Genomic alterations involved in fluoroquinolone resistance development in Staphylococcus aureus.

AIM: Fluoroquinolone (FQ) is a potent antibiotic class. However, resistance to this class emerges quickly which hinders its application. In this study, mechanisms leading to the emergence of multidrug-resistant (MDR) Staphylococcus aureus (S. aureus) strains under FQ exposure were investigated. METHODOLOGY: S. aureus ATCC 29213 was serially exposed to ciprofloxacin (CIP), ofloxacin (OFL), or levofloxacin (LEV) at sub-minimum inhibitory concentrations (sub-MICs) for 12 days to obtain S. aureus -1 strains and antibiotic-free cultured for another 10 days to obtain S. aureus-2 strains. The whole genome (WGS) and target sequencing were applied to analyze genomic alterations; and RT-qPCR was used to access the expressions of efflux-related genes, alternative sigma factors, and genes involved in FQ resistance. RESULTS: A strong and irreversible increase of MICs was observed in all applied FQs (32 to 128 times) in all S. aureus-1 and remained 16 to 32 times in all S. aureus-2. WGS indicated 10 noticeable mutations occurring in all FQ-exposed S. aureus including 2 insdel mutations in SACOL0573 and rimI; a synonymous mutation in hslO; and 7 missense mutations located in an untranslated region. GrlA, was found mutated (R570H) in all S. aureus-1 and -2. Genes encoding for efflux pumps and their regulator (norA, norB, norC, and mgrA); alternative sigma factors (sigB and sigS); acetyltransferase (rimI); methicillin resistance (fmtB); and hypothetical protein BJI72_0645 were overexpressed in FQ-exposed strains. CONCLUSION: The emergence of MDR S. aureus was associated with the mutations in the FQ-target sequences and the overexpression of efflux pump systems and their regulators.

Factors influencing adverse events following immunization with AZD1222 in Vietnamese adults during first half of 2021.

BACKGROUND: COVID-19 vaccines have been speedily developed and deployed. The more vaccine doses are delivered to users, the more common adverse events following immunization (AEFI) are reported. This study aimed to identify factors affecting AEFI in Vietnamese people receiving the COVID-19 vaccine AZD1222 developed by AstraZeneca and Oxford University. METHODS: In July 2021, an online cross-sectional survey was conducted among Vietnamese who have been vaccinated with COVID-19 vaccines. The questionnaire collected demographic characteristics, medical history, types of injected vaccines, common AEFI, and post-vaccination activities from respondents. The effects of host-related factors on AEFI including 24 specific symptoms were also explored. RESULTS: After screening, 1028 participants who were Vietnamese, over 18 years old and received at least one dose of AZD1222, were included in the study. Only 40/1028 (3.9%) participants reported not having any AEFI, whereas 25/1028 (2.4%) reported to have severe symptoms. The most common AEFI were moderate fever (69.4%), muscle aches (68.6%), followed by fatigue/ sleepiness (62.5%), body aches (59.4%), headache (58.5%), pain at injection site (58.3%) and chills (45.7%). Data analysis showed that females complained about AEFI particularly gastrointestinal symptoms more frequently than males. Age of participants and number of doses were also important factors affecting AEFI as the increase of age or number of vaccine doses was associated with the decrease of self-reported AEFI frequency. CONCLUSIONS: This study provides a detailed assessment of risk factors associated with AEFI in Vietnamese people vaccinated with AZD1222. It seems that gender, age and vaccine doses are important factors affecting AEFI.

Physiological versatility of the genus Rhodocista.

A new purple bacterium (strain T4), capable of heterotrophic aerobic and phototrophic anaerobic growth, was isolated from waste water of a noodle factory near Hanoi, Vietnam. A comparison of 16S rDNA sequences revealed its association with the genus Rhodocista. The isolate, tentatively named "Rhodocista hanoiensis", forms cysts after growth on butyrate-containing plates at 42 degrees C. The vegetative cells form short (under aerobic conditions) or long curve-shaped rods. In contrast to other species of this genus T4 does not need any supplines (growth factors, not synthesized by the organisms). Comparative studies of T4 with Rhodocista centenaria (Rhodospirillum centenum) and Rhodocista pekingensis revealed a remarkable physiological versatility regarding nutrient spectra and survival properties of this genus.