Shamsuzzaman, S. M. | bioRxiv Science

bioRxiv2021

Immunogenicity and efficacy of Heat Inactivated Whole-Cell Vaccine to increase murine survival after Extensively drug-resistant Acinetobacter baumannii infection.

Due to the rapid emergence of extensively drug-resistant (XDR) strains worldwide there is a necessity for greater consideration for the role of preventive vaccines to combat these pathogens. The study reported the effectiveness of a heat-inactivated whole-cell vaccine (HI-WCV) against A. baumannii to produce protective immunity with evaluation of the bactericidal antibody responses in mice after intramuscular inoculation with different XDR strains of A. baumannii. Six XDR A. baumannii strains emulsified with complete freunds adjuvant (CFA) were used for intramuscular inoculation in the experimental group of mice (n=4) in three different phases on 14 days interval whereas placebo-controlled mice (n=4) received phosphate-buffered saline emulsified with CFA in same the schedule. Serum was collected from tail blood of each mouse on 10th day after each inoculation and by cardiac puncture on 14th day after lethal dose from the experimental group and after death of the placebo-controlled group. Mice inoculated with heat-inactivated whole-cell vaccine survived and showed a higher neutralizing (IgG) antibody response after 2nd (>7-fold titre) and 3rd inoculation (>12-fold titre) whereas all mice from placebo-controlled group did not survived. Sera from experimental group of mice collected (38th day) after 3rd inoculation resulted in higher serum bactericidal killing index (42.12) after three hours incubation with an XDR A. baumannii over sera collected after 1st and 2nd inoculation (50% cutoff value=14.5). These results suggest that intramuscular vaccination with heat-inactivated whole-cell vaccine stimulated IgG antibody responses that can increase murine survival after XDR A. baumannii infection.

immunology↗

bioRxiv2020

Colistin Susceptibility Pattern In Gram Negative Bacilli Isolated From Patients Of Dhaka Medical College Hospital With Distribution Of Antibiotic Resistance Genes Among Them.

Colistin is one of the last resort of antibiotics used specifically in the treatment of multidrug resistant gram negative bacilli. Though an older class of antibiotic with no use in last four decades, resurgence of colistin use is also causing emergence of colistin resistant gram negative bacilli.The aim of this cross sectional study was to investigate the colistin susceptibility and resistant pattern along with colistin resistant genes in gram negative bacilli among different samples in Dhaka medical college hospital. Total 300 samples (wound swab, urine, endotracheal aspirate, blood and sputum) were collected from 2015 to 2016. 204 gram negative bacilli were isolated and tested for resistance to colistin by disc diffusion method. Then, the prevalence of colistin resistant genes (pmrA, pmrB, pmrC, mgrB, phoP, phoQ, lpxA, lpxC, lpxD, mcr-1) was detected by polymerase chain reaction method (PCR). Among 204 gram negative bacilli, 22 (10.78%) colistin resistance was identified. PCR analysis revealed that 50% of these isolates contained pmrA gene, followed by phoP gene (27.27%). The prevalence of pmrB, phoQ, mgrB, lpxC and lpxD were 22.72%, 13.63%, 13.63%, 13.63%, 13.63%, and 13.63% respectively among the isolates. Colistin resistance is widespread among gram negative bacilli isolated from human infections. Colistin resistance (10.78%) found in the study is quite alarming. A restricted and rational use of the colistin is the need of hour.

microbiology↗