Papers by Brigitte Koenig
BMC Veterinary Research, 2010
Background: Bovine Tuberculosis (BTB) is a widespread and endemic disease of cattle in Ethiopia. ... more Background: Bovine Tuberculosis (BTB) is a widespread and endemic disease of cattle in Ethiopia. Information relating to genotypic characteristics of Mycobacterium bovis strains affecting the cattle population in Ethiopia is limited. We carried out molecular characterization of M. bovis strains isolated from BTB infected cattle using the spoligotyping technique. The relationship between distribution of spoligotypes and recorded variables was also investigated. A new approach that can numerically reflect the degree of genetic polymorphism in a M. bovis population was also developed. The study was conducted from July 2006 to January 2007 in cattle slaughtered at five representative abattoirs in Ethiopia. Results: Forty-five M. bovis isolates were obtained from 406 pathologic tissue specimens collected from 337 carcasses with lesions compatible with BTB. Twelve spoligotypes were identified from 34 distinct strains; with SB1176 as a dominant spoligotype (41.2% of the isolates) followed by SB0133 (14.7%). Comparison of spoligotypes with an M. bovis global database http://www.mbovis.org revealed six new spoligotypes which were subsequently registered in the database with international identification codes of SB1517, SB1518, SB1519, SB1520, SB1521 and SB1522. The majority of strains were obtained from cattle slaughtered at Addis Ababa abattoir. On the basis of the Spoligotype Evolutionary Index, SEI (a numeric expression approach to make standardized comparison of spoligotype evolution), M. bovis isolates from Ethiopia were relatively more heterogeneous (SEI = 3.2) compared to isolates from other countries. This might be attributed to extensive livestock movement linked to trading or seasonal migration, high degree of livestock mingling, and also diversities of the country's agricultural and livestock ecosystems, in addition to lack of disease control measures that led to high infection prevalence. Multiple spoligotype infection was recorded in nine (50%) of infected carcasses and this may indicate the prevailing high degree of super infection. Conclusions: This study provided molecular evidence for the widespread distribution of M. bovis in the cattle population in Ethiopia. It also demonstrated a relatively high degree of genetic polymorphism of the isolates. Further molecular investigation of M. bovis strains in humans and other domestic animals is recommended in order to elucidate the zoonotic importance as well as reservoirs and pattern of transmission among various hosts.
International Journal of Medical Microbiology, 2007
Pregnancy Hypertension: An International Journal of Women's Cardiovascular Health, 2017
Journal of Microbiological Methods, 2007
Classical phenotypic and biochemical testing do not lead to correct identification of the distinc... more Classical phenotypic and biochemical testing do not lead to correct identification of the distinct Staphylococcus species. Therefore, the aim of our study was to develop a method for the reliable and accurate determination of distinct Staphylococcus species. In the present study, the 931-934-bp partial sequences of the glyceraldehyde-3-phosphate dehydrogenase-encoding (gap) gene of 28 validly described Staphylococcus species were amplified and sequenced. By using the respective sequence information we performed a terminalrestriction fragment length polymorphism (T-RFLP) analysis. For T-RFLP the partial gap gene was amplified with double-fluorescently labelled primers and digested with the restriction enzymes DdeI, BspHI and TaqI. Distinctive T-RFLP patterns were rendered by the use of capillary electrophoresis with laser-induced fluorescence detection. This molecular method allowed us to identify all 28 Staphylococcus species with high specificity. This was validated by analysis of 34 Staphylococcus epidermidis and 28 Staphylococcus haemolyticus isolates. These results demonstrate the feasibility and applicability of the T-RFLP method based on the partial gap gene sequences for rapid and accurate species identification.
Journal of Medical Microbiology, 1997
Staphylococcus aureus produces numerous bi-component toxins, e.g., Panton-Valentine leukocidin (L... more Staphylococcus aureus produces numerous bi-component toxins, e.g., Panton-Valentine leukocidin (Luk-PVL) and y-haemolysin, which consist of type S and F proteins. Previous studies showed that Luk-PVL induces inflammatory mediator release from human granulocytes that might reflect the in-vivo effects, e.g., dermonecrosis by Luk-PVL. Clinical isolates not only harbour the two genes coding for Luk-PVL (S-protein: LukS-PVL, F-protein: LuW-PVL) but also the three genes encoding y-haemolysin (Sprotein: HlgA, HlgB; F-protein: HlgC). The interaction of all the possible potential toxins with human granulocytes was studied with regard to the generation of oxygen metabolites (chemiluminescence response), enzyme activity (P-glucuronidase) and histamine release as well as interleukin (IL)-8 generation. The data clearly show that the individual subunits (S, F) differ in their activities. The following activities were obtained for the S components: LukS-PVL > HlgC > HlgA; the F components LukF-PVL and HlgB were similarly active. Thus, the toxins LukS-PVL/LukF-PVL and LukS-PVL/HlgB were the most potent inducers of inflammatory mediator release from human granulocytes, followed by HlgC/LukF-PVL and HlgC/HlgB and to a lesser degree by the toxins HlgA/LukF-PVL and HlgA/HlgB. The data indicate that class S components and class F components are interchangeable and give toxins with genuine biological activities.
International Archives of Allergy and Immunology, 1997
Pseudomonas aeruginosa phospholipase C (PLC) is a critical component in the pathogenesis of sever... more Pseudomonas aeruginosa phospholipase C (PLC) is a critical component in the pathogenesis of severe P. aeruginosa infections. However, P. aeruginosa can produce a hemolytic (PLC-H) as well as a nonhemolytic (PLC-N) variant, both having a MW of about 77 kD. In the past, studies did not distinguish between both types of PLC with regard to the induction of inflammatory mediators from human cells. We compared the ability of P. aeruginosa PLC-H and PLC-N to generate leukotriene B4 (by HPLC) and oxygen (O2-) metabolites (luminol-enhanced chemiluminescence), and to release beta-glucuronidase and histamine (fluorophotometry from human granulocytes. Therefore, human neutrophilic granulocytes (PMN; 1 x 10(7)) or human peripheral blood mononuclear cells (5 x 10(6)) were treated with purified P. aeruginosa PLC-H (up to 10 units) as well as culture supernatants (cutoff: MW > 50,000) of P. aeruginosa PAOl capable of producing both PLC-H and PLC-N, and PAOl mutant strains deficient in the production of either or both phospholipases. Controls were PLC-H from Clostridium perfringens and PLC-N from Bacillus cereus. PLC-H-containing P. aeruginosa culture supernatant, purified P. aeruginosa PLC-H as well as PLC-H from P. perfringens activated human leukocytes for a significant (p < 0.05) increase in inflammatory mediator release. In this regard, purified PLC-H (10 units) from P. aeruginosa activated human PMN for a significant increase in the generation of oxygen metabolites (30 +/- 5.4 x 10(3) cpm) and in leukotriene B4 (6.1 +/- 2.0 ng), in the release of beta-glucuronidase (15.8 +/- 1.1%) and of histamine (25.8 +/- 6.2%) as compared to the corresponding control values (3 +/- 1 x 10(3) cpm; 0.2 +/- 0.1 ng; 5.1 +/- 1.0%, 5.1 +/- 1.5%). Culture supernatants containing no PLC or only PLC-N, as well as PLC-N from B. cereus, failed to activate or only slightly stimulated human granulocytes for inflammatory mediator release. The data thus provide evidence that P. aeruginosa PLC-H can be a potent inducer of inflammatory mediator release, at least in vitro. Our results therefore contribute to the understanding of the pathophysiological role of P. aeruginosa PLCs.
Infection and Immunity, 1994
We analyzed the transcription and release of interleukin-8 (IL-8) from human polymorphonuclear gr... more We analyzed the transcription and release of interleukin-8 (IL-8) from human polymorphonuclear granulocytes (PMNs) and a lymphocyte-monocyte-basophil (LMB) cell population stimulated for different time periods (30 min to 16 h) with pore-forming bacterial toxins (Panton-Valentine leukocidin [Luk-PV] and alveolysin [Alv]) as well as with the erythrogenic toxin A (ETA) as a superantigen. At high toxin concentrations (500 ng/10(7) cells), Luk-PV and Alv led to a decreased IL-8 generation from LMBs within the first 30 min; with PMNs, a slight increase in IL-8 release was observed. Under these conditions, stimulation with ETA did not lead to an altered cellular IL-8 release. At lower concentrations (5 and 0.5 ng/10(7) cells), all three toxins led to a continuous increase (over 16 h) in IL-8 release and IL-8 mRNA expression of PMNs and LMBs. Preincubation of the cells with the protein tyrosine kinase inhibitors lavendustin A and tyrphostin 25 led to a reduction of the toxin-mediated effect...
Pregnancy Hypertension, 2018
Background: Preeclampsia is a life-threatening disease in pregnancy, and its complex pathomechani... more Background: Preeclampsia is a life-threatening disease in pregnancy, and its complex pathomechanisms are poorly understood. In preeclampsia, lipid metabolism is substantially altered. In late onset preeclampsia, remnant removal disease like lipoprotein profiles have been observed. Lipid apheresis is currently being explored as a possible therapeutic approach to prolong preeclamptic pregnancies. Here, apheresis-induced changes in serum lipid parameters are analyzed in detail and their implications for preeclamptic lipid metabolism are discussed. Methods: In the Freiburg H.E.L.P.-Apheresis Study, 6 early onset preeclamptic patients underwent repeated apheresis treatments. Serum lipids pre-and post-apheresis and during lipid rebound were analyzed in depth via ultracentrifugation to yield lipoprotein subclasses. Results: The net elimination of Apolipoprotein B and plasma lipids was lower than theoretically expected. Lipids returned to previous pre-apheresis levels before the next apheresis even though apheresis was repeated within 2.9 ± 1. 2 days. Apparent fractional catabolic rates and synthetic rates were substantially elevated, with fractional catabolic rates for Apolipoprotein B / LDL-cholesterol being 0.7 ± 0.3 / 0.4 ± 0.2 [day − 1 ] and synthetic rates being 26 ± 8 / 17 ± 8 [mg*kg − 1 *day − 1 ]. The distribution of LDL-subclasses after apheresis shifted to larger buoyant LDL, while intermediatedensity lipoprotein-levels remained unaffected, supporting the notion of an underlying remnant removal disorder in preeclampsia. Conclusion: Lipid metabolism seems to be highly accelerated in preeclampsia, likely outbalancing remnant removal mechanisms. Since cholesterol-rich lipoprotein remnants are able to accumulate in the vessel wall, remnant lipoproteins may contribute to the severe endothelial dysfunction observed in preeclampsia. Trial registration: ClinicalTrails.gov, NCT01967355.
Infection and Immunity, 1994
The Escherichia coli alpha-hemolysin represents a potent stimulus for inflammatory mediator relea... more The Escherichia coli alpha-hemolysin represents a potent stimulus for inflammatory mediator release (O2-, beta-glucuronidase release, and leukotriene generation) from human polymorphonuclear granulocytes, for histamine release from a suspension of human lymphocyte/monocyte basophil cells (LMB), and for serotonin release and 12-hydroxyeicosatetraenoic acid generation from human platelets. In contrast, the E. coli alpha-hemolysin leads to a downregulation of cytokine release (interleukin-1 beta [IL-1 beta], IL-6, and tumor necrosis factor alpha) from human LMB. Recently, it became apparent that the E. coli alpha-hemolysin is composed of several functional structures. We analyzed the role of pore formation, pore stability, and calcium-dependent membrane binding for inflammatory mediator release by using washed bacteria as well as culture supernatants of isogenic recombinant E. coli strains expressing no hemolysin (Hly-), the wild-type hemolysin (Hly+), or hemolysin molecules deficient ...
An ever-growing number of metagenomes can be used for biomining and the study of microbial functi... more An ever-growing number of metagenomes can be used for biomining and the study of microbial functions. The use of learning algorithms in this context has been hindered, because they often need input in the form of low-dimensional, dense vectors of numbers. We propose such a representation for genomes callednanotextthat scales to very large data sets.The underlying model is learned from a corpus of nearly 150 thousand genomes spanning 750 million protein domains. We treat the protein domains in a genome like words in a document, assuming that protein domains in a similar context have similar “meaning”. This meaning can be distributed by a neural net over a vector of numbers.The resulting vectors efficiently encode function, preserve known phylogeny, capture subtle functional relationships and are robust against genome incompleteness. The “functional” distance between two vectors complements nucleotide-based distance, so that genomes can be identified as similar even though their nucle...
Infection and Drug Resistance, 2018
The aim of this study was to assess the pomegranate juice against the growth and toxin production... more The aim of this study was to assess the pomegranate juice against the growth and toxin production of multidrug-resistant Clostridium difficile hypervirulent strain NAP1/027/BI and also against the growth of beneficial bacteria to prevent or suppress C. difficile infection (CDI). Materials and methods: Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were taken as parameters for the assessment of antimicrobial property of the pomegranate juice. Four different C. difficile hypervirulent strains NAP1/027/BI, Lactococcus lactis spp., Lactobacillus casei, and Bifidobacterium animalis were subjected to the broth dilution method to determine the MIC and MBC. Enzyme-linked immunosorbent assay (ELISA) was performed to determine clostridial toxin B (TcdB) production in the presence of pomegranate juice. Results: The MIC and MBC of pomegranate juice containing punicalagin were found to be 390 µg/mL for all C. difficile hypervirulent strain NAP1/027/BI, and the growth of L. lactis spp., L. casei, and B. animalis was not inhibited. Pomegranate juice reduced TcdB production in C. difficile hypervirulent strain NAP1/027/BI. Conclusion: This study highlights the potential of pomegranate juice to reduce CDI without affecting the beneficial bacteria. Pomegranate juice may be a useful antimicrobial agent to prevent or suppress CDI, avoiding the use of antibiotics.
Journal of Clinical Sciences, 2016
Background: Penicillin is recommended as the first-line agent for intrapartum antibiotic prophyla... more Background: Penicillin is recommended as the first-line agent for intrapartum antibiotic prophylaxis (IAP). Although Group B Streptococcus (GBS) strains are generally susceptible to penicillin with only occasional resistance, they show varying resistance to erythromycin, clindamycin, and tetracycline. Therefore, knowledge of the resistance profile of GBS in the local environment will be useful for administration of appropriate intrapartum antibiotics prophylaxis. Methodology: Rectovaginal swabs collected from pregnant women were cultured for GBS using conventional media. Kirby-Bauer disc diffusion method was performed according to the Clinical and Laboratory Standards Institute guidelines on GBS isolates to determine the antibiotic susceptibility patterns of the isolates. Inducible clindamycin resistance was detected by using the D-zone test. Resistance determinants genes were discerned with conventional polymerase chain reaction. Results: Carriage rates of GBS among pregnant women studied were 19.7%. GBS colonizing the pregnant mothers were uniformly susceptible (100%) to penicillin, vancomycin, and ceftriaxone. Only three (6.5%) of the isolates showed inducible clindamycin resistance. ermA gene was present in all three GBS isolates with inducible macrolide-lincosamide-streptogramin resistance. ermB was absent in all the strains tested. mefA/E gene was carried by two of the macrolide-clindamycin resistance isolates. tetM gene was carried by all isolates with tetracycline resistance phenotypes. Conclusion: In this study, all GBS isolates were susceptible to penicillin G, the recommended antibiotic for IAP. The presence of resistance to erythromycin and inducible resistance to clindamycin excludes the use of these agents as alternatives in cases of penicillin allergy. In this case, vancomycin is the drug of choice as recommended in the updated Centers for Disease Control guideline.
Plants have been used in ethno-medicine for ages in the treatment of various diseases. In the cur... more Plants have been used in ethno-medicine for ages in the treatment of various diseases. In the current study, the leaves of C. jagus are investigated for antimicrobial activities. The leaves were dried and extracted successively with hexane, ethylacetate and methanol. The concentrated extracts were screened for activity against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, Salmonella typhi, Klebisidlae pneumonae, Candida albicans, Aspergillus niger, Penicillium notatum and Rhizopus stolonifer at concentrations between 6.25 and 200 mg/ml using the agar diffusion method. The Minimum Inhibitory Concentration (MIC) was also determined. The percentage yields obtained were 0.92 %, 1.20 % and 25.2 % for the hexane, ethylacetate and methanol extracts respectively. The zones of inhibition of the organisms by the extracts generally increased with the concentrations. The methanol extract showed the best activity of the three extracts tested. The methanol extract had values ranging between 20 mm and 26 mm against the bacteria at 200 mg/ml. This extract also showed values between 18 mm and 20 mm against the fungi at 200 mg/ml. The lowest MICs values (of 2.5 mg/ml) were obtained against S. aureus, E. coli, B. subtilis and S. typhi. The polar constituents in the leaves of the plant are likely responsible for the antimicrobial properties observed. None of the extracts showed activity comparable to those of the standard drugs, however the methanol extract showed some potential as a source of antimicrobial compounds.
Historia Y Sociedad, Aug 25, 2011
Asian Pacific Journal of Tropical Medicine, 2015
To determine the prevalence and risk factors associated with drug resistance tuberculosis (TB) at... more To determine the prevalence and risk factors associated with drug resistance tuberculosis (TB) at facility-base level in Tanga, Tanzania. Methods: A total of 79 Mycobacterium tuberculosis (MTB) isolates included in the study were collected from among 372 (312 new and 60 previously treated) TB suspects self-referred to four TB clinics during a prospective study conducted from November 2012 to January 2013. Culture and drug susceptibility test of the isolates was performed at the institute of medical microbiology and epidemiology of infectious diseases, University hospital, Leipzig, Germany. Data on the patient's characteristics were obtained from structured questionnaire administered to the patients who gave informed verbal consent. Unadjusted bivariate logistic regression analysis was performed to assess the risk factors for drug resistant-TB. The significance level was determined at P < 0.05. Results: The overall proportions of any drug resistance and MDR-TB were 12.7% and 6.3% respectively. The prevalence of any drug resistance and MDR-TB among new cases were 11.4% and 4.3% respectively, whereas among previously treated cases was 22.2% respectively. Previously treated patients were more likely to develop anti-TB drug resistance. There was no association between anti-TB drug resistances (including MDR-TB) with the risk factors analysed. Conclusions: High proportions of anti-TB drug resistance among new and previously treated cases observed in this study suggest that, additional efforts still need to be done in identifying individual cases at facility-base level for improved TB control programmes and drug resistance survey should continuously be monitored in the country.
British Journal of Social and Clinical Psychology, 1979
Varying degrees of organization of verbal material were presented to determine their use in sente... more Varying degrees of organization of verbal material were presented to determine their use in sentence reproduction by acute and chronic schizophrenic subjects, a psychiatric (alcoholic) control group, and a healthy control group. The material consisted of six-word sentences presented over earphones, with background noise of differing intensity. The main result was that schizophrenics use verbal organization as effectively as healthy and psychiatric controls when reproducing the sentences. The noise distraction influenced performance of all groups similarly. Results suggest that performance of schizophrenics is facilitated by structured material (semantic and syntactic organization). The results do not suggest that either the linguistic repertoire or the application of linguistic rules is specifically affected in schizophrenia. The flatter performance slope of schizophrenics with increasing contexual constraints, found by some researchers, is explained by the unspecific effect of task difficulty.
South African journal of child health
Background. In line with the World Health Organization (WHO) guideline on chloroquine (CQ) resist... more Background. In line with the World Health Organization (WHO) guideline on chloroquine (CQ) resistance, CQ was withdrawn as the first-line antimalarial drug in Nigeria in 2005 as a result of widespread resistance. It was expected that its sensitivity and clinical usefulness would be restored with time. This study therefore aimed to determine the level of CQ resistance in Nigerian children aged less than 60 months. Methods. We monitored the resistance pattern 5 years after withdrawal of CQ, using the pfcrt K76T mutation as a molecular marker for CQ resistance. Results. Of 98 Plasmodium falciparum-positive blood samples, 95 (96.9%) showed the K76T mutation. Twenty-seven (27.6%) of the children had been treated with CQ at home before presentation at the clinic, while 50 (51.0%) had taken other antimalarials. Conclusion. Our results indicate that there is an urgent need to re-evaluate antimalarial drug policy in Nigeria, especially when 27.6% of our study population still use CQ at home despite its withdrawal as first-line antimalarial. This may require effective legislation against the manufacture, importation and use of CQ in Nigeria, if the purpose behind its withdrawal is to be achieved.
Uploads
Papers by Brigitte Koenig