High prevalence of comorbidity and need for up-referral among inpatients at a district-level hospital with specialist tuberculosis services in South Africa – the need for specialist support

Objectives. To define the patient population at Cape Town’s district-level hospital offering specialist tuberculosis (TB) services, concerning the noted increase in complex, sick HIV-TB co-infected patients requiring increased levels of care. Methods. A cross-sectional study of all hospitalised adult patients in Brooklyn Chest Hospital (a district-level hospital offering specialist TB services) from 27 to 30 October 2008. Outcome measures were: type of TB and drug sensitivity, HIV co-infection, comorbidity, Karnofsky performance score, and frequency and reason for referral to other health care facilities. Results. More than two-thirds of patients in the acute wards were HIV-co-infected, of whom 98% had significant comorbidities and 60% had a Karnofsky performance score ≤30. Twenty-eight per cent of patients did not have a confirmed diagnosis of TB. In contrast, long-stay patients with multidrug-resistant (MDR), pre-extensively (pre-XDR) and extensively drug-resistant (XDR) TB had a lower prevalence of HIV co-infection, but manifested high rates of comorbidity. Overall, one-fifth of patients required up-referral to higher levels of care. Conclusions. District-level hospitals such as Brooklyn Chest Hospital that offer specialist TB services share the increasing burden of complex, sick, largely HIV-co-infected TB patients with their secondary and tertiary level counterparts. To support these hospitals effectively, outreach, skills transfer through training, and improved radiology resources are required to optimise patient care

The mechanisms responsible for 2-dimensional pattern formation in bacterial macrofiber populations grown on solid surfaces: fiber joining and the creation of exclusion zones

BACKGROUND: When Bacillus subtilis is cultured in a complex fluid medium under conditions where cell separation is suppressed, populations of multicellular macrofibers arise that mature into ball-like structures. The final sedentary forms are found distributed in patterns on the floor of the growth chamber although individual cells have no flagellar-driven motility. The nature of the patterns and their mode of formation are described in this communication. RESULTS: Time-lapse video films reveal that fiber-fiber contact in high density populations of macrofibers resulted in their joining either by entwining or supercoiling. Joining led to the production of aggregate structures that eventually contained all of the fibers located in an initial area. Fibers were brought into contact by convection currents and motions associated with macrofiber self-assembly such as walking, pivoting and supercoiling. Large sedentary aggregate structures cleared surrounding areas of other structures by dragging them into the aggregate using supercoiling of extended fibers to power dragging. The spatial distribution of aggregate structures in 6 mature patterns containing a total of 637 structures was compared to that expected in random theoretical populations of the same size distributed in the same surface area. Observed and expected patterns differ significantly. The distances separating all nearest neighbors from one another in observed populations were also measured. The average distance obtained from 1451 measurements involving 519 structures was 0.73 cm. These spacings were achieved without the use of flagella or other conventional bacterial motility mechanisms. A simple mathematical model based upon joining of all structures within an area defined by the minimum observed distance between structures in populations explains the observed distributions very well. CONCLUSIONS: Bacterial macrofibers are capable of colonizing a solid surface by forming large multicellular aggregate structures that are distributed in unique two-dimensional patterns. Cell growth geometry governs in an hierarchical way the formation of these patterns using forces associated with twisting and supercoiling to drive motions and the joining of structures together. Joining by entwining, supercoiling or dragging all require cell growth in a multicellular form, and all result in tightly fused aggregate structures

Failure to eradicate Isospora belli diarrhoea despite immune reconstitution in adults with HIV--a case series

Isospora belli causes diarrhoea in patients with AIDS. Most respond to targeted therapy and recommendations are that secondary prophylaxis can be stopped following immune reconstitution with ART. We report eight cases of chronic isosporiasis that persisted despite standard antimicrobial therapy, secondary prophylaxis, and good immunological and virological response to ART. Median CD4 nadir was 175.5 cells/mm 3 and median highest CD4 while symptomatic was 373 cells/mm 3 . Overall 34% of stool samples and 63% of duodenal biopsy specimens were positive for oocytes. Four patients died, two remain symptomatic and two recovered. Possible explanations for persistence of symptoms include host factors such as antigen specific immune deficiency or generalised reduction in gut immunity. Parasite factors may include accumulating resistance to co-trimoxazole. Research is required to determine the optimum dose and duration of co-trimoxazole therapy and whether dual therapy may be necessary. Mortality was high and pending more data we recommend extended treatment with high-dose co-trimoxazole in similar cases

The Viscous Nonlinear Dynamics of Twist and Writhe

Exploiting the "natural" frame of space curves, we formulate an intrinsic dynamics of twisted elastic filaments in viscous fluids. A pair of coupled nonlinear equations describing the temporal evolution of the filament's complex curvature and twist density embodies the dynamic interplay of twist and writhe. These are used to illustrate a novel nonlinear phenomenon: ``geometric untwisting" of open filaments, whereby twisting strains relax through a transient writhing instability without performing axial rotation. This may explain certain experimentally observed motions of fibers of the bacterium B. subtilis [N.H. Mendelson, et al., J. Bacteriol. 177, 7060 (1995)].Comment: 9 pages, 4 figure

Twirling Elastica: Kinks, Viscous Drag, and Torsional Stress

Biological filaments such as DNA or bacterial flagella are typically curved in their natural states. To elucidate the interplay of viscous drag, twisting, and bending in the overdamped dynamics of such filaments, we compute the steady-state torsional stress and shape of a rotating rod with a kink. Drag deforms the rod, ultimately extending or folding it depending on the kink angle. For certain kink angles and kink locations, both states are possible at high rotation rates. The agreement between our macroscopic experiments and the theory is good, with no adjustable parameters.Comment: 4 pages, 4 figure