Background: Diagnosis of tuberculous (TB) pleuritis is difficult and better diagnostic tools are needed. New blood based interferon-gamma (IFN-γ) tests are promising, but sensitivity could be low in HIV positive patients. The IFN-γ tests have not yet been validated for use in pleural fluid, a compartment with higher level of immune activation than in blood.

BackgroundAdenosine Deaminase Activity (ADA) is a commonly used marker for the diagnosis of tuberculous pleural effusion. There has been concern about its usefulness in immunocompromised patients, especially HIV positive patients with very low CD4 counts. The objective of this study was to evaluate the sensitivity of ADA in pleural fluid in patients with low CD4 counts.Materials and MethodsThis was a retrospective case control study. Medical files of patients with tuberculous pleuritis and non-tuberculous pleuritis were reviewed. Clinical characteristics, CD4 cell counts in blood and biochemical markers in pleural fluid, including ADA were recorded.ResultsOne ninety seven tuberculous pleuritis and 40 non- tuberculous pleuritis patients were evaluated. Using the cut-off value of 30 U/L, the overall sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of ADA was 94%, 95%, 19, and 0.06 respectively. The mean CD4 cell counts among TB pleuritis patients was 29 and 153 cells/microL in patients with CD4 <50 cells/microL and >50 cells/microL, (p<0.05) respectively. The corresponding mean ADA values for these patients were 76 U/L and 72 U/L respectively (p>0.5). There was no correlation between ADA values and CD4 cell counts (r = −0.120, p = 0.369).ConclusionADA analysis is a sensitive marker of tuberculous pleuritis even in HIV patients with very low CD4 counts in a high TB endemic region. The ADA assay is inexpensive, rapid, and simple to perform and is of great value for the immediate diagnosis of tuberculous pleuritis while waiting for culture result and this has a positive impact on patient outcome.

BackgroundApart from localized gastrointestinal infections, Escherichia coli and Salmonella species are major causes of systemic disease in both humans and animals. Salmonella spp. cause invasive infections such as enteric fever, septicemia, osteomyelitis and meningitis while certain types of E. coli can cause systemic infections, includingpyelonephritis, meningitis and septicemia. These characteristic requires the involvement of a myriad of virulence factors.MethodsThis study investigated the virulence factors of Escherichia coli and Salmonella species in clinical specimens from patients with diarrhoea presenting to health care centres in Oliver R. Tambo District Municipality, Eastern Cape Province, Republic of South Africa. Microbiology analysis involved the use of cultural and molecular techniques.ResultsOut of a total of 315 samples screened, Salmonella isolates were obtained in 119 (37.8%) of cases and these comprised: S. choleraesuis (6%), S. enteritidis (4%), S. eppendorf (1%), S. hadar (1%), S. isangi (8%), S. panama (1%), S. typhi (52%), S. typhimurium (25%) and untyped Salmonella spp. (2%). Among the Salmonella species 87 (73.1%) were invasive. Using molecular diagnostic methods, diarrheagenic E. coli were detected in 90 cases (28.6%): the greater proportion of this were enteroaggregative E. coli (EAEC) 37 (41.1%), enteropathogenic E. coli (EPEC) 21 (23.3%) and enterohemorrhagic E. coli (EHEC) 21 (23.3%). The predominant virulence gene among the diarrheagenic E. coli was EAEC heat-stable enterotoxin astA genes while the virulence genes identified in the Salmonella strains were 15 (12.6%) flic and 105 (88.2%) inv genes. The amino acid identity of the representative genes showed 95-100% similarity to corresponding blast searched sequence.ConclusionsThis study showed the diversity of virulence gene expression in two major enteric pathogens. S. typhi and enteroaggregative E. coli were the predominant enteropathogens in our study area with an indication that EAEC is endemic within our study population. It was observed among other things that some diarrheagenic E. coli isolated from apparently asymptomatic subjects expressed some virulence genes at frequency as high as seen in diarrheagenic cases. This study underlines the importance of understanding the virulence composition and diversity of pathogens for enhanced clinico-epidemiological monitoring and health care delivery.