Pulsed-field gel electrophoresis as an epidemiologic tool in the investigation of laboratory acquired Salmonella typhi infection.

Strains of Salmonella typhi implicated in two separate cases of laboratory acquired infection from patients and the medical laboratory technologists who processed the patients' samples were analysed by pulsed-field gel electrophoresis. Although all four isolates were of bacteriophage type E1, PFGE was able to demonstrate that the strains responsible for the two laboratory acquired cases were not genetically related. The PFGE patterns of the isolates from the MLTs were found to be identical to those of the corresponding patients after digestion with restriction enzyme AvrII. This provided genetic as well as epidemiological evidence for the source of the laboratory acquired infections.

Disinfection: gaps between recommended and actual practice.

Basic practices on disinfection was surveyed in 6 hospitals using an observation and interview checklist. Two surveys were done, one pre-(first survey) and one post-intervention (second survey). The disinfection and sterilization policy of the Ministry of Health was not available in 66 (70.2%) and 12 (13%) of the units in the first and second survey respectively. In the second survey, staff in all the units washed disinfectant containers before refilling compared with 41.5% of the units in the first survey. Dilution of disinfectants not recommended was found to be used in the first survey. Storing cleaned and sterile items in disinfectants, using disinfectant as a substitute for sterilization of autoclavable items and not decontaminating spillages were some of the wrong practices observed. Considerable improvements were made in the second survey. Improper usage of disinfectants was also indicated by failure of the in-use test. Rate of failure of disinfectants in-use decreased from 11.6% in the first survey to 5.0% in the second survey. To ensure proper disinfection practices, a comprehensive training program on disinfection is required for nurses and attendants.

An evaluation of knowledge and awareness of disinfection and sterilization among health care workers.

Awareness of the disinfection and sterilization policy among hospital staff and their knowledge in basic principles and methods of disinfection and sterilization were studied before and after intervention using a self-administered questionnaire. Survey results showed that awareness (56.2%) before intervention was unsatisfactory. The nurses were more aware of the policy than other groups of medical personnel. Those unaware of the policy perform duties from memory or verbal instructions. A significant increase in awareness to 73.3% was observed after intervention (p < 0.05). Knowledge on methods of decontamination, disinfection and sterilization of equipment varies widely from 28.8% to 90.1%. 23.1% were unaware of the temperature used for sterilization while 72.4% did not know how containers of disinfectant should be refill. Only 14.7% knew the recommended method for washing containers. With education improvement was observed. The average knowledge improved from 44.4% to 57.3%. Our results indicated that continuous in-service education is needed to improve, supplement and update knowledge in this field after basic training. In addition orientation programs for new staff should also be aimed at creating awareness and providing information on guidelines and policies related to their duties.

Epidemiology and control of malaria in Malaysia.

In spite of more than 30 years of control activities, malaria continues to be the most important parasitic infection in Malaysia, accounting for 39,189 confirmed cases in 1991, giving an annual parasite incidence rate of 2.2 per 1,000 population. Some factors contributing to the continued transmission of malaria are the development of drug resistant Plasmodium falciparum, changes in vector behavior, and ecological changes due to socio-economic reasons. Malaria parasite rates are higher among the Aborigines, land scheme settlers and those in intimate contact with the jungle, like loggers. There has been no substantial change in the proportion of the three common malaria species responsible for infections, P. falciparum, P. vivax, P. malariae and mixed infections accounting for about 70%, 28%, 1% and 1%, respectively of all infections. Drug resistant P. falciparum is unevenly distributed in Malaysia, but based on clinical experience and in vitro drug sensitivity studies, chloroquine resistance is frequently encountered. There has been clinical and laboratory evidence of resistance to sulfadoxine/pyrimethamine combination as well as quinine, but all these have so far been successfully treated with a combination of quinine and tetracycline. The eradication of the disease is impossible in the near future but there is confidence that with better surveillance techniques and the use of alternative control measures like permethrin impregnated bed-nets to complement existing ones, the target of bringing down the annual parasite incidence to 2 per 1,000 population during the Sixth Malaysian Plan period (1991-1995) can be achieved.

Heavy metal and disinfectant resistance in clinical isolates of gram-negative rods.

Ninety-five clinical strains of Gram-negative bacteria were examined for resistance to mercury, silver and disinfectants. 41% of the strains possessed resistance to mercury, 21% to silver and 7.3% of the strains were resistant to chlorhexidine. Mercury resistance was shown to be plasmid-mediated in 17 strains and silver resistance in 10 strains. Chlorhexidine resistance was not shown to be transferable.

Antibiotic resistance and R plasmids in coliforms isolated from some Malaysian cooked foods.

Forty samples of Malaysian cooked foods were examined for the presence of antibiotic-resistant coliforms and R plasmids. Twenty seven (68%) of the foods had antibiotic-resistant coliforms and 5 (13%) had R plasmids. Nineteen samples (48%) had total bacterial counts over 10(6) per gm and in 5 samples, no coliforms were detected. Our findings show that cooked food may be one possible way by which R plasmids are spread. The control of the spread of R plasmids is discussed.

Enterotoxin production by Staphylococcus aureus strains isolated from humans, foods and animals in Malaysia.

Enterotoxin production by strains of Staphylococcus aureus isolated from human, food and animal sources was investigated. Of the 130 isolates studied, 27 (20.8%) were found to be enterotoxigenic. The most common enterotoxin detected from human sources was enterotoxin C whereas enterotoxin B occurred more frequently in staphylococcal strains of food origin. The 2 enterotoxigenic strains, from animals isolated from a dog and a goat, produced enterotoxins A and C, respectively. Enterotoxin E was not detected alone from any of the enterotoxigenic strains studied, but occurred together with other enterotoxins. The need to detect enterotoxin in staphylococcal strains and in suspected foods for the confirmation of staphylococcal food poisoning is discussed.

Occurrence of coliform bacteria other than Escherichia coli in foods.

An evaluation of the BGLB (44 degrees C) confirmation test for the enumeration of E. coli as an index of sanitary quality of some foods was made. Out of 70 samples tested, 43 (61.4%) samples contained E. coli. A total of 347 BGLB gas positive cultures obtained were subjected to the IMViC procedure. It was found that 42.7% of these BGLB gas positives were E. coli and 57.3% were ten other coliform bacteria giving the following IMViC patterns: 31.4% --++, 6.3% -+-+, 4.3% each of +-++ and -+++, 3.2% ++-+, 2.9% ++++, 2% ---+, 1.4% +++-, 1.2% --+- and 0.3% -++-. Some of the possible reasons for obtaining low recovery of E. coli in foods by the BGLB test have been discussed. The various fields to be investigated for the improvement of the test procedure and thus the elimination of false positives have been suggested.

A bacteriological study of some frozen and nonfrozen foods.

Over a period of 19 months, a total of 331 food samples were submitted to the Food Section of the Bacteriology Division for bacteriological examination. These included 184 samples of frozen seafoods from exporters and 147 samples of fresh, nonfrozen foods from food caterers. The total bacterial count for frozen seafoods ranged from 1 x 10(2) to 2.98 x 10(6) per gm with a mean of 2.14 x 10(5) per gm. Coliforms, Escherichia coli and Staphylococcus aureus were present in 48.9%, 3.3% and 8.2% of the samples examined respectively. Two of the cooked prawn samples showed the presence of Vibrio parahaemolyticus. For the fresh, nonfrozen foods, the total bacterial count ranged from 1 x 10(2) to 3.87 x 10(6) per gm with a mean of 2.58 x 10(5) per gm. The examination also showed that 74.8% were coliform positive, 14.9% were E. coli positive, and 4.8% were S. aureus positive. V. parahaemolyticus was not isolated in any of the samples tested. Other pathogens, namely, Vibrio cholerae, Salmonella and Shigella were not isolated from any of the foods examined. The bacterial levels in these foods were determined and their sanitary and public health significance is discussed.

Hydrogen sulphide production as an aid to the identification of Vibrio parahaemolyticus.

In this study 18 strains of Vibrio parahaemolyticus from food and 8 from humans were tested for hydrogen sulphide production on various modifications of Russel's Triple Sugar slopes and on TSI. All strains showed a characteristic surface browning on RTS with Andrade's indicator. This was not seen when RTS with phenol red as indicator or TSI were used. Appearance of this phenomenon allows unknown strains to be suspected as being Vibrio parahaemolyticus.

Seroreactivity to syphilis in Malaysian blood donors and expectant mothers.

Seroreactivity to syphilis is high among Malaysian blood donors and expectant mothers indicating a high degree of treponemal infection. Further epidemiological studies are required to ascertain what proportion of these could be syphilis and what porportion yaws. Blood donors hava a higher reactivity rate than expectant mothers, the reasons probably being soical. The titres obtained in the VDRL test appear to have a relation to FTA-ABS reactivity although this is not to say treponematosis can be excluded on the basis of low titre VDRL results.