The relation of phylogroups, serogroups, virulence factors and resistance pattern of Escherichia coli isolated from children with septicemia

The characterization of virulent and drug-resistant Escherichia coli strains helps to control and provide more accurate information regarding infection and eradication. The aim of this study was to determine the relationship between antibiotic susceptibility, phylogroups and virulence factors of E. coli isolates from children with septicaemia. One hundred dereplicated E. coli isolates were collected from paediatric patients with septicaemia in five hospitals in Tehran (May 2015 to May 2018). The antibiotic susceptibility of isolates was performed as per the 2016 guidelines of the Clinical and Laboratory Standards Institute. Extended-spectrum β-lactamases and carbapenemase genes, phylogroups, serogroups and virulence encoding genes were detected by PCR. Phylogroup B2 was dominant (40%) among strains, followed by phylogroups D (30%), A (8%) and B1 (7%). CTX-M1 was significantly higher in the B2 group (n = 21, p 0.001). Furthermore, the virulence genes iutA (n = 27, p 0.002), csgA (n = 39, p <0.001), kpsMII (n = 39, p 0.002), ibeA (n = 4, p 0.004), vat (n = 5, p 0.003), traT (n = 24, p <0.001), sat (n = 12, p 0.001) and hlyA (n = 33, p <0.001) showed significantly higher rates in phylogroup B2. Three O25/CTXM1/OXA-48 and cnf, iutA, csgA and traT positive isolates belonged to phylogroup B2. Pulsed-field gel electrophoresis analysis showed 85% similarity among 25% of isolates. More than half of the isolates were multidrug-resistant E. coli. A significant relation was observed among iutA, csgA, kpsMII, ibeA, vat, traT, sat and hlyA genes and phylogroup B2. The characterization of virulent and drug-resistant strains helps control and properly eliminate infections. There was no genetic relation among strains in the pulsed-field gel electrophoresis pattern.

Risk factors and control strategies for silicotuberculosis as an occupational disease

Silicotuberculosis is critical in community settings among workers and employees exposed to silica dust. Older age of entry (>30 years), male sex, infection with human immunodeficiency virus (HIV), exposure duration, smoking, chronic obstructive pulmonary disease, migration, the severity of the silicosis and the intensity of the exposure are potential risk factors. Lack of timely diagnosis and treatment for tuberculosis (TB) may also raise the rate of infection; previous treatment of TB is possibly associated with the development of silicotuberculosis in more than half of patients, increasing with age (>40 years). Identification of risk factors benefits not only the academic research community, but also the workers or employees and policy making. Some strategies can be implemented, such as controlling or reducing exposure to silica dust, ensuring continuity of treatment of TB or extended anti-TB treatment, management of the situation by occupational health professionals, prevention of oscillating migration, providing workers with compensation, training and education in occupational health, improving the quality of life of miners and workers, intensive medical surveillance and TB screening in routine health check ups, and policy making for higher immunity to inhibit inhalation of dust by workers or employees.

The association of surface adhesin genes and the biofilm formation among Klebsiella oxytoca clinical isolates

Bacterial adhesins mediate the attachment and biofilm production leading to the persistence of colonized strains. The aim of this study was evaluation of the association of surface adhesin genes with the biofilm formation among Klebsiella oxytoca isolates. Among 50 isolates of K. oxytoca from patients with antibiotic-associated diarrhoea, the susceptibility test, MIC (according to CLSI 2016) and phenotypic biofilm formation (with microtitre tissue-plate assay) were performed. The presence of adhesins was investigated using PCR. Thirty-three (66%) isolates produced moderate-level biofilms, but none of them exhibited strong biofilm formation. The presence of adhesins was as follows: fimA, 60% (n = 30), mrkA, 42% (n = 21), matB, 96% (n = 48) and pilQ, 92% (n = 46). The biofilm formation was related to the presence of fimA (odds ratio (OR) 0.8571, 95% CI 1.733–6.267, p <0.0001), mrkA (OR 0.2462, 95% CI 2.723–4.622, p 0.001), matB (OR 0.4521, 95% CI 1.353–5.332, p 0.008) and pilQ (OR 0.1481, 95% CI 1.691–6.117, p <0.0001). The npsB toxin-encoding gene was detected among 46 (92%) isolates. Resistance to non-β-lactam antibiotics was significantly associated with the presence of adhesin-encoding genes. The presence of adhesins and the capsular encoding gene was significantly associated with biofilm formation among K. oxytoca isolates. The presence of surface adhesin-encoding genes was significantly associated with the biofilm formation and also with resistance to non-β-lactam antibiotics among K. oxytoca clinical isolates. In addition, biofilm production was not significantly associated with β-lactam resistance among the isolates.