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A. Heterotrophic Plate Count

Heterotrophic plate count (HPC), also known as Standard Plate Count is used to

determine the presence of heterotrophs in microbial isolates by measuring colony formation on

culture media. Although the majority of these organisms do not present a health risk to

immunocompetent individuals, some of the bacteria present may be opportunistic pathogenswhich are mainly associated with nosocomial infections.

HPC is a good technique in measuring the overall bacteriological quality of the sample. It

is a valuable tool to assess microbial density of chopping boards of Miag-ao Public Market. A

value of 5.0 x 103

to 1.0 X 104CFU ml-1

is the HPC value considered safe according to

international standards and we should take into account that all samples obtained have values

above 1.0 X 104CFU ml-1(Reasoner, 1990). However, this value is only applicable for drinking

water since microbial density in food are log concentration higher (Wadhwa et al., in press.

Wadhwa et al (in press) concluded that high HPC values for food or surfaces where food is

prepared has a higher health risk than that of drinking water.

A high heterotrophic plate count signifies that the area wherein the samples were taken

from has poor sanitation and that proper hygiene management is not maintained. Also, the

presence of high microbial density in chopping boards indicate the poor infrastructure of shops

such as poor drainage, differentiation between clean and unclean operations, keeping more than

two kinds of meats in a shop without proper separation of meat areas in the shops and by a

constant flow of contamination from the unsuitable floors of the shops. In addition, the chopping

boards used in Miag-ao Public Market have rough, porous wooden surfaces that play a role in

harboring and multiplying the organism. In fact, proper cleaning and disinfection of the wooden

chopping boards are not possible for the shops personnel. This poses a great health risk since themicroorganisms found on the chopping boards can easily contaminate the meat through surface

contact. This is a great public health concern since meats that are for domestic consumption are

chopped in these boards.

However, the results obtained using an HPC test are not an accurate assessment of total

heterotrophic concentrations but are indications of cultrable organisms present. It should be

considered that only 1% of the total bacteria found using direct microscopy are enumerated using

HPC procedures. Possible explanations for this difference include the presence of some bacteria

in a viable but non-culturable state and the fact that HPC media do not provide the complex

nutritional requirements necessary for the growth of all heterotrophs. Therefore, there is apossibility that the HPC values obtained during laboratory analysis do not reflect the total

bacterial density found on the chopping boards but rather only provides an index for assessing

the presence of heterotrophs. Since Heterotrophic Plate Count is not a very accurate technique,

further examinations should be done for a better assessment of the situation.

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