Biosafety of Campylobacter jejuni from raw vegetables consumed as ulam with reference to their resistance to antibiotics

Antibiotic resistance in campylobacter is an emerging global public health problem after MRSA and VRE. Fluoroquinolone and macrolide resistance have been found to be more common in this world leading foodborne pathogen. A total of fifty-six isolates of Campylobacter jejuni obtained from raw vegetables which are consumed as ulam (salad) in Malaysia, were tested with 12 antibiotics used clinically and agriculturally. The resistance was determined using the disk diffusion method. Results were determined by hierarchic numerical methods to cluster strains and antibiotics according to similarity profiles. Fifty five C. jejuni isolates from different isolation sites were all clustered together into ten groups. This indicates that the commodities (raw salad vegetables/ulam) where the isolates originated might share a similar source of cross-contamination along the production route. All antibiotics tested correlated and there were four groupings reflecting their mode of actions. Generally, C. jejuni isolates were found to be highly resistant to erythromycin (91.1%) and tetracycline (85.7%). Both agents are popular antibiotics used clinically to treat bacterial infections. On the other hand, the C. jejuni isolates showed high percentage (80.4%) of resistance towards enrofloxacin, an extensively used antimicrobial agent in agriculture practices. This study showed that C. jejuni isolates were highly multi-resistance to as many as 10 antibiotics. Therefore, in terms of biosafety, the presence of antibiotic resistance strains in the food chain has raised concerns that the treatment of human infections will be compromised

Health risk assessment of PM10 exposure among Malaysian adult population based on physical activity pattern

Introduction Most health advisories related to outdoor physical activity during haze are general in nature. The advisories normally advise everyone to reduce or limit prolonged exertion or heavy exertion without mentioning the acceptable duration for performing outdoor physical activity causing difficulty for public to decide to stop or cancel a particular outdoor or sport event. The aim of this paper is to determine the acceptable duration for performing outdoor physical activity pattern based on API level. Methods Health risk assessment approach that comprises of hazard identification, exposure assessment, dose-response, and risk characterization steps were used to determine the potential inhaled dose and risk associated with performing the physical activity during haze. We have considered many factors that include time spent for physical activity patterns for Malaysian adult, age, physical intensity-specific inhalation rate (m3/min), and the indoor/outdoor ratio of PM10. A hypothetical exposure scenario of PM10 was created using the breakpoints of PM10 concentration for the calculation of respective API levels. Results The association between physical activity pattern, API level and risk quotient were presented in the form of risk radar diagram. In general, based on the average estimate, everyone should avoid high intensity physical activity and moderate exertion when API reach > 175 and > 200 respectively. Whereas, based on the high estimate, everyone should avoid high intensity physical activity and moderate exertion when API reach > 135 and > 150 respectively. Below the said API, the duration for performing prolonged exertion and heavy exertion should be adjusted according to the API level as stated in the recommended maximum duration for performing physical activity. Conclusions Reducing the physical activity is an effective strategy to lower the dose of inhaled pollutants and reduce the health risk during poor air quality. Based on the assessment, the recommended maximum duration for performing the physical activity based on API level was established as a guide for the authority or public to plan their activity during poor air quality

Health Risk Assessment of PM10 Exposure among School Children and the Proposed API Level for Closing the School during Haze in Malaysia

Introduction: During haze, at what level should Air Pollutant Index (API) showed, public or private school be closed is not without controversy and is very much debated. Therefore, the aim of this paper is to objectively quantify the potential inhaled dose of PM10 associated with exposure at school and home microenvironments during haze. The result of the health risk assessment will be used to propose the API level for closing the school during haze episode. Methods: A hypothetical haze exposure scenario was created using the breakpoints of PM10 concentration for calculation of API and respective inhaled dose during haze. To determine the potential inhaled dose, we have considered many factors that include time spent for specific physical intensity at school and home microenvironments, age-specific and physical intensity-specific inhalation rate (m3/min), and the indoor/outdoor ratio of PM10. To calculate risk quotient (RQ), the inhaled dose was compared with the health reference dose computed based on the concentration of PM10 in the Malaysian Ambient Air Quality Standard. Results: When considering the specific exposure at each microenvironment (school and home), the potential inhaled dose of PM10 was substantially lower when school is closed for both primary and secondary school. The calculated risk quotient (RQ) indicates that primary school children are likely to be affected at slightly lower PM10 concentration (equivalent to API of 197) as compared to secondary school children. Short duration of high physical activity intensity during school breaks has contributed to a large proportion of inhaled dose among school children indicating the important to avoid physical activities during haze. Conclusion: Based on the assessment, taking into account the uncertainty of risk assessment methodology, we proposed school to be closed when API reach 190 for both primary and secondary schools. These findings and recommendations are only valid for naturally ventilated school and applicable in the context of the current API calculation system and the existing Recommended Air Quality Guideline values in Malaysia