Rat bite fever, a diagnostic challenge: case report and review of 29 cases.

Rats can transmit Streptobacillus moniliformis, which may cause rat-bite fever (RBF), a rare and potentially lethal zoonosis. Fastidious in vitro growth and unspecific symptoms, including fever, arthralgia, and polymorphous skin lesions, complicate the diagnosis. Rat-bite fever follows exposure to contaminated bodily fluids of infected rodents; however, reports on Streptobacillus moniliformis-related infections are few so far. A female patient presented with painful hemorrhagic pustules and purpuric lesions on hands and feet. She developed fever and migratory polyarthralgia. Blood culture yielded growth with Streptobacillus moniliformis. The patient owned rats and handled contaminated rat feces and urine, making this the most likely etiology of infection. We report a case of RBF due to Streptobacillus moniliformis in a rat handling-patient. Difficulties in clinical and microbiological diagnosis highlight the need for a thorough and complete history-taking and a greater understanding of this rare infectious disease.

Quality assurance of gelcards centrifuged multiple times before use for testing.

BACKGROUND: Further use of reagents, that have not been consumed in total by tests in the laboratory, is of financial and ecological interest. If there are no instructions by the manufacturer, such a procedure must be validated thoroughly. As gelcards of the DiaMed-ID Micro Typing System contain 6 microtubes for immunohematological reactions, sometimes not all of these microtubes are needed at the same time. METHODS: Gelcards "NaCl, enzyme test and cold agglutinins" and "Liss/Coombs" were not recentrifuged or 1 to 5 times recentrifuged. Gelcards "DiaClon ABD confirmation for patients" were not recentrifuged or recentrifuged once before being used for testing. RESULTS: The use of gelcards, recentrifuged up to 5 times or recentrifuged 1 time, respectively, before use, provided no false positive or false negative results. CONCLUSIONS: Quality assurance of gelcards, that had been centrifuged several times before being used for testing, is an example for economical and safe use of resources in the laboratory.

Evaluation of a new monoclonal anti-k (anti-KEL2) reagent.

BACKGROUND: The first monoclonal anti-k (anti-KEL2) reagent of the IgM-class (clone: LK1) for the tube spin method is now commercially available. As this reagent is directly agglutinating in contrast to conventional polyclonal anti-k reagents requiring an indirect antiglobulin test, we studied the reaction characteristics of this new reagent carefully before starting its use in our routine blood grouping laboratory. METHODS: The titer of the monoclonal anti-k reagent (manufacturer: Biotest, D-63303 Dreieich) was compared with that of two polyclonal anti-k reagents. The avidity was tested with 2 K+k+ red blood cells (RBCs). The reactivity was examined by 10 K+k+ and 3 K-k+ blood samples. Specificity was tested with 12 k- RBCs from several antibody identification panels and from well known blood donors. The influence of a positive direct antiglobulin test was examined by using antibody-loaded RBCs. RESULTS: The titer of the monoclonal reagent was the same as that of one of the polyclonal reagents and one geometrical titer step lower than that of the other. At immediate spin and after 5, 10 and 15 minutes incubation at room temperature the reactions of the monoclonal reagent were clear. All 10 K+k+ and all 3 K-k+ blood samples were detected. No false positive reactions were found with RBCs carrying the most important antigens of the ABO, Lewis, P, Rhesus, Kell, Duffy, Kidd, Lutheran, Colton, and Cartwright system. After loading k- D+ RBCs with an incomplete anti-D no false positive reactions were seen. Loading K-k+ RBCs with incomplete anti-k also had no significant influence on the reaction. CONCLUSIONS: Several general advantages of monoclonal reagents of the IgM-class were seen in the new monoclonal anti-k as well: direct agglutination without an indirect antiglobulin test; rapid and simple performance; use in a saline milieu also allowing the examination of RBCs with a positive direct antiglobulin test; lack of false positive reactions caused by contaminating antibodies in the reagent. As in Germany two different reagents must be used for testing a RBC antigen, a further anti-k reagent with a different monoclonal antibody of the IgM-class would be a useful addition.

Hemolytic Transfusion Reactions.

SUMMARY: The risk of hemolytic transfusion reactions (HTRs) is approximately 1:70,000 per unit. Acute HTRs occurring during or within 24 h after administration of a blood product are usually caused by transfusion of incompatible red blood cells (RBCs), and, more rarely, of a large volume of incompatible plasma. Delayed HTRs are caused by a secondary immune response to an antigen on the donor's RBCs. In some patients with delayed HTRs, an additional bystander hemolysis of the patient's RBCs can be assumed. Different mechanisms lead to intra- and extra-vascular hemolysis, such as complete complement activation, phagocytosis of RBCs covered with C3b by macrophages after incomplete complement activation, or destruction of RBCs covered only with IgG by direct cell-cell contact with K cells. The clinical consequences of HTRs are triggered via several pathophysiological pathways like formation of anaphylatoxins, release of cytokines causing a systemic inflammatory response syndrome, activation of the kinin system, the intrinsic clotting cascade and fibrinolysis resulting in hypotension, disseminated intravascular coagulation, diffuse bleeding, and disruption of microcirculation leading to renal failure and shock. In the following, the symptoms of HTR are introduced, laboratory investigations and treatment are described, and some recommendations for prevention are given.

Relationship between ABO and Secretor genotype with plasma levels of factor VIII and von Willebrand factor in thrombosis patients and control individuals.

In contrast to earlier reports, this study examined the relationship between plasma levels of factor VIII (FVIII) and von Willebrand factor (VWF) and ABO blood group and secretor status at the genetic level in 355 patients with venous thrombosis as well as in 236 controls. ABO glycosyl transferase alleles A(1) and B were more frequent in the thrombosis collective and alleles O(1), O(2) and A(2) were more frequent in the controls. A low-risk group for venous thrombosis of individuals with genotypes O(1)O(1), O(1)O(2) and O(1)A(2) (H-antigen rich) could be distinguished from a high-risk group with genotypes A(1)A(1), A(1)B, O(1)A(1) and O(1)B (H-antigen poor). In both the thrombosis and control groups, the H-antigen rich group showed significantly lower levels of FVIII coagulant activity (FVIII:C) and VWF antigen (VWF:Ag) than the H-antigen poor group. The frequency of the different secretor genotypes in the thrombosis group was not different from that in the control group. No significant differences of FVIII:C and VWF:Ag levels were seen between SeSe, Sese and sese individuals in the thrombosis and in the control group. Thus the risk of venous thrombosis is associated with the ABO blood group genotype but not with secretor status.

Use of the enzyme method for antibody identification.

Enzyme methods for red blood cell antibody testing may have two goals: detection of weak antibodies by increasing the strength of the reactions and differentiation of the antibodies in an antibody mixture by abolishing the reaction of antibodies against enzyme-labile antigens. We analyzed the phenotype listing sheets of all lots of one year (expiration date in 2002) of 8 products (5 manufacturers) (together 130 worksheets). The aim was to find out how often some antibodies could only be detected after enzyme treatment, when there is an additional antibody against one of the following enzyme-labile antigens in the patient's serum: Fya, Fyb, M, N, S and s. If there is one of these antibodies against an enzyme-labile antigen, an additional antibody against one of the following enzyme-stable antigens D, C, E, c, e, CW, K, Kpa, Jsa, Jka, Jkb, Lea, Leb, P1, Lua cannot be detected on average in 20% of the panels. Moreover, in a further 37% of the panels there is no red blood cell suspension carrying the Kpa, in 44% none carrying the Jsa and in 19% no one carrying the Lua antigen. On the other hand, an antibody against one of the high-incidence antigens k, Kpb, Jsb or Lub can be detected in each of the 130 panels, also if there is an additional antibody directed against one of the above-mentioned enzyme-labile antigens. As also nowadays in some antibody identification panels antibodies against some enzyme-stable antigens might be covered by antibodies against enzyme-labile antigens, the enzyme method can be a helpful completion in antibody differentiation in some sera with multiple antibodies.

The molecular basis of the Rhesus antigen Ew.

BACKGROUND: The Rhesus antigen Ew (ISBT designation 004 011) was first described in 1955. It is defined by a specific antibody, but its molecular genetic basis has not yet been resolved. STUDY DESIGN AND METHODS: Two individuals serologically characterized to express the rare Rhesus antigen Ew were analyzed by sequencing of all 10 exons of the RHCE gene. RESULTS: A nucleotide exchange at position 500 (T500A) resulting in a Met167Lys amino acid substitution was found in both individuals. Moreover, we show that an individual carrying the Ew antigen is capable to produce an alloantibody against the wild-type E antigen. CONCLUSION: The single-point mutation T500A in exon 4 of the RHCE gene is a molecular basis of the rare Rhesus antigen Ew.