Microbiologie médicale et diagnostic

 Background: Liver abscesses constitute a major economic problem and there exists very less information in association with liver abscesses in ovine. Although studies in several countries have reported on the incidence of ovine hepatic abscesses at abattoirs, few surveys have identified the etiology and pathological characteristics of these abscesses.
Aim: The aim of this research is histopathological and bacteriological study on hepatic abscesses of Herrik sheep.
Methods: The lesion specimens of 5000 condemned sheep livers were collected from four provinces (Western Azerbaijan, Eastern Azerbaijan, Kordestan and Kermanshah) abattoirs for bacteriological (aerobic and anaerobic) culture and pathologic examination.
Results: Grossly, 230 liver abscesses (4.6%) found that 110 cases were in female sheep (47.8%) and 120 cases were in male sheep (52.1%). Most of the abscesses were found in diaphragmatic surface (23.48%), visceral surface (22.1%) and right lobes (21.3%) of the livers. Regarding the presence of abscesses, there was no significant difference between sexes, lobes and surfaces of livers (p>0.05). The following bacteria were isolated: from 120 of which, Corynebacterium (52.4%) was isolated, and from 26 of which, Pasteurella (11.3%), from 25 of which, Escherichia coli (11.1%), from 16 of which, Proteus (7.2%), from 16 of which, Pseudomonas aeruginosa (7.2%), from 13 of which, streptococcus (5.5%), from 12 of which, staphylococcus (5.3%) were isolated and no bacteria were isolated from the remaining 2 liver abscesses.
Conclusions: Our study suggested that Corynebacterium pseudotuberculosis is the most prevalent bacterium incriminated for hepatic abscesses in sheep. Histologically, these lesions had a core of caseous necrosis, encircled by a zone of necrotic phagocytic cells and bacteria with cellular characteristics of Corynebacterium pseudotuberculosis and a connective tissue capsule with calcification

 Background: Time to Positivity (TTP) of blood cultures is defined as the time elapsed between the start of incubation and the automated alert signal indicating growth in the culture bottle. This study evaluates the TTP of blood cultures in patients with Staphylococcus aureus Bacteremia (SAB) and assesses the relationship between TTP and mortality,
Methods: We performed a retrospective study involving adults who had SAB between May 2007 and May 2010 in a tertiary hospital. TTP was defined as the time between onset of incubation and growth detection using an automated blood culture system.
Results: A total of 167 SAB were evaluated. Patient’s median age was 72 years (range, 18-95 years). The median TTP was 13.6 h (range, 3.6-95.2 h). Attributable mortality rate (27.5%) was not related to the TTP (P=0.558) nor to the comorbidities. Age >60 years was the only independent predictor of attributable mortality (P<0.001). Univariate analysis revealed a significantly shorter TTP in persistent bacteremia, endovascular source of infection, catheter-related infection and in community-acquired SAB. A TTP >11.3 h had a negative predictive value of 96.4% for endocarditis. TTP was not related to methicillin susceptibility nor resistance of Staphylococcus aureus (P=0.934).
Conclusion: In our elderly population, shorter TTP was significantly associated with a central source of infection and a persistent SAB. In addition for the first time, community-acquired SAB was associated with a shorter TTP. TTP  may contribute to a better management of SAB by facilitating clinical decisions, especially in endocarditis

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 This study was undertaken to investigate the prevalence of the hepatitis B virus (HBV) variant with the pre-S mutant circulating in the United Arab Emirates (UAE). The sequences of the pre-S and S regions were determined in serum samples of 90 HBV DNA-positive subjects who had been enrolled in the study. The results showed that genotypes D and A accounted for 77.8% and 17.8% respectively. The distribution of the HBV antigen subtypes was: ayw2 (78.9%), adw2 (14.4%), and adw (2.2%). Sequencing analysis showed that pre-S mutations were present in 4 samples (4.4%), with pre-S2 deletion as the most common mutant (50%). The pre-S mutations were associated with older age and a higher mean HBV DNA level. The study demonstrated that HBV genotypes D and A were the predominant strains circulating in the UAE and that the HBV pre-S mutant is very rare in this area, appearing only in genotype C.

A sensitive, specific and rapid diagnostic test for the detection of Orientia tsutsugamushi, the causative agent of scrub typhus, is necessary to accurately and promptly diagnose patients and ensure that they receive proper treatment. A Loop-Mediated Isothermal Amplification (LAMP) assay targeting the 47-kDa gene of tsutsugamushi was developed. The LAMP assay was capable of detecting eleven different strains of Orientia at levels comparable to that of the quantitative PCR based method of detection. Ten patient specimens, confirmed to be positive for Orientia by two different PCR methods, were tested and nine out of ten were determined to be positive by LAMP. In terms of specificity, the assay was able to differentiate between Orientia and other phylogenetically similar bacteria as well as mouse and human host DNA. In addition to being sensitive and specific, the LAMP reaction was completed in 1 hour, demonstrating that it is a highly time-efficient method of diagnosing scrub typhus.

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