Abstract

ESTIMATION OF RESISTANCE TO HEAVY METALS OF BACTERIAL PATHOGENS CAUSING RESPIRATORY INFECTIONS AMONG WORKERS OF AL-BAIJI OIL REFINERY IN IRAQ

*Mohemid M. Al-Jebouri,Abdeljalil H. Al-Samarrai, and Riydh A. Abdeljabar

Abstract

Aims:The most realizable contaminants which are abundant in environment of oil refinery are heavy metals. Some heavy metals like Cu and Zn are essential for bacteria, but even those are highly toxic for all kinds of organisms including bacteria. Resistance to heavy metal, as many authors mentioned, is highly correlated with resistance to antibiotic due to their existence at the same plasmid. Thus, the minimal inhibitory concentration (MIC) of heavy metal is used to investigate the metal tolerance level in certain bacteria.The present study is an attempt to assess the variation of heavy metals resistance among bacterial pathogens isolated from oil refinery workers compares to resistance of the same chemicals among the same bacteria isolated from community patients in hospitals. Methodology: With regard to the refinery workers, from October 2008 to September 2009, two hundred samples were taken from patients with upper respiratory tract infections (URTIs) and lower respiratory tract infections (LRTIs). They were employed in the North Refineries Company in Al-Baiji town. Those patients were from different residences, either rural or urban inhabitants, and some of them were living in the resident near by the refinery. Equal number of samples was also taken from patients hospitalized in Tikrit teaching hospital from May 2009 to October 2009 as control samples for comparison. Minimal inhibitory concentration (MIC), under defined test conditions inhibits the visible growth of the bacterium being investigated. MIC values are used to determine susceptibilities of bacteria to heavy metals including cadimium, copper, nickel, lead,vanadium and zinc, Results: The susceptibility of these groups was tested against the six heavy metals (cadmium, copper, nickel, lead, vanadium and zinc) as a minimal inhibitory concentration (MIC). Results showed that isolates of refinery recorded 73% from the highest values of MICs, while isolates of hospital recorded only 27% of them. Conclusions: Inhalation of metal particles might be more dangerous than other routes like digestive system or skin. Workers with low experience, associated with short employment, constituted the highest percentage of infections. Bacteria isolated from patients of the refinery were more virulent due to their relative high metal resistance comparing with those of hospital.

Keywords: Oil refinery, heavy metals, resistance, respiratory infections, bacteria.