Biomedical subjects

M Salfinger

Publications and source records attributed to M Salfinger.

At least 19 recordsLinked to original sources

PubMed2002

Analysis of tuberculosis surveillance in Hungary in 2000.

SETTING: Hungary, Central Europe, with a population of 10.3 million living in 20 administrative districts (19 counties and the capital). OBJECTIVE: To summarize the results of the first year of the revised National Tuberculosis Surveillance System. DESIGN: Retrospective survey of the National Tuberculosis Surveillance Center (NTSC) database. METHODS: Analysis of data on all tuberculosis cases reported to the NTSC in 2000. Drug susceptibility results were evaluated in line with WHO and IUATLD definitions. RESULTS: During 2000, a total of 3598 patients with tuberculosis were reported. Only 40% of these were bacteriologically confirmed. Although susceptibility testing has been required for previously untreated culture-positive cases, only 801 (67.8% of the bacteriologically confirmed cases) were tested in 2000. Drug resistance was detected in 10.7% of previously untreated and in 23.5% of previously treated patients. Multidrug-resistant (MDR) cases were not common: only 1.5% of the isolates from previously untreated patients and 4.9% of those from previously treated patients were MDR. CONCLUSIONS: The results suggest that the NTSC should work towards increasing the numbers of cases that are bacteriologically confirmed. In addition, some form of surveillance system should be instituted to ensure that mandatory susceptibility testing is performed on all isolates from previously untreated tuberculosis patients.

Adolescent↗

PubMed2001

Laboratory diagnosis of mycobacterial infections: new tools and lessons learned.

Even in the 21st century, tuberculosis continues to be a problem. Although the number of cases continues gradually to decrease in the United States, cases get more difficult to treat, specifically those that are multiple-drug resistant. Infection of one-third of the world's population ensures that tuberculosis will not disappear in the near future. In light of this, it will be useful to know the goals for the health care system and how these goals may be accomplished. Laboratory testing in the mycobacteriology field is experiencing more changes today than ever before. Determining what assays will be most useful to the clinician is a challenge, and acceptance of the new technology by the medical community an even greater one. Clinicians must use the best available resources to determine the most appropriate care for their patients and work together with the laboratory to ensure that the communication channels are open. This review focuses on current state-of-the-art resources useful for accurate and rapid laboratory diagnosis of mycobacterial infections.

Bacteriological Techniques↗

PubMed2001

The molecular basis of resistance to isoniazid, rifampin, and pyrazinamide in Mycobacterium tuberculosis.

Multidrug-resistant (MDR) strains of Mycobacterium tuberculosis have emerged worldwide. In many countries and regions, these resistant strains constitute a serious threat to the efficacy of tuberculosis control programs. An important element in gaining control of this epidemic is developing an understanding of the molecular basis of resistance to the most important antituberculosis drugs: isoniazid, rifampin, and pyrazinamide. On the basis of this information, more exacting laboratory testing, and ultimately more appropriate and timely treatment regimens, can be developed.

Antibiotics, Antitubercular↗

PubMed2001

Cluster of tuberculosis cases in North Carolina: possible association with atomizer reuse.

BACKGROUND: Three patients with identical strains of M tuberculosis (TB) underwent bronchoscopy on the same day at hospital A. METHODS: We reviewed each patient's clinical history, hospital A's infection control practices for bronchoscopies, and specimen and isolate handling at each of 3 laboratories involved. We searched for possible community links between patients. Restriction fragment length polymorphism was performed on TB isolates. RESULTS: The first patient who underwent bronchoscopy had biopsy-confirmed granulomatous pulmonary TB. A sputum sample collected from the third patient 6 weeks after the bronchoscopy produced an isolate with an identical restriction fragment length polymorphism pattern to isolates collected during the bronchoscopies. No evidence existed for community transmission or laboratory contamination; the only common link was the bronchoscopy. Different bronchoscopes were used for each patient. Hospital ventilation and wall-suctioning were functioning well. Respiratory technicians reported sometimes reusing the nozzles of atomizers on more than one patient. A possible mechanism for transmission was contamination from the first patient of the atomizer if it was used to apply lidocaine to the pharynx and nasal passages of other patients. CONCLUSIONS: A contaminated atomizer may have caused TB transmission during bronchoscopy. Hospital A changed to single-use atomizers after this investigation.

Aged↗

PubMed2001

Molecular characterization of rifampin-resistant isolates of Mycobacterium tuberculosis from Hungary by DNA sequencing and the line probe assay.

Two regions of rpoB associated with rifampin resistance were sequenced in 29 rifampin-resistant (determined by the proportion method) isolates of Mycobacterium tuberculosis obtained from patients from three counties in Hungary. Of the 29 resistant strains, 27 had a mutation in either the 81-bp region (26 strains) or the N-terminal region (1 strain), while the other 2 strains had no mutations in either region. The locations and frequencies of the mutations differed from those previously reported. The most common mutation in this study, D516V, was found in 38% of the Hungarian strains, a frequency 2 to 10 times higher than that found in studies from other countries. These same 29 isolates were also evaluated with the Inno-LiPA Rif. TB test (LiPA), a reverse hybridization assay for the rapid detection of rifampin resistance. Although LiPA detected the presence of an rpoB mutation in 26 of the resistant isolates, the type of mutation could not be determined in 4 isolates because the mutations present were not among those included on the LiPA strip. In addition, a silent mutation in one of the rifampin-susceptible control strains was interpreted as rifampin resistant by LiPA. These findings demonstrate the importance of validating this rapid molecular test by comparison with DNA sequence results in each geographic location before incorporating the test into routine diagnostic work.

Antitubercular Agents↗

PubMed2001

Lessons from a proficiency testing event for acid-fast microscopy.

OBJECTIVES: To evaluate the routine performance and the technical parameters of different acid-fast staining methods: Kinyoun, Ziehl-Neelsen (ZN), auramine, and auramine-rhodamine. DESIGN AND PARTICIPANTS: The performance of 167 laboratories was analyzed using prestained and unstained slides. SETTING: Laboratories holding New York State permits. RESULTS: The results revealed that Kinyoun's cold carbol fuchsin method is inferior to both the ZN and fluorochrome (auramine and/or auramine-rhodamine) methods. Even though 91% of the participants used commercial staining kits, the study identified unexpected errors concerning the concentration of carbol fuchsin, time for staining and counterstaining, and the concentration of acid alcohol for decolorization, which may significantly influence the sensitivity. Besides these findings, the present study showed that the examination of < 300 view fields may also decrease the sensitivity of acid-fast microscopy. In addition, we found that the sensitivity and specificity of the ZN and fluorochrome methods are comparable if the procedural standards are followed. CONCLUSIONS: The strict and ongoing quality control of the "simple to perform" acid-fast microscopy and the immediate review of commercially available staining kits are necessary. Because of the rapidity of the fluorochrome method, laboratories with large specimen numbers should use this technique. In all other cases, the ZN method should be used. Moreover, all clinicians should be aware of the method of acid-fast microscopy used and the proficiency of the laboratory in performing the assay.

Benzophenoneidum↗

PubMed2000

False-positive results for Mycobacterium celatum with the AccuProbe Mycobacterium tuberculosis complex assay.

Mycobacterium celatum type 1 was found to cross-react in the AccuProbe Mycobacterium tuberculosis complex assay. Subsequently, we found a statistically significant increase in the relative light units with lower temperatures, suggesting that it is necessary to perform this AccuProbe assay at between 60 and 61 degrees C. We also recommend the inclusion of M. celatum type 1 as a negative control.

DNA Probes↗

PubMed2000

Use of the National Committee for Clinical Laboratory Standards guidelines for disk diffusion susceptibility testing in New York state laboratories.

Accurate antimicrobial susceptibility testing is vital for patient care and surveillance of emerging antimicrobial resistance. The National Committee for Clinical Laboratory Standards (NCCLS) outlines generally agreed upon guidelines for reliable and reproducible results. In January 1997 we surveyed 320 laboratories participating in the New York State Clinical Evaluation Program for General Bacteriology proficiency testing. Our survey addressed compliance with NCCLS susceptibility testing guidelines for bacterial species designated a problem (Staphylococcus aureus and Enterococcus species) or fastidious (Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria gonorrhoeae) organism. Specifically, we assessed compliance with guidelines for inoculum preparation, medium choice, number of disks per plate, and incubation conditions for disk diffusion tests. We also included length of incubation for S. aureus and Enterococcus species. We found overall compliance with the five characteristics listed above in 80 of 153 responding laboratories (50.6%) for S. aureus and 72 of 151 (47.7%) laboratories for Enterococcus species. The most common problem was an incubation time shortened to less than 24 h. Overall compliance with the first four characteristics was reported by 92 of 221 (41.6%) laboratories for S. pneumoniae, 49 of 163 (30.1%) laboratories for H. influenzae, and 11 of 77 (14.3%) laboratories for N. gonorrhoeae. Laboratories varied from NCCLS guidelines by placing an excess number of disks per plate. Laboratories also reported using alternative media for Enterococcus species, N. gonorrhoeae, and H. influenzae. This study demonstrates a need for education among clinical laboratories to increase compliance with NCCLS guidelines.

Anti-Bacterial Agents↗

PubMed2000

Access to newer laboratory procedures: a call for action.

Healthy People 2010, an initiative from the federal government, calls for action from tuberculosis controllers and tuberculosis laboratories in the fight to eliminate tuberculosis. Many patients, such as immunocompromised patients and those infected with multidrug-resistant tuberculosis strains, pose a challenge for care and diagnosis. Fortunately, many changes have occurred in the last decade to facilitate more rapid and accurate testing to assist with the care of these patients. California, Florida, New York and Texas have almost 50% of the tuberculosis cases in the United States, and their public health laboratories utilize different approaches to meet the same goal of rapid and accurate testing of specimens. With the targets of Healthy People 2010 (e.g., to reduce the average time for a laboratory to confirm and report tuberculosis cases to 2 days for 75% of cases) already looming on the horizon, innovative methods for achieving these goals should be evaluated. Using these public health laboratories as models, rapid, gold-standard testing methods should be provided to all patients in the United States. Soon it will be the year 2010..., are you ready to swiftly move forward?

Bacterial Typing Techniques↗

PubMed1999

Multicenter laboratory validation of susceptibility testing of Mycobacterium tuberculosis against classical second-line and newer antimicrobial drugs by using the radiometric BACTEC 460 technique and the proportion method with solid media.

In a large multicenter study involving six major study sites in the United States, Canada, and Europe, the susceptibilities of 272 Mycobacterium tuberculosis strains to classical second-line antituberculosis (anti-TB) drugs (capreomycin, cycloserine, ethionamide, and kanamycin) and newer compounds (amikacin, clofazimine, ofloxacin, and rifabutin) were determined by the radiometric BACTEC 460 procedure and the conventional proportion method on Middlebrook 7H10 agar. Previously established critical concentrations for classical second-line anti-TB drugs were compared with several concentrations in liquid medium to establish equivalence. MICs of newer compounds determined in liquid medium were either the same or up to four times lower than those determined in agar medium. After establishing critical concentrations (breakpoints) in the extended testing of clinical isolates, we obtained an excellent overall correlation between the two systems, with no errors with amikacin, kanamycin, and ofloxacin and very few major or very major errors with the other drugs; however, for cycloserine, no breakpoint concentration could be recommended due to repeatedly inconsistent results by both methods. Based on these data we conclude that the BACTEC 460 procedure is a simple and rapid method requiring 4 to 8 days on average to generate accurate antimicrobial susceptibility testing (AST) results for eight anti-TB drugs other than those considered primary ones. These data not only fill a major gap of knowledge regarding the critical test concentrations of secondary anti-TB drugs but also provide a baseline for future evaluations of M. tuberculosis AST with the more recently developed, nonradiometric broth-based culture systems.

Anti-Bacterial Agents↗

PubMed1999

Evaluation of mycology laboratory proficiency testing.

Changes over the last decade in overt proficiency testing (OPT) regulations have been ostensibly directed at improving laboratory performance on patient samples. However, the overt (unblinded) format of the tests and regulatory penalties associated with incorrect values allow and encourage laboratorians to take extra precautions with OPT analytes. As a result OPT may measure optimal laboratory performance instead of the intended target of typical performance attained during routine patient testing. This study addresses this issue by evaluating medical mycology OPT and comparing its fungal specimen identification error rates to those obtained in a covert (blinded) proficiency testing (CPT) program. Identifications from 188 laboratories participating in the New York State mycology OPT from 1982 to 1994 were compared with the identifications of the same fungi recovered from patient specimens in 1989 and 1994 as part of the routine procedures of 88 of these laboratories. The consistency in the identification of OPT specimens was sufficient to make accurate predictions of OPT error rates. However, while the error rates in OPT and CPT were similar for Candida albicans, significantly higher error rates were found in CPT for Candida tropicalis, Candida glabrata, and other common pathogenic fungi. These differences may, in part, be due to OPT's use of ideal organism representatives cultured under optimum growth conditions. This difference, as well as the organism-dependent error rate differences, reflects the limitations of OPT as a means of assessing the quality of routine laboratory performance in medical mycology.

Candida↗

PubMed1998

Evaluation of a polymerase chain reaction-based universal heteroduplex generator assay for direct detection of rifampin susceptibility of Mycobacterium tuberculosis from sputum specimens.

In a double-blind study, 655 sputum specimens were obtained from individuals suspected of having tuberculosis and were analyzed for the presence of Mycobacterium tuberculosis and rifampin susceptibility with use of a polymerase chain reaction (PCR)-based universal heteroduplex generator assay (PCR/UHG-Rif). Of the specimens containing viable M. tuberculosis, 100% of the smear-positive (n = 41) and 50% of the smear-negative (n = 6) specimens tested positive for the organism by PCR/UHG-Rif. Nineteen of 537 culture-negative specimens tested positive for M. tuberculosis by PCR/UHG-Rif and were from patients with confirmed tuberculosis who were receiving antituberculosis therapy at the time of specimen collection. Thirty-five specimens contained nontuberculous mycobacteria and were negative by PCR/UHG-Rif. Genotypic evidence of rifampin resistance in five of six culture-confirmed, rifampin-resistant isolates was obtained by PCR/UHG-Rif, yielding a sensitivity and specificity for the assay of 83% and 98.2%, respectively. These results demonstrate the feasibility of using a PCR-based assay directly on sputum specimens for simultaneous detection of M. tuberculosis and rifampin susceptibility, and they suggest that patients with smear-positive, untreated tuberculosis and those presenting with suspected drug-resistant tuberculosis are the most appropriate groups for testing by PCR/UHG-Rif.

Antibiotics, Antitubercular↗

PubMed1998

Diagnostic tools in tuberculosis. Present and future.

Leadership will play a major role in the management of tuberculosis in the future. Many populations, such as immunocompromised patients and immigrants from countries with a higher prevalence of tuberculosis, create a challenge for care and diagnosis. Mycobacterial laboratory testing has undergone many changes in the past 10 years with the advent of nucleic acid probes for identification of Mycobacterium tuberculosis, and more recently nucleic acid amplification and beyond where computer technology meets molecular biology. In the past, changes for tuberculosis testing were not incorporated rapidly, sometimes taking 20 years or more to be fully implemented. The dynamics of acceptance of change and more rapid implementation need to be understood. With the use of such programs as Fast Track for Tuberculosis Testing, this can be accomplished more readily. New technologies can be provided to all users of such a network within a short amount of time and health care providers can equally benefit from this novel approach. The tuberculosis laboratory cannot stand alone. It must work together with other players, in order to eliminate tuberculosis.

Adult↗

PubMed1997

Drug resistance in tuberculosis.

Drug-resistant tuberculosis remains a worldwide problem. New laboratory methods have improved our ability to more rapidly identify resistant strains, but the most effective approach is to prevent the appearance of resistance by appropriate choice of antibiotics and directly-observed therapy. Mycobacterium tuberculosis is treated with familiar and unique drugs; consequently, mechanisms of resistance have some unique features. All drug resistance thus far identified develops by mutational events rather than acquisition of resistance genes from other bacteria. An agenda is presented for countering the appearance of further drug resistance in mycobacteria.

Anti-Bacterial Agents↗

PubMed1997

A new agent of mycobacterial lymphadenitis in children: Mycobacterium heidelbergense sp. nov.

Nontuberculous mycobacterial lymphadenitis presents an increasing clinical problem in immunocompetent young children. A slowly growing, nonphotochromogenic mycobacterium was recovered twice (isolates 2553/91 and 2554/91) from the lymphatic tissue of a child with recurrent cervical lymphadenitis. It could be differentiated biochemically from described Mycobacterium species, although it most closely resembled Mycobacterium malmoense by thin-layer chromatography and high-performance liquid chromatography of mycolic acids. A striking characteristic of the isolate was its high degree of susceptibility to antituberculous drugs in vitro, including isoniazid. Direct determination of the 16S rRNA gene sequence revealed a unique sequence and positioned the strain phylogenetically on a branch separate from M. malmoense within a group of slowly growing mycobacteria that show a high degree of similarity to M. simiae at the 16S rRNA gene level. Despite 99.6% sequence identity with M. simiae at the 16S rRNA gene level, DNA-DNA hybridization studies (hydroxyapatite method) demonstrated DNA relatedness of less than 40%. We conclude that this organism is a new species for which we propose the name M. heidelbergense. A culture of the type strain, strain 2554/91, has been deposited in the American Type Culture Collection as strain ATCC 51253.

Antitubercular Agents↗

PubMed1996

Diagnostic performance of amplified Mycobacterium tuberculosis direct test with cerebrospinal fluid, other nonrespiratory, and respiratory specimens.

The Gen-Probe Amplified Mycobacterium tuberculosis Direct Test (MTD) was adapted to be used for cerebrospinal fluid (CSF) and a large variety of other nonrespiratory specimens. Standardized with artificially spiked dilution series of CSF, the modified MTD procedure consists of (i) increasing the amount of sample 10-fold, (ii) pretreating the specimen with a detergent, and (iii) increasing the amplification time from 2 to 3 h. Performance of MTD in a clinical mycobacteriology laboratory was tested over an extended period of time, involving a total of 322 nonrespiratory as well as 1,117 respiratory specimens from 998 patients. Results from MTD were compared with those from microscopy, culture, analysis of tuberculostearic acid by gas-liquid chromatography-mass spectrometry (CSF only), and the final clinical diagnosis. When MTD results were compared with resolved data, the sensitivity, specificity, and positive and negative predictive values for MTD were 93.1, 97.7, 90.0, and 98.5%, respectively, for nonrespiratory specimens and 86.6, 96.4, 76.8, and 98.1%, respectively, for respiratory specimens. Our data demonstrate that (i) MTD is a robust, highly sensitive and specific technique for the rapid detection of M. tuberculosis complex in all types of clinical specimens, (ii) there was no statistically significant difference (P > 0.005) in sensitivity and specificity for nonrespiratory compared with respiratory specimens, and (iii) repeating all MTDs which yield a result between 30,000 and 200,000 relative light units would help prevent a large number of false positives and, thus, enhance test specificity.

Adolescent↗

PubMed1994

The new diagnostic mycobacteriology laboratory.

Recent surveys in the USA show that many mycobacteriology laboratories continue to use less-than-optimum culture and susceptibility testing methods. This seems to be true for European countries as well. The past few years have brought significant changes to the clinical tuberculosis laboratory. High-performance liquid chromatography and direct detection of acid-fast bacilli in clinical specimens aim at the same goal: increased sensitivity and specificity of the diagnostic approach and reduction of turnaround time. This review outlines a brief comparison between contemporary traditional methods and the latest developments in the direct detection of acid-fast bacilli. If patient care and public health are always considered paramount, regardless of admission time, hospital type, etc., the current concept of services has several shortcomings. One way to manage this situation is to sort and allocate specimens according to a system of priorities. There is a growing realization that no single method by itself is the best. To streamline the best choice for laboratory diagnosis, an additional dynamic acid-fast network is presented: 'Point-of-Care,' 'Fast Track,' and 'Specialty' laboratories. The physician interacts with all three types of laboratories, so ongoing communication between the physician and the laboratory is essential. Laboratorians must work together in the formation of this dynamic acid-fast network to improve service rendered for our patients.

Bacteriological Techniques↗

PubMed1994

Mycobacterial identification by computer-aided gas-liquid chromatography.

The suitability of the Microbial Identification System (MIS) marketed by Microbial ID (Newark, DE, USA) for routine diagnosis of clinically important mycobacteria was investigated and assessed. Cellular fatty acids were extracted from 1077 stock and recent clinical isolates. They were analyzed using a gas-liquid chromatograph combined with MIS software. The MIS system finally identifies the isolates by comparing their fatty-acid compositions with a standard library for mycobacteria. As the library search usually results in more than one possible match, suitable identification criteria were determined. The stricter these criteria are, the more the percentage of false-positive identifications can be reduced, but at the cost of more cases that remain undecided and require additional analysis. Under conditions similarity index (SI) SI1 > or = 0.4 and SI1-SI2 > or = 0.1, 63% of all isolates were correctly and 6% incorrectly identified.

Chromatography, Gas↗