Research Articles (Medical Microbiology)

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Browsing Research Articles (Medical Microbiology) by Subject "Antibiotics"

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    Antibiotic stewardship ward rounds and a dedicated prescription chart reduce antibiotic consumption and pharmacy costs without affecting inpatient mortality or re-admission rates
    (Public Library of Science, 2013-12-09) Boyles, Tom H.; Whitelaw, Andrew; Bamford, Colleen; Moodley, Mischka; Bonorchis, Kim; Morris, Vida; Rawoot, Naazneen; Naicker, Vanishree; Lusakiewicz, Irena; Black, John; Stead, David; Lesosky, Maia; Raubenheimer, Peter; Dlamini, Sipho; Mendelson, Marc
    Background Antibiotic consumption is a major driver of bacterial resistance. To address the increasing burden of multi-drug resistant bacterial infections, antibiotic stewardship programmes are promoted worldwide to rationalize antibiotic prescribing and conserve remaining antibiotics. Few studies have been reported from developing countries and none from Africa that report on an intervention based approach with outcomes that include morbidity and mortality. Methods An antibiotic prescription chart and weekly antibiotic stewardship ward round was introduced into two medical wards of an academic teaching hospital in South Africa between January-December 2012. Electronic pharmacy records were used to collect the volume and cost of antibiotics used, the patient database was analysed to determine inpatient mortality and 30-day re-admission rates, and laboratory records to determine use of infection-related tests. Outcomes were compared to a control period, January-December 2011. Results During the intervention period, 475.8 defined daily doses were prescribed per 1000 inpatient days compared to 592.0 defined daily doses/1000 inpatient days during the control period. This represents a 19.6% decrease in volume with a cost reduction of 35% of the pharmacy’s antibiotic budget. There was a concomitant increase in laboratory tests driven by requests for procalcitonin. There was no difference in inpatient mortality or 30-day readmission rate during the control and intervention periods. Conclusions Introduction of antibiotic stewardship ward rounds and a dedicated prescription chart in a developing country setting can achieve reduction in antibiotic consumption without harm to patients. Increased laboratory costs should be anticipated when introducing an antibiotic stewardship program.
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    Clonal expansion of colistin-resistant Acinetobacter baumannii isolates in Cape Town, South Africa
    (Elsevier, 2020) Snyman, Yolandi; Whitelaw, Andrew Christopher; Reuter, Sandra; Dramowski, Angela; Maloba, Motlatji Reratilwe Bonnie; Newton-Foot, Mae
    Objectives: To describe colistin-resistant Acinetobacter baumannii isolates in Cape Town, South Africa. Methods: A. baumannii isolates identified on Vitek 2 Advanced Expert System were collected from Tygerberg Hospital referral laboratory between 2016 and 2017. Colistin resistance was confirmed using broth microdilution and SensiTest. mcr-1–5 were detected using PCR and strain typing was performed by rep-PCR. Whole genome sequencing (WGS) was performed on a subset of isolates to identify chromosomal colistin resistance mechanisms and strain diversity using multilocus sequence typing (MLST) and pairwise single nucleotide polymorphism analyses. Results: Twenty-six colistin-resistant and six colistin-susceptible A. baumannii were collected separately based on Vitek susceptibility; 20/26 (77%) were confirmed colistin-resistant by broth microdilution. Four colistin-resistant isolates were isolated in 2016 and 16 in 2017, from five healthcare facilities. Thirteen colistin-resistant isolates and eight colistin-susceptible isolates were identical by rep-PCR and MLST (ST1), all from patients admitted to a tertiary hospital during 2017. The remaining colistin-resistant isolates were unrelated. Conclusions: An increase in colistin-resistant A. baumannii isolates from a tertiary hospital in 2017 appears to be clonal expansion of an emerging colistin-resistant strain. This strain was not detected in 2016 or from other hospitals. Identical colistin-susceptible isolates were also isolated, suggesting relatively recent acquisition of colistin resistance.
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    Plasmid-mediated mcr-1 colistin resistance in Escherichia coli and Klebsiella spp. clinical isolates from the Western Cape region of South Africa
    (BioMed Central, 2017-08-03) Newton-Foot, Mae; Snyman, Yolandi; Maloba, Motlatji Reratilwe Bonnie; Whitelaw, Andrew Christopher
    Background: Colistin is a last resort antibiotic for the treatment of carbapenem-resistant Gram negative infections. Until recently, mechanisms of colistin resistance were limited to chromosomal mutations which confer a high fitness cost and cannot be transferred between organisms. However, a novel plasmid-mediated colistin resistance mechanism, encoded by the mcr-1 gene, has been identified, and has since been detected worldwide. The mcr-1 colistin resistance mechanism is a major threat due to its lack of fitness cost and ability to be transferred between strains and species. Surveillance of colistin resistance mechanisms is critical to monitor the development and spread of resistance.This study aimed to determine the prevalence of the plasmid-mediated colistin resistance gene, mcr-1, in colistin-resistant E. coli and Klebsiella spp. isolates in the Western Cape of South Africa; and whether colistin resistance is spread through clonal expansion or by acquisition of resistance by diverse strains. Methods: Colistin resistant E. coli and Klebsiella spp. isolates were collected from the NHLS microbiology laboratory at Tygerberg Hospital. Species identification and antibiotic susceptibility testing was done using the API® 20 E system and the Vitek® 2 Advanced Expert System™. PCR was used to detect the plasmid-mediated mcr-1 colistin resistance gene and REP-PCR was used for strain typing of the isolates. Results: Nineteen colistin resistant isolates, including 12 E. coli, six K. pneumoniae and one K. oxytoca isolate, were detected over 7 months from eight different hospitals in the Western Cape region. The mcr-1 gene was detected in 83% of isolates which were shown to be predominantly unrelated strains. Conclusions: The plasmid-mediated mcr-1 colistin resistance gene is responsible for the majority of colistin resistance in clinical isolates of E. coli and Klebsiella spp. from the Western Cape of South Africa. Colistin resistance is not clonally disseminated; the mcr-1 gene has been acquired by several unrelated strains of E. coli and K. pneumoniae. Acquisition of mcr-1 by cephalosporin- and carbapenem-resistant Gram negative bacteria may result in untreatable infections and increased mortality. Measures need to be implemented to control the use of colistin in health care facilities and in agriculture to retain its antimicrobial efficacy.