Recent approaches to early diagnosis of candida albicans in blood samples of immunocompromised patients

Candidemia is now considered an important and common infection among immunocompromised patients. The aim of this study was to evaluate Real-Time PCR and ELISA for detection of antigen and IgM antibody of Candida albicans as diagnostic tools in comparison with blood culture as a gold standard. The study included 80 persons divided into control group that included 20 healthy persons and patients group that included 30 patients with hematological malignancy and 30 patients in intensive care unit [ICU], all patients were carefully selected to be highly suspected clinically to have candidemia

Results: Blood culture revealed 25 positive candida cases among the 60 patients, 19 cases of them were C. albicans. Real-Time PCR had sensitivity of 100%, specificity of 95.1% and accuracy of 96.6%. ELISA for mannan antigen had sensitivity of 84.2%, specificity of 100% and accuracy of 95%. Detection of IgM antibody by ELISA had sensitivity of 73.7%, specificity of 92.7% and accuracy of 86.7% for diagnosis of C. albicans

Conclusion: Real-Time PCR had the highest sensitivity and accuracy, ELISA for mannan antigen had the highest specificity while ELISA for IgM antibody had the lowest sensitivity, specificity and accuracy. Results of diagnosing C. albicans candidemia by Real-Time PCR and ELISA for mannan antigen are promising and can be useful as rapid diagnostic tools

Soluble triggering receptor expressed on myeloid cells-1 as a diagnostic tool for acute bacterial meningitis

Acute bacterial meningitis is a life threatening disease with high morbidity and mortality. It is well known that one clinical or biological criterion may be unable to distinguish bacterial meningitis from nonbacterial meningitis. Our objective was to determine the value of Soluble Triggering Receptor Expressed on Myeloid Cells-1 [sTREM-1] in cerebrospinal fluid [CSF] for diagnosis of acute bacterial meningitis. After hospital admission and clinical examination, CSF analysis was done [chemical, cytological, bacteriological and estimation of sTREM -1 by ELISA]. Blood samples were taken for ESR, glucose estimation and testing of high sensitivity CRP [hs CRP]. According to CSF analysis we classified the studied patients into 16 patients with acute bacterial meningitis and 9 patients with non-bacterial meningitis. CSF sTREM-1 was significantly higher in patients with bacterial meningitis in comparison with patients with non bacterial meningitis [98.4 +/- 32.7 vs 21.4 +/- 6.4 pg/mL, P<0.001]. As regard the diagnostic values of sTREM-1; area under the receiver operating characteristic [ROC] curve was 0.948 [95% confidence interval [CI] 0.86-1.03], sensitivity [87.5%], specificity [89.9%], while area under the ROC curve of hs CRP was 0.872 [95% [CI] 0.73 -1.02], sensitivity [81.3%], specificity [55.6%]. CSF sTREM-1 level had significant positive correlation with CSF protein [r= 0.57, P<0.001], total leucocytic count [r= 0.64, P<0.001], polymorph nuclear leucocytic[PMNL] count [r= 0.68, P<0.001], ESR [r= 0.79, P<0.001], and hs CRP [r= 0.83, P<0.001], and significant negative correlation with CSF glucose [r= -0.62, P<0.001] and CSF/serum glucose ratio [r= -0.67, P<0.001]. There was no significant difference in sTREM-1 level between survivors and non survivors. In conclusion sTREM-1 might be useful in differentiating bacterial from non-bacterial acute meningitis

Evaluation of diagnostic value of quantiferon -TB gold test in active pulmonary tuberculosis

Tuberculosis [TB] remains the single infectious disease, causing the highest mortality in humans, leading to 3 million deaths annually. The aim of this study was to evaluate Quantiferon-TB Gold test as a method for rapid diagnosis of active pulmonary tuberculosis in comparison to tuberculin skin test [TST], sputum smear for acid fast bacilli [AFB], and sputum PCR. The study included 40 subjects who were suspected to have pulmonary TB, there were 26 cases diagnosed as active pulmonary TB by culture method, the other 14 cases was diagnosed as another pulmonary diseases and considered as control group

Results: Sputum smears for AFB had sensitivity of 46.2%, specificity of 100 %.TST had sensitivity of 76.9%, specificity of 64.3%. PCR had sensitivity of 92.3%, specificity of 100 %. Quantiferon-TB Gold had sensitivity of 84.6%, its specificity was 100 %. The combined sensitivity of Quantiferon-TB Gold test with sputum smear for AFB was 88.5% which was higher than the sensitivity of each test alone and was comparable with PCR sensitivity alone or when combined with Quantiferon -TB Gold test

Conclusion: Quantiferon-TB Gold test had good sensitivity, very high specificity and can be used as an additional rapid immunological test and may replace TST in diagnosis of active TB. The combination of Quantiferon-TB Gold test with sputum smear for AFB may be used for exclusion of active pulmonary TB

Diagnosis of chlamydia pneumoniae respiratory infection by cell culture compared with nested touchdown polymerase chain reaction and microimmunoflourescence

Chlamydia pneumoniae is a common cause of respiratory tract infection and community acquired pneumonia. This work was designed to evaluate different diagnostic methods with different types of samples for diagnosis of C. pneumoniae infection. The study included 50 subjects, classified into two groups; the patients group: included 40 patients; 25 males and 15 females presented with different pulmonary lesions, their ages ranged from 17 to 70 years with mean+/-SD of 47.75 +/-14.3 and 10 age and sex matched apparently healthy individuals served as controls. All patients and control were subjected to the following investigations; Hep-2 cell culture followed by detection of C. pneumoniae by immunofluorescence, polymerase chain reaction [PCR] to detect C. pneumoniae DNA and microimmunofluorescence [MIF] to detect C. pneumoniae antibodies [IgG and IgM]. The study results showed that 28 patients were diagnosed positive for C. pneumoniae by PCR compared with 17 positive by Hep-2 cell culture and 17 positive by MIF. There were 8 patients showed positive results by the three methods, 9 were positive by Hep-2 cell culture and PCR techniques, 8 were positive by PCR and MIF techniques, three were positive by PCR only and one patient showed positive IgM antibodies. All the 17 culture positive samples in this study were detected by PCR which emphisizes the high sensitivity of PCR. In addition, 11 of the culture negative samples were positive by PCR and 8 of these were confirmed by MIF technique. Three cases that were positive by PCR could not be confirmed by MIF. When we used the results of cell culture technique as a gold standard test and compared with those of PCR and MIF the sensitivity of PCR was 100%, while the sensitivity of MIF was 47.1%. The specificity of PCR was low 52.2% while that of MIF was 60.9%. The positive predective value, negative predective value, and accuracy of PCR were 60.7%, 100% and 72.5% respectively while those of MIF were 47.1% 60.9% and 55%. The positive results of C. pneumoniae infection were increased in sputum samples than nasopharyngeal swabs 60% versus 40% by cell culture and 90 % versus 70 % by PCR. From this study, we can conclude that although cell culture is frequently taken as the gold standard test in microbiological practice; this may not be valid with organisms that are difficult to grow as C. pneumoniae. MIF is of value as a complement to the C. pneumonia detection methods to distinguish acute infection from pre-existing infection. When sputum samples can be obtained, are superior to nasopharyngeal swabs. As a final point, PCR is a rapid and sensitive technique, and we suggest that PCR can be used along with another diagnostic method for prompt diagnosis