Professor Emeritus at the University of Pennsylvania, Perelman School of Medicine (2021), immediate past Director of the Wm Pepper Laboratory of Clinical Medicine (2009-2020) and past Associate Director of Clinical Microbiology.(1982-2020)
The Agilent 2100 bioanalyzer (Agilent Technologies, Palo Alto, Calif.) utilizes capillary electro... more The Agilent 2100 bioanalyzer (Agilent Technologies, Palo Alto, Calif.) utilizes capillary electrophoresis on a microchip device (LabChip 7500; Caliper Technologies, Mountain View, Calif.) that is capable of rapidly sizing small DNA fragments. To determine whether the system could replace conventional restriction fragment length polymorphism (RFLP) typing by agarose gel electrophoresis, we compared the analyzer with conventional flagellin RFLP for typing Campylobacter jejuni . Ninety-seven isolates representing 46 Fla types were initially analyzed. Correct Fla types were detected in 59% of the isolates. The major problem with the system was in resolving samples containing multiple DNA fragments differing from 8 to 20 bp. Overall, the bioanalyzer has the potential to replace conventional RFLP analysis by gel electrophoresis, but improvements in the chip separation are needed.
A healthy 23-year-old man with fever and a tender mass in his right anterior neck was found to ha... more A healthy 23-year-old man with fever and a tender mass in his right anterior neck was found to have a branchial cleft cyst infected with Bordetella bronchiseptica . Initial testing suggested a Brucella species, but further laboratory testing identified the organism definitively. B. bronchiseptica infection in healthy adults is an unusual event.
<p><b>Objective:</b> This study was designed to determi... more <p><b>Objective:</b> This study was designed to determine if the presence of specific ganglioside-like moieties in <i>Campylobacter</i> 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.</p> <p><b>Methods:</b> We studied <i>Campylobacter</i> 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 <i>Campylobacter</i> enteritis alone.</p> <p><b>Results:</b> All GBS patients had antiganglioside antibodies. Anti-GM1 and anti-GD1a titers were significantly elevated in post-<i>Campylobacter</i> GBS, both axonal and demyelinating, compared with normal control subjects or those with uncomplicated Campylobacter diarrhea. <i>Campylobacter</i> isolated from patients with GBS and with enteritis alone had similar ganglioside-like moieties.</p> <p><b>Conclusions:</b> 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 <i>Campylobacter</i> infection. These findings have important implications for the development of vaccines against <i>Campylobacter jejuni</i>.</p&gt
We evaluated the MicroSeq 500 16S rDNA Bacterial Sequencing Kit (PE Applied Biosystems), a 500-bp... more We evaluated the MicroSeq 500 16S rDNA Bacterial Sequencing Kit (PE Applied Biosystems), a 500-bp sequence-based identification system, for its ability to identify clinical Mycobacterium isolates. The organism identity was determined by comparing the 16S rDNA sequence to the MicroSeq database, which consists primarily of type strain sequences. A total of 113 isolates (18 different species), previously recovered and identified by routine methods from two clinical laboratories, were analyzed by the MicroSeq method. Isolates with discordant results were analyzed by hsp65 gene sequence analysis and in some cases repeat phenotypic identification, AccuProbe rRNA hybridization (Gen-Probe, Inc., San Diego, Calif.), or high-performance liquid chromatography of mycolic acids. For 93 (82%) isolates, the MicroSeq identity was concordant with the previously reported identity. For 18 (16%) isolates, the original identification was discordant with the MicroSeq identification. Of the 18 discrepant ...
The protein II (P.II) outer membrane proteins of Neisseria gonorrhoeae, which have been implicate... more The protein II (P.II) outer membrane proteins of Neisseria gonorrhoeae, which have been implicated in gonococcal pathogenesis, have been previously shown to undergo a type of phase variation in which expression of any of several different forms of the proteins may be switched on or off. We identified six electrophoretically distinct forms of P.II proteins (designated P.IIa through P.IIf) within strain FA1090, and we isolated colonial variants of FA1090 that expressed only one of the six different P.II protein forms. Two monoclonal antibodies that bound specifically and differentially to P.II proteins were produced. One antibody bound to proteins P.IIb and P.IId and was bactericidal for all colonial variants expressing P.IIb. The second antibody bound to P.IIa and was bactericidal for colonial variants expressing P.IIa. P.II protein profiles of survivors of antibody killing indicated that multiple P.II protein species may be expressed on a single bacterium and that P.II protein switc...
We recently developed a molecular typing system for Campylobacter jejuni and Campylobacter coli b... more 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, ...
Hybridomas secreting monoclonal antibodies against an apparent strain-specific cell surface antig... more Hybridomas secreting monoclonal antibodies against an apparent strain-specific cell surface antigen of Neisseria gonorrhoeae were produced. Spleen cells from BALB/c mice immunized with whole gonococci were fused with mouse myeloma cell line Sp2/0, and hybrid cells were selected in culture. One hybridoma that secreted antibodies reactive with the immunizing strain was cloned by limiting dilution to obtain cell lines secreting monoclonal antibodies. These antibodies reacted with purified outer membranes from the immunizing strain as well as with whole gonococci. Binding of antibodies to whole gonococci was highly strain specific, with most gonococcal strains showing less than 1% of the binding with the immunizing strain. Antibodies did not bind to the other Neisseria species tested. Binding of monoclonal antibodies to whole gonococci of the immunizing strain was not dependent on state of piliation. The extent of antibody binding did vary in different colonial variants of the immunizin...
Clinical and diagnostic laboratory immunology, 1996
We performed a retrospective study on patients who had a positive screening antibody test result ... more 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, an...
The Agilent 2100 bioanalyzer (Agilent Technologies, Palo Alto, Calif.) utilizes capillary electro... more The Agilent 2100 bioanalyzer (Agilent Technologies, Palo Alto, Calif.) utilizes capillary electrophoresis on a microchip device (LabChip 7500; Caliper Technologies, Mountain View, Calif.) that is capable of rapidly sizing small DNA fragments. To determine whether the system could replace conventional restriction fragment length polymorphism (RFLP) typing by agarose gel electrophoresis, we compared the analyzer with conventional flagellin RFLP for typing Campylobacter jejuni . Ninety-seven isolates representing 46 Fla types were initially analyzed. Correct Fla types were detected in 59% of the isolates. The major problem with the system was in resolving samples containing multiple DNA fragments differing from 8 to 20 bp. Overall, the bioanalyzer has the potential to replace conventional RFLP analysis by gel electrophoresis, but improvements in the chip separation are needed.
A healthy 23-year-old man with fever and a tender mass in his right anterior neck was found to ha... more A healthy 23-year-old man with fever and a tender mass in his right anterior neck was found to have a branchial cleft cyst infected with Bordetella bronchiseptica . Initial testing suggested a Brucella species, but further laboratory testing identified the organism definitively. B. bronchiseptica infection in healthy adults is an unusual event.
<p><b>Objective:</b> This study was designed to determi... more <p><b>Objective:</b> This study was designed to determine if the presence of specific ganglioside-like moieties in <i>Campylobacter</i> 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.</p> <p><b>Methods:</b> We studied <i>Campylobacter</i> 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 <i>Campylobacter</i> enteritis alone.</p> <p><b>Results:</b> All GBS patients had antiganglioside antibodies. Anti-GM1 and anti-GD1a titers were significantly elevated in post-<i>Campylobacter</i> GBS, both axonal and demyelinating, compared with normal control subjects or those with uncomplicated Campylobacter diarrhea. <i>Campylobacter</i> isolated from patients with GBS and with enteritis alone had similar ganglioside-like moieties.</p> <p><b>Conclusions:</b> 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 <i>Campylobacter</i> infection. These findings have important implications for the development of vaccines against <i>Campylobacter jejuni</i>.</p&gt
We evaluated the MicroSeq 500 16S rDNA Bacterial Sequencing Kit (PE Applied Biosystems), a 500-bp... more We evaluated the MicroSeq 500 16S rDNA Bacterial Sequencing Kit (PE Applied Biosystems), a 500-bp sequence-based identification system, for its ability to identify clinical Mycobacterium isolates. The organism identity was determined by comparing the 16S rDNA sequence to the MicroSeq database, which consists primarily of type strain sequences. A total of 113 isolates (18 different species), previously recovered and identified by routine methods from two clinical laboratories, were analyzed by the MicroSeq method. Isolates with discordant results were analyzed by hsp65 gene sequence analysis and in some cases repeat phenotypic identification, AccuProbe rRNA hybridization (Gen-Probe, Inc., San Diego, Calif.), or high-performance liquid chromatography of mycolic acids. For 93 (82%) isolates, the MicroSeq identity was concordant with the previously reported identity. For 18 (16%) isolates, the original identification was discordant with the MicroSeq identification. Of the 18 discrepant ...
The protein II (P.II) outer membrane proteins of Neisseria gonorrhoeae, which have been implicate... more The protein II (P.II) outer membrane proteins of Neisseria gonorrhoeae, which have been implicated in gonococcal pathogenesis, have been previously shown to undergo a type of phase variation in which expression of any of several different forms of the proteins may be switched on or off. We identified six electrophoretically distinct forms of P.II proteins (designated P.IIa through P.IIf) within strain FA1090, and we isolated colonial variants of FA1090 that expressed only one of the six different P.II protein forms. Two monoclonal antibodies that bound specifically and differentially to P.II proteins were produced. One antibody bound to proteins P.IIb and P.IId and was bactericidal for all colonial variants expressing P.IIb. The second antibody bound to P.IIa and was bactericidal for colonial variants expressing P.IIa. P.II protein profiles of survivors of antibody killing indicated that multiple P.II protein species may be expressed on a single bacterium and that P.II protein switc...
We recently developed a molecular typing system for Campylobacter jejuni and Campylobacter coli b... more 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, ...
Hybridomas secreting monoclonal antibodies against an apparent strain-specific cell surface antig... more Hybridomas secreting monoclonal antibodies against an apparent strain-specific cell surface antigen of Neisseria gonorrhoeae were produced. Spleen cells from BALB/c mice immunized with whole gonococci were fused with mouse myeloma cell line Sp2/0, and hybrid cells were selected in culture. One hybridoma that secreted antibodies reactive with the immunizing strain was cloned by limiting dilution to obtain cell lines secreting monoclonal antibodies. These antibodies reacted with purified outer membranes from the immunizing strain as well as with whole gonococci. Binding of antibodies to whole gonococci was highly strain specific, with most gonococcal strains showing less than 1% of the binding with the immunizing strain. Antibodies did not bind to the other Neisseria species tested. Binding of monoclonal antibodies to whole gonococci of the immunizing strain was not dependent on state of piliation. The extent of antibody binding did vary in different colonial variants of the immunizin...
Clinical and diagnostic laboratory immunology, 1996
We performed a retrospective study on patients who had a positive screening antibody test result ... more 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, an...
Uploads
Papers by I. Nachamkin