SEROTYPES OF SHIGELLA FLEXNERI FOUND IN CHILDREN IN MEXICO CITY*
JORGE OLARTE, EMMA GALINDO AND SAMUEL B. FORMAL
Laborator~ of Intestinal Bacteriology, Hospital
Infantil, Mexico,
D. F., and the Division of Immunology, Walter Reed Army Institute of Research, Washington, D. C.Previous studies (1) have shown that or- ganisms belonging to the genus Shigella are the most common bacteria1 pathogens found in children over six months old with gastroen- teritis, in Mexico City. Shigella Jlexneri has been the most prevalent species isolated in this city (l-3). The purpose of this paper is to report the incidence of the various sero- types of Sh. Jllezneri isolated from children in Mexico City during the period from 1953- 1957.
MATERIAL AND METHODS
Children with gastroenteritis admitted to the Hospital Infantil in Mexico City served as the source of al1 cultures. Standard pro- cedures were used in the isolation, identifica- tion, and serologic typing of the bacteria.
RESULTS
A total of 159 strains of Sh.
JEexneri were
collected from diierent individuals with gastroenteritis during the period from 1953 to 1957. The incidence of Shigella JEexneri serotypes appears in Table 1, and, as can be seen, Sh. Jlexneri 2it was by far the most common type encountered.DISCUSSION
Shigeíla jlexneri 2a was the most common Flexner serotype found in individuals ad- mitted to the Children’s Hospital in Mexico City between 1953 and 1957. This single serotype accounted for 53 per cent of the total number of cultures isolated of this species. In the neighboring country of Guatemala, Beck et al. (4) found that Sh. jlexneri 2a made up only 4.6 per cent of the Shigella Group B cultures isolated by them,
* Received for publication on May 12, 1959.
and Floyd (5) observed that while Sh. Jlex- neri 2a is common in Egypt, it is by no means the predominant Flexner serotype. Since our sampling was limited to the Hospital In- fantil, it is not known whether a similar dis- tribution of jlexneri serotypes would be en- countered if a random sample were made of the city’s population; nor is it known whether Sh. JEexnerz’ 2a predominates in other areas of Mexico.
There is a high prevalence of Sh. Flez- neri 2 in llapan. Before the end of World War II, the predominant Flexner serotype in that country was Sh. Jlexneri 2a; serotype 2b was rarely seen (6). Thereafter, a change occurred. By 1951 Sh. Jlexneri type 2 still accounted for 70 per cent of the group B dysentery strains isolated, but instead of being a rare occurrence, type 2b made up over 50 per cent of the Sh. jlexneri type 2
TABLE l.-Incidence of the various serotypes of Shigella JEexneri found in Mexico City.
TYP~ la Ib 2a 2b 3 4 4a 4b 5 6 X Y Total.
Number of strains isolated during the following years
1 -- -- : .9X3 - 5 14 2 3 1 2 3 1 - 31 193 1 8 2 1 - 12 - 195: - 19 2 4 5 1 1 2 - 34 - 1956 _- 2 2 23 3 9 1 1 4 - .- 45 - 19% - 4 21 1 3 2 6 37 Total
6 3.5 8 5.0 85 53.0 6 3.5 7 4.0 20 12.5
4 2.5
1 0.5
2 1.0
13 8.0 4 2.5 3 2.0 159
1
.-
-
33 cent
of tota1
508 BOLETIN DE LA OFICINA
cultures (7). With the great increase in world-wide travel that has taken place, it will be interesting to observe whether similar shifts occur in other countries. It is to be noted that there has been no suggestion of change in the frequency of type 2a in the course of this study.
SANITARIA PANAMERICANA
SUMMARY
A survey was made to determine the dis- tribution of Xhigella jtexneri serotypes in
Mexican children with gastroenteritis. Out of a total of 159 strains of Xh. Jlexneri that
were isolated, 85 (53 per cent) were Xh. Jlexneri 2a. The possible epidemiological
significance of this finding is discussed.
REFERENCES
(1) Ola&, J.; Ramos-Alvarez, M., and Galindo, tral America. 1. Preliminary findings on
E.: Isolation of Shigella, Salmonella and cultural surveys of normal population enteropathogenic E. coli from the rectal groups in Guatemala, Am. Jour. Trop. Med. swabs of 802 sporadic cases of diarrhea, Bol. Hyg., 6:62-71, 1957.
Med. Hosp. Infant. Mex., 14:263-268, 1957. (5) Floyd, T. M.: The incidence of Shigella or- (2) Zozaya, E., and Villanueva, E. : Clasificación ganisms in a group of Egyptian village
serológica, según los tipos de Andrews e children, ilm. Jour. Trop. Med. Hyg., 3:294- Inman de Shigella paradysenteriae aisladas 302, 1954.
en la ciudad de México, Rev. Inst. Sal&. y (6) Fukumi, H.; Nakaya, R.; Nakayama, T., and Enf. Trop., 4:127-137, 1943. Sayama, E.: On the distribution of Shigella (3) Olarte, J., and Varela, G.: Clasificación de 626 jlexneri type 2a and 2b in Japan, Japan.
cultivos de ShigeZEa aislados de niños con Med. Jour., 4:33-36,1957.
diarrea en la Ciudad de México, Rev. Inst. (7) Nakaya, R.; Nakayama, T.; Sayama, E., and Salub. Enf. Trop., 13:65-69, 1953. Fukumi, H.: Shigella type distribution in (4) Be&, M. D.; Muñoz, J. A., and Scrimshaw, Japan in 1951, Jap. Jour. Med. Sci. Biol.,
N. S.: Studies on diarrheal diseases in Cen- 5:421-423, 1952.
FRECUENCIA DE SEROTIPOS DE SH. FLEXNERI EN NIÑOS DE LA CIUDAD DE MEXICO (Resumen)
Se estudió la distribución de los diversos sero- flelneri aisladas durante los años de 1953 a 1957,
tipos de Shigella Jlexneri encontrados en niños 85 (53%) correspondieron al tipo Xh. jlexneri Za.
con gastroenteritis atendidos en el Hospital Se discute el significado epidemiológico que este
