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Francis A Drobniewski

Publications and source records attributed to Francis A Drobniewski.

6 recordsLinked to original sources
PubMed2006

Progression toward an improved DNA amplification-based typing technique in the study of Mycobacterium tuberculosis epidemiology.

While high-copy-number IS6110-based restriction fragment length polymorphism (HCN-RFLP) is the gold standard for typing most Mycobacterium tuberculosis strains, the time taken for culturing and low throughput make it impractical for large-scale prospective typing of large numbers of isolates. The development of a new method, mycobacterial interspersed repetitive units (MIRU), a variation of the original variable-number tandem repeat (VNTR) technique, may provide a viable alternative. Panels based on the original 12-loci MIRU (12MIRU), a combination of 12MIRU and remaining ETR loci (15MIRU-VNTR), and an extended panel with an additional 10 novel regions (25VNTR) were used to study three populations with varying degrees of epidemiological data. MIRU discrimination increased with panel size and the addition of spoligotyping. Combining these two techniques enabled a reduction in the panel size from 25 to 14 loci without a significant loss in discrimination. However, 25VNTR alone or in combination with spoligotyping still possessed weaker discrimination than RFLP for high-copy-number isolates.

Bacterial Typing Techniques↗
PubMed2006

Evaluation of MGIT 960-based antimicrobial testing and determination of critical concentrations of first- and second-line antimicrobial drugs with drug-resistant clinical strains of Mycobacterium tuberculosis.

The objectives of this study were to (i) compare agreement of the MGIT 960 system for first-line drugs with a methodology (the resistance ratio method [RRM]) that had been used in clinical trials, relating drug susceptibility to clinical outcome; (ii) compare the performance of the MGIT 960, RRM, and microtiter plate assay (MPA) methodologies for second-line drug testing; and (iii) define critical concentrations for ciprofloxacin and moxifloxacin for liquid-culture-based testing. The large collection of clinical isolates of Mycobacterium tuberculosis (n = 247) used included 176 (71%) multidrug-resistant isolates. The results for MGIT 960 and the RRM for rifampin and isoniazid (n = 200) were in excellent (99 to 100%) agreement for all strains. For streptomycin, 97% of the results at the critical concentration and 92% at high concentration, and for pyrazinamide 92% of results overall, were concordant, but for ethambutol, fewer than 85% (65% for the critical concentration and 84% for the high concentration) of the MGIT-based results were concordant with those for the RRM. The MGIT 960, RRM, and MPA assays (n = 133) correlated well for most second-line drugs tested. For susceptibility to ofloxacin, the MGIT 960 and MPA results were in full agreement. The amikacin and rifabutin results obtained by MGIT 960 agreed with the RRM results in 131 (99%) cases, and for capreomycin, they agreed for 129 of 133 isolates tested (97%). For prothionamide testing, only a limited number of drug-resistant isolates were available for testing and drawing definitive conclusions. We propose critical concentrations of 1.0 microg/ml and 0.125 microg/ml for ciprofloxacin and moxifloxacin, respectively, for liquid-culture-based testing.

Antitubercular Agents↗
PubMed2005

Mycobacterium tuberculosis Beijing genotype, northern Malawi.

In a 7-year population-based study in Malawi, we showed that Beijing genotype tuberculosis (TB) increased as a proportion of TB cases. All the Beijing genotype strains were fully drug sensitive. Contact histories, TB type, and case-fatality rates were similar for Beijing and non-Beijing genotype TB.

Adolescent↗
PubMed2004

DNA fingerprint changes in tuberculosis: reinfection, evolution, or laboratory error?

BACKGROUND: DNA fingerprint patterns of Mycobacterium tuberculosis strains vary within individuals and between epidemiologically linked individuals because of pattern evolution, new infections, and laboratory error. We explored the importance of these factors. METHODS: Cultures from individuals in northern Malawi who had been diagnosed with tuberculosis (TB) during 1996-2001 were fingerprinted with restriction fragment-length polymorphism (RFLP). Probable laboratory error was inferred by use of dates or isolated positive cultures. Pattern evolution was explored within and between individuals, and the relative importance of relapse and reinfection was estimated in individuals with recurrent TB. RESULTS: RFLP results were available for 930 isolates from 806 individuals. The maximum laboratory-error rate was 3.9%. Pattern evolution was more common in linked individuals (17%) than on relapse (11%) or during treatment (3%). Twenty individuals had recurrent TB after completing treatment: in human immunodeficiency virus (HIV)-positive individuals, 7 of 12 recurrences were due to reinfection, compared with 0 of 8 in HIV-negative individuals (P=.01). CONCLUSIONS: The rate of DNA fingerprint-pattern evolution is not linear, and rates of change calculated from repeat cultures within individuals may not be applicable to transmission between individuals. The high proportion of recurrence due to reinfection found in HIV-positive individuals suggests that secondary prophylaxis and/or antiretroviral treatments are needed for such individuals.

Adolescent↗
PubMed2002

Evaluation of a rapid PCR-based epidemiological typing method for routine studies of Mycobacterium tuberculosis.

Restriction fragment length polymorphism (RFLP) based on the insertion sequence IS6110 is used to investigate episodes of suspected transmission of infection of tuberculosis but usually takes a number of weeks from receipt of request to obtain a result. Often investigations would benefit from a more rapid method, possibly one containing an amplification step. The method employed uses a simple DNA extraction followed by a PCR step involving a single primer. Restriction enzyme analysis was performed when the patterns obtained from the PCR products were indistinguishable, especially when only single similar-size bands were obtained. The isolates used were strains of Mycobacterium tuberculosis submitted for epidemiological investigations as part of (i) possible contact-outbreak (22 episodes involving between 2 and 20 patients), (ii) possible incidents of laboratory cross-contamination (21 episodes), and (iii) possible change in drug resistance pattern or a case of reinfection (1 patient). The PCR products giving similar patterns were then subjected to restriction enzyme analysis. In conclusion it has been shown that this method is rapid, with results within 1 to 2 days of the request being received; is reproducible; and gives the same results as does RFLP. The restriction enzyme analysis stage has improved the efficiency of the technique.

Bacterial Typing Techniques↗