Biolog identification of non-sorbitol fermenting bacteria isolated on E. coli O157 selective CT-SMAC agar

E. coli O157:H7 is recognised as an important human pathogen world-wide and has been associated with diseases such as haemorrhagic colitis (HC), haemolytic uraemic syndrome (HUS) and thrombotic thrombocytopaenic purpura (TTP). Accurate laboratory detection of E. coli O157:H7 is important for diagnostic purposes and to justify epidemiological data on E. coli O157:H7. A well-known phenotypic characteristic of E. coli O157:H7 bacteria is their inability to ferment sorbitol. This characteristic is often used to isolate these organisms from food and water using selective agar medium such as SMAC. However, the high number of false positive results obtained by a number of researchers when selectively screening for E. coli O157: H7 on CT-SMAC has prompted an investigation to determine which other sorbitol-negative bacteria also grow on CT-SMAC. The agar medium used for the investigation consisted of Sorbitol MacConkey agar (SMAC) supplemented with Cefiximetellurite (CT). All sorbitol-negative colonies obtained from CT-SMAC, after selective enrichment and IMS were identified using the Biolog microbial identification system. The majority of sorbitol-negative isolates identified were Burkholderia, Pseudomonas, Vibrio and Aeromonas spp. Only two E. coli O157:H7 isolates were identified with Biolog and confirmed with a polymerase chain reaction (PCR) specific for the shiga toxin 1 (Stx1) genes and with O157 and H7 antisera. The inability of the CT-SMAC agar medium to specifically select for E.coli O157:H7 was confirmed by the results of this study. These observations call for further improvement of affordable methods for the selective isolation of E. coli O157:H7 in the presence of large numbers of interfering bacteria capable of growing on CT-SMAC.This work was supported with a grant awarded by the National Research Foundation of South Africa

Oropharyngeal HPV infection: prevalence and sampling methods among HIV-infected men in South Africa.

Worldwide, 96,000 cases of oropharyngeal cancer (OPC) occurred in 2012. Human papillomavirus (HPV) is a risk factor for OPC. Data on oropharyngeal HPV infection are limited. There is no consensus on the best sampling method for detecting the infection. We describe the prevalence of oropharyngeal HPV infection among HIV-infected men and compare the performance of oral rinses and swabs in detecting oropharyngeal HPV infection. Paired oral rinses and swabs for 181 men were tested for HPV DNA using the Roche Linear Array. Performance was determined by the number of infections detected and the percentage of samples with adequate DNA extraction. Agreement between sampling methods was assessed by the kappa statistic. Prevalence of oropharyngeal HPV infection with rinse samples was 1.8% (three infections) and 0.6% (one infection) with swabs (p = 0.06). Adequate cellular DNA extraction was more likely with rinse (93.4%) than swab samples (89.0%, p = 0.05). There was moderate agreement between the methods (kappa = 0.49). The prevalence of oropharyngeal HPV DNA infection among this predominantly heterosexual sample of men living with HIV was low and consistent with the infrequent oral sex practices. Oral rinse performed better than oral swab in detecting oropharyngeal HPV DNA infection and might contribute to screening for OPCs

Incidence, Persistence, Clearance, and Correlates of Genital Human Papillomavirus Infection and Anogenital Warts in a Cohort of Men Living With Human Immunodeficiency Virus in South Africa.

OBJECTIVE: To estimate the incidence; persistence and correlates of human papillomavirus (HPV) infection and anogenital warts (AGW) among men living with human immunodeficiency virus (MLHIV). METHODS: Overall, 304 MLHIV 18 years or older were enrolled and attended follow-up visits at 6, 12, and 18 months. Clinicians examined for AGW, collected blood, and penile swabs for HPV testing (Roche Linear Array) at each visit. Time to AGW incidence or clearance was estimated by Kaplan-Meier method. Factors associated with persistent HPV infection and AGW clearance were evaluated with generalized estimating equations and Cox regression, respectively. RESULTS: Mean age of participants was 38 years (standard deviation, 8 years); 25% reported more than 1 sexual partner in the past 3 months. Most (65%) participants were on antiretroviral treatment (ART) with a median CD4 count of 445 cells/?L (interquartile range, 328-567). Prevalence of HPV infection and AGW at enrolment were 79% (224 of 283) and 12% (36 of 304), respectively. Two hundred fifty-nine men were followed up for a median (interquartile range) 1.4 years (0.5-1.7 years). Incidence of any-genital HPV infection was 2.9 (95% confidence interval, 1.5-5.5) per 100 person-years. Persistence of any-genital HPV infection was 35% (68 of 192) and was higher among MLHIV with low CD4 count (adjusted odds ratio, 3.54; 95% confidence interval, 2.07-6.05). Incidence of AGW was 1.4 per 100 person-years. Men living with human immunodeficiency virus with high CD4 count were more likely to clear AGW than those with low CD4 count (adjusted hazard ratio, 3.69; 95% confidence interval, 1.44-9.47). No associations were observed between persistent genital HPV infection, AGW clearance with enrolment ART status or duration. CONCLUSIONS: Human immunodeficiency virus-positive men have a high burden of genital HPV infection and AGW. The ART and HPV vaccine could reduce this burden

Prevalence of anogenital HPV infection, related disease and risk factors among HIV-infected men in inner-city Johannesburg, South Africa: baseline findings from a cohort study.

BACKGROUND: Persistent high-risk human papillomavirus (HR-HPV) infection is associated with the development of anogenital cancers, particularly in men living with HIV (MLWH). We describe the prevalence of anogenital HPV infection, abnormal anal cytology and anogenital warts (AGWs) in MLWH in Johannesburg, and explore whether HPV infection and receipt of antiretroviral treatment is associated with detection of abnormal anal cytology and AGWs. METHODS: We enrolled a cohort of 304 sexually-active MLWH ≥18 years, who completed a questionnaire and physical examination. Genital swabs were collected from all men and intra-anal swabs from 250 (82%). Swabs were tested for HPV DNA and genotypes, and anal smears graded using the Bethesda classification. Factors associated with anogenital disease were assessed by logistic regression models. RESULTS: Two thirds were receiving antiretroviral treatment, for a median 33 months (IQR = 15-58) and 54% were HIV-virologically suppressed. Only 5% reported ever having sex with men. Among 283 genital swabs with valid results, 79% had any HPV, 52% had HR-HPV and 27% had >1 HR-HPV infection. By comparison, 39% of the 227 valid intra-anal swabs had detectable HPV, 25% had any HR-HPV and 7% >1 HR infection. While most anal smears were normal (51%), 20% had ASCUS and 29% were LSIL. No cases had HSIL or cancer. Infection with >1 HR type (adjusted OR [aOR] = 2.39; 95%CI = 1.02-5.58) and alpha-9 types (aOR = 3.98; 95%CI = 1.42-11.16) were associated with having abnormal cytology. Prevalence of AGWs was 12%. Infection with any LR type (aOR = 41.28; 95%CI = 13.57-125.62), >1 LR type (aOR = 4.14; 95%CI = 1.60-10.69), being <6 months on antiretroviral treatment (aOR = 6.90; 95%CI = 1.63-29.20) and having a CD4+ count <200 cells/μL (aOR = 5.48; 95%CI: 1.60-18.78) were associated with having AGWs. CONCLUSIONS: In this population, anogenital HR-HPV infection and associated low-grade disease is common, but severe anal dysplasia was not detected. Findings reinforce the need for HPV vaccination in men for preventing both AGWs and HR-HPV infection. Given the absence of anal HSILs, however, the findings do not support the use of anal screening programmes in this population

Prevalence and Antimicrobial Resistance of Mycoplasma genitalium Infection Among Women Living With Human Immunodeficiency Virus in South Africa: A Prospective Cohort Study.

This prospective cohort study of 622 women living with human immunodeficiency virus (HIV) from Johannesburg (2012) detected Mycoplasma genitalium in 7.4% (95% confidence interval [CI]: 5.5-9.7, 46/622), with detection more likely with lower CD4 counts(adjusted odds ratio [AOR] 1.02 per 10 cells/μL decrease, 95% CI: 1.00-1.03) and higher plasma HIV-1 RNA (AOR 1.15 per log copies/mL increase, 95% CI: 1.03-1.27). No mutations for macrolide/quinolone resistance was detected

Variations in water use by a mature mangrove of Avicennia germinans, French Guiana

In the tropical intertidal zones, little is known on water uptake by mangroves. Transpiration rates are generally measured at leaf level, but few studies exist on water use at tree or stand levels. The objective of this study was to measure sap flow in trees of different sizes to appreciate the range of variation in water use that may exist in a site dominated by 80% mature Avicennia germinans. The results showed that from the dry to the wet season the mean water use increased from 3.2 to 5.3 dm3 d−1 in small trees (DBH ∼ 13 cm), from 11.5 to 30.8 dm3 d−1 in medium trees (∼24 cm) and from 40.8 to 64.1 dm3 d−1 in large ones (∼45 cm). Sapwood remained active up to a depth of 8 cm with radial variations within the stem. Weak correlations were obtained with VPD and net radiation. This study confirmed that transpiration was larger under low levels of salinity. Water use at stand level (∼1900 living stems ha−1) was estimated to be in the range of 5.8 to 11.8 m3 ha−1 d−1 according to the season

Lack of macrolide resistance in Mycoplasma genitalium infections in a cohort of pregnant women in South Africa

No abstract available.http://sti.bmj.comhj2022Medical Microbiolog

Odor supported place cell model and goal navigation in rodents

Experiments with rodents demonstrate that visual cues play an important role in the control of hippocampal place cells and spatial navigation. Nevertheless, rats may also rely on auditory, olfactory and somatosensory stimuli for orientation. It is also known that rats can track odors or self-generated scent marks to find a food source. Here we model odor supported place cells by using a simple feed-forward network and analyze the impact of olfactory cues on place cell formation and spatial navigation. The obtained place cells are used to solve a goal navigation task by a novel mechanism based on self-marking by odor patches combined with a Q-learning algorithm. We also analyze the impact of place cell remapping on goal directed behavior when switching between two environments. We emphasize the importance of olfactory cues in place cell formation and show that the utility of environmental and self-generated olfactory cues, together with a mixed navigation strategy, improves goal directed navigation

Mild forms of hypophosphatasia mostly result from dominant negative effect of severe alleles or from compound heterozygosity for severe and moderate alleles

<p>Abstract</p> <p>Background</p> <p>Mild hypophosphatasia (HPP) phenotype may result from <it>ALPL </it>gene mutations exhibiting residual alkaline phosphatase activity or from severe heterozygous mutations exhibiting a dominant negative effect. In order to determine the cause of our failure to detect a second mutation by sequencing in patients with mild HPP and carrying on a single heterozygous mutation, we tested the possible dominant effect of 35 mutations carried by these patients.</p> <p>Methods</p> <p>We tested the mutations by site-directed mutagenesis. We also genotyped 8 exonic and intronic <it>ALPL </it>gene polymorphisms in the patients and in a control group in order to detect the possible existence of a recurrent intronic mild mutation.</p> <p>Results</p> <p>We found that most of the tested mutations exhibit a dominant negative effect that may account for the mild HPP phenotype, and that for at least some of the patients, a second mutation in linkage disequilibrium with a particular haplotype could not be ruled out.</p> <p>Conclusion</p> <p>Mild HPP results in part from compound heterozygosity for severe and moderate mutations, but also in a large part from heterozygous mutations with a dominant negative effect.</p

Clinical Characteristics of Mycoplasma genitalium and the Usefulness of Syndromic Management Among Women Living With Human Immunodeficiency Virus.

We report the clinical symptoms and examination findings of Mycoplasma genitalium (MG) in women living with human immunodeficiency virus in South Africa. If we relied on syndromic management alone to treat MG, only 15 of 46 MG-infected women would have received. appropriate treatment: sensitivity of 32.6% (95% confidence interval, 19.5-48.0) and specificity of 67.4% (95% confidence interval, 63.4-71.2)