Determining risk factors for the spread of XDR bacteria in Pakistan, and examining interventions to prevent their dissemination

Most epidemiological studies concerning multidrug resistance (MDR) or extensively drug resistance (XDR) emphasise the prevalence of resistance in clinical settings whereas environmental contamination is often ignored a topic of increasingly great concern, especially in low middle-income countries (LMICs). This thesis reports on the prevalence and associations of carbapenemases and extended spectrum blactamases ESBLs) in clinical and environmental settings in and the effects of climate factors and local hospital cleaning regimes on the XDR rate in post-surgical infections. Furthermore, I attempted to restore sensitivity to carbapenem antibiotics by introducing peptide nucleic acid (PNA) as an alternative therapy. A preliminary study of environmental samples isolated from Karachi, Pakistan demonstrated the presence of New Deli Metalo-β-lactamase (blaNDM) and cefotaxime β-lactamase (blaCTX-M-15) in animal’s faeces, insects, hospital surface and drinking water. Similarly, the environmental (insect and hospital surface) and clinical (surgical wound) samples from Peshawar, Pakistan revealed very high rates of blaNDM, blaCTXM- 15 and Oxacillin β-lactamase (blaOXA-48)- like. Additionally, strains with similar restriction length polymorphism (REP) profiles and STs (sequence types) were recovered from environmental and clinical samples indicating their possible spread across clinical and environmental sectors. In the Peshawar study, the collected in winter were shown to carry more resistance compared to summer. However, the cleaning regime had no significant association with the carriage of resistance. iii Finally, it was attempted to use PNA to inhibit the expression of carbapenemases. However, despite exhibiting antimicrobial properties when targeted to the acyl carrier protein gene (acpP), PNA was unable to restore the sensitivity of resistant strains to carbapenem antibiotics. The current work herein contributes to the understanding that contaminated touch surfaces may play an essential role in the transfer of MDR bacteria, whereas insects may be a key vector in their dissemination across distant niches. Such holistic studies are crucial in determining the role of atypical environmental co-factors in contributing to the increased resistance dissemination in LMICs