Increasing consumption of nitrofurantoin (NIT) for treatment of acute uncomplicated urinary tract infections (UTI) highlights the need to monitor emerging NIT resistance mechanisms. This study investigated the molecular epidemiology of the multidrugresistant efflux gene oqxAB and its contribution to nitrofurantoin resistance by using Escherichia coli isolates originating from patients with UTI (n ‫؍‬ 205; collected in 2004 to 2013) and food-producing animals (n ‫؍‬ 136; collected in 2012 to 2013) in Hong Kong. The oqxAB gene was highly prevalent among NIT-intermediate (11.5% to 45.5%) and -resistant (39.2% to 65.5%) isolates but rare (0% to 1.7%) among NIT-susceptible (NIT-S) isolates. In our isolates, the oqxAB gene was associated with IS26 and was carried by plasmids of diverse replicon types. Multilocus sequence typing revealed that the clones of oqxAB-positive E. coli were diverse. The combination of oqxAB and nfsA mutations was found to be sufficient for high-level NIT resistance. Curing of oqxAB-carrying plasmids from 20 NIT-intermediate/resistant UTI isolates markedly reduced the geometric mean MIC of NIT from 168.9 g/ml to 34.3 g/ml. In the plasmid-cured variants, 20% (1/5) of isolates with nfsA mutations were NIT-S, while 80% (12/15) of isolates without nfsA mutations were NIT-S (P ‫؍‬ 0.015). The presence of plasmid-based oqxAB increased the mutation prevention concentration of NIT from 128 g/ml to 256 g/ml and facilitated the development of clinically important levels of nitrofurantoin resistance. In conclusion, plasmid-mediated oqxAB is an important nitrofurantoin resistance mechanism. There is a great need to monitor the dissemination of this transferable multidrug-resistant efflux pump.

This study investigated the prevalence of IncX plasmid subtypes in commensal and pathogenic Escherichia coli isolates and the biological features of the IncX4 subtype. Two hundred and twenty-five E. coli isolates from multiple sources (47 chickens, 41 pigs, 30 cattle and 107 humans) obtained during the period 2006-2012 were tested for the presence of IncX1 to IncX5. Overall, the prevalence of IncX plasmids in chicken, pig, cattle and human isolates were 21.2 % (10/47), 19.5 % (8/41), 3.3 % (1/30) and 4.8 % (5/107), respectively. IncX4 was the most common subtype, followed by IncX1 and IncX3, while no IncX2 or IncX5 were found. Seven out of 16 (43.8 %) IncX4 plasmids were found to carry bla CTX-M genes and six of them originating from different host sources (four chickens, one pig and one human) had identical or highly similar RFLP patterns. Three IncX4 plasmids carrying bla CTX-M from different host sources were investigated further. It was found that the IncX4 plasmids had little effect on bacterial host growth parameters after their introduction to J53 recipients. Conjugation experiments demonstrated that the IncX4 plasmids could be efficiently transferred at 30-42 6C at rates which were generally 10 2 -10 5 -fold higher than those for the epidemic IncFII plasmid carrying bla CTX-M (pHK01). In conclusion, the IncX plasmids are more common than previously recognized. The efficient transfer of IncX4 plasmid at different temperatures and the lack of fitness burden on bacterial hosts highlight the ability of this plasmid replicon to be an important vehicle for dissemination of antimicrobial resistance.

Dealing with health and disease is an area of concern for social workers. The establishment of medical social service in a health setting has more than 100 years of history in the USA and more than 60 years in Hong Kong. Despite the increasing popularity of Chinese Medicine (CM) used by the Hong Kong people, there has been no medical social service presence in the CM system. A pilot project demonstrated a successful interdisciplinary collaboration model between social work and CM irrespective of different social work methods, that is, individual work, groupwork, and community-based services. In this article, we will relate the opportunities and difficulties that we encountered in setting up the first medical social service in the CM system. Drawing on our experience, we found that both professions benefited from the interdisciplinary collaboration. CM was able to expand its scope of service to increase the service quality and promote primary health care in the community with the support of social work. Conversely, social workers found that CM is a good resource for providing innovative services to meet the various needs of the people in the community. There was also a ripple effect of incorporating CM elements into social service. The interface between the disciplines of social work and CM can widen the scope of their contributions on health. Implications for CM social service in social work will also be examined.

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