Mirosław Łuczak

Effects of bacteriophages on free radical production and phagocytic functions

Reactive oxygen species (ROS) play a major role in mediating antibacterial functions of phagocytic cells. However, excessive ROS production may cause oxidative stress and tissue damage. Uncompensated ROS release has been implicated in a variety of disorders. Novel means of controlling elevated ROS production are urgently needed. We showed that homologous but not the heterologous phages inhibited, in a dose dependent manner, the degree of chemiluminescence in phagocytes induced by Escherichia coli. Treatment of the cells with the phages alone resulted in a small increase in ROS production. Homologous phages also facilitated phagocytosis when preincubated with bacteria. On the other hand, both homologous and heterologous phages inhibited phagocytosis following preincubation with phagocytic cells. The treatment of infected and uninfected mice with phages did not significantly alter the rate of phagocytosis by blood granulocytes and monocytes. In conclusion, we showed that bacteriophages can decrease ROS production by phagocytes. Although in some in vitro experimental models the phages tended to diminish phagocytosis, this phenomenon may be of little significance in clinical situations, since the process of eliminating bacteria in phage-treated patients is predominantly accomplished by both phages and phagocytes.

Studies of insect peptides alloferon, Any-GS and their analogues. Synthesis and antiherpes activity

The subject of these studies was synthesis and determination of biological properties of a series of insect peptides, such as alloferon, Any‐GS and their analogues. The synthesis of 14 peptides was performed by the solid‐phase method. Biological effect of these peptides was evaluated by the antiviral test against Human Herpes Virus type 1 (HHV‐1) in vitro using a Vero cell line. It was found that the investigated peptides inhibit the replication of HHV‐1 in Vero cells. Copyright

Recent Emergence of an Epidemic Clindamycin-Resistant Clone of Clostridium difficile among Polish Patients with C. difficile-Associated Diarrhea

ABSTRACT Analysis of both the antibiotic resistance and the virulence characteristics of anaerobic human microbial pathogens is important in order to improve our understanding of a number of clinically significant infectious diseases, including Clostridium difficile-associated diarrhea (CDAD). We determined the presence of the clindamycin resistance-associated gene ermB and the ribotype of 33 C. difficile strains isolated from Polish patients suffering from CDAD. While all strains produced cytotoxin B (TcdB), enterotoxin A (TcdA) was produced by a subset of 15 strains only. The results showed that a single ermB-positive, TcdA−B+C. difficile strain with ribotype A has disseminated widely in the two Warsaw hospitals under investigation. Although different strains with the same phenotype were detected, the genotype A strain appeared to be the only one with a clear epidemic character. Apparently, enhanced local spread of CDAD-causing C. difficile may be restricted to a limited number of bacterial genotypes only.

Clonal Spread of a Clostridium difficile Strain with a Complete Set of Toxin A, Toxin B, and Binary Toxin Genes among Polish Patients with Clostridium difficile-Associated Diarrhea

ABSTRACT Clinically relevant Clostridium difficile strains usually produce toxins A and B. Some C. difficile strains can produce an additional binary toxin. We report clonality among five strains carrying all toxin genes from Polish patients with C. difficile-associated diarrhea. In another strain, possible recombination between binary toxin genes is documented.

Toxin Profiles and Resistances to Macrolides and Newer Fluoroquinolones as Epidemicity Determinants of Clinical Isolates of Clostridium difficile from Warsaw, Poland

ABSTRACT Amplified fragment length polymorphism genotypes, antibiotic resistance profiles, and toxin profiles of Clostridium difficile strains from Warsaw were determined. The isolates segregate in six major genotypes, coinciding with toxin profiles. Most of the toxin A-negative toxin B-positive toxin CDT-negative strains possess ermB, and several strains were resistant to fluoroquinolones. Resistograms and toxin types of C. difficile strains are epidemicity determinants.

Further studies on the antiviral activity of alloferon and its analogues

The subject of our studies was the synthesis, biological evaluation, and conformational studies of insect tridecapeptide alloferon (H‐His‐Gly‐Val‐Ser‐Gly‐His‐Gly‐Gln‐His‐Gly‐Val‐His‐Gly‐OH) and its analogues such as: [des‐His1]‐, [Lys1]‐, [Arg1]‐, and [Ala1]‐alloferon. These peptides were synthesized to check the influence of the His residue at position 1 of the alloferon chain on its antiviral activity. Two aspects of the biological effects of these peptides were determined: (i) the cytotoxicity in vitro in the Vero, LLC‐MK2, and HEp‐2 cell lines, and (ii) the antiviral activity in vitro in respect to DNA and RNA viruses. We found that alloferon inhibited the herpes virus multiplication and failed to affect the coxsackie virus replication, whereas [Lys1]‐alloferon exhibited a high inhibitory action towards both viruses. Moreover, the peptides did not show any cytotoxic activity against the Vero, LLC‐MK2, and HEp‐2 cells. The preliminary circular dichroism conformational studies showed that the peptides investigated seem to prefer an unordered conformation. Copyright

Clostridium difficile and enterotoxigenic Bacteroides fragilis strains isolated from patients with antibiotic associated diarrhoea

From the fecal samples of 332 patients with a clinical diagnosis of antibiotic associated diarrhoea (AAD), 131 Clostridium difficile strains were isolated. For detection of toxin A in the isolated strains the enzymatic immunoassay was used. The cytopathic effect was determined on McCoy cell line. PCR was used for the detection of non-repeating and repeating sequences of toxin A gene and non-repeating sequences of toxin B gene. One hundred and six isolated C. difficile strains were TcdA(+)TcdB(+), 10 strains TcdA(-)TcB(+) and 15 were non-toxigenic TcdA(-)TcdB(-). Out of the same fecal samples 50 Bacteroides fragilis strains were isolated. All B. fragilis strains were tested in PCR reaction for fragilysine gene detection (bft). In 9 strains (18%) this gene was detected and the strains could be assumed as enterotoxigenic Bacteroides fragilis (ETBF). In 4 fecal samples toxigenic C. difficile (TcdA(+)TcdB(+)) was found simultaneously with ETBF. One sample contained C. difficile (TcdA(-)TcdB(+)) and ETBF. Out of 4 fecal samples only ETBF was isolated. The cytotoxicity of ETBF strains was tested on HT29/C1 human colon carcinoma cell line. The cytotoxicity titer in the range of 20 and 80 was observed.

Microbiological findings and treatment of EBV-associated hemophagocytic lymphohistiocytosis: a case report.

Epstein–Barr virus (EBV) is the major triggering factor for hemophagocytic syndrome or hemophagocytic lymphohistiocytosis (HLH). In patients with EBV-HLH, the EBV-infected T cells or natural killer cells are mostly mono- or oligoclonally proliferating, whereby hypercytokinemia plays a major role and causes hemophagocytosis, cellular damage, and dysfunction of various organs. This report describes the detection and treatment of EBV-associated HLH in the case of a 17-year-old male. Serum samples and skin swabs were tested for the presence of viral DNA using real-time PCR techniques. To confirm the molecular biological tests, electron microscopy was also performed. EBV DNA was detected with real-time PCR in both blood samples and skin swabs. The level of viral DNA constantly decreased during the applied therapy. The presence of the virus in the skin was confirmed by the appearance of herpes virus-like particles detected by electron microscopy in fluid taken from skin ulcerations. The results show that in terms of treatment, special therapeutic measures are required to control the cytokine storm generated by EBV and to suppress proliferating EBV genome-containing cells because the clinical course is often fulminate and results in a poor outcome. Therefore the potential of chemotherapy with a combination of steroids, etoposide, and cyclosporine to control HLH was assessed in the adolescent, who met the stringent diagnostic criteria for this reactive disorder of the mononuclear phagocyte system.

Prevalence of human herpesvirus 6 antibodies and DNA in allogeneic stem cell transplant patients: two-year single centre experience

Introduction:Human herpesvirus 6 (HHV-6) has been recognized as a potentially significant pathogen in hemopoietic stem cell transplant (HSCT) recipients. Different clinical manifestations have been described, including fever, skin rash, bone marrow suppression, and encephalitis.Materials and Methods:A retrospective review of a group of 26 adult recipients of allogeneic HSCTs was conducted. Serum samples taken before transplant were examined for the presence of specific anti-HHV-6 IgM and IgG antibodies. After transplantation, quantitative real-time PCR was used to determine viral load in plasma samples from days 0–80 post-transplant.Results:HHV-6 DNA was detected in plasma samples in 8 (30%) of the 26 recipients between days 18 and 40 after transplantation. All of them developed fever of unknown origin and over 50% had graft-versus-host disease features. Three individuals from this group died during detectable HHV-6 viremia. Another two recipients showed a single positive PCR result at a later time. Infection with HHV-6 was thus confirmed in 10 (38.5%) of the 26 graft recipients.Conclusions:There is a high frequency of detectable HHV-6 viral load in stem cell transplant recipients in Poland. Further investigation to monitor HHV-6 reactivation in graft recipients will be important to improve outcome for these patients.

Comparison of two methods used for monitoring low-copy cytomegalovirus infection in a patient with chronic myeloid leukemia after unrelated umbilical cord blood transplantation

Introduction:Detection of human cytomegalovirus (CMV, HHV-5) DNA in clinical specimens is considered a cornerstone in the diagnosis of HHV-5 disease. The present study compared two quantitative methods used for diagnosing cytomegalovirus infection in a 21-year-old woman with chronic myeloid leukemia after an unrelated umbilical cord blood transplantation.Materials and Methods:Blood samples were tested for the presence of HHV-5 DNA using the LightCycler PCR, the quantitative Eclipse® CMV DNA Detection Kit, and a qualitative in-house PCR assay using primers that amplify part of the HHV-5 MIE gene.Results:Results from samples containing a low cytomegalovirus load were more accurate with the LightCycler test than those obtained with the Eclipse® test, which underestimated the viral load of samples containing low DNA copy numbers.Conclusions:These findings underline the value of novel PCR methods used in current therapeutic procedures and in monitoring antiviral therapy with nucleoside analogs. The high level of sensitivity, specificity, accuracy, and rapidity provided by the LightCycler instrument are favorable for the use of this system in the detection of HHV-5 DNA in clinical specimens.