Characterization of Acinetobacter baumannii Co-producing Carbapenemases OXA-23 and OXA-66, and armA 16S Ribosomal RNA Methylase at a University Hospital in South Korea / 대한임상미생물학회지

BACKGROUND: In the present study, the resistance mechanisms against carbapenems and aminoglycosides for 23 strains of multi-drug-resistant Acinetobacter baumannii isolated at a university hospital were investigated. METHODS: The minimal inhibitory concentrations (MICs) were determined via broth microdilution or Etest. The genes encoding OXA-type carbapenemases and 16S rRNA methylase were identified using multiplex PCR, and the amplified products were sequenced. Conjugation experiments were conducted, and an epidemiologic study was performed using enterobacterial repetitive intergenic consensus (ERIC)-PCR. RESULTS: In the isolates, the MICs of the tested aminoglycosides, including arbekacin, were >1024 microg/mL; the MICs of aztreonam, cefepime, ceftazidime, and ciprofloxacin ranged from 64 to 128 microg/mL; and the MICs of carbapenem ranged from 32 to 64 microg/mL, as determined through the broth microdilution test. According to the E-test, the MICs of ampicillin/sulbactam and colistin were 8 and 0.25 to 0.38 microg/mL, respectively. Sequence analysis confirmed that all of the isolates expressed carbapenemases OXA-23 and OXA-66, as well as armA 16S rRNA methylase. In addition, ISAba1 was identified upstream of the gene encoding OXA-23. OXA-23 and armA were not transferred to Escherichia coli J53 cells in the transconjugation experiments. ERIC-PCR molecular fingerprinting produced a single pattern in all cases. CONCLUSION: The co-production of OXA-23 and armA 16S rRNA methylase may be attributed to the multidrug resistance of the A. baumannii isolates in the present study. Stricter surveillance and more rapid detection are necessary to prevent the spread of this type of resistance in the future.

Antiproliferative Effect of Phenylbutyrate in AsPC-1 Pancreatic Cancer Cell Line

PURPOSE: Phenylbutyrate is an effective redifferentiating agent in several human cancers. Recently phenylbutyrate has been reported to inhibit histone deacetylase activity. We investigated the effects of sodium 4-henylbutyrate (Na-4-PB) on cell proliferation in a human pancreatic cancer cell line. METHODS: A human pancreatic cancer cell line, Aspc-1 was purchased from Korean Cell Line Bank. Antiproliferative effects of sodium 4-phenylbutyrate were measured by MTT assay and their mechanisms were evaluated by apoptosis assay and cell cycle analysis. RESULTS: After 3 days of treatment with Na-4-PB at the concentration of 2.5, 5, 7.5, and 10 mM, relative growth inhibition compared to control was 21.3+/-8.3% (mean+/-SD), 37.8+/-2.3%, 46.7+/-0.5%, and 56.7+/-1.7% respectively (p < 0.05). Antiproliferative effect of Na-4-PB was also time-dependent. Combination treatment with Na-4-PB and troglitazone, a PPARg agonist, increased antiproliferative effects but was not synergistic. After 48 hour treatment with Na-4-PB, early apoptotic cell population in control, 2.5, and 5 mM of Na-4-PB was 29.6%, 44.2%, and 65.9%, respectively. After 24 hour treatment with Na-4- PB, G0/G1 phase population in control, 2.5, and 5 mM of Na-4-PB was 55.0%, 67.4%, and 65.8%, respectively. CONCLUSION: Na-4-PB inhibited pancreatic cancer cell proliferation by inducing apoptosis and cell cycle arrest at G0/G1 phase in time- and dose-dependent manner. Combination treatment with Na-4-PB and other chemotherapeutic agents such as troglitazone, a PPARg agonist, can enhance antiproliferative effects. Na-4-PB might be a promising potential therapeutic agent for patients with pancreatic cancer.

Diagnosis of Palpable Breast Masses by the Modified Triple Test Score: A prospective study / 한국유방암학회지

PURPOSE: The modified triple test (MTT; physical examination, ultrasonography, and fine-needle aspiration cytology) for palpable breast masses yielded 100% diagnostic accuracy when all 3 components were concordant (all benign or all malignant) in our previous study. However, about 30% of cases were discordant and required open or core needle biopsy. This study is designed to evaluate the modified triple test by scoring system, based on our experience, and to develop a method to further limit the need for surgical biopsy of discordant cases. METHODS: The MTT was performed in 175 palpable breast masses of 166 female patients between August 1998 and June 2001 at the Outpatient Clinic, Department of Surgery, Chungbuk National University Hospital. Each component of the MTT was assigned 1, 2, or 3 points for a benign, suspicious, or malignant result, respectively, yielding a total modified triple test score (MTTS) from 3 to 9 points, and 25 cases with 3 points of MTTS were clinically followed up without histological confirmation. RESULTS: Among 175 cases, concordant cases were 120 (68.6%); benign cases was 66 (37.7%), and malignant cases were 54 (30.8%). Concordant cases had 100% of diagnostic accuracy, sensitivity, and specificity. Among the 25 cases of benign concordant (MTTS 3 points), no case was proved to be malignant through clinical follow-up observation. Total discordant cases were 55 (31.4%); 15 cases of 4 points (8.6%), 11 cases of 5 points (6.3%), 4 cases of 6 points (2.3%), 18 cases of 7 points (10.3%), 7 cases of 8 points (4.0%). In each discordant group, 0 cases of 4 points (0%), 2 cases of 5 points (18.2%), 3 cases of 6 points (75%), 15 cases of 7 points (83.8%), and 7 cases of 8 points (100%) were proved to be malignant by histologic confirmation. Aspiration cytology has the highest specificity and positive predictive value of the 3 MTT components. CONCLUSION: Palpable breast masses that score 3 or 4 points by MTTS are benign and could be clinically followed up, and masses that score 8 or 9 points are malignant and should undergo defiitive therapy. Confirmatory biopsy might be applied on only 20% of the masses the reserve MMTTS of 5, 6, and 7 points.