Stroke in Sierra Leone. the stroke risk factors for people with HIV: A prospective case-control study.

BACKGROUND: HIV infection rates are relatively low in Sierra Leone and in West Africa but the contribution of HIV to the risk factors for stroke and outcomes is unknown. In this study, we examined stroke types, presentation, risk factors and outcome in HIV stroke patients compared with controls. METHODS: We used data from the Stroke in Sierra Leone Study at 2 tertiary hospitals in Freetown, Sierra Leone. A case control design was used to compare stroke type, presentation, risk factors and outcome in sero-positive HIV patients with HIV negative stroke controls. Controls were matched for age and gender and a 1:4 ratio cases to controls was used to optimize power. Analysis was performed using the Pearson x2 for categorical variable, Paired-T test and Mann-Whitney U test for continuous variables. A p-value of less than 0.05 was taken as the level of statistical significance. RESULTS: Of 511 (51.8%) stroke patients tested for HIV, 36 (7.1%) were positive. Univariate unmatched analysis showed a stroke mean age of 49 years in HIV-positive versus 58 years in HIV-negative population (p = <0.001). In the case-control group, ischaemic stroke is the major type reported in both populations, HIV-negative population: 77 (53.5%) versus HIV-positive: 25 (69.4%) (p = 0.084). Hypertension is the most prevalent risk factor in both groups, HIV-positive: 23 (63.9%) versus HIV-negative: 409 (86.1%) (p = 0.001). Lower CD4+ count is associated in-hospital mortality (p = <0.001). CONCLUSION: These findings support the current call for timely management of stroke and HIV through integrated care.

Stroke in Sierra Leone: Case fatality rate and functional outcome after stroke in Freetown.

BACKGROUND: There is limited information on long-term outcomes after stroke in sub-Saharan Africa (SSA). Current estimates of case fatality rate (CFR) in SSA are based on small sample sizes with varying study design and report heterogeneous results. AIMS: We report CFR and functional outcomes from a large, prospective, longitudinal cohort of stroke patients in Sierra Leone and describe factors associated with mortality and functional outcome. METHODS: A prospective longitudinal stroke register was established at both adult tertiary government hospitals in Freetown, Sierra Leone. It recruited all patients ⩾ 18 years with stroke, using the World Health Organization definition, from May 2019 until October 2021. To reduce selection bias onto the register, all investigations were paid by the funder and outreach conducted to raise awareness of the study. Sociodemographic data, National Institute of Health Stroke Scale (NIHSS), and Barthel Index (BI) were collected on all patients on admission, at 7 days, 90 days, 1 year, and 2 years post stroke. Cox proportional hazards models were constructed to identify factors associated with all-cause mortality. A binomial logistic regression model reports odds ratio (OR) for functional independence at 1 year. RESULTS: A total of 986 patients with stroke were included, of which 857 (87%) received neuroimaging. Follow-up rate was 82% at 1 year, missing item data were <1% for most variables. Stroke cases were equally split by sex and mean age was 58.9 (SD: 14.0) years. About 625 (63%) were ischemic, 206 (21%) primary intracerebral hemorrhage, 25 (3%) subarachnoid hemorrhage, and 130 (13%) were of undetermined stroke type. Median NIHSS was 16 (9-24). CFR at 30 days, 90 days, 1 year, and 2 years was 37%, 44%, 49%, and 53%, respectively. Factors associated with increased fatality at any timepoint were male sex (hazard ratio (HR): 1.28 (1.05-1.56)), previous stroke (HR: 1.34 (1.04-1.71)), atrial fibrillation (HR: 1.58(1.06-2.34)), subarachnoid hemorrhage (HR: 2.31 (1.40-3.81)), undetermined stroke type (HR: 3.18 (2.44-4.14)), and in-hospital complications (HR: 1.65 (1.36-1.98)). About 93% of patients were completely independent prior to their stroke, declining to 19% at 1 year after stroke. Functional improvement was most likely to occur between 7 and 90 days post stroke with 35% patients improving, and 13% improving between 90 days to 1 year. Increasing age (OR: 0.97 (0.95-0.99)), previous stroke (OR: 0.50 (0.26-0.98)), NIHSS (OR: 0.89 (0.86-0.91)), undetermined stroke type (OR: 0.18 (0.05-0.62)), and ⩾1 in-hospital complication (OR: 0.52 (0.34-0.80)) were associated with lower OR of functional independence at 1 year. Hypertension (OR: 1.98 (1.14-3.44)) and being the primary breadwinner of the household (OR: 1.59 (1.01-2.49)) were associated with functional independence at 1 year. CONCLUSION: Stroke affected younger people and resulted in high rates of fatality and functional impairment relative to global averages. Key clinical priorities for reducing fatality include preventing stroke-related complications through evidence-based stroke care, improved detection and management of atrial fibrillation, and increasing coverage of secondary prevention. Further research into care pathways and interventions to encourage care seeking for less severe strokes should be prioritized, including reducing the cost barrier for stroke investigations and care.

COVAC1 phase 2a expanded safety and immunogenicity study of a self-amplifying RNA vaccine against SARS-CoV-2.

Background: Lipid nanoparticle (LNP) encapsulated self-amplifying RNA (saRNA) is well tolerated and immunogenic in SARS-CoV-2 seronegative and seropositive individuals aged 18-75. Methods: A phase 2a expanded safety and immunogenicity study of a saRNA SARS-CoV-2 vaccine candidate LNP-nCoVsaRNA, was conducted at participating centres in the UK between 10th August 2020 and 30th July 2021. Participants received 1 µg then 10 µg of LNP-nCoVsaRNA, ∼14 weeks apart. Solicited adverse events (AEs) were collected for one week post-each vaccine, and unsolicited AEs throughout. Binding and neutralisating anti-SARS-CoV-2 antibody raised in participant sera was measured by means of an anti-Spike (S) IgG ELISA, and SARS-CoV-2 pseudoneutralisation assay. (The trial is registered: ISRCTN17072692, EudraCT 2020-001646-20). Findings: 216 healthy individuals (median age 51 years) received 1.0 µg followed by 10.0 µg of the vaccine. 28/216 participants were either known to have previous SARS-CoV2 infection and/or were positive for anti-Spike (S) IgG at baseline. Reactogenicity was as expected based on the reactions following licensed COVID-19 vaccines, and there were no serious AEs related to vaccination. 80% of baseline SARS-CoV-2 naïve individuals (147/183) seroconverted two weeks post second immunization, irrespective of age (18-75); 56% (102/183) had detectable neutralising antibodies. Almost all (28/31) SARS-CoV-2 positive individuals had increased S IgG binding antibodies following their first 1.0 µg dose with a ≥0.5log10 increase in 71% (22/31). Interpretation: Encapsulated saRNA was well tolerated and immunogenic in adults aged 18-75 years. Seroconversion rates in antigen naïve were higher than those reported in our dose-ranging study. Further work is required to determine if this difference is related to a longer dosing interval (14 vs. 4 weeks) or dosing with 1.0 µg followed by 10.0 µg. Boosting of S IgG antibodies was observed with a single 1.0 µg injection in those with pre-existing immune responses. Funding: Grants and gifts from the Medical Research Council UKRI (MC_PC_19076), the National Institute for Health Research/Vaccine Task Force, Partners of Citadel and Citadel Securities, Sir Joseph Hotung Charitable Settlement, Jon Moulton Charity Trust, Pierre Andurand, and Restore the Earth.

Enhanced immune responses following heterologous vaccination with self-amplifying RNA and mRNA COVID-19 vaccines.

The optimal vaccination strategy to boost responses in the context of pre-existing immune memory to the SARS-CoV-2 spike (S) glycoprotein is an important question for global public health. To address this, we explored the SARS-CoV-2-specific humoral and cellular immune responses to a novel self-amplifying RNA (saRNA) vaccine followed by a UK authorised mRNA vaccine (BNT162b2) in individuals with and without previous COVID-19, and compared these responses with those who received an authorised vaccine alone. 35 subjects receiving saRNA (saRNA group) as part of the COVAC1 clinical trial and an additional 40 participants receiving an authorised SARS-CoV-2 vaccine only (non-saRNA group) were recruited. Antibody responses were measured by ELISA and a pseudoneutralisation assay for wildtype, Delta and Omicron variants. Cellular responses were measured by IFN-Æ´ ELISpot and an activation induced marker (AIM) assay. Approximately 50% in each group had previous COVID-19 prior to vaccination, confirmed by PCR or antibody positivity on ELISA. All of those who received saRNA subsequently received a full course of an authorised vaccine. The majority (83%) of those receiving saRNA who were COVID-19 naïve at baseline seroconverted following the second dose, and those with previous COVID-19 had an increase in antibody titres two weeks following saRNA vaccination (median 27-fold), however titres were lower when compared to mRNA vaccination. Two weeks following the 2nd authorised mRNA vaccine dose, binding and neutralising antibody titres were significantly higher in the saRNA participants with previous COVID-19, compared to non-saRNA, or COVID-19 naive saRNA participants. Cellular responses were again highest in this group, with a higher proportion of spike specific CD8+ than CD4+ T cells when compared to those receiving the mRNA vaccine only. These findings suggest an immunological benefit of increased antigen exposure, both from natural infection and vaccination, particularly evident in those receiving heterologous vaccination with saRNA and mRNA.

Safety and immunogenicity of a self-amplifying RNA vaccine against COVID-19: COVAC1, a phase I, dose-ranging trial.

BACKGROUND: Lipid nanoparticle (LNP) encapsulated self-amplifying RNA (saRNA) is a novel technology formulated as a low dose vaccine against COVID-19. METHODS: A phase I first-in-human dose-ranging trial of a saRNA COVID-19 vaccine candidate LNP-nCoVsaRNA, was conducted at Imperial Clinical Research Facility, and participating centres in London, UK, between 19th June to 28th October 2020. Participants received two intramuscular (IM) injections of LNP-nCoVsaRNA at six different dose levels, 0.1-10.0µg, given four weeks apart. An open-label dose escalation was followed by a dose evaluation. Solicited adverse events (AEs) were collected for one week from enrolment, with follow-up at regular intervals (1-8 weeks). The binding and neutralisation capacity of anti-SARS-CoV-2 antibody raised in participant sera was measured by means of an anti-Spike (S) IgG ELISA, immunoblot, SARS-CoV-2 pseudoneutralisation and wild type neutralisation assays. (The trial is registered: ISRCTN17072692, EudraCT 2020-001646-20). FINDINGS: 192 healthy individuals with no history or serological evidence of COVID-19, aged 18-45 years were enrolled. The vaccine was well tolerated with no serious adverse events related to vaccination. Seroconversion at week six whether measured by ELISA or immunoblot was related to dose (both p<0.001), ranging from 8% (3/39; 0.1µg) to 61% (14/23; 10.0µg) in ELISA and 46% (18/39; 0.3µg) to 87% (20/23; 5.0µg and 10.0µg) in a post-hoc immunoblot assay. Geometric mean (GM) anti-S IgG concentrations ranged from 74 (95% CI, 45-119) at 0.1µg to 1023 (468-2236) ng/mL at 5.0µg (p<0.001) and was not higher at 10.0µg. Neutralisation of SARS-CoV-2 by participant sera was measurable in 15% (6/39; 0.1µg) to 48% (11/23; 5.0µg) depending on dose level received. INTERPRETATION: Encapsulated saRNA is safe for clinical development, is immunogenic at low dose levels but failed to induce 100% seroconversion. Modifications to optimise humoral responses are required to realise its potential as an effective vaccine against SARS-CoV-2. FUNDING: This study was co-funded by grants and gifts from the Medical Research Council UKRI (MC_PC_19076), and the National Institute Health Research/Vaccine Task Force, Partners of Citadel and Citadel Securities, Sir Joseph Hotung Charitable Settlement, Jon Moulton Charity Trust, Pierre Andurand, Restore the Earth.

A Prospective Stroke Register in Sierra Leone: Demographics, Stroke Type, Stroke Care and Hospital Outcomes.

Introduction: Stroke is the second most common cause of adult death in Africa. This study reports the demographics, stroke types, stroke care and hospital outcomes for stroke in Freetown, Sierra Leone. Methods: A prospective observational register recorded all patients 18 years and over with stroke between May 2019 and April 2020. Stroke was defined according to the WHO criteria. Pearson's chi-squared test was used to examine associations between categorical variables and unpaired t-tests for continuous variables. Multivariable logistic regression, to explain in-hospital death, was reported as odds ratios (ORs) and 95% confidence intervals. Results: Three hundred eighty-five strokes were registered, and 315 (81.8%) were first-in-a-lifetime events. Mean age was 59.2 (SD 13.8), and 187 (48.6%) were male. Of the strokes, 327 (84.9%) were confirmed by CT scan. Two hundred thirty-one (60.0%) were ischaemic, 85 (22.1%) intracerebral haemorrhage, 11 (2.9%) subarachnoid haemorrhage and 58 (15.1%) undetermined stroke type. The median National Institutes of Health Stroke Scale on presentation was 17 [interquartile range (IQR) 9-25]. Haemorrhagic strokes compared with ischaemic strokes were more severe, 20 (IQR 12-26) vs. 13 (IQR 7-22) (p < 0.001), and occurred in a younger population, mean age 52.3 (SD 12.0) vs. 61.6 (SD 13.8) (p < 0.001), with a lower level of educational attainment of 28.2 vs. 40.7% (p = 0.04). The median time from stroke onset to arrival at the principal referral hospital was 25 hours (IQR 6-73). Half of the patients (50.4%) sought care at another health provider prior to arrival. One hundred fifty-one patients died in the hospital (39.5%). Forty-three deaths occurred within 48 hours of arriving at the hospital, with median time to death of 4 days (IQR 0-7 days). Of the patients, 49.6% had ≥1 complication, 98 (25.5%) pneumonia and 33 (8.6%) urinary tract infection. Male gender (OR 3.33, 1.65-6.75), pneumonia (OR 3.75, 1.82-7.76), subarachnoid haemorrhage (OR 43.1, 6.70-277.4) and undetermined stroke types (OR 6.35, 2.17-18.60) were associated with higher risk of in-hospital death. Discussion: We observed severe strokes occurring in a young population with high in-hospital mortality. Further work to deliver evidence-based stroke care is essential to reduce stroke mortality in Sierra Leone.

SARS-CoV-2 lateral flow assays for possible use in national covid-19 seroprevalence surveys (React 2): diagnostic accuracy study.

OBJECTIVE: To evaluate the performance of new lateral flow immunoassays (LFIAs) suitable for use in a national coronavirus disease 2019 (covid-19) seroprevalence programme (real time assessment of community transmission 2-React 2). DESIGN: Diagnostic accuracy study. SETTING: Laboratory analyses were performed in the United Kingdom at Imperial College, London and university facilities in London. Research clinics for finger prick sampling were run in two affiliated NHS trusts. PARTICIPANTS: Sensitivity analyses were performed on sera stored from 320 previous participants in the React 2 programme with confirmed previous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Specificity analyses were performed on 1000 prepandemic serum samples. 100 new participants with confirmed previous SARS-CoV-2 infection attended study clinics for finger prick testing. INTERVENTIONS: Laboratory sensitivity and specificity analyses were performed for seven LFIAs on a minimum of 200 serum samples from participants with confirmed SARS-CoV-2 infection and 500 prepandemic serum samples, respectively. Three LFIAs were found to have a laboratory sensitivity superior to the finger prick sensitivity of the LFIA currently used in React 2 seroprevalence studies (84%). These LFIAs were then further evaluated through finger prick testing on participants with confirmed previous SARS-CoV-2 infection: two LFIAs (Surescreen, Panbio) were evaluated in clinics in June-July 2020 and the third LFIA (AbC-19) in September 2020. A spike protein enzyme linked immunoassay and hybrid double antigen binding assay were used as laboratory reference standards. MAIN OUTCOME MEASURES: The accuracy of LFIAs in detecting immunoglobulin G (IgG) antibodies to SARS-CoV-2 compared with two reference standards. RESULTS: The sensitivity and specificity of seven new LFIAs that were analysed using sera varied from 69% to 100%, and from 98.6% to 100%, respectively (compared with the two reference standards). Sensitivity on finger prick testing was 77% (95% confidence interval 61.4% to 88.2%) for Panbio, 86% (72.7% to 94.8%) for Surescreen, and 69% (53.8% to 81.3%) for AbC-19 compared with the reference standards. Sensitivity for sera from matched clinical samples performed on AbC-19 was significantly higher with serum than finger prick at 92% (80.0% to 97.7%, P=0.01). Antibody titres varied considerably among cohorts. The numbers of positive samples identified by finger prick in the lowest antibody titre quarter varied among LFIAs. CONCLUSIONS: One new LFIA was identified with clinical performance suitable for potential inclusion in seroprevalence studies. However, none of the LFIAs tested had clearly superior performance to the LFIA currently used in React 2 seroprevalence surveys, and none showed sufficient sensitivity and specificity to be considered for routine clinical use.

Clinical and laboratory evaluation of SARS-CoV-2 lateral flow assays for use in a national COVID-19 seroprevalence survey.

BACKGROUND: Accurate antibody tests are essential to monitor the SARS-CoV-2 pandemic. Lateral flow immunoassays (LFIAs) can deliver testing at scale. However, reported performance varies, and sensitivity analyses have generally been conducted on serum from hospitalised patients. For use in community testing, evaluation of finger-prick self-tests, in non-hospitalised individuals, is required. METHODS: Sensitivity analysis was conducted on 276 non-hospitalised participants. All had tested positive for SARS-CoV-2 by reverse transcription PCR and were ≥21 days from symptom onset. In phase I, we evaluated five LFIAs in clinic (with finger prick) and laboratory (with blood and sera) in comparison to (1) PCR-confirmed infection and (2) presence of SARS-CoV-2 antibodies on two 'in-house' ELISAs. Specificity analysis was performed on 500 prepandemic sera. In phase II, six additional LFIAs were assessed with serum. FINDINGS: 95% (95% CI 92.2% to 97.3%) of the infected cohort had detectable antibodies on at least one ELISA. LFIA sensitivity was variable, but significantly inferior to ELISA in 8 out of 11 assessed. Of LFIAs assessed in both clinic and laboratory, finger-prick self-test sensitivity varied from 21% to 92% versus PCR-confirmed cases and from 22% to 96% versus composite ELISA positives. Concordance between finger-prick and serum testing was at best moderate (kappa 0.56) and, at worst, slight (kappa 0.13). All LFIAs had high specificity (97.2%-99.8%). INTERPRETATION: LFIA sensitivity and sample concordance is variable, highlighting the importance of evaluations in setting of intended use. This rigorous approach to LFIA evaluation identified a test with high specificity (98.6% (95%CI 97.1% to 99.4%)), moderate sensitivity (84.4% with finger prick (95% CI 70.5% to 93.5%)) and moderate concordance, suitable for seroprevalence surveys.

Screening for methicillin-resistant Staphylococcus aureus colonization using sponges.

OBJECTIVE Nasal swab culture is the standard method for identifying methicillin-resistant Staphylococcus aureus (MRSA) carriers. However, this method is known to miss a substantial portion of those carrying MRSA elsewhere. We hypothesized that the additional use of a sponge to collect skin culture samples would significantly improve the sensitivity of MRSA detection. DESIGN Hospitalized patients with recent MRSA infection were enrolled and underwent MRSA screening of the forehead, nostrils, pharynx, axilla, and groin with separate swabs and the forehead, axilla, and groin with separate sponges. Staphylococcal cassette chromosome mec (SCCmec) typing was conducted by polymerase chain reaction (PCR). PATIENTS A total of 105 MRSA patients were included in the study. RESULTS At least 1 specimen from 56.2% of the patients grew MRSA. Among patients with at least 1 positive specimen, the detection sensitivities were 79.7% for the swabs and 64.4% for the sponges. Notably, 86.4% were detected by a combination of sponges and nasal swab, and 72.9% were detected by a combination of pharyngeal and nasal swabs, whereas only 50.9% were detected by nasal swab alone (P<0.0001 and P=0.0003, respectively). Most isolates had SCCmec type II (59.9%) and IV (35.7%). No correlation was observed between the SCCmec types and collection sites. CONCLUSION Screening using a sponge significantly improves MRSA detection when used in addition to screening with the standard nasal swab.

Colistin-resistant Acinetobacter baumannii: beyond carbapenem resistance.

BACKGROUND: With an increase in the use of colistin methansulfonate (CMS) to treat carbapenem-resistant Acinetobacter baumannii infections, colistin resistance is emerging. METHODS: Patients with infection or colonization due to colistin-resistant A. baumannii were identified at a hospital system in Pennsylvania. Clinical data were collected from electronic medical records. Susceptibility testing, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing (MLST) were performed. To investigate the mechanism of colistin resistance, lipid A was subjected to matrix-assisted laser desorption/ionization mass spectrometry. RESULTS: Twenty patients with colistin-resistant A. baumannii were identified. Ventilator-associated pneumonia was the most common type of infection. Nineteen patients had received intravenous and/or inhaled CMS for treatment of carbapenem-resistant, colistin-susceptible A. baumannii infection prior to identification of colistin-resistant isolates. The 30-day all-cause mortality rate was 30%. The treatment regimen for colistin-resistant A. baumannii infection associated with the lowest mortality rate was a combination of CMS, a carbapenem, and ampicillin-sulbactam. The colistin-susceptible and -resistant isolates from the same patients were highly related by PFGE, but isolates from different patients were not, suggesting evolution of resistance during CMS therapy. By MLST, all isolates belonged to the international clone II, the lineage that is epidemic worldwide. Phosphoethanolamine modification of lipid A was present in all colistin-resistant A. baumannii isolates. CONCLUSIONS: Colistin-resistant A. baumannii occurred almost exclusively among patients who had received CMS for treatment of carbapenem-resistant, colistin-susceptible A. baumannii infection. Lipid A modification by the addition of phosphoethanolamine accounted for colistin resistance. Susceptibility testing for colistin should be considered for A. baumannii identified from CMS-experienced patients.

Molecular features of community-associated extended-spectrum-ß-lactamase-producing Escherichia coli strains in the United States.

We characterized 30 community-associated extended-spectrum-ß-lactamase-producing Escherichia coli isolates collected from five hospitals in the United States. Nineteen sequence types were identified. All sequence type 131 (ST131) isolates had the fimH30 allele. IncFII-FIA-FIB was the most common replicon type among the blaCTX-M-carrying plasmids, followed by IncFII-FIA and IncA/C. Restriction analysis of the IncFII-FIA-FIB and IncFII-FIA plasmids yielded related profiles for plasmids originating from different hospitals. The plasmids containing blaCTX-M or blaSHV were stably maintained after serial passages.

Microbiological features of KPC-producing Enterobacter isolates identified in a U.S. hospital system.

Microbiological data regarding Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacter spp. are scarce. In this study, 11 unique KPC-producing Enterobacter isolates were identified among 44 ertapenem-nonsusceptible Enterobacter isolates collected between 2009 and 2013 at a hospital system in Western Pennsylvania. All cases were healthcare-associated and occurred in medically complex patients. While pulsed-field gel electrophoresis showed diverse restriction patterns overall, multilocus sequence typing identified Enterobacter cloacae isolates with sequence types 93 and 171 from 2 hospitals each. The levels of carbapenem minimum inhibitory concentrations were highly variable. All isolates remained susceptible to colistin and tigecycline, and the majority, to amikacin and doxycycline. A blaKPC-carrying IncN plasmid conferring trimethoprim-sulfamethoxazole resistance was identified in 3 of the isolates. Spread of blaKPC in Enterobacter spp. appears to be due to a combination of plasmid-mediated and clonal processes.

Molecular epidemiology of KPC-producing Escherichia coli: occurrence of ST131-fimH30 subclone harboring pKpQIL-like IncFIIk plasmid.

Of 20 Klebsiella pneumoniae carbapenemase (KPC)-producing Escherichia coli isolates identified at hospitals in western Pennsylvania, 60% belonged to the epidemic ST131-fimH30 subclone. IncFIIk was the most common replicon type for the blaKPC-carrying plasmids (n = 8). All IncFIIk plasmids possessed a scaffold similar to that of pKpQIL, and seven of them were borne by ST131-fimH30 isolates. IncN plasmids conferred resistance to trimethoprim-sulfamethoxazole, and IncA/C plasmids conferred resistance to gentamicin. Three blaKPC-carrying plasmids (IncA/C and IncN) possessed blaSHV-7/12 and qnrA1 or qnrS1.

Targeting NAD+ metabolism in the human malaria parasite Plasmodium falciparum.

Nicotinamide adenine dinucleotide (NAD+) is an essential metabolite utilized as a redox cofactor and enzyme substrate in numerous cellular processes. Elevated NAD+ levels have been observed in red blood cells infected with the malaria parasite Plasmodium falciparum, but little is known regarding how the parasite generates NAD+. Here, we employed a mass spectrometry-based metabolomic approach to confirm that P. falciparum lacks the ability to synthesize NAD+ de novo and is reliant on the uptake of exogenous niacin. We characterized several enzymes in the NAD+ pathway and demonstrate cytoplasmic localization for all except the parasite nicotinamidase, which concentrates in the nucleus. One of these enzymes, the P. falciparum nicotinate mononucleotide adenylyltransferase (PfNMNAT), is essential for NAD+ metabolism and is highly diverged from the human homolog, but genetically similar to bacterial NMNATs. Our results demonstrate the enzymatic activity of PfNMNAT in vitro and demonstrate its ability to genetically complement the closely related Escherichia coli NMNAT. Due to the similarity of PfNMNAT to the bacterial enzyme, we tested a panel of previously identified bacterial NMNAT inhibitors and synthesized and screened twenty new derivatives, which demonstrate a range of potency against live parasite culture. These results highlight the importance of the parasite NAD+ metabolic pathway and provide both novel therapeutic targets and promising lead antimalarial compounds.

In vitro responses of Acinetobacter baumannii to two- and three-drug combinations following exposure to colistin and doripenem.

We compared in vitro killing of colistin, doripenem, and sulbactam by time-kill methods against Acinetobacter baumannii isolates collected from patients before and after colistin-doripenem treatment (initial and recurrent isolates, respectively). Colistin-doripenem bactericidal activity against recurrent isolates was attenuated (mean log10 kill, -5.74 versus -2.88; P = 0.01) but was restored by adding sulbactam. Doripenem MICs rather than colistin MICs correlated with the activity of colistin-doripenem. Among colistin-resistant isolates, colistin-doripenem-sulbactam combinations achieved greater killing than colistin-doripenem alone (-5.65 versus -2.43; P = 0.04).

Aerosolization of Acinetobacter baumannii in a trauma ICU*.

OBJECTIVE: To establish the presence of air contamination with Acinetobacter baumannii in the trauma ICU. DESIGN: Point prevalence microbiological surveillances. SETTINGS: A 1,500-bed public teaching hospital in the Miami metro area. PATIENTS: Trauma ICU patients. MEASUREMENTS: Pulsed field electrophoresis was performed on environmental and clinical isolates to determine the association of any isolates from the air with clinical isolates. MAIN RESULTS: Out of 53 patient areas cultured, 12 (22.6%) had their air positive for A. baumannii. The presence of an A. baumannii-positive patient (underneath the plate) was associated with positive air cultures for A. baumannii (11 of 21 [52.4%] vs 0 of 25 [0%]; p < 0.0001). However, we were not able to find differences in air contamination based on the presence of A. baumannii in respiratory secretions versus absence (p = 1.0). Air and clinical isolates were found to be clonally related. CONCLUSIONS: Aerosolization of A. baumannii in the ICUs is a concern, and its role in the transmission of this organism among patients should be further clarified.