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Biomedical subjects

F Stock

Publications and source records attributed to F Stock.

At least 19 recordsLinked to original sources
PubMed2006

Genotypic analysis of invasive Streptococcus pneumoniae from Mali, Africa, by semiautomated repetitive-element PCR and pulsed-field gel electrophoresis.

As part of a large, ongoing study of invasive infections in pediatric patients in Bamako, Mali, 106 cases of invasive pneumococcal disease were identified from June 2002 to July 2003 (J. D. Campbell et al., Pediatr. Infect. Dis. J. 23:642-649, 2004). Of the 12 serotypes present, the majority of isolates were not contained in PCV7 (the 7-valent pneumococcal conjugate vaccine), including 1 isolate that was serotype 1, 12 isolates that were serotype 2, 58 isolates that were serotype 5, 7 isolates that were serotype 7F, and 1 isolate that was serotype 12F. To determine whether clonal dissemination of the predominant serotypes had taken place, genotyping was performed on 100 S. pneumoniae isolates by using two methods: pulsed-field gel electrophoresis (PFGE) of SmaI-digested genomic DNA, and the Bacterial Barcodes repetitive-element PCR (rep-PCR) method. Criteria for delineating rep-PCR genotypes were established such that isolates of different serotypes were generally not grouped together. The two methods were equally discriminatory within a given pneumococcal serotype. PFGE separated the isolates into 15 genotypes and 7 subtypes; rep-PCR separated isolates into 15 genotypes and 6 subtypes. Using either method, isolates within serotypes 2, 5, and 7 formed three large, separate clusters containing 1 genotype each. Both methods further distinguished related subtypes within serotypes 2 and 5. Interestingly, one of the PFGE subtypes of serotype 5 is indistinguishable from the Columbia(5)-19 clone circulating in Latin America since 1994. The data support that serotypes 2 and 5 were likely to be the result of dissemination of particular clones, some of which are responsible for invasive disease over a broad population range.

Adolescent↗
PubMed2004

Biological effects of imidazolium ionic liquids with varying chain lengths in acute Vibrio fischeri and WST-1 cell viability assays.

Detailed biological studies of methyl- and some ethylimidazolium ionic liquids in luminescent bacteria as well as in the IPC-81 (leukemia cells) and C6 (glioma cells) rat cell lines are presented. Effective concentrations in these test systems are generally some orders of magnitude lower than effective concentrations [corrected] of the conventional solvents acetone, acetonitrile, methanol, and methyl t-butyl ether. No general influence of the anionic compound in the ionic liquids on toxicity could be found, although they seem to modulate toxicity in some cases. The clear influence of the alkyl chain length on toxicity was quantified by linear regression analysis. Alkyl chain length of the longer alkyl chain was varied from 3 to 10 carbon atoms. Consequences for a design of sustainable alternative solvents are briefly sketched.

Animals↗
PubMed2004

Comparison of automated culture systems with a CFR/USP-compliant method for sterility testing of cell-therapy products.

BACKGROUND: Although widely used, commercially available automated culture methods are not US Food and Drug Administration-approved for sterility testing of cell-therapy products. For cell-therapy products regulated under Section 351 of the Public Health Service Act, sterility testing must be performed by the methods described in 21 CFR 610.12 and USP <71> (CFR/USP method), or by methods demonstrated to be equivalent. METHODS: Two automated methods, BacT/Alert (BTA; bioMerieux) and Bactec (Becton Dickinson), were compared with the CFR/USP method. Representative mononuclear cell (MNC) products were formulated using six different product media. MNC product aliquots containing 10-50 x 10(6) cells in a 0.5 mL volume were seeded with organisms, and cultured for 14 days in aerobic and anaerobic bottles of each system. Ten different organisms at target concentrations of 10 and 50 colony-forming units (CFU) per bottle were tested. RESULTS: Positives were detected in a mean (range) of 72% (7-100%) of cultures for CFR/USP, 82% (0-100%) for BTA, and 93% (57-100%) for Bactec. For nine of the 10 organisms tested, overall detection rates for BTA and Bactec were equivalent to or higher than CFR/USP. Of the six product media tested, detection of organisms was impaired only by the medium containing multiple antibiotics: this occurred in all three systems. Both BTA and Bactec had shorter times to detection than the CFR/USP method, with overall means (ranges) of 87 (24-264) h for CFR/USP, 24 (12-54) h for BTA, and 33 (12-80) h for Bactec. Detection occurred consistently within 7 days for both BTA and Bactec, but not for CFR/USP. DISCUSSION: Both BTA and Bactec are superior to the CFR/USP method for overall detection and time to detection of organisms in MNC products suspended in commonly used media. These data support general use of either BTA or Bactec for sterility testing of a variety of cell-therapy products, and suggest that a 7-day culture period is sufficient to detect clinically relevant organisms. These results confirm the need for bacteriostasis and fungistasis testing of antibiotic-containing products, even when antibiotic-binding substances are used.

Anti-Bacterial Agents↗
PubMed2003

Multidrug-resistant Corynebacterium striatum pneumonia in a heart transplant recipient.

Corynebacterium striatum is a rare, but likely underreported, cause of serious infections in immunocompromised hosts and generally is susceptible to multiple classes of antimicrobial agents. Here we report the first case of C. striatum infection in a solid organ transplant recipient. Three years after heart transplantation, a 58-year-old man developed bilateral pneumonia and pulmonary embolism. He did not improve with levofloxacin, piperacillin/tazobactam, and heparin treatment. A homogeneous population of abundant gram-positive rods was repeatedly demonstrated in sputum and bronchoalveolar lavage fluid, and C. striatum was grown in pure culture. The isolate was unusual for its multidrug-resistant (MDR) antimicrobial susceptibility pattern. The pneumonia resolved with 4 weeks of vancomycin therapy, in combination with rifampin given only during the first 2 weeks of treatment. The isolation of coryneforms ("diphtheroids") is often attributed to contamination. Their abundant presence on direct examination of specimens and/or their growth in pure culture suggest a pathogenic role, however, and indicate the need for accurate microbiological identification, particularly in immunocompromised hosts who have been hospitalized and previously treated with antibiotics. Combination therapy that includes vancomycin may be the most prudent treatment for MDR C. striatum infections.

Amphotericin B↗
PubMed2002

Mandibular ramus flexure and gonial eversion as morphologic indicators of sex.

Recently, two mandibular traits--ramus flexure and gonial eversion--have come under close scrutiny (Loth & Henneberg 1996, 2000). The present study investigates the reliability of these two traits when each is applied as a single and independent indicator of sex, including the question of repeatability. The investigation was designed to give insights into possible confounding factors such as age and remodeling after tooth loss. Two samples, one of forensic (N = 153) and one of archaeological provenance (N = 80), were examined. The forensic sample was evaluated by a single observer while the archaeological sample was independently scored by three different observers. The results document that age and localized tooth loss seriously reduce the accuracy of these traits. For ramus flexure, male accuracy was only 66%, while female accuracy was even lower (32%). Overall accuracy was 59%. It is believed that the original scoring system devised by Loth and Henneberg (1996) creates an inherent bias in favor of males. For gonial eversion, a similar picture emerged (75.4% for males, 45.2% for females and 69.3% overall accuracy). Furthermore, both indicators are prone to intra- as well as inter-observer bias. While both possess some merit as sex indicators, they show marked functional and adaptive responses and may not be suitable for all samples.

Adult↗
PubMed2001

The use of oral washes to diagnose Pneumocystis carinii pneumonia: a blinded prospective study using a polymerase chain reaction-based detection system.

Pneumocystis carinii pneumonia (PCP) can be diagnosed by direct microscopic examination of induced sputum or by bronchoalveolar lavage (BAL). However, many institutions have little diagnostic success with induced sputum, and BAL is invasive and expensive. This prospective, blinded study assessed oral washes as a more convenient specimen than either sputum or BAL fluid and used a dissociation-enhanced lanthanide fluoroimmunoassay time-resolved fluorescent hybridization polymerase chain reaction (PCR) detection system that is feasible for clinical laboratories. The study assessed 175 oral washes, each paired with either an induced sputum that was positive for Pneumocystis or a BAL sample. The PCR test based on the Pneumocystis major surface glycoprotein primers had a sensitivity of 91% and a specificity of 94%, compared with a test based on mitochondrial large subunit rRNA primers, which had a sensitivity of 75% and a specificity of 96%. These results suggest that oral washes can provide a useful sample for diagnosis of PCP when a sensitive PCR detection system is used.

Bronchoalveolar Lavage↗
PubMed2000

Resistance to multiple fluoroquinolones in a clinical isolate of Streptococcus pyogenes: identification of gyrA and parC and specification of point mutations associated with resistance.

A strain of Streptococcus pyogenes resistant to multiple fluoroquinolones was isolated from the blood of an immunocompromised patient. Resistance to fluoroquinolones in S. pyogenes has not been previously studied. Compared to 10 sensitive strains of S. pyogenes, the fluoroquinolone-resistant clinical isolate of S. pyogenes presented point mutations in gyrA, predicting that serine-81 was changed to phenylalanine and that methionine-99 was changed to leucine, and in parC, predicting that serine-79 was changed to tyrosine. The mechanism of fluoroquinolone resistance in this isolate of S. pyogenes appears to be analogous to previously reported mechanisms for Streptococcus pneumoniae.

Anti-Infective Agents↗
PubMed2000

Evaluation of a new culture medium for Borrelia burgdorferi.

We evaluated the new MPM medium for the growth of Borrelia burgdorferi. All 18 blood samples from 17 patients with Lyme disease were negative. Growth studies showed that by day 4, most organisms in MPM were not viable. Our results reinforce the use of BSK medium as the primary choice for growing B. burgdorferi.

Bacteriological Techniques↗
PubMed1998

Detection of Legionella by PCR in respiratory specimens using a commercially available kit.

Using polymerase chain reaction (PCR) for the detection of pathogens that are difficult to grow, such as Legionella species, may reduce difficulties encountered with culture and immunofluorescent staining. We evaluated a commercial PCR and hybridization kit, designed for environmental samples, for the detection of Legionella in respiratory specimens. Sixteen Legionella species cultures tested positive with the Perkin Elmer Legionella EnviroAmp Amplification and Detection kits (Perkin Elmer, Foster City, Calif). The assay detected as few as 100 colony-forming units per milliliter of spiked bronchoalveolar lavage (BAL) fluid, and no false-negative results were obtained. PCR inhibition by blood in the specimens was removed by washing pelleted specimens in sterile distilled water. Of 126 specimens screened with the kit, 1 induced sputum and 3 BAL specimens were positive by PCR. All 4 were validated as true-positive results by culture or serologic testing. The entire PCR and hybridization assay can be completed in less than 6 hours, whereas isolation and identification by culture requires up to 12 days, and serologic conversion may not be demonstrated for weeks. Molecular techniques based on direct extraction and amplification of DNA from respiratory specimens nay be useful for the timely diagnosis of legionellosis.

Bronchoalveolar Lavage Fluid↗
PubMed1997

Infections with Roseomonas gilardii and review of characteristics used for biochemical identification and molecular typing.

Roseomonas is a recently described genus of gram-negative coccobacilli formerly designated as "pink-coccoid" groups I through IV by the Centers for Disease Control and Prevention (Atlanta, Ga) because of the organism's characteristic pink colonies. Since 1991 we have isolated Roseomonas from eight patients; in seven from blood cultures and in one from a skin lesion. The seven blood isolates were from patients with clinically significant underlying diseases who had central venous catheters in place; the majority were associated with polymicrobial catheter infections. Additional characteristics of their infections are described. The eight isolates had originally been identified by us as Centers for Disease Control (CDC) pink-coccoid group III. These organisms were re-identified using the criteria of Rihs et al, and all isolates fit most closely with Roseomonas gilardii. Antibiotic profiles were fairly homogeneous showing susceptibility to many antibiotics, but uniform resistance to cefoxitin, ceftazidime, and piperacillin. Attempts to determine whether the isolates were the same strain by pulsed-field gel electrophoresis suggested that 3 of the isolates were similar. Random amplified polymorphic DNA analysis, however, demonstrated that each of the eight isolates was a unique strain.

Adult↗
PubMed1997

Lack of clinical utility of bronchoalveolar lavage cultures for cytomegalovirus in HIV infection.

This study assessed the presence of cytomegalovirus (CMV) in bronchoalveolar lavage (BAL) in three subpopulations of HIV-infected patients and correlated its presence with clinical status during 3 mo of follow-up. Nineteen asymptomatic volunteers, six patients with CMV retinitis, and 46 patients with acute pulmonary symptoms underwent BAL and were assessed for CMV by cytopathology, conventional shell vial cultures, and antigen detection. Transbronchial biopsies were also obtained when possible and evaluated for histopathologic changes of CMV. All patients were followed for approximately 3 mo. Cytomegalovirus was detected in BAL in nine of 19 (47%) asymptomatic volunteers, in all six patients with CMV retinitis, and in 33 of 46 (72%) patients with pulmonary symptoms. Only one symptomatic patient with a positive CMV BAL culture developed clinically significant CMV pulmonary disease; this patient developed disseminated CMV and died. The only other death occurred in a patient with CMV retinitis who developed staphylococcal bacteremia. None of the asymptomatic volunteers or patients with CMV retinitis developed evidence of CMV pneumonia or any other organ disease with CMV. Cytomegalovirus is frequently detected in BAL from HIV-infected patients regardless of their pulmonary symptoms and its presence does not clinically predict significant pulmonary morbidity or mortality in 3 mo of follow-up.

AIDS-Related Opportunistic Infections↗
PubMed1997

[The mad man and his doctor].

There weren't specialist physicians for mental diseases in Antiquity, but mad men were usually attended to by doctors from the time of Hippocrates to Late Antiquity. The therapies were generally physical (pharmaceutical and dietetic), but some schools of medicine (Asclepiades, Celsus, Caelius Aurelianus) took into consideration the psychological behaviour and experimented with a sort of relational therapy of madness.

Greek World↗
PubMed1996

Comparison of PCR-based approaches to molecular epidemiologic analysis of Clostridium difficile.

Representative isolates of the 10 serogroups of Clostridium difficile and 39 clinical isolates (30 toxigenic and 9 nontoxigenic), including 5 isolates from a confirmed nosocomial outbreak, were analyzed by using two previously described arbitrary-primer PCR (AP-PCR) molecular typing methodologies (AP-PG05 and AP-ARB11) and PCR ribotyping. The two AP-PCR methods investigated gave comparable results; AP-PG05 and AP-ARB11 identified 8 and 7 groups among the serogroup isolates and classified the clinical isolates into 21 and 20 distinct groups, respectively. PCR ribotyping also identified 8 unique groups among the serogroup isolates but classified the clinical isolates into 23 groups. In addition, when results obtained by the PCR methods were compared with typing data generated by pulsed-field gel electrophoresis (PFGE), PCR ribotyping and PFGE were found to be in agreement for 83% (29 of 35) of isolates typeable by both techniques while AP-PG05 was in agreement with PFGE for 60% (20 of 33) and AP-ARB11 was in agreement with PFGE for only 44% (17 of 36). These results indicate that PCR ribotyping is a more discriminatory approach than AP-PCR for typing C. difficile and, furthermore, that this technique generates results that are in higher concordance with those obtained by using an established method for differentiating isolates of this organism on a molecular level than are results generated by using AP-PCR.

Bacterial Typing Techniques↗
PubMed1995

PCR amplification of rRNA intergenic spacer regions as a method for epidemiologic typing of Clostridium difficile.

From January to March 1993, a suspected outbreak of antibiotic-associated diarrhea occurred on a pediatric oncology ward of the Clinical Center Hospital at the National Institutes of Health. Isolates of Clostridium difficile obtained from six patients implicated in this outbreak were typed by both PCR amplification of rRNA intergenic spacer regions (PCR ribotyping) and restriction endonuclease analysis of genomic DNA. Comparable results were obtained with both methods; five of the six patients were infected with the same strain of C. difficile. Subsequent analysis of 102 C. difficile isolates obtained from symptomatic patients throughout the Clinical Center revealed the existence of 41 distinct and reproducible PCR ribotypes. These data suggest that PCR ribotyping provides a discriminatory, reproducible, and simple alternative to conventional molecular approaches for typing strains of C. difficile.

Bacterial Typing Techniques↗
PubMed1995

Comparison of pigment production and motility tests with PCR for reliable identification of intrinsically vancomycin-resistant enterococci.

Forty-eight clinical isolates identified as either Enterococcus faecium or Enterococcus faecalis with the MicroScan system (Dade International, MicroScan Inc., West Sacramento, Calif.) were further characterized by two supplementary biochemical tests (pigment production and motility). Twenty isolates (42%), all initially identified as E. faecium, were motile. Of these 20, 8 isolates (17%) produced yellow pigment and were identified as Enterococcus casseliflavus and the remaining 12 (25%) were nonpigmented and were identified as Enterococcus gallinarum. Identical identification results were obtained when PCR amplification of regions of the vanC gene was used as a technique for differentiating these organisms. The results of this study indicate that motility and pigment production tests together with commercial test systems are sufficient for reliable identifications of E. faecium, E. casseliflavus, and E. gallinarum.

Bacteriological Techniques↗
PubMed1994

Improved enrichment broth for cultivation of fastidious organisms.

An enrichment broth developed in our laboratory, fastidious broth (FB), was compared with two commercially available broth media, supplemented thioglycolate broth and enriched eugonic broth. FB supported the growth of a number of organisms that were not cultivatable in either of the other two media, including Corynebacterium jeikeium, Haemophilus influenzae, Neisseria gonorrhoeae, and Streptococcus pneumoniae. In addition, for several organisms that were able to grow in all three broths, including Neisseria meningitidis, Nocardia asteroides, and Actinomyces spp., both the time of incubation and the starting inoculum necessary to enable detection of growth were decreased significantly by using FB.

Bacteria↗