Bacterial Contamination of Vegetables Served in Hospitals
Chertsak Dhiraputra MD *, Chuntima Tiensasitorn MSc*, Wanida Techachaiwiwat MSc*, Naruemol Jirapanakorn MSc*, Kanchana Kachintorn RN**, Somwang Danchaivijitr MD***
Affiliation : *Department of Microbiology, **Center for Nosocomial Infection Control, ***Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok
Objectives : To study bacterial contamination of fresh vegetables before cleaning and before serving to
patients in 14 hospitals.
Materials and Methods : Aerobic plate count was performed and emphasized on total viable aerobic bacteria,
fecal coliform, fecal Escherichia coli and enteric pathogens in fresh vegetables including romaine lettuce,
onion, parsley, celery and tomato before cleaning and before serving. Hospital nutrition officers who were
involved in food purchasing and processing were interviewed.
Results : One hundred and six of 403 of fresh vegetable samples (26.3%) before cleaning were contaminated
with > 107 colony forming unit per gram (CFU/gram) of viable aerobic bacteria, 106 of 178 samples (59.6%)
contained MPN/fecal coliform >1,100 / gram, 78 samples (43.8%) contained MPN fecal E.coli >10/gram.
Enteric bacteria were isolated from 7.2% of the total 304 samples including non typhoid Salmonella (1
sample), Vibrio cholerae non O1/O139 (7 samples) and Aeromonas species (14 samples). Forty of 396 ready
to serve vegetable samples (10.1%) contained > 107 CFU/gram of viable aerobic bacteria. Seventy five of 183
(40.9%) samples contained >1,100 MPN fecal coliform/gram and 43 (23.5%) contained >10 MPN fecal E.
coli/gram. Enteric bacteria were also detected in 7.6% of the samples including V. cholerae non O1/O139 (6
samples) and Aeromonas species (17 samples).
There were three different ways in obtaining fresh vegetables to the hospitals : by auction (50%),
wholesalers (21.4%) and retailers (14.2%). There were also different standards of transportation, packag-
ing, delivery and food processing, particularly cleaning methods.
Conclusion : Ready-to-eat fresh vegetables were contaminated in high percentages with microorganisms in
the number that exceeded the standard. Better management is required to safeguard patients.
Keywords : Bacterial contamination, Vegetables, Hospital
