Abstract：
BACKGROUND: Chronic leg ulcers are hard to treat and can be a burden, particularly in resource-limited settings where diagnosis is a challenge. Staphylococcus aureus is among the common bacteria isolated from chronic wounds with a great impact on wound healing, particularly in patients with co-morbidities. Antimicrobial resistance genes and virulence factors in Staphylococcus aureus isolates were assessed to support healthcare professionals to make better therapeutic choices, and importantly to curb the development and spread of antibiotic resistance.
METHODS: A cross-sectional study involved both inpatients and outpatients with chronic leg ulcers was conducted from August 2022 to April 2023 in 2 health facilities in Kilimanjaro region in Tanzania. Antimicrobial susceptibility testing was done using the disc diffusion method. Further, whole genome sequencing was performed to study the genotypic characteristics of the isolates.
RESULTS: A total of 92 participants were recruited in which 9 participants were only positive for 10 Staphylococcus aureus isolates upon culture. Five STs among 9 isolates were identified. Most of them belonged to ST8 (44%), with 1 isolate does not belong to any ST. Additionally, 50% of the isolates were methicillin-resistant Staphylococcus aureus (MRSA). All S. aureus isolates had almost similar virulence factors such as hemolysin, proteases and evasions that promote toxin production, protease production and host immune evasion respectively. Moreover, all mecA positive S. aureus isolates were phenotypically susceptible to cefoxitin.
CONCLUSIONS: Presence of mecA positive S. aureus isolates which are also phenotypically susceptible to cefoxitin implies the possibility of classifying MRSA as MSSA. This may result in the possible emergence of highly cefoxitin - resistant strains in health care and community settings when subsequently exposed to beta-lactam agents. Therefore, combination of whole genome sequencing and conventional methods is important in assessing bacterial resistance and virulence to improve management of patients.
METHODS: A cross-sectional study involved both inpatients and outpatients with chronic leg ulcers was conducted from August 2022 to April 2023 in 2 health facilities in Kilimanjaro region in Tanzania. Antimicrobial susceptibility testing was done using the disc diffusion method. Further, whole genome sequencing was performed to study the genotypic characteristics of the isolates.
RESULTS: A total of 92 participants were recruited in which 9 participants were only positive for 10 Staphylococcus aureus isolates upon culture. Five STs among 9 isolates were identified. Most of them belonged to ST8 (44%), with 1 isolate does not belong to any ST. Additionally, 50% of the isolates were methicillin-resistant Staphylococcus aureus (MRSA). All S. aureus isolates had almost similar virulence factors such as hemolysin, proteases and evasions that promote toxin production, protease production and host immune evasion respectively. Moreover, all mecA positive S. aureus isolates were phenotypically susceptible to cefoxitin.
CONCLUSIONS: Presence of mecA positive S. aureus isolates which are also phenotypically susceptible to cefoxitin implies the possibility of classifying MRSA as MSSA. This may result in the possible emergence of highly cefoxitin - resistant strains in health care and community settings when subsequently exposed to beta-lactam agents. Therefore, combination of whole genome sequencing and conventional methods is important in assessing bacterial resistance and virulence to improve management of patients.
摘要：
背景：慢性腿部溃疡难以治疗，可能是一种负担，特别是在资源有限的情况下，诊断是一个挑战。金黄色葡萄球菌是从慢性伤口中分离出的常见细菌之一，对伤口愈合有很大影响。特别是在有合并症的患者中。评估了金黄色葡萄球菌分离株中的抗菌药物耐药基因和毒力因子，以支持医疗保健专业人员做出更好的治疗选择。重要的是遏制抗生素耐药性的发展和传播。
方法：2022年8月至2023年4月，在坦桑尼亚乞力马扎罗地区的2家医疗机构进行了一项涉及住院和门诊患者慢性腿部溃疡的横断面研究。使用圆盘扩散法进行抗菌药物敏感性测试。Further,进行了全基因组测序以研究分离株的基因型特征.
结果：共招募了92名参与者，其中9名参与者在培养时仅对10个金黄色葡萄球菌分离株呈阳性。鉴定了9个分离株中的5个STs。其中大多数属于ST8（44％），具有1个分离物不属于任何ST。此外,50％的分离物是耐甲氧西林金黄色葡萄球菌（MRSA）。所有金黄色葡萄球菌分离株具有几乎相似的毒力因子，如溶血素，促进毒素产生的蛋白酶和逃避，蛋白酶的产生和宿主免疫逃避。此外，所有mecA阳性金黄色葡萄球菌分离株均对头孢西丁敏感.
结论：存在对头孢西丁表型敏感的mecA阳性金黄色葡萄球菌分离株意味着将MRSA分类为MSSA的可能性。当随后暴露于β-内酰胺剂时，这可能导致在医疗保健和社区环境中可能出现高头孢西丁抗性菌株。因此,全基因组测序和常规方法的结合对于评估细菌耐药性和毒力以改善患者管理非常重要。
方法：2022年8月至2023年4月，在坦桑尼亚乞力马扎罗地区的2家医疗机构进行了一项涉及住院和门诊患者慢性腿部溃疡的横断面研究。使用圆盘扩散法进行抗菌药物敏感性测试。Further,进行了全基因组测序以研究分离株的基因型特征.
结果：共招募了92名参与者，其中9名参与者在培养时仅对10个金黄色葡萄球菌分离株呈阳性。鉴定了9个分离株中的5个STs。其中大多数属于ST8（44％），具有1个分离物不属于任何ST。此外,50％的分离物是耐甲氧西林金黄色葡萄球菌（MRSA）。所有金黄色葡萄球菌分离株具有几乎相似的毒力因子，如溶血素，促进毒素产生的蛋白酶和逃避，蛋白酶的产生和宿主免疫逃避。此外，所有mecA阳性金黄色葡萄球菌分离株均对头孢西丁敏感.
结论：存在对头孢西丁表型敏感的mecA阳性金黄色葡萄球菌分离株意味着将MRSA分类为MSSA的可能性。当随后暴露于β-内酰胺剂时，这可能导致在医疗保健和社区环境中可能出现高头孢西丁抗性菌株。因此,全基因组测序和常规方法的结合对于评估细菌耐药性和毒力以改善患者管理非常重要。
