Elakrout, Alhussien Ali2026-06-082026-06-082019https://hdl.handle.net/10566/23136The emergence of virulent and drug-resistant bacterial strains such as methicillin-resistant Staphylococcus aureus (MRSA) is a global public health burden. The World Health Organization (WHO) has placed MRSA and vancomycin-intermediate-sensitive S. aureus (VISA) and vancomycin-resistant S. aureus (VRSA) on a high global priority pathogens list of antibiotic-resistant bacteria to promote the research and development of novel and effective antibiotic therapeutic rationales. Uncomplicated S. aureus bacteraemia (e.g., mild skin infections) may be treatable with the conventional regimens of antibiotics, but resistance strains of the bacteria (e.g., invasive infections), often persist as a high load of bacterial DNA in blood, and has been linked to increased mortality in world populations, irrespective of country or location. Several lines of evidence imply that combinations of vancomycin (a glycopeptide antibiotic that targets cell wall synthesis) and ß-lactam antibiotics that target the penicillin-binding proteins (PBPs) improve clearance of MRSA bloodstream infections (BSIs). However, acquired resistance to virtually the entire spectrum of ß-lactams hinders the therapeutic benefit of such antibiotic combinations. Hospital/health care-associated resistant S. aureus infections (HA-MRSA) and community-associated resistant S. aureus infections (CAMRSA), continue to be among the most common and challenging life-threatening infections worldwide. Furthermore, the increased rate of resistance among MRSA and vancomycin resistant Enterococcus (VRE) underscore the dire need for the discovery of novel anti-MRSA and anti-VRE compounds. The degree of ß-lactam resistance varies among clinical MRSA isolates, particularly with regard to those mediated by chromosomal mutations and the novel exogenous resistance gene which encodes PBP2a, i.e., mecA. PBP2a is the key resistance factor of ß-lactams, but the evolution of this mecA gene product and its mechanisms remain elusive. Nonetheless, it is widely accepted that in MRSA, PBP2a reduces the binding affinity to ßlactam antibiotics, rendering them ineffective. Besides HA-MRSA and CA-MRSA, colonization by livestock-associated MRSA (LA-MRSA) presents a major threat to both animal and human health, e.g., MRSA clonal complex (CC) 398 has spread from pigs to humans, but rarely from person to person. Even though LA-MRSA CC398 has been deemed less virulent than other MRSA strains, it particularly colonizes pig farmers. Recent studies indicate that an increasing number of people are being infected with LA-MRSA CC398. LAMRSA in mink is considered a human health hazard to farmers and farm workers, who handle the animals and are at risk of bites and scratches from colonized sites. Likewise, MRSA is also present in rabbits, cattle (e.g., dairy cows) and poultry, and, as such, has become an emerging threat to public health because of the spread from animals to humans via animal husbandry, and the health care and food processing industry. Generally, the irrational use of antibiotics is the main cause of the emergence of antibiotic resistant S. aureus strains. Globally, in both developed and developing countries, MRSA represents a serious public health concern because of the rapid spread of this bacterium around the world coupled with the evolution of new genetically distinct HA-MRSA, CA-MRSA and LA-MRSA strains. Additionally, the development of cross-resistance to other non-ß-lactams, including vancomycin, has only exacerbated the burden of MRSA infections. In many countries such as the USA, UK, Europe and Iran, the MRSA epidemic has been well documented. However, in South America and Africa, there seems to be a paucity on available data concerning MRSA strains. Equally, in Libya, detailed information is lacking regarding MRSA contagiousness risk, but conscious efforts are currently being directed at understanding the molecular epidemiology of S. aureus isolates, not only in terms of the persistence and spread of CA-MRSA, HA-MRSA and LA-MRSA, but also to focus awareness on prudent antibiotic prescription policy and use, as well as prevention and control of MRSA transmission in hospital, community and food production settings. The aim of this study was to compare antibiotic sensitivities of Staphylococcus aureus isolates in human patient samples from Misurata hospitals and laboratories as well as poultry samples from commercial markets in Libya. The objectives of the study were to (1) analyze laboratory and hospital samples from patients as well as poultry samples for bacterial and fungal growth, using standard bacterial isolate identification and antibiotic susceptibility tests; (2) compare traditional bacterial culture methods that are used to measure MRSA strains with modern molecular methods to isolate the mecA1 and mecA2 genes, using PCR; (3) determine the diagnostic profile of the bacterial and fungal species in patient and poultry specimens; (4) evaluate the Staphylococcus aureus antibiotic sensitivity and resistance profiles for patient and poultry samples; (5) compare Staphylococcus aureus antibiotic sensitivity and resistance profiles in patient specimens according to gender, age group and location (site collected); (6) compare Staphylococcus aureus antibiotic sensitivity and resistance profiles in poultry samples according to location and different parts of the chicken after slaughter; (7) identify and detect the MRSA contamination in chicken samples.enStaphylococcus aureusMethicillin-resistant staphylococcus aureus (MRSA) in humans and poultryAntibiotic resistance profilesMultidrug resistance mecA1 and mecA2 genesAltered penicillin-binding proteinThesis