Development of an antimicrobial susceptibility surveillance system for Neisseria gonorrhoeae in Malawi: comparison of methods.

Susceptibility of Neisseria gonorrhoeae to gentamicin, the primary treatment for gonorrhea in Malawi since 1993, was determined by using agar dilution MICs, E-test MICs, disc diffusion, and clinical cure rate. Agar dilution MICs were slightly higher in 1996 than in 1993 isolates, with a concomitant drop in the clinical cure rate. E-test MICs were substantially lower than agar dilution determinations, with only 77.4% within 1 log2 concentration

High Levels of Human Immunodeficiency Virus Type 1 in Blood and Semen of Seropositive Men in Sub-Saharan Africa

High levels of human immunodeficiency virus type 1 (HIV-1) replication, as reflected in HIV-1 RNA concentrations in blood and semen, probably contribute to both rapid disease progression and enhanced sexual transmission. Semen and blood were collected from 49 Malawian and 61 US and Swiss (US/Swiss) HIV-1.seropositive men with similar CD4 cell counts and no urethritis or exposure to antiretroviral drugs. Median seminal plasma and blood plasma HIV-1 RNA concentrations were > 3-fold (P = .034) and 5-fold (P = .0003) higher, respectively, in the Malawian men. Similar differences were observed in subsets of the Malawian and US/Swiss study groups matched individually for CD4 cell count (P = .035 and P <.002, respectively). These observations may help explain the high rates of HIV-1 sexual transmission and accelerated HIV-1 disease progression in sub-Saharan Afric

Effects of Genital Tract Inflammation on Human Immunodeficiency Virus Type 1 V3 Populations in Blood and Semen

We have examined cell-free viral populations in the blood plasma and seminal plasma compartments of men infected with subtype C human immunodeficiency virus type 1 (HIV-1) using the V3-specific heteroduplex tracking assay (V3-HTA). We studied two cohorts of subjects who had visited either a sexually transmitted disease (STD) clinic for genital tract inflammation in the form of urethritis (n = 43) or a dermatology clinic (controls, n = 14) in Malawi. We have previously shown that the presence of urethritis is associated with an eightfold increase in virus load in the seminal plasma compartment (M. S. Cohen et al., Lancet 349:1868–1873, 1997). The purpose of this study was to determine whether genital tract inflammation and its treatment caused genetic instability in cell-free HIV-1 populations. In a cross-sectional analysis at study entry, three-fourths of the STD and control subjects had multiple V3 populations in their blood while 60% of the STD subjects and 79% of the control subjects had multiple V3 populations in their semen. Overall, one-fourth of all of the subjects showed discordance between results with blood and semen specimens when samples were compared for the presence and absence of subpopulations. When differences in the relative levels of abundance of bands were also taken into account, two-fifths of all of the subjects showed discordance between the compartments. Among the subset of subjects in whom multiple virus populations could be detected, half showed discordance between the compartments. There were no differences between STD and control cohorts for these comparisons of the compartments in this cross-sectional analysis at study entry. Longitudinal analysis of the viral populations from two separate clinic visits over 1 to 4 weeks showed that the complexity of each V3 population as measured by Shannon entropy was different in blood and semen at the two time points, indicating that the blood and semen constitute different compartments for HIV-1. The seminal plasma compartment was more dynamic than the blood plasma compartment for the STD subjects who were treated for urethritis, with changes being noted in the presence or absence of V3-HTA bands in the semen of 29% of these subjects but in the blood of only 9% of these subjects. However, the changes were generally small. Overall, our results suggest that 40% of male subjects show discordance between seminal and blood viral populations and that the complexity of each V3 population was different between the two compartments. Both of these results point to the partial independence of the seminal compartment as a viral niche within the body

Characterization of V3 Sequence Heterogeneity in Subtype C Human Immunodeficiency Virus Type 1 Isolates from Malawi: Underrepresentation of X4 Variants

We have examined the nature of V3 sequence variability among subtype C human immunodeficiency virus type 1 (HIV-1) sequences from plasma-derived viral RNA present in infected men from Malawi. Sequence variability was assessed by direct sequence analysis of the V3 reverse transcription-PCR products, examination of virus populations by a subtype C V3-specific heteroduplex tracking assay (V3-HTA), and selected sequence analysis of molecular clones derived from the PCR products. Sequence variability in V3 among the subtype C viruses was not associated with the presence of basic amino acid substitutions. This observation is in contrast to that for subtype B HIV-1, where sequence variability is associated with such substitutions, and these substitutions are determinants of altered coreceptor usage. Evolutionary variants in subtype C V3 sequences, as defined by the V3-HTA, were not correlated with the CD4 level in the infected person, while such a correlation was found with subtype B V3 sequences. Viruses were isolated from a subset of the subjects; all isolates used CCR5 and not CXCR4 as a coreceptor, and none was able to grow in MT-2 cells, a hallmark of the syncytium-inducing phenotype that is correlated with CXCR4 usage. The overall sequence variability of the subtype C V3 region was no greater than that of the conserved regions of gp120. This limited sequence variability was also a feature of subtype B V3 sequences that do not carry the basic amino acid substitutions associated with altered coreceptor usage. Our results indicate that altered coreceptor usage is rare in subtype C HIV-1 isolates in sub-Saharan Africa and that sequence variability is not a feature of the V3 region of env in the absence of altered coreceptor usage

Ecophysiological Examination of the Lake Erie Microcystis Bloom in 2014: Linkages between Biology and the Water Supply Shutdown of Toledo, OH

Annual cyanobacterial blooms dominated by Microcystis have occurred in western Lake Erie (U.S./Canada) during summer months since 1995. The production of toxins by bloom-forming cyanobacteria can lead to drinking water crises, such as the one experienced by the city of Toledo in August of 2014, when the city was rendered without drinking water for \u3e2 days. It is important to understand the conditions and environmental cues that were driving this specific bloom to provide a scientific framework for management of future bloom events. To this end, samples were collected and metatranscriptomes generated coincident with the collection of environmental metrics for eight sites located in the western basin of Lake Erie, including a station proximal to the water intake for the city of Toledo. These data were used to generate a basin-wide ecophysiological fingerprint of Lake Erie Microcystis populations in August 2014 for comparison to previous bloom communities. Our observations and analyses indicate that, at the time of sample collection, Microcystis populations were under dual nitrogen (N) and phosphorus (P) stress, as genes involved in scavenging of these nutrients were being actively transcribed. Targeted analysis of urea transport and hydrolysis suggests a potentially important role for exogenous urea as a nitrogen source during the 2014 event. Finally, simulation data suggest a wind event caused microcystin-rich water from Maumee Bay to be transported east along the southern shoreline past the Toledo water intake. Coupled with a significant cyanophage infection, these results reveal that a combination of biological and environmental factors led to the disruption of the Toledo water supply. This scenario was not atypical of reoccurring Lake Erie blooms and thus may reoccur in the future

Ecophysiological Examination of the Lake Erie <i>Microcystis</i> Bloom in 2014: Linkages between Biology and the Water Supply Shutdown of Toledo, OH

Annual cyanobacterial blooms dominated by <i>Microcystis</i> have occurred in western Lake Erie (U.S./Canada) during summer months since 1995. The production of toxins by bloom-forming cyanobacteria can lead to drinking water crises, such as the one experienced by the city of Toledo in August of 2014, when the city was rendered without drinking water for >2 days. It is important to understand the conditions and environmental cues that were driving this specific bloom to provide a scientific framework for management of future bloom events. To this end, samples were collected and metatranscriptomes generated coincident with the collection of environmental metrics for eight sites located in the western basin of Lake Erie, including a station proximal to the water intake for the city of Toledo. These data were used to generate a basin-wide ecophysiological fingerprint of Lake Erie <i>Microcystis</i> populations in August 2014 for comparison to previous bloom communities. Our observations and analyses indicate that, at the time of sample collection, <i>Microcystis</i> populations were under dual nitrogen (N) and phosphorus (P) stress, as genes involved in scavenging of these nutrients were being actively transcribed. Targeted analysis of urea transport and hydrolysis suggests a potentially important role for exogenous urea as a nitrogen source during the 2014 event. Finally, simulation data suggest a wind event caused microcystin-rich water from Maumee Bay to be transported east along the southern shoreline past the Toledo water intake. Coupled with a significant cyanophage infection, these results reveal that a combination of biological and environmental factors led to the disruption of the Toledo water supply. This scenario was not atypical of reoccurring Lake Erie blooms and thus may reoccur in the future