[Significance of laboratory statistics in tuberculosis control in Medimurje County]

Microbiological diagnosis of tuberculosis is the axis of any national tuberculosis control program. Tuberculosis notification rate in Medimurje County has been equivalent to the national average, except in 2009 when it (23/100,000) surpassed the national rate of 19.3/100,000. The aim of this study was to analyze laboratory results (age, sex, site of the disease, drug susceptibility test results, and genotyping results) in tuberculosis control in Medimurje County.

A prospective study of genotyping all newly isolated Mycobacterium tuberculosis strains is currently conducted at the Croatian National Institute of Public Health, Tuberculosis Diagnostic Department. The genotyping method used is determining variable number of tandem repeats of mycobacterial repetitive interspersed unit. Between 2007 and 2009, a total of 59 strains from patients coming from Medimurje County were genotyped, 27 (45.8%) of which had a unique genotype in the national database, while 32 (54.2%) were grouped in 22 clusters with 2 to 22 pertaining strains. Two of 22 clusters, one with two and one with five members each, were made up from strains isolated solely in Medimurje County. These strains are not only characteristic of the County, but the patients they originated from had most likely been exposed to the same route of transmission. The remaining 25 strains were grouped in 20 clusters. The patients they came from were from different parts of Croatia, while the number of Medimurje natives in these clusters varied between 1 and 3. A relatively high percentage of strains of unique genotype pointed to a relatively low degree of recent transmission. The results of molecular epidemiology analysis as part of monitoring the routes of tuberculosis transmission, showed the efficiency of counter epidemic measures by detection of unexpected routes of transmission and by identification of strains present in a given community, which more often than others cause disease.