Sachie Yomoda

Detection of a Variant Metallo-β-Lactamase, IMP-10, from Two Unrelated Strains of Pseudomonas aeruginosa and an Alcaligenes xylosoxidans Strain

ABSTRACT The gene blaIMP-10 of a variant metallo-β-lactamase, IMP-10, had a single base replacement of G by T at nucleotide 145, which led to an amino acid alteration of Val49 to Phe compared to the IMP-1 enzyme, indicating that IMP-10 was a point mutation derivative of IMP-1. Highly purified enzymes revealed that IMP-10 was different from IMP-1 in its extremely low hydrolyzing activities for penicillins, such as benzylpenicillin, ampicillin, and piperacillin.

Presence of Pseudomonas putida Strains Harboring Plasmids Bearing the Metallo-β-Lactamase Gene blaIMP in a Hospital in Japan

ABSTRACT To determine the persistence and spread of antibiotic-resistant strains in Gunma University Hospital, 83 Pseudomonas putida strains (each from a different patient) were isolated from January 1997 through December 2001. Of the 83 strains isolated, 27 were resistant to carbapenems. All 27 produced metallo-β-lactamase and were found to be PCR positive for the blaIMP gene. Most (22 strains) were primarily isolated from the wards (W7 [9 strains] and W4 [8 strains]). Another five blaIMP-positive P. putida strains from wards W7 and W4 were obtained by swabbing around the water pipes. A total of 32 blaIMP-positive P. putida strains were assessed by pulsed-field gel electrophoresis (PFGE) and testing of drug susceptibility to 10 chemotherapeutic agents. Both PFGE and MIC patterns revealed that there were long-term resident strains among inpatients and hospital environments. The blaIMP genes of 22 of 32 strains were all transferable to a recipient strain of Pseudomonas aeruginosa by conjugation or transformation and conferred resistance to carbapenems and cephems. The blaIMP plasmids were conjugally transmissible among P. aeruginosa strains and mediated resistance to amikacin as well as β-lactams. Ten of the 22 plasmids mediated additional resistance to gentamicin and tobramycin. Plasmids with identical DNA and drug resistance patterns were found in P. putida strains with identical PFGE patterns and with different PFGE patterns. We presumed that P. putida was one of the resident species in inpatients and especially in hospital environments, spreading drug resistance genes via plasmids among P. putida strains and supplying them to more pathogenically important species, such as P. aeruginosa.

Identification of amylase-binding monoclonal immunoglobulins in multiple myeloma associated with macroamylasemia

Hyperamylasemia caused by the ectopic production of amylase in multiple myeloma was fi rst described in 1988 [1]. Subsequently, several cases of amylase-producing multiple myeloma have been reported [2 – 8], and amylase-producing myeloma cell lines have been established [2,9]. Th us, ectopic production of amylase in immunoglobulin-producing cells is considered a cause of hyperamylasemia associated with multiple myeloma, and serum amylase is suggested to be a reliable disease activity index in patients with amylaseproducing myeloma [7]. Hyperamylasemia is also known to be caused by macroamylase, an immunoglobulin – amylase complex [10]. In a rare case with immunoglobulin Aκ (IgAκ ) multiple myeloma and macroamylasemia reported by Sagristani et al . [11], hyperamylasemia was not present at the diagnosis of myeloma and appeared at the relapse of the disease, with the appearance of an additional γ -chain oligoclonal component. Th ey suggested a possible role of these chains in producing macroamylasemia in the patient. We experienced a rare case of multiple myeloma associated with macroamylasemia and Hashimoto disease, and identifi ed amylase-binding monoclonal immunoglobulins produced by myeloma cells for the fi rst time. A Japanese woman was diagnosed with Hashimoto disease when she was 65 years old. She had a fi rm, diff use goiter and clinical fi ndings of hypothyroidism, with suppressed serum free thyroid hormones, elevated serum thyrotropin and increased titers of thyroglobulin antibodies ( 26214400 ) and microsomal antibodies ( 26214400 ). Treatment with L-thyroxine was started. At the age of 72, she was found to have a markedly increased serum amylase (2366 IU/L, normal range: 37 – 160 IU/L) and decreased urinary amylase (5 IU/L, normal range: 51 – 964 IU/L). Th ere was no evidence of a disorder of the salivary gland or pancreas. Amylase isozyme showed an atypical broad single peak. Th in-layer gel fi ltration of amylase showed a strong band with a high molecular weight. Th e patient was, therefore, diagnosed to have macroamylasemia. Although the serum total protein and globulin were elevated (8.5 g/dL and 4.0 g/ dL, respectively), further examination was not performed. Th yroglobulin antibodies and microsomal antibodies were 1638400 and 1638400 , respectively, at that time. At the age of 75, she was found to have an increased serum IgA (2170 mg/dL, normal range: 84 – 438 mg/dL). Other immunoglobulins were moderately decreased (IgG 440 mg/dL, IgM 31 mg/dL, IgD less than 0.6 mg/dL, IgE less than 5.0 U/mL). Immunoelectrophoresis showed the presence of a monoclonal band of IgAλ . Light chains were not observed in her urine. No punched-out lesion was observed in skeletal X-radiography. Bone marrow aspiration showed moderate plasma cell proliferation (6%), which suggested a diagnosis of IgAλ type monoclonal gammopathy with undetermined signifi cance at that time. Macroamylase was still present, and thyroglobulin antibodies and microsomal antibodies were decreased to 6400 and 1600 , respectively. At the age of 77, her serum amylase was still high at 2674 IU/L, while thyroglobulin antibodies and microsomal antibodies were further decreased to 400 and 400 , respectively. Serum IgA was increased to 3710 mg/dL. Bone marrow aspiration showed marked plasma cell proliferation (30%), which indicated a diagnosis of multiple myeloma (stage IIB). In spite of therapy with melphalan and prednisone, serum IgA and amylase did not decrease, and the patient died of renal failure. Th e patient had IgAλ type multiple myeloma associated with macroamylasemia and Hashimoto disease. In order to investigate whether the monoclonal immunoglobulins were involved in macroamylasemia or Hashimoto disease, we examined the binding of monoclonal immunoglobulins to amylase and thyroid autoantigens. Immunofi xation analysis of macroamylase was performed using serum obtained from the patient at the age of 75. Th e serum was applied to a cellulose acetate membrane (Titan III; Helena, Urawa, Japan) and electrophoresed for 36 min at 280 V at 4 ° C. Rabbit anti-human λ , κ , IgM, IgA and IgG antibodies (Dako, Tokyo, Japan) were applied to the membrane L eu k L ym ph om a D ow nl oa de d fr om in fo rm ah ea lth ca re .c om b y U ni ve rs ity o f B ri tis h C ol um bi a on 1 1/ 23 /1 4