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Biomedical subjects

I Nachamkin

Publications and source records attributed to I Nachamkin.

At least 37 records · Page 2Linked to original sources
PubMed1998

Campylobacter jejuni lipopolysaccharides in Guillain-Barré syndrome: molecular mimicry and host susceptibility.

OBJECTIVE: This study was designed to determine if the presence of specific ganglioside-like moieties in Campylobacter lipopolysaccharides (LPSs) is related to the development of Guillain-Barré syndrome (GBS), and to discover how frequently such moieties, including GM1, are present in these LPSs. METHODS: We studied Campylobacter isolates and sera from seven patients with GBS (five acute motor axonal neuropathy, one acute inflammatory demyelinating polyneuropathy, and one Fisher's syndrome), and compared them with similar specimens from patients with Campylobacter enteritis alone. RESULTS: All GBS patients had antiganglioside antibodies. Anti-GM1 and anti-GD1a titers were significantly elevated in post-Campylobacter GBS, both axonal and demyelinating, compared with normal control subjects or those with uncomplicated Campylobacter diarrhea. Campylobacter isolated from patients with GBS and with enteritis alone had similar ganglioside-like moieties. CONCLUSIONS: These results indicate that patients who develop GBS respond differently to the ganglioside-like epitopes on Campylobacter than do non-GBS diarrhea patients. Our findings support a role for host susceptibility as a determinant for the outcome following Campylobacter infection. These findings have important implications for the development of vaccines against Campylobacter jejuni.

Adult↗
PubMed1997

Microbiologic approaches for studying Campylobacter species in patients with Guillain-Barré syndrome.

Campylobacter jejuni is now considered to be the most common cause of bacterial diarrheal disease in the United States. Sufficient evidence exists to support the hypothesis that C. jejuni induces Guillain-Barré syndrome (GBS); however, many questions about the biology of the organism and host factors need to be answered. In order to study the role of C. jejuni and other Campylobacter species as a cause of GBS, isolates from patients with different forms of GBS and appropriate control populations must be obtained. To continue to study this association, research teams must have laboratory support for isolating and characterizing Campylobacter strains. This review summarizes current knowledge about the laboratory aspects of Campylobacter infection that may be pertinent to studies on GBS.

Bacterial Typing Techniques↗
PubMed1997

Detection of resistance to isoniazid, rifampin, and streptomycin in clinical isolates of Mycobacterium tuberculosis by molecular methods.

Molecular techniques can detect drug resistance in Mycobacterium tuberculosis, but whether these methods are practical for clinical laboratory use and the management of tuberculosis is unclear. We evaluated several available molecular methods (restriction fragment length polymorphism [RFLP], heteroduplex, and direct DNA sequence analyses) for detecting resistance to isoniazid, rifampin, and streptomycin and compared these methods with conventional methods for susceptibility testing. RFLP analysis detected the mutation at position S315T in katG in 12 (44.4%) of 27 isoniazid-resistant strains. Heteroduplex analysis of rpoB, detected 16 (76.2%) of 21 rifampin-resistant strains, whereas direct DNA sequencing detected all rifampin-resistant strains. RFLP analysis of the rpsL gene detected only nine (28.1%) of 32 streptomycin-resistant strains, while direct DNA sequencing detected nearly 68% of streptomycin-resistant strains. The specificity of all of the above-mentioned methods was excellent. RFLP analysis for katG and direct DNA sequencing of rpoB and rpsL may be practical methods for routine use in clinical microbiology laboratories or molecular pathology laboratories with good molecular capabilities and autosequencers. Despite the less than optimal sensitivity for some assays, resistance can be detected rapidly. However, molecular methods are not yet capable of replacing more traditional methods of susceptibility testing for M. tuberculosis.

Antibiotics, Antitubercular↗
PubMed1997

Motor nerve terminal degeneration provides a potential mechanism for rapid recovery in acute motor axonal neuropathy after Campylobacter infection.

We investigated the possible mechanisms of paralysis and recovery in a patient with the acute motor axonal neuropathy (AMAN) pattern of the Guillain-Barré syndrome. The AMAN pattern of GBS is characterized clinically by acute paralysis without sensory involvement and electrodiagnostically by low compound motor action potential amplitudes, suggesting axonal damage, without evidence of demyelination. Many AMAN patients have serologic or culture evidence of recent Campylobacter jejuni infection. Pathologically, the most severe cases are characterized by wallerian-like degeneration of motor axons affecting the ventral roots as well as peripheral nerves, but some fatal cases have only minor changes in the roots and peripheral nerves, and some paralyzed patients with the characteristic electrodiagnostic findings of AMAN recover rapidly. The mechanism of paralysis and recovery in such cases has been uncertain. A 64-year-old woman with culture-proven Campylobacter upsaliensis diarrhea developed typical features of AMAN. She improved quickly following plasmapheresis. Her serum contained IgG anti-GM1 antibodies. The lipopolysaccharide of the organism bound peanut agglutinin. This binding was blocked by cholera toxin, suggesting that the organism contained the Gal(beta1-3)GalNAc epitope of GM1 in its lipopolysaccharide. Motor-point biopsy showed denervated neuromuscular junctions and reduced fiber numbers in intramuscular nerves. In contrast, the sural nerve biopsy was normal and skin biopsy showed normal dermal and epidermal innervation. In AMAN the paralysis may reflect degeneration of motor nerve terminals and intramuscular axons. In addition, the anti-GM1 antibodies, which can bind at nodes of Ranvier, might produce failure of conduction. These processes are potentially reversible and likely to underlie the capacity for rapid recovery that characterizes some cases of AMAN.

Biopsy↗
PubMed1996

Molecular detection of bacterial DNA in venereal-associated arthritis.

OBJECTIVE: To evaluate the utility of polymerase chain reaction (PCR) amplification in detecting DNA from venereal-associated microorganisms in the synovial fluid of patients with inflammatory arthritis. METHODS: Oligonucleotide primers were developed for nested PCR based on Chlamydia, Ureaplasma, and Neisseria DNA sequences. PCR products were detected by gel electrophoresis and dot-blot hybridization. Primers specific for the target bacterial DNA were used to search for bacterial DNA in 61 synovial fluid specimens from patients with inflammatory arthritis, including several clinically associated with venereal infection. RESULTS: Five of the 61 synovial fluid specimens were positive for Neisseria gonorrhoeae DNA. Four of the 5 patients had clinical diagnoses of gonococcal arthritis; the other patient had an unexplained monarthritis. One specimen from a patient with a clinical diagnosis of gonococcal arthritis was negative for N gonorrhoeae. Three of the 61 specimens were positive for Chlamydia DNA. Two were derived from patients with clinical diagnoses of reactive arthritis or Reiter's syndrome, and 1 was from a patient with unexplained monarthritis. One of the 61 specimens was positive from Ureaplasma DNA; this sample was from a patient with a clinical diagnosis of Reiter's syndrome. In an additional patient with Reiter's syndrome, Ureaplasma DNA was also found in prostate biopsy tissue and a urine sample obtained after prostate massage (synovial fluid not available). CONCLUSION: These data support the classification of these 3 venereal-associated arthritides as infectious processes, and suggest that PCR for bacterial DNA is a useful method for detecting infectious agents in synovial fluid.

Adolescent↗
PubMed1996

Detection and molecular typing of Campylobacter jejuni in fecal samples by polymerase chain reaction.

In order to determine whether polymerase chain reaction (PCR) could be used to detect Campylobacter jejuni directly in stool samples, DNA from 66 frozen culture positive and negative fecal samples was purified by column chromatography. The flaA gene was amplified using primers directed against the conserved 5' and 3' regions and produced a 1.7 kb amplicon. Fifteen of 18 (83%) C. jejuni culture positive samples were detected by agarose gel electrophoresis and ethidium bromide staining. The test was negative in one sample containing C. coli. Twelve samples containing other enteric pathogens were negative as were 34 of 35 culture negative samples. Flagellin gene typing (see reference 14) of the flaA gene product from two stool samples in which the patients' stool isolate was also available showed the identical flagellin gene types suggesting that molecular typing of Campylobacter could potentially be performed on stool samples without the need for culture.

Bacterial Typing Techniques↗
PubMed1996

Utilization of tests for Lyme disease antibody at a university hospital.

We performed a retrospective study on patients who had a positive screening antibody test result for antibody to Borrelia burgdorferi to determine the clinical indicators used by physicians to order this test. Eighty-two evaluable patients who were screen positive (indirect enzyme-linked immunosorbent assay) between August 1991 and March 1993 were included. Additional tests, isotype-specific capture immunoglobulin enzyme immunoassay and Western blot (immunoblot) analysis (immunoglobulin G), were performed on positive samples. Of 82 patients with a positive screening test result, 54 (66%) had no serologic evidence of Lyme disease on the basis of additional testing (positive predictive value, 34%). Only 28 of 82 patients (34%) had clinical indicators suggestive of Lyme disease. Antibody screening tests may provide misleading information if they are not accompanied by more specific assays. Inappropriate testing of patients without indications of Lyme disease is frequently performed, and the ordering practices of physicians should be reassessed.

Antibodies, Bacterial↗
PubMed1996

Analysis of HL and O serotypes of Campylobacter strains by the flagellin gene typing system.

We recently developed a molecular typing system for Campylobacter jejuni and Campylobacter coli based on restriction fragment length polymorphism analysis of the flagellin gene,flaA (I.Nachamkin, K. Bohachick, and C.M. Patton, J. Clin. Microbiol. 31:1531-1536, 1993). We extended the typing system to 83 flagellin types (designated flaA-1,flaA-2, etc.) on the basis of analysis of 404 isolates of C. jejuni and C. coli including common serotypes isolated in the United States, a selection of less common serotypes, and serotype reference strains. Of the 295 strains previously shown to belong to common HL and O serotypes (C. M. Patton, M.A. Nicholson, S.M. Ostroff, A.A. Ries, I.K. Wachsmuth, and R.V. Tauxe, J. Clin. Microbiol. 31:1525-1530, 1993), six flaA types accounted for 53.6% of strains as follows: flaA-1, 21.7%; flaA-7, 14.9%; flaA-27, 5.1%; flaA-49, 4.4%; flaA-13, 3.7%; and flaA-21, 3.7%. Seventy-five percent of the strains were within 15 flaA types, 90% were within 30 flaA types, and all 295 strains were contained within 52 flaA types. Within each HL or O serotype, there usually were multiple flaA types. For 12 common HL serotypes and 7 common O serotypes, more than 50% of these isolates were a single flaA type. A database was developed by using commercially available restriction fragment length polymorphism analysis software (ProRFLP; DNA ProScan, Inc., Nashville, Tenn.) that should allow other investigators to perform typing with this system.

Animals↗
PubMed1995

Blocking antibody assay for confirmation of urogenital Chlamydia infection.

We evaluated the Syva MicroTrak Chlamydia Blocking Antibody Assay as a confirmatory assay for the detection of Chlamydia trachomatis in urogenital specimens. During a 5-month period, 109 positives were obtained (4.9%) by the MicroTrak II Enzyme Immunoassay as implemented with the Syva XL automated enzyme immunoassay instrument. Of 98 evaluable samples, 92 (93.9%) were confirmed as positive by the blocking assay, and 3 blocking-negative samples had organisms detected by direct fluorescent-antibody analysis (blocking sensitivity, 96.8%). We found that direct fluorescent-antibody analysis of samples with a specimen-to-cutoff absorbance ratio of < or = 2.0 was a reasonable confirmation alternative and was more cost-effective than the blocking assay.

Adult↗
PubMed1995

Comparison of MicroScan WalkAway system and Vitek system for identification of gram-negative bacteria.

In a prospective side-by-side comparison conducted from September through November 1994, we compared the MicroScan WalkAway system, a conventional biochemical identification system (Dade MicroScan, Inc., Sacramento, Calif.), with the Vitek system (bioMerieux Vitek, Hazelwood, Mo. [analysis software version AMS-RO8.2] for the identification of gram-negative bacteria. Three-hundred thirty-one nonurine isolates and 493 urine isolates were tested. For nonurinary isolates, there was 91.5% agreement between the two methods. For urinary isolates, there was 97.4% agreement between the two methods. Overall, there was 95% agreement between the two systems. The results suggest that the current version of the MicroScan WalkAway system with conventional panels is essentially comparable to the current Vitek system.

Bacterial Typing Techniques↗
PubMed1994

Immunoglobulin A antibodies directed against Campylobacter jejuni flagellin present in breast-milk.

We studied the relationship between IgA anti-campylobacter flagellin antibodies in breast milk samples and protection of breastfed infants living in a rural Mexican village from campylobacter infection. There were fewer episodes of campylobacter infection (symptomatic and asymptomatic combined) in infants breastfed with milk containing specific anti-flagellin antibodies (1.2/child/year, 95% CI 0.6-1.8) versus non-breastfed children (3.3/child/year, 95% CI 1.8-4.8; P < 0.01). Infants breastfed with milk that was anti-flagellin antibody negative by ELISA also had fewer episodes of infection compared with non-breastfed children, but the difference did not reach statistical significance (1.8/child/year, 95% CI 0.7-3.0 versus 3.3/child/year, 95% CI 1.8-4.8, P > 0.05). Breastfeeding has a protective effect against campylobacter infection and is associated with the presence of specific antibodies directed against campylobacter flagellin.

Analysis of Variance↗
PubMed1993

Production of chemoattractant by Helicobacter pylori.

Helicobacter pylori is present in the antral region of the stomach in a majority of patients with gastritis type B. The specific mechanism whereby the organism participates in the development of disease remains uncertain. Since the organism is not invasive, we postulate that H. pylori produces a chemoattractant that recruits inflammatory cells to the antral region of the stomach. H. pylori was grown under microaerophilic conditions at 37 degrees C for 72 hr in Brucella broth containing 1% fetal bovine serum. Culture supernates were harvested after removal of organisms by centrifugation and filtration. The putative chemoattractant in culture supernates as well as that which might be present endogenously in the growth medium (negative control) was assayed against human neutrophils (PMN) in modified Boyden blind-well chambers using 3.0-microns membranes. We found that H. pylori supernates are chemotactic and showed up to 130% activity when compared to the positive chemoattractant control (zymosan-activated serum, a source of C5a). Minimal activity was observed with virgin growth medium. The chemoattractant activity is proportional to the number of colony forming units (CFU) of H. pylori. Preliminary characterization of the activity shows that the chemoattractant is stable in a boiling water bath for 15 min, activity is lost within 1 hr in acid or alkali, and the chemotactic factor has an approximate molecular weight of 8500 daltons. The factor has no amino-sugar and is negative for the lipid A portion of lipopolysaccharide.(ABSTRACT TRUNCATED AT 250 WORDS)

Cells, Cultured↗
PubMed1993

Role of Campylobacter jejuni flagella as colonization factors for three-day-old chicks: analysis with flagellar mutants.

Campylobacter jejuni, an important cause of human gastrointestinal infection, is a major food-borne pathogen in the United States and worldwide. Since poultry becomes colonized and/or contaminated during the early stages of production and is a major food-borne source for this organism, we studied the role of C. jejuni flagella on the ability of the bacterium to colonize the chicken gastrointestinal tract. Three-day-old chicks were orally challenged with a motile wild-type strain of C. jejuni IN9 or with flagellar mutants created from IN9 by disrupting the flagellin genes with a kanamycin resistance cassette by using shuttle mutagenesis (A. Labigne-Roussel, P. Courcoux, and L. Tompkins, J. Bacteriol. 170:1704-1708, 1988). One mutant, IN9-N3, lacked flagella and was nonmotile. The other, IN9-N7, produced a truncated flagellum and was partially motile. Three-day-old chicks were orally challenged with different doses of the wild-type strain and the two mutants. At challenge doses ranging from 3.0 x 10(4) to 6.6 x 10(8) CFU per chick, only the fully motile, wild-type strain colonized the chick ceca. Our results show that intact and motile flagella are important colonization factors for C. jejuni in chicks.

Animals↗
PubMed1993

Evaluation of the Vitek EPS enteric pathogen screen card for detecting Salmonella, Shigella, and Yersinia spp.

We evaluated the Vitek EPS card as a screen for the enteric pathogens Salmonella spp., Shigella spp., and Yersinia enterocolitica. Salmonella spp., Shigella spp., and Y. enterocolitica (125, 54, and 5 isolates, respectively) and 81 nonenteric pathogens that might be selected for screening from primary plates (non-lactose fermenters) were tested. The EPS card correctly identified 183 of 184 pathogens tested (sensitivity, 99.5%). Of 81 nonenteric pathogens screened with the EPS card, 8 were identified as possible enteric pathogens (specificity, 90.1%). We reviewed our stool culture records over the past 1.5 years and analyzed the specificities of TSI-urea screens for 300 stool cultures that had suspicious colonies. From 55 of 300 stool cultures, either Salmonella spp. or Shigella spp. were isolated, and from 245 stool cultures, no pathogen was isolated. Of the 245 negative cultures, 166 gave false-positive screening-test results that resulted in further biochemical identification procedures (Analytab Products or Vitek identification). Thus, the specificity of the TSI-urea screen in our experience was 32.2%. The Vitek EPS card was shown to be a more cost-effective screening procedure than the TSI-urea screen.

Bacteriological Techniques↗
PubMed1993

Flagellin gene typing of Campylobacter jejuni by restriction fragment length polymorphism analysis.

We developed and studied a molecular typing approach for Campylobacter spp. with restriction fragment length polymorphism (RFLP) analysis of the flagellin gene flaA in C. jejuni. Using polymerase chain reaction, we amplified the flaA gene from strains comprising different HL:O serotypes by using a primer set directed at the conserved 5' and 3' flaA gene sequence to generate a 1.7-kb amplicon. The amplicon was further digested with the restriction enzyme DdeI, and the fragments generated were analyzed by agarose gel electrophoresis. In 43 non-outbreak strains of six common HL serotypes (HL 1, 2, 4, 5, 9, and 36) in the United States, 18 RFLP patterns were observed. In U.S. outbreak strains previously studied by 10 other typing methods, flaA typing correlated with the HL serotype within each outbreak, and six additional flaA types were identified. Our results suggest that RFLP analysis of the flaA gene from Campylobacter spp. has sufficient discrimination to be useful as a practical typing method for clinical and epidemiologic investigations.

Bacterial Typing Techniques↗