OBJECTIVE: To determine the resistance of Mycobacterium tuberculosis to first- and second-line agents in adult pulmonary tuberculosis (TB) patients in Cameroon using a novel phenotypic assay.SETTING: ...Samples were collected from TB patients at Bamenda Hospital in Bamenda,
Cameroon.DESIGN: Samples were collected consecutively from adult pulmonary TB patients over a 2-month period. TREK SensititreTM MYCOTB panels were used to perform phenotypic drug susceptibility testing (DST). Susceptibility/resistance was determined by comparing minimum inhibitory
concentrations to standard critical concentrations established for first- and second-line anti-tuberculosis drugs.RESULTS: Of 103 sputum samples processed, growth on Löwenstein-Jensen media was confirmed in 78 samples, 65 of which were suitable for DST. Thirty-nine strains (60%) were
susceptible to all first- and second-line drugs. Five strains (8%) were categorized as multidrug-resistant TB. Two strains (3%) were classified as pre-extensively drug-resistant TB. Of those isolates susceptible to first-line drugs, 20% were resistant to at least one second-line drug.CONCLUSION:
Antimicrobial resistance may be higher than assumed in TB strains in Cameroon, especially with regard to second-line drugs. There remains a need for rapid, comprehensive DST.
We analyze 26 luminous compact blue galaxies (LCBGs) in the Hubble Space Telescope ACS Ultra Deep Field (UDF) at z 6 0.2-1.3, to determine whether these truly are small galaxies or, rather, bright ...central starbursts within existing or forming large disk galaxies. Surface brightness profiles from UDF images reach fainter than rest-frame 26.5 B mag arcsec super(-2) even for compact objects at z 6 1. Most LCBGs show a smaller, brighter component that is likely star-forming, and an extended, roughly exponential component with colors suggesting stellar ages from 100 Myr to a few gigayears. Scale lengths of the extended components are mostly 2 kpc, more than 1.5-2 times smaller than those of nearby large disk galaxies like the Milky Way. Larger, very low surface brightness disks can be excluded down to faint rest-frame surface brightnesses ( 26 B mag arcsec sub(-2)). However, one or two of the LCBGs are large, disklike galaxies that meet LCBG selection criteria because of a bright central nucleus, possibly a forming bulge. These results indicate that 90% of high-z LCBGs are small galaxies that will evolve into small disk galaxies, or low-mass spheroidal or irregular galaxies in the local universe, assuming passive evolution and no significant disk growth. The data do not reveal signs of disk formation around small, H II galaxy-like LCBGs, nor do they suggest a simple inside-out growth scenario for larger LCBGs with a disklike morphology. Irregular blue emission in distant LCBGs is relatively extended, suggesting that nebular emission lines from star-forming regions sample a major fraction of an LCBG's velocity field.
We are currently analysing image data for a large sample of blue compact dwarf galaxies (BCDs), obtained in multiple optical broad- and narrow-band filters. We present preliminary results of a ...multi-band analysis of two typical BCDs, Mrk 5 and I Zw 123, for which surface-brightness profiles, colour profiles, colour maps and H sub( alpha ) equivalent-width maps have been derived. We demonstrate how a combination of these different processing methods allows a separate analysis of the young and old stellar populations with respect to their colours and spatial distributions. By comparing the derived colours with the predictions of evolutionary synthesis models, we estimate ages of the distinct stellar populations. The surface-brightness profiles of Mrk 5 show an exponential decay at large photometric radii, with slopes typically found for BCDs. In the case of the very compact object I Zw 123, the surface-brightness profile of the underlying stellar component can be described either by an exponential or an R super(5) law. We discuss briefly how noise effects can influence the intrinsic slope of surface brightness profiles at low surface-brightness levels. For compact objects with extended starbursts, the study of the underlying stellar population can thereby be rendered difficult.
We have analyzed deep Near Infrared (NIR) broad band images for a sample of Blue Compact Dwarf Galaxies (BCDs), observed with the ESO NTT and Calar Alto 3.6 m telescopes. The data presented here ...allows for the detection and quantitative study of the extended stellar low-surface brightness (LSB) host galaxy in all sample BCDs. NIR surface brightness profiles (SBPs) of the LSB host galaxies agree at large galactocentric radii with those from optical studies, showing also an exponential intensity decrease and compatible scale lengths. At small to intermediate radii (within 1–3 exponential scale lengths), however, the NIR data reveals for more than one half of our sample BCDs evidence for a significant flattening of the exponential profile of the LSB component. Such profiles (type V SBPs, Binggeli & Cameron CITE) have rarely been detected in the LSB component of BCDs at optical wavelengths, where the relative flux contribution of the starburst, being stronger than in the NIR, can readily hide a possible central intensity depression in the underlying LSB host. The structural properties, frequency and physical origin of type V LSB profiles in BCDs and dwarf galaxies in general have not yet been subject to systematic studies. Nevertheless, the occurrence of such profiles in an appreciable fraction of BCDs would impose important new observational constraints to the radial mass distribution of the stellar LSB component, as well as to the photometric fading of these systems after the termination of star-forming activities. We test the suitability of two empirical fitting functions, a modified exponential distribution (Papaderos et al. CITE) and the Sérsic law, for the systematization of the structural properties of BCD host galaxies which show a type V intensity distribution. Either function has been found to satisfactorily fit a type V distribution. However, it is argued that the practical applicability of Sérsic fits to the LSB emission of BCDs is limited by the extreme sensitivity of the achieved solutions to, e.g., small uncertainties in the sky subtraction and SBP derivation. We find that most of the sample BCDs show in their stellar LSB host galaxy optical-NIR colors indicative of an evolved stellar population with subsolar metallicity. Unsharp-masked NIR maps reveal numerous morphological details and indicate in some cases, in combination with optical data, appreciable non-uniform dust absorption on a spatial scale as large as ~1 kpc.
Using data from the DEEP2 Galaxy Redshift Survey and HST/ACS imaging in the Extended Groth Strip, we select nearly 100 interacting galaxy systems, including kinematic close pairs and morphologically ...identified merging galaxies. Spitzer MIPS 24 km fluxes of these systems reflect the current dusty star formation activity, and at a fixed stellar mass (M sub(*)) the median infrared luminosity (L sub(IR)) among merging galaxies and close pairs of blue galaxies is twice (1.9 c 0.4) that of control pairs drawn from isolated blue galaxies. Enhancement declines with galaxy separation, being strongest in close pairs and mergers and weaker in wide pairs compared to the control sample. At 6 0.9, 7.1% 6 4.3% of massive interacting galaxies (M sub(*) > 2 x 10 super(10) M sub( )) are found to be ULIRGs, compared to 2.6% 6 0.7% in the control sample. The large spread of L sub(IR)/M sub(*) among interacting galaxies suggests that this enhancement may depend on the merger stage as well as other as yet unidentified factors (e.g., galaxy structure, mass ratio, orbital characteristics, presence of AGN or bar). The contribution of interacting systems to the total IR luminosity density is moderate ( 36%).
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