Serogroups, and drug resistance of nontyphoidal Salmonella in symptomatic patients with community-acquired diarrhea and chicken meat samples in Tehran

BACKGROUND

Salmonella is considered as a main cause of community-acquired diarrhea in humans, however, sources of the multi-drug resistant (MDR) strains and their link with the disease are not well known.

AIMS

This study aimed to investigate the frequency, serogroup diversity, and antimicrobial susceptibility patterns of Salmonella strains in poultry meat and stool samples of patients with community acquired diarrhea in Tehran.

METHODS

We compared the frequency of non-typhoidal Salmonella serogroups, the similarities of their resistance patterns to 10 antimicrobial compounds, the prevalence of extended spectrum β-lactamase (ESBL) and ampicillinase C (AmpC) genetic determinants, and class 1 and 2 integrons in 100 chicken meat and 400 stool samples of symptomatic patients in Tehran during June 2018 to March 2019.

RESULTS

Salmonella was isolated from 75% and 5.5% of the chicken meats and human stool samples, respectively. The chicken meat isolates mainly belonged to serogroup C (88%, 66/75), while the human stool isolates were mainly related to serogroup D (59.1%, 13/22). The MDR phenotype and the most common rates of resistance to antibiotics, including tetracycline, trimethoprim/sulfamethoxazole (TS) and azithromycin, were detected in 4.5% and 45.3%, 59% and 13.6%, 43% and 9.1%, 42% and 9.1% of the human stool and chicken meat samples, respectively. Carriage of bla _CTX, bla _SHV, and bla _PER genes in the meat isolate with ESBL resistance phenotype and bla _ACC, bla _FOX, and bla _CMY-2 among the 7 meat strains with AmpC resistance phenotype was not confirmed using polymerase chain reaction (PCR). High prevalence of class 1 and 2 integrons was characterized and showed a correlation with resistance to TS and chloramphenicol.

CONCLUSION

These findings showed a lack of association between chicken meats and human isolates due to discrepancy between the characterized serogroups and resistance phenotypes.

Challenges of implementing Iranian national laboratory standards

After four years of publishing the Iranian National Laboratory Standard and following a strategic plan to implement its requirements, it was decided to review the taken actions, evaluating the achievements and the failures, as well as analyzing the gaps and planning the interventional activities to resolve the problems. A thorough evaluation revealed that the progress of implementation process varies considerably in different provinces, as well as in laboratories in different public and private sectors. Diversity and heterogeneousity of laboratories throughout the country is one of unresolvable problems. Although we encounter shortage of resources in the country, improper allocation or distribution of resources and budgets make the problems more complicated. Inadequacy of academic training in laboratory sciences has resulted in necessity of holding comprehensive post-graduate training courses. Revising academic curriculum of laboratory sciences could be mostly helpful, moreover there should be organized, training courses with pre-determined practical topics. providing specific technical guidelines, to clarify the required technical details could temporarily fill the training gaps of laboratory staff. Inadequate number of competent auditors was one of the difficulties in universities. Another important challenge returns to laboratory equipment, developing the national controlling system to manage the laboratory equipment in terms of quality and accessibility has been planned in RHL. At last cultural problems and resistance to change are main obstacles that have reduced the pace of standardization, it needs to rationalize the necessity of establishing laboratory standards for all stakeholders.

Quality assurance program for molecular medicine laboratories

BACKGROUND

Molecular diagnostic methods have played and continuing to have a critical role in clinical laboratories in recent years. Therefore, standardization is an evolutionary process that needs to be upgrade with increasing scientific knowledge, improvement of the instruments and techniques. The aim of this study was to design a quality assurance program in order to have similar conditions for all medical laboratories engaging with molecular tests.

METHODS

We had to design a plan for all four elements; required space conditions, equipments, training, and basic guidelines. Necessary guidelines was prepared and confirmed by the launched specific committee at the Health Reference Laboratory.

RESULTS

Several workshops were also held for medical laboratories directors and staffs, quality control manager of molecular companies, directors and nominees from universities. Accreditation of equipments and molecular material was followed parallel with rest of program. Now we are going to accredit medical laboratories and to evaluate the success of the program.

CONCLUSION

Accreditation of medical laboratory will be succeeding if its basic elements are provided in advance. Professional practice guidelines, holding training and performing accreditation the molecular materials and equipments ensured us that laboratories are aware of best practices, proper interpretation, limitations of techniques, and technical issues. Now, active external auditing can improve the applied laboratory conditions toward the defined standard level.

Molecular beacon probes-base multiplex NASBA Real-time for detection of HIV-1 and HCV

BACKGROUND AND OBJECTIVES

Developed in 1991, nucleic acid sequence-based amplification (NASBA) has been introduced as a rapid molecular diagnostic technique, where it has been shown to give quicker results than PCR, and it can also be more sensitive. This paper describes the development of a molecular beacon-based multiplex NASBA assay for simultaneous detection of HIV-1 and HCV in plasma samples.

MATERIALS AND METHODS

A well-conserved region in the HIV-1 pol gene and 5'-NCR of HCV genome were used for primers and molecular beacon design. The performance features of HCV/HIV-1 multiplex NASBA assay including analytical sensitivity and specificity, clinical sensitivity and clinical specificity were evaluated.

RESULTS

The analysis of scalar concentrations of the samples indicated that the limit of quantification of the assay was <1000 copies/ml for HIV-1 and <500 copies/ml for HCV with 95% confidence interval. Multiplex NASBA assay showed a 98% sensitivity and 100% specificity. The analytical specificity study with BLAST software demonstrated that the primers do not attach to any other sequences except for that of HIV-1 or HCV. The primers and molecular beacon probes detected all HCV genotypes and all major variants of HIV-1.

CONCLUSION

This method may represent a relatively inexpensive isothermal method for detection of HIV-1/HCV co-infection in monitoring of patients.