Chuan Hun Ding

Screening for New Delhi metallo-β-lactamase-1 in enterobacteriaceae: Is there a role for the modified hodge test?

Objective: The New Delhi metallo-β-lactamase-1 (NDM-1) enzyme is a plasmid-encoded enzyme that inactivates carbapenem antibiotics. This study aims to ascertain if the modified Hodge test (MHT) has a role in screening for NDM-1 in Enterobacteriaceae with reduced carbapenem susceptibility. Methods: Over a period of one year, all Enterobacteriaceae isolates from all clinical specimens with reduced susceptibility to at least one carbapenem were subjected to MHT and conventional polymerase chain reaction (PCR) detection of the NDM-1 gene. Results: A total of 13,098 Enterobacteriaceae isolates were screened and 63 (0.48%) had reduced susceptibility to at least one carbapenem. Out of the 63 isolates, 45 (71.4%) were MHT-positive. The NDM-1 gene was detected in 18 of the 63 isolates (28.6%). All 18 PCR-positive isolates were also MHT-positive. Thus, the sensitivity and specificity of the MHT in detecting NDM-1 in Enterobacteriaceae with reduced carbapenem susceptibility are 100% and 40%, respectively. Conclusion: The MHT is a useful test to screen for the presence of NDM-1 in Enterobacteriaceae with reduced carbapenem susceptibility. However, due to its rather low specificity, all MHT-positive isolates should be subjected to alternative tests (e.g. PCR) for confirmation, especially if other types of carbapenemases (e.g. KPC) are prevalent.

Presence of anti-mitochondrial antibodies and elevated serum immunoglobulin G levels: is this primary biliary cirrhosis-autoimmune hepatitis overlap syndrome?

Primary biliary cirrhosis in combination with autoimmune hepatitis has been termed “overlap syndrome”, but its diagnosis is challenging. We report a case of a 43-year-old lady who presented with a six-month history of jaundice and pruritus. She subsequently developed gum bleeds. Laboratory investigations revealed hypochromic microcytic anemia, abnormal coagulation profiles, elevated serum alanine transferase and alkaline phosphatase levels, and raised serum IgG and IgM levels. Her serum was also positive for anti-nuclear and anti-mitochondrial antibodies. The findings from her abdominal CT scan were suggestive of early liver cirrhosis and the histopathological examination results of her liver biopsy were consistent with primary biliary cirrhosis. The patient was treated with ursodeoxycholic acid and her liver function test parameters normalized after six months.

Seroprevalence of acute dengue in a Malaysian tertiary medical centre.

Objectives: The aims of this study were to determine the seroprevalence of acute dengue in Universiti Kebangsaan Malaysia (UKM) Medical Centre and its correlation with selected haematological and biochemical parameters. Methods: This cross-sectional study was conducted from January to June 2015. A patient was serologically diagnosed with acute dengue if the dengue virus IgG, IgM or NS-1 antigen was reactive. Results: Out of 1,774 patients suspected to have acute dengue, 1,153 were serologically diagnosed with the infection, resulting in a seroprevalence of 64.9%. Dengue-positive patients had a lower mean platelet count (89 × 109/L) compared to the dengue-negative patients (171 × 109/L) (p<0.0001). The mean total white cell count was also lower in the dengue-positive cases (4.7 × 109/L vs. 7.2 × 109/L; p<0.0001). The mean haematocrit was higher in patients with acute dengue (42.5% vs. 40.0%; p<0.0001). Likewise, the serum alanine transaminase level was also higher in patients with acute dengue (108 U/L vs. 54 U/L; p<0.0001). Conclusions: Dengue is very prevalent in UKM Medical Centre as most patients suspected to have acute dengue had serological evidence of the infection. The platelet count was the single most likely parameter to be abnormal (i.e. low) in patients with acute dengue.