Mark Melzer

An automated molecular test for Mycobacterium tuberculosis and resistance to rifampin (Xpert MTB/RIF) is sensitive and can be carried out in less than 2 h

Commentary on: BoehmeCCNabetaPHillemannD. Rapid molecular detection of tuberculosis and rifampin resistance. N Engl J Med 2010;363:1005–15.

Previous treatment in predicting drug-resistant tuberculosis in an area bordering East London, UK.

OBJECTIVESnTo determine the utility of risk assessment in selecting Mycobacterium tuberculosis isolates for rifampin resistance or rpoB genotyping compared to non-selectively genotyping all isolates. Secondly, we examined the association between past treatment and drug resistance.nnnMETHODSnFrom January 2003 to December 2006, demographic, clinical, and laboratory data were prospectively collected on patients with laboratory-confirmed tuberculosis (TB). On the basis of past treatment for active TB infection or known exposure to drug-resistant TB, selected samples were sent to a mycobacterial reference laboratory for rpoB genotyping. A multivariable logistic regression model was developed to examine the association between past treatment and drug resistance, adjusted for other factors. Sensitivity, specificity, and negative and positive predictive values of past treatment as a predictor for drug resistance were determined.nnnRESULTSnThere were 392 patient episodes of culture-proven TB. Thirty-three drug-resistant isolates were cultured from 30 patients: 29 (87.9%) were isoniazid-resistant, three (9.1%) were multidrug-resistant (MDR), and one (3.0%) was rifampin mono-resistant. One patient with isoniazid resistance developed recurrent disease, and two isolates, initially isoniazid-resistant, mutated and became MDR TB. Based on risk assessment, rpoB genotyping was performed on 19 samples, and two (10.5%) had mutations that predicted multiple drug resistance. Although for MDR TB, a past history of treatment predicted two out of three patients with acquired resistance, adjusted analysis did not demonstrate a significant association between previous treatment of active TB and drug resistance (odds ratio 1.5, 95% confidence interval (CI) 0.4-5.6). The positive predictive value of past treatment as a predictor for drug resistance was 12.0% (95% CI 2.6-31.2%).nnnCONCLUSIONnAlthough numbers of MDR TB were too small to draw meaningful conclusions, past treatment may be useful in selecting samples for rpoB genotyping. Overall, previous treatment had a low positive predictive value for drug resistance in an area bordering East London.

Community-acquired Klebsiella pneumoniae meningitis in an alcoholic patient with an infected pancreatic pseudocyst; a case report and review of literature

We report a case of a 49-year-old male with a history of chronic alcoholism and evidence of a pancreatic pseudocyst on CT scanning. He presented with a 3-days history of fever, loss of appetite and upper abdominal pain. Blood cultures grew Klebsiella pneumoniae and he improved clinically with a seven-day course of intravenous co-amoxiclav and metronidazole. Two weeks later he was readmitted to hospital with impaired consciousness and septic shock, and died three days later in intensive care. Post mortem examination revealed bacterial meningitis and an infected pancreatic pseudocyst. Klebsiella pneumoniae was isolated from the pancreas and meninges.