Identification of Serotypes and Assessment of' Multiple Drug Resistance In 360 Shigella Isolates
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Date
1980-06
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Addis Ababa University
Abstract
Three hundred and sixty urban and rural Shigellae isolates
were analysed in respect to serogrouping, serotyping, biochemotyping
and drug resistance. S. flexneri (50.55%) was most common, followed
by £. dysenteriae (32.78%), ~. b~£ii (11.39%) and £. sonnei (5.28%).
Isolation rates of £. ftysenteriae, £. flexneri and fl. sonnei were
eomparablo in rural and urban areas, except for fl. boydii which is
more common in urban areas (significant at P=0.05).
Out of the thirty-two known Shigella serotypes, twenty-two
were identified in this study (i.e. fl. dysenteria~ 1,2, 3, 4, 6, 7;
,2. flexneri I, 2, 3, 4, 6; E.. boydii 1, 2, 3, 4, 5, 8, 9, 10, 12, 111;
and E.. sonnei). Urban isolates were represented by 22 serotypes
compared to only 11 in rural areas. E.. dysenteriae serotypo 1
(Shiga's bacillus) Was more common in rural areas (34.48%) than in
urban areas (17.22%), and this difference is· significant (P=O,05).
Ninteen patterns of drug resistance were observed, with TSu
(21.11%), TCACbSSu (19.72%) and TSSu (12.50%) being comparatively
more common. There \'Iere nine patterns of drug resistance in
8erogroup A, 12 patterns in ll, 8 patterns in C, and 5 patterns in D.
TCACbSSu pattern (53.39%) in serogroup A, TSu (41.76%) in B, and
TSSu (26.31%) in D Vlere observed. lIitnin serogroup A, 81.82% of
fl' dysenteriae serotype 1 was associated with the TCACbSSu pattern.
There were Ii patterns of resistance in urban areas compared to 10
in rural areas. The prominence of TCACbSSu pattern in rural areas
was related to the Iligh isolation rate of fl. dysenteriae type 1 in
these places. In rural areas, 14.94% of Shigella isolates were
classified as sensitive to all drugs tested, compared to 26.37% in
urban areas and this difference is significant (P=0.05).
Identification of rare biochemotypes included: a) three strains
of mannitol negative ~. flexneri type 6, b) a strain of gas
productng ~. boydii type 14, nnd c) a strain of 'invasive'
~. ££1i (0:164) serologically cross reacting in ~. dysenteriae
serotype 3· antiserum.
Based on the present study, it is recommended that: a) a further
study of Shigella be persued, b) a Shigella reference center be
established, c) an improvement of sanitation be stressed,
d) chemotherapy be discourae;ed and e) a national policy for drug
sale be enacted.
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Biology