Biomedical subjects

Ralf M Hagen

Publications and source records attributed to Ralf M Hagen.

7 recordsLinked to original sources

PubMed2006

Brucella endocarditis in prosthetic valves.

Human brucellosis is a multiple organ disease that presents with fever and is most often transmitted via contaminated, unpasteurized goat milk and cheese. In chronic cases, focal complications (eg, spondylitis, neurobrucellosis and endocarditis) are frequently seen. Although the disease may be severely debilitating, the mortality rate is low. Fatal cases are often due to endocarditis. Because Brucella endocarditis is a rare complication (2% to 5%), therapeutic considerations are based on single-case experiences only. Therapy includes long-term antibiotic treatment using combinations of various antimicrobial drugs and surgical valve replacement when required. A case of Brucella endocarditis complicated by the infection of two valvular prostheses implanted after involvement of the mitral and aortic valve due to rheumatic fever is described. The patient was successfully treated by a medical and surgical approach. Therapeutic strategies in Brucella endocarditis are discussed in light of the current literature.

Anti-Bacterial Agents↗

PubMed2005

Failure of a short-term antibiotic therapy for human brucellosis using ciprofloxacin. A study on in vitro susceptibility of Brucella strains.

BACKGROUND: Human brucellosis is characterized byfocal complications, chronic courses, and therapeutic failures. METHODS: In a relapsed case of brucellosis after short-term antibiotic therapy using doxycycline and ciprofloxacin two Brucella strains were isolated, before and after treatment. In vitro susceptibilities of both isolates were determined by E tests including a great variety of antibiotics. In a killing rate experiment the bactericidal activities of doxycycline, streptomycin, rifampin and ciprofloxacin as single agents and in combinations were determined. RESULTS: Lowest MIC values were measured for doxycycline and ciprofloxacin. MICs did not change under therapy. Streptomycin alone exhibited the most effective killing within 6 h, whereas the other single agents did not show bactericidal activity. Doxycycline plus ciprofloxacin was the most active combination in vitro. CONCLUSION: Routine susceptibility testing of Brucellae is not obligatory as most of the 'traditional' anti-Brucella antibiotics are active in vitro and bactericidal efficacy may differ in vivo.

Anti-Infective Agents↗

PubMed2005

Growth characteristics of Bacillus anthracis compared to other Bacillus spp. on the selective nutrient media Anthrax Blood Agar and Cereus Ident Agar.

Anthrax Blood Agar (ABA) and Cereus Ident Agar (CEI) were evaluated as selective growth media for the isolation of Bacillus anthracis using 92 B. anthracis and 132 other Bacillus strains from 30 species. The positive predictive values for the identification of B. anthracis on ABA, CEI, and the combination of both were 72%, 71%, and 90%, respectively. Thus, less than 10% of all species were misidentified using both nutrient media. Species which might be misidentified as B. anthracis were B. cereus, B. mycoides, and B. thuringiensis. Particularly, 30% of B. weihenstephanensis strains were misidentified as B. anthracis.

Agar↗

PubMed2005

Development of a real-time PCR assay for rapid identification of methicillin-resistant Staphylococcus aureus from clinical samples.

A major drawback of mecA PCR to detect methicillin-resistant Staphylococcus aureus (MRSA) directly from patient materials is the high frequency of methicillin-resistant coagulase-negative staphylococci. Therefore, a reliable detection method for MRSA from clinical samples using real-time PCR was developed. The PCR assay targeting the integration site (orfX) of the staphylococcal cassette chromosome mec (SCCmec) was evaluated in MRSA SCCmec reference strains (n = 9), MRSA ST strains (n = 16) and clinical isolates of MRSA (n = 124), MSSA (n = 53), methicillin-resistant coagulase-negative staphylococci (n = 47), and methicillin-susceptible, coagulase-negative staphylococci (n = 32). The diagnostic values of the assay were 98% sensitivity and 100% specificity. Furthermore, the PCR detection method was evaluated with 60 swabs from different body sites which were incubated overnight in brain-heart infusion. The PCR gave positive results for 27 of 29 swabs which were found to contain MRSA by conventional methods. The diagnostic values of the PCR assay for these samples were 93% sensitivity and 100% specificity. To determine the in vitro sensitivity of the assay, swabs were inoculated with serially diluted bacterial suspensions. After overnight enrichment the detection limit of the PCR was less than 10 CFU/swab. This new real-time PCR assay proved to be a fast, sensitive and specific tool for MRSA detection in a routine microbiological laboratory.

Anti-Bacterial Agents↗

PubMed2005

Pulmonary melioidosis associated with bronchiolitis obliterans organizing pneumonia.

We report a case of pulmonary melioidosis associated bronchiolitis obliterans with organizing pneumonia (BOOP). While antibiotic treatment alone did not show any major effect, addition of corticosteroids resulted in rapid clinical improvement. To our knowledge this is the first documented case of melioidosis associated with organising pneumonia. The possible therapeutic implications for the treatment of severe pulmonary melioidosis are discussed.

Adult↗

PubMed2005

Attempted passive prophylaxis with a monoclonal anti-Burkholderia pseudomallei exopolysaccharide antibody in a murine model of melioidosis.

Melioidosis is a severe gram-negative infection caused by the facultative intracellular bacterium Burkholderia pseudomallei, which is responsible for a broad spectrum of symptoms in both humans and animals. No licensed vaccine currently exists. This study evaluated the protective effect of a monoclonal antibody (Mab Ps6F6) specific to B. pseudomallei exopolysaccharide in an outbred murine model of sub-acute melioidosis. When administered before the infectious challenge, Ps6F6 significantly increased resistance to infection and restrained bacterial burden in the spleen over a 30-days period. Patterns of IFN-gamma production were similar in the treated and non treated groups of mice. However, Ps6F6 lowered IFN-gamma levels over the duration of the assay period, except on day 1, suggesting a transient and rapid production of IFN-gamma under Ps6F6 control. Minor but persisting increases occurred in IL-12 levels while TNF-alpha was detected only in the controls at the later stages of infection. No IL-10 secretion was detected in both groups of mice. These data suggest that passive prophylaxis with Mab Ps6F6 provide a moderate and transient induction of inflammatory responses in infected mice but failed to trigger a sterilizing protective immunity.

Animals↗

PubMed2002

A possible pitfall in the identification of Burkholderia mallei using molecular identification systems based on the sequence of the flagellin fliC gene.

Amotile Burkholderia mallei and motile Burkholderia pseudomallei display a high similarity with regard to phenotype and clinical syndromes, glanders and melioidosis. The aim of this study was to establish a fast and reliable molecular method for identification and differentiation. Despite amotility, the gene of the filament forming flagellin (fliC) could be completely sequenced in two B. mallei strains. Only one mutation was identified discriminating between B. mallei and B. pseudomallei. A polymerase chain reaction-restriction fragment length polymorphism assay was designed making use of the absence of an AvaII recognition site in B. mallei. All seven B. mallei, 12 out of 15 B. pseudomallei and 36 closely related apathogenic Burkholderia thailandensis strains were identified correctly. However, in three B. pseudomallei strains a point mutation at gene position 798 (G to C) disrupted the AvaII site. Therefore, molecular systems based on the fliC sequence can be used for a reliable proof of strains of the three species but not for the differentiation of B. mallei and B. pseudomallei isolates.

Base Sequence↗