serum levels of the soluble 53 kDa protein (s53) after its partial isolation on gel fiberglass affinity chromatography columns. RESULTS: The blood of cancer patients before tumor removal contained a high amount of s53 protein which did not change significantly over several subsequent months (4.5 and 4.7 mg/ml, respectively). The average serum level of CEA was relatively low but with extremely high deviations (48 +/- 128 ng/ml). In patients with recurrent cancer and metastases, the serum concentrations of the s53 protein and CEA remained at high levels and their changes during the period studied were not significant (3.9 +/- 3.5 and 6.1 +/- 2.9 for s53; 56.5 +/- 148.5 and 209.9 +/- 867.3 for CEA). Disease progression was accompanied by slight increase in the serum levels of the s53 protein (3.5 +/- 2.2 and 7.6 +/- 4.6) or CEA (143.3 +/- 98.5 and 244.9 +/- 873.8). Despite the absence of statistically significant changes in the serum levels of the s53 protein in different groups of patients, on an individual basis such changes could be detected and could be of diagnostic value. CONCLUSIONS: Findings suggest that HPLC determinations of blood levels of the s53 protein can be a useful means of monitoring cancer patients only if tumor removal is complete and the patient exhibits a subsequent sharp decrease in the p53 protein serum level. In such cases, a following increase in the serum level of the p53 protein reflects the initiation of a new neoplastic formation which can then be detected a few months earlier than by any other available method. However, if the patient's immune system reacts weakly to the operation and the blood concentration of the s53 protein remains high, neither CEA nor s53 levels can be used for monitoring purposes.

The role of the soluble p53 antigen and its autoantibodies as markers for diagnosis of colon cancer: a comparative study.

The role of various serological tumor markers, p53 soluble antigen and its autoantibodies, was evaluated for the detection of colon cancer in humans. An HPLC technique was used to measure serum levels of both forms of p53 protein after their partial isolation on gel fiberglass affinity chromatography columns. Tumor-associated proteins (TAP) in the form of either antigens or autoantibodies were about 4% of the total protein isolated from the serum of colon cancer patients. The absolute amount of each of the two types of TAP was also similar: 14.69 2.88 and 18.29 3.85 mg ml-1, respectively. The amount of p53 autoantibodies was higher than those of p53 antigen, but the difference was not significant: 9.35 3.48 and 6. 19 3.87 mg/ml, respectively (p>0.05). A good correlation was found between the total amount of tumor-associated antigens (TAA) and the amount of p53 antigen (r=0.69), total amount of IgG and the amount of p53 autoantibodies (r=0.46), and between both forms of p53 protein (r=0.46). A high coefficient of regression was found between the total amount of TAA and the amount of p53 antigen (b=2.4). Relationships between Duke's stage in colon cancer and the serum levels of p53 protein were weak: 0.33 and -0.32 for p53 antigen and its autoantibodies, respectively. Serum determination of p53 autoantibodies has no advantage over the determination of p53 antigen. Both forms of p53 protein can be isolated with extremely high accuracy for the pathological diagnosis of cancer (87-93%). Specificity of the method was proved using of commercial p53 PAb OD1: the GFG columns with this antibody were able to isolate the same proteins which were isolated by GFG columns with anti-p53 IgG. Moreover, the isolation of p53 protein was performed with higher effectiveness using the GFG columns with entrapped anti-p53 IgG than those columns with commercial DO1 PAb.

Comparative study of the role of serum levels of p53 antigen and its tumor cell concentration in colon cancer detection.

The role of serum levels of p53 antigen in detection of colon cancer was studied in different groups of cancer and noncancer patients and was compared with the results of immunohistochemical analyses. The p53 antigen was isolated from the human serum as a cytoplasmic fraction using the recently described new type of columns for affinity chromatography, gel fiberglass columns (Zusman and Zusman, 1995). Its concentration was detected by high performance liquid chromatography. The serum level of the p53 antigen significantly increased in cancer patients (3.6 mg ml(-1)) as compared to its concentration in patients with benign tumors (1.7 mg ml(-1)) or in patients with noncancer disorders (0.49 mg ml(-1)), and this was found to be a result of higher concentration of p53 protein in tumor cells. Coefficient of correlation between cellular concentration of p53 protein and its serum level was 0.44 in noncancer lesions and 0.48 in cancer patients. Serum levels of p53 antigen was shown to be highly active either in patients with noncancer lesions or in patients with cancer (r = 0.46 and 0.51 respectively), whereas the cell determination of p53 protein was effective only among noncancer patients (r = 0.61) but not in cancer patients (r = 0.22). The findings suggests that serum determination of p53 antigen can perhaps reveal this oncoprotein already in the early stages of cancer or even predict the putative development of cancer. The possibility to use the serum-levels of p53 antigen in the follow up patients with chronic diseases and to detect transformation of these diseases into cancer, or monitoring former cancer patients in order to detect as early as possible the incidence of recurrent cancer is discussed.

Gel fiberglass as a new matrix of affinity chromatography columns for isolation of colon cancer-associated antigens.

Gel fiberglass (GFG), a new affinity biosensor, was used to isolate human p53 antigen with rabbit anti-rat p53 IgG. The biosensor was prepared as a membrane from glass fibers covered with oxysilanes. A thin layer of protein, trapped in gel glass during its preparation, is deposited on the surface of a lattice of glass fibers. In such conditions, a maximum number of protein molecules may contact external agents percolated through a membrane. The membranes demonstrate high stability and can be stored in dry conditions or several months at room temperature. Columns for affinity chromatography were prepared from the GFG membranes and were used to isolate various proteins, including the tumor-associated antigens (TAA). The capacity of such columns was calculated as the amount mg of protein isolated from 1 ml of TAA-containing serum. In colon cancer patients, up to 5-6 mg TAA were extracted from 1 mi of sera. Two main components of cytoplasmic TAA isolated in our experiments were p64 and p53 proteins. Their concentration was determined by HPLC. The p53 protein has been isolated from the serum of cancer patients in the highest concentration yet reported, up to 3-4 mg/ml. In our previous studies, isolation of p53 protein was based on its affinity reaction with anti-p53 IgG generated against antigens of the same species. Herein, we report for the first time the capability to isolate human p53 antigen using GFG columns with entrapped anti-rat p53 IgG. Blood levels of p53 antigen isolated were very similar in both experiments. This has both theoretical and practical significance, demonstrating that the GFG membranes have great potential for isolating macromolecules utilizing various ligands. The finding facilitates an easy and highly effective method to isolate antigens from different organs, both animal and human, which can be used for important goals including diagnosis, therapy and generation of specific antibodies.

HPLC determination of serum levels of soluble p53 antigen as a new method for colon cancer detection, and its clinical implication.

Previously, we have described a new modification of affinity chromatography columns for isolation of the cytoplasmic, soluble form of tumor-associated antigens (TAA) from the serum of colon cancer patients (Oncol Rep 2: 679-683, 1995). In this communication, we have shown that the main proteins of these TAA were p64 and p53. The correlation coefficient between each of these proteins and the total amount of TAA or total serum protein ranged from 0.55 to 0.93. The serum level of p53 antigen was shown to be related to the tumorigenicity: the correlation and regression coefficients between the serum level of p53 protein and the progress in colon cancer were 0.48 and 0.88, respectively, p<0.001. Therefore, the determination of serum concentration of this protein can serve as a screening tool for cancer detection. The serum level of p53 protein ranges between 0.24 to 0.94 mg/ml in patients with non cancer diseases, and between 1.0 to 2.0 mg/ml in patients with polyposis and in a high risk group, respectively, increases over 2.0 mg/ml in primary colon cancer patients and up to 5.0 mg/ml in cancer patients with metastases. The sensitivity and specificity of our method achieved 92% and 96%, respectively, and accuracy 88%. The presence of p53 protein in the cytoplasm of cells from patients with non cancer diseases may explain why p53 antigen is presented in their sera. Our method can be useful to detect cancer development either as a primary illness or as a recurrent disorder. It is possible to follow up patients with chronic diseases and to detect transformation of these diseases into cancer, or to follow up former cancer patients in order to detect as early as possible incidence of recurrent cancer. It should also be emphasized that our method allows the detection of patients with polyposis or those of high risk groups who exhibit a tendency to develop colon cancer.