Biology subjects

Madhi, S.

Publications and source records attributed to Madhi, S..

3 recordsLinked to original sources

bioRxiv2022

Novavax NVX-COV2373 triggers potent neutralization of Omicron sub-lineages

The SARS-CoV-2 Omicron (B.1.1.529) Variant of Concern (VOC) and its sub-lineages (including BA.2, BA.4/5, BA.2.12.1) contain spike mutations that confer high level resistance to neutralizing antibodies. The NVX-CoV2373 vaccine, a protein nanoparticle vaccine, has value in countries with constrained cold-chain requirements. Here we report neutralizing titers following two or three doses of NVX-CoV2373. We show that after two doses, Omicron sub-lineages BA.1 and BA.4 were resistant to neutralization by 72% (21/29) and 59% (17/29) of samples. However, after a third dose of NVX-CoV2373, we observed high titers against Omicron BA.1 (GMT: 1,197) and BA.4 (GMT: 582), with responses similar in magnitude to those triggered by three doses of an mRNA vaccine. These data are of particular relevance as BA.4 is emerging to become the dominant strain in many locations, and highlight the potential utility of the NVX-CoV2373 vaccine as a booster in resource-limited environments.

immunology↗

bioRxiv2019

Antimicrobial susceptibility and serotype distribution of Streptococcus agalactiae recto-vaginal colonizing isolates from pregnant women at a tertiary hospital in Pretoria, South Africa: an observational descriptive study letter

IntroductionStreptococcus agalactiae or Group B Streptococcus (GBS) is a significant cause of neonatal sepsis. Intrapartum antibiotic prophylaxis is recommended for pregnant women identified to be recto-vaginally colonised between 34-37 weeks gestational age to decrease the risk of invasive disease in their newborns. The aim of this study was to investigate serotype distribution and antimicrobial susceptibility patterns of GBS isolates cultured from recto-vaginal specimens during pregnancy. MethodsSixty-nine archived maternal colonizing isolates were tested against penicillin, erythromycin, clindamycin, vancomycin and levofloxacin. Minimum Inhibitory Concentration (MIC) testing was performed using the E-test method. Serotyping was performed by latex agglutination method. ResultsThe most common serotypes detected were Ia (54%), III (20%), V (16%), II (6%), IV (2%) and Ib (1%), respectively. All isolates were fully susceptible to penicillin, vancomycin and levofloxacin. Eight (11%) and 50 (56%) isolates showed intermediate resistance to erythromycin and clindamycin respectively, and one isolate was resistant to erythromycin. MLSB phenomenon was noted in 3 (4%) of the isolates. ConclusionGBS colonizing isolates remain susceptible to penicillin and remains the drug of choice for intrapartum antibiotic prophylaxis and treatment of invasive disease in newbrons. Macrolides should only be used if clinically indicated due to the high prevalence of intermediate resistance. A hexavalent GBS vaccine currently under development would provide coverage for 100% of the isolates identified in this study.

microbiology↗

bioRxiv2018

Joint sequencing of human and pathogen genomes reveals the genetics of pneumococcal meningitis

Streptococcus pneumoniae is a common nasopharyngeal colonizer, but can also cause life-threatening invasive diseases such as empyema, bacteremia and meningitis. Genetic variation of host and pathogen is known to play a role in invasive pneumococcal disease, though to what extent is unknown. In a genome-wide association study of human and pathogen we show that human variation explains almost half of variation in susceptibility to pneumococcal meningitis and one-third of variation in severity, and identified variants in CCDC33 associated with susceptibility. Pneumococcal variation explained a large amount of invasive potential, but serotype explained only half of this variation. Newly developed methods identified pneumococcal genes involved in invasiveness including pspC and zmpD, and allowed a human-bacteria interaction analysis, finding associations between pneumococcal lineage and STK32C.

genomics↗