Akinyemi Kabiru O, Iwalokun Bamidele A, Alafe Olajide O, Mudashiru Sulaiman A, Fakorede Christopher
Department of Microbiology, Lagos State University, Ojo, Lagos, Nigeria.
Biochemistry and Nutrition Division, Nigerian Institute of Medical Research, Yaba, Lagos, Nigeria.
Infect Drug Resist. 2015 May 11;8:99-106. doi: 10.2147/IDR.S78876. eCollection 2015.
The global spread of bla CTX-M-I extended-spectrum beta-lactamase (ESBL)-producing Salmonella spp. remains a major threat to treatment and control. Evidence of emergence and spread of this marker are lacking in Nigeria. This study investigated bla CTX-M-I ESBL production among Salmonella isolates from hospitalized patients.
Patients (158 total) made up of two groups were evaluated. Group A was composed of 135 patients with persistent pyrexia and group B was composed of 23 gastroenteritis patients and their stool samples. Samples were cultured, and isolates were identified and were subjected to antibiotic susceptibility testing by standard methods. Isolates were further screened for ESBL production, bla CTX-M-I genes and transferability by double disk synergy test, plasmid extraction, polymerase chain reaction, and conjugation experiment.
Thirty-five (25.9%) Salmonella isolates were identified from group A, of which 74.3% were S. typhi, 22.9% were S. paratyphi and two (5.7%) were invasive non-typhoidal S. enteritidis. Nine Plasmodium falciparum infections were recorded, four of which were identified as co-infections with typhoidal Salmonella. Only two (8.7%) S. enteritidis samples were obtained from group B (P>0.05). A total of 24 isolates were ESBL-positive, eliciting resistance to five to seven antibiotics, and were multiple-drug resistant. ESBL production due to the bla CTX-M-I gene cluster was detected in eleven (45.8%) Salmonella isolates. Nine (81.8%) of the eleven bla CTX-M-I ESBL producers were S. typhi and two (18.2%) isolates were S. enteritidis. Four of nine S. typhi bla CTX-M-I ESBL-producing strains harbored 23 kb self-transmissible plasmid that was co-transferred with cefotaxime and augmentin resistance to Escherichia coli j53-2 transconjugants.
This study revealed the emergence of bla CTX-M-I S. typhi as an agent of persistent pyrexia with potential to spread to other Enterobacteriaceae in Lagos, Nigeria. Cautionary prescription and judicious use of third-generation cephalosporins, particularly cefotaxime, for the treatment of typhoid fever and routine screening for P. falciparum co-infection with ESBL-producing Salmonella in the laboratories during diagnosis of persistent pyrexia conditions in patients are recommended.
产bla CTX-M-I型超广谱β-内酰胺酶（ESBL）的沙门氏菌在全球范围内传播，仍然是治疗和控制方面的重大威胁。在尼日利亚，缺乏关于该标志物出现和传播的证据。本研究调查了住院患者分离出的沙门氏菌中bla CTX-M-I型ESBL的产生情况。
对两组共158名患者进行了评估。A组由135名持续发热患者组成，B组由23名肠胃炎患者及其粪便样本组成。对样本进行培养，通过标准方法鉴定分离株并进行药敏试验。通过双纸片协同试验、质粒提取、聚合酶链反应和接合实验，进一步筛选分离株的ESBL产生情况、bla CTX-M-I基因及可转移性。
从A组中鉴定出35株（25.9%）沙门氏菌分离株，其中74.3%为伤寒沙门氏菌，22.9%为副伤寒沙门氏菌，2株（5.7%）为侵袭性非伤寒肠炎沙门氏菌。记录到9例恶性疟原虫感染，其中4例被鉴定为与伤寒沙门氏菌合并感染。仅从B组获得2株（8.7%）肠炎沙门氏菌样本（P>0.05）。共有24株分离株ESBL阳性，对五至七种抗生素耐药，且为多重耐药。在11株（45.8%）沙门氏菌分离株中检测到由bla CTX-M-I基因簇导致的ESBL产生。11株产bla CTX-M-I型ESBL的菌株中，9株（81.8%）为伤寒沙门氏菌，2株（18.2%）为肠炎沙门氏菌。9株产bla CTX-M-I型ESBL的伤寒沙门氏菌菌株中有4株携带23 kb的自我传递质粒，该质粒与头孢噻肟和阿莫西林/克拉维酸耐药性一起共同转移至大肠杆菌j53-2接合子。
本研究揭示了产bla CTX-M-I型的伤寒沙门氏菌在尼日利亚拉各斯作为持续发热病原体出现，并有可能传播至其他肠杆菌科细菌。建议谨慎处方并明智使用第三代头孢菌素，尤其是头孢噻肟，用于治疗伤寒热，并在患者持续发热病症诊断期间，在实验室对恶性疟原虫与产ESBL沙门氏菌的合并感染进行常规筛查。
