Julia ML LING

Julia ML LING

B.Sc., M.Phil., Ph.D. (University of Hong Kong), MLS (W. Ontario)
Adjunct Associate Professor
Department of Microbiology,
Faculty of Medicine, The Chinese University of Hong Kong
Email

meilunling@cuhk.edu.hk

Research interest
Salmonella enterica serotype Enteritidis
Salmonellosis remains a major public health concern in many countries. The incidence of salmonella infections has been on the increase over the past ten years. The most common organism responsible for the illness is Salmonella enterica serotype Enteritidis. There has been a gradual increase in group D salmonella infections, particularly S. Enteritidis, in Hong Kong since 1989. S. Enteritidis has become the most common group D Salmonella isolate and the third most common Salmonella serotype from extraintestinal sources seen in this city. S. Enteritidis causes gastroenteritis and other acute infections. However, little information on its antimicrobial susceptibilities and epidemiology is available, will help prevent spread of the infections and allow the rational choice of treatment. We have thus investigated the antimicrobial susceptibilities, characteristics of resistant strains, and the molecular epidemiology of this organism. Over 99% of 275 S. Enteritidis isolated in this locality between 1989 and 1996 were susceptible to 17 of the 19 antimicrobial agents that were tested. About 90% of isolates had similar or identical molecular patterns, suggesting that there was a predominant clone of S. Enteritidis circulating in Hong Kong.
Salmonella enterica serotype Typhi
Typhoid fever remains an important cause of morbidity and mortality in many developing countries. It is also a problem in countries where the infection is rare but where local people travel to and acquire it in endemic places. Typhoid fever is endemic in Hong Kong with an average yearly incidence of 2.7 per 100,000 population. We have developed a simple and rapid molecular method for the epidemiological typing of Salmonella entetica serotype Typhi in a busy laboratory. Using this and other molecular biological techniques, we found that there appeared to be no major outbreak of typhoid fever in Hong Kong since there was considerable heterogeneity among isolates.
Salmonella enterica serotype Typhimurium and serotype Derby
Salmonella enterica serotype Typhimurium and serotype Derby continue to be two of the most prevalent pathogen isolated from diarrhoeal patients in Hong Kong. Most patients belong to the young age group and the illnesses frequently require hospitalization and often complicated with septicaemia or meningitis, resulting in serious sequelae. Epidemiological investigation is important in identifying the source of infection so that steps can be taken to eliminate the source and further spread of the infection can be prevented. It will also promote awareness and enable health-care workers to adopt appropriate measures to reduce the incidence of salmonellosis in Hong Kong. In such investigation, detailed strain identification and differentiation of related from unrelated strains is often essential. We therefore developed new molecular methods for this purpose.
Publications (Representative)

  1. Ling JM, Wise, R, Woo THS, Cheng AF. Investigation of the epidemiology of hospital isolates of Acinetobacter anitratus by two molecular methods. J Hosp Infect 1996;32:29-38.
  2. Ling JM, Lo NWS, Ho YM, Kam KM, Ma CH, Wong SC, Cheng AF. Emerging resistance in Salmonella enterica serotype Typhi in Hong Kong. Intl J Antimicrobial Agents 1996; 7:161-166.
  3. Ling JM, Ng TKC, Cheng AF, Norrby SR. Susceptibilities to 23 antimicrobial agents and b-lactamase production of blood culture isolates of Acinetobacter sp in Hong Kong. Scand J Infect Dis, 1996;Suppl 101:21-25.
  4. Ling JM, Koo IC, Kam KM, Cheng AF. Antimicrobial susceptibilities and molecular epidemiology of Salmonella enterica serotype Enteritidis in Hong Kong from 1986 to 1996. J Clin Microbiol, 1998;36:1693-9.
  5. Ling JM, Lo, NWS, Ho YM, Kam KM, Hoa NTT, Phi LT. Molecular methods for the epidemiological typing of Salmonella enterica serotype Typhi from Hong Kong and Vietnam. J Clin Microbiol 2000;38:292-300.
  6. Ling JM, Koo IC, Cheng AF. Epidemiological analysis of Salmonella enterica serotype typhimurium from Hong Kong by ribotyping and pulsed-field gel electrophoresis. Scand J Infect Dis, 2001;33:272-278.
  7. Ling JM, Chan EWC, Cheng AF. Molecular epidemiological analysis of Salmonella enterica serotype Derby infections in Hong Kong . J Infect, 2001:42:145-153.
  8. Ling JM, Char TS, Cheng AF. Distribution and antimicrobial susceptibilities of enterococci isolated in Hong Kong . J Infect, 2002;45:257-262.
  9. Ling JM, Lam AW, Chan EW, Cheng AF. What have we learnt from community-acquired infections in Hong Kong ? J Antimicrob Chemother 2003;51:895-904.
  10. Ling JM, Chan EW, Lam AW, Cheng AF. Mutations in topoisomerase genes of fluoroquinolone-resistant salmonellae in Hong Kong . Antimicrob Agents Chemother 2003;47:3567-3573.

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