Biomedical subjects

Max Maurin

Publications and source records attributed to Max Maurin.

8 recordsLinked to original sources

PubMed2006

Quantitative real-time Legionella PCR for environmental water samples: data interpretation.

Quantitative Legionella PCRs targeting the 16S rRNA gene (specific for the genus Legionella) and the mip gene (specific for the species Legionella pneumophila) were applied to a total of 223 hot water system samples (131 in one laboratory and 92 in another laboratory) and 37 cooling tower samples (all in the same laboratory). The PCR results were compared with those of conventional culture. 16S rRNA gene PCR results were nonquantifiable for 2.8% of cooling tower samples and up to 39.1% of hot water system samples, and this was highly predictive of Legionella CFU counts below 250/liter. PCR cutoff values for identifying hot water system samples containing >10(3) CFU/liter legionellae were determined separately in each laboratory. The cutoffs differed widely between the laboratories and had sensitivities from 87.7 to 92.9% and specificities from 77.3 to 96.5%. The best specificity was obtained with mip PCR. PCR cutoffs could not be determined for cooling tower samples, as the results were highly variable and often high for culture-negative samples. Thus, quantitative Legionella PCR appears to be applicable to samples from hot water systems, but the positivity cutoff has to be determined in each laboratory.

Air Conditioning↗

PubMed2005

Abdominal aortic aneurysm and Coxiella burnetii infection: report of three cases and review of the literature.

Coxiella burnetii, the etiologic agent of Q fever, is mainly responsible for endocarditis with negative blood culture results, but only a few cases of C. burnetii infections of aortic aneurysms have been published. We report three cases of abdominal aortic aneurysms treated in patients with Q fever infection with simultaneous endocarditis (n = 1) and previous history of cardiac valve replacement for endocarditis (n = 1). A coeliac aortic aneurysm was diagnosed in one patient treated for acute Q fever with persistent serologic results showing chronic infection despite adequate antibiotic therapy and without endocarditis. Resection of the aneurysm cured the chronic infection, and C. burnetii was identified by culture of the aneurysmal wall. In the two other cases, chronic infection of C. burnetii was diagnosed by serologic examination after surgery for an abdominal aortic aneurysm. One patient with negative blood culture results had amaurosis fugax due to endocarditis and required aortic valve replacement; recurrent fever without evidence of valve dysfunction or infection developed in one patient who had had prosthetic cardiac valve replacement 6 months earlier for endocarditis. Aortic aneurysms were treated with in situ prosthetic grafts and long-term antibiotic therapy. At a mean follow-up of 12 years, no septic aortic complications occurred, and serologic test results have remained negative. The presence of an aortic aneurysm and cardiac valve disease seems to be a predisposing factor for chronic C. burnetii infection. Diagnosis particularly relies on the physician's awareness of this condition and is confirmed by serologic examination. Aortic aneurysm resection is mandatory to cure the chronic infection and must be associated with long-term antibiotic therapy.

Aged↗

PubMed2004

Measurement of the antibiotic susceptibility of Coxiella burnetii using real time PCR.

The objective of this study was to determine MICs of antibiotics for two reference strains of Coxiella burnetii using real time quantitative PCR. The method was very sensitive and specific and allowed the evaluation of the doubling time of Nine Mile and Q212 strains: 37 and 15 h, respectively. Dose response curves of antibiotics were used to determine MICs. Those of doxycycline, fluoroquinolone compounds and rifampicin were in the range 1-4 mg/l. Telithromycin was the most effective macrolide compound with MICs of 1-2 mg/l. The results confirmed previous reports on the accuracy of this new method for the determination of the antibiotic susceptibility of C. burnetii and could be used for the screening of new drugs.

Animals↗

PubMed2003

Can Whipple's disease be transmitted by gastroscopes?

OBJECTIVE: To determine whether disinfection protocols currently used for gastroscopes are effective against cultures of Tropheryma whipplei. DESIGN: The bactericidal activity of 2% glutaraldehyde and two peracetic acids on the Twist-Marseille strain of T. whipplei grown in cell monolayers was determined. PATIENTS: Two patients who were diagnosed as having Whipple's disease 3 years after they had had intestinal biopsies. RESULTS: The disinfectants reduced bacteria by approximately 2 log to 3 log10 after 5 to 60 minutes of contact. CONCLUSION: The bactericidal activity of a disinfectant is usually considered significant if it causes a 5 log10 or greater reduction in viable bacterial titers. Disinfecting gastroscopes with 2% glutaraldehyde or peracetic acids for 20 minutes may be insufficient to prevent transmission of T. whipplei on the instruments or stop false-positive results on polymerase chain reaction.

Actinomycetales↗

PubMed2003

Antibiotic susceptibilities of Anaplasma (Ehrlichia) phagocytophilum strains from various geographic areas in the United States.

We tested the antibiotic susceptibilities of eight strains of Anaplasma phagocytophilum (the agent of human granulocytic ehrlichiosis) collected in various geographic areas of the United States, including Minnesota, Wisconsin, California, and New York. The results are homogeneous and show that doxycycline, rifampin, and levofloxacin are the most active antibiotics against these strains in vitro.

Anaplasma phagocytophilum↗

PubMed2003

Culture and antibiotic susceptibility of Bartonella quintana in human erythrocytes.

Bartonella quintana, the agent of trench fever, has recently been implicated in various diseases, in particular, bacteremia and endocarditis in homeless people. The host cell of Bartonella spp. is believed to be the erythrocyte, and in the present study we demonstrate that B. quintana can be cultured in vitro in human erythrocytes. The bacteria were found to be intraerythrocytic by laser confocal microscopy with Bartonella species-specific monoclonal antibodies. Infections with B. quintana decreased the life span of erythrocytes in culture from 8.6 to 4.8 days. In the culture system we found that most of the antibiotics that we tested (doxycycline, fluoroquinolone compounds, and beta-lactams) were not bactericidal. Gentamicin was bactericidal at 4 micro g/ml, as was rifampin, but to a lesser extent. At this concentration, gentamicin has been shown to enter erythrocytes slowly and to reach a peak level of 0.26 micro g/ml after 24 h. At 0.26 micro g/ml, however, we found that gentamicin was not able to kill extracellular B. quintana, even after 96 h of incubation. We hypothesize that erythrocytes may be a reservoir for B. quintana and that the bactericidal activity of gentamicin that we observed occurs mainly when the bacteria emerge from the erythrocytes and are found extracellularly. It would appear that gentamicin should be administered for at least 5 days to cure patients infected with B. quintana.

Anti-Bacterial Agents↗

PubMed2003

Wolbachia pipientis growth kinetics and susceptibilities to 13 antibiotics determined by immunofluorescence staining and real-time PCR.

Wolbachia spp. are strict intracellular bacteria that infect a wide range of arthropods and filarial nematodes. Filarial nematodes are important causes of human diseases. There is increasing evidence that Wolbachia spp. influence important functions in the biology of the hosts, specifically, infertility. Preliminary experiments with humans and animals have suggested that antibiotics with activity against Wolbachia may help to treat filariasis. In this study, we determined using a real-time quantitative PCR assay the growth kinetics of a strain of Wolbachia pipientis from a mosquito grown in Aa23 cells. The doubling time was estimated to be 14 h. We then determined the susceptibilities of this strain to 13 antibiotics by two methods: an immunofluorescent-antibody test and a real-time quantitative PCR assay. Both techniques gave similar results. Doxycycline and rifampin were the most effective compounds, with MICs of 0.125 and 0.06 to 0.125 micro g/ml, respectively. Fluoroquinolones were less effective, with MICs of 2 to 4 micro g/ml for ciprofloxacin, 2 micro g/ml for ofloxacin, and 1 micro g/ml for levofloxacin. beta-Lactams (penicillin G, amoxicillin, ceftriaxone) were not effective at concentrations up to 128 micro g/ml. The MIC of erythromycin was >32 micro g/ml, whereas that of telithromycin was 8 micro g/ml. Other antibiotic compounds were bacteriostatic only at high concentrations, including gentamicin, co-trimoxazole, and thiamphenicol. The real-time PCR assay was a convenient and reliable technique for determination of the antibiotic susceptibilities of WOLBACHIA: It may help in the future to simplify antibiotic susceptibility testing of strict intracellular pathogens.

Animals↗

PubMed2002

Evaluation of antibiotic susceptibilities of three rickettsial species including Rickettsia felis by a quantitative PCR DNA assay.

Rickettsiae grow only intracellularly, and the antibiotic susceptibilities of these bacteria have been assessed by either plaque, dye uptake, or immunofluorescence assays, which are time-consuming. We used a quantitative PCR (with the LightCycler instrument) to assess the levels of inhibition of Rickettisa felis, R. conorii, and R. typhi DNA synthesis in the presence of various antibiotics. We established the kinetics of rickettsial DNA during growth and showed that R. conorii grows more quickly than R. typhi in cell culture, with maximum replication occurring after 5 and 7 days, respectively. The MICs of the antibiotics tested for R. conorii and R. typhi by the quantitative PCR assay were similar to those previously obtained by plaque and dye uptake assays. We found that R. felis is susceptible to doxycycline, rifampin, thiamphenicol, and fluoroquinolones but not to gentamicin, erythromycin, amoxicillin, or trimethoprim-sulfamethoxazole. The resistance of this new species to erythromycin is consistent with its current taxonomic position within the spotted fever group. We believe that quantitative PCR could be used in the future to simplify and shorten antibiotic susceptibility assays of other rickettsiae and other strict intracellular pathogens.

Anti-Bacterial Agents↗