Phage types of Salmonella typhi isolated in Malaysia over the 10-year period 1970–1979

Abstract

SUMMARYThe pattern of phage types of 2553 strains of Salmonella typhi isolated over the 10-year period 1970-9 was studied. During the period 29 different phage types were encountered, not including the categories of 'untypable strains', 'degraded Vi-strains' and Vi negative strains. For the period as a whole, the commonest phage types encountered were A (20-9 %), E1 (14-8 %), D1 (10-3%), degraded Vi positive strains (10-3 %), untypable Vi strains (7 3 %), C4 (7'1 %), D2 (4 4%), E2 (3'9 %) and type 25 (2-6 %). There were phage types which appeared in the early years of the period and then disappeared (types B2, D. and D1-N). Others only made their appearance in recent years (K1 and 53). Notable differences were also seen in the predilection of some phage types for certain geographical areas.

Epidemiology of typhoid fever in Singapore

“…The predominant phage types among indigenous isolates in the 1970's [29] were BI, Dl and A and continued to be so in the 1980's while the predominant phage types in the neighbouring countries of Malaysia were A, El and Dl [30] and Indonesia were I + lV, D2 and A [31], with phage type A being common in all three countries. Since chloramphenicol resistance in S. typhi was reported in England in 1950 [32], it has spread eastwards to Greece, Israel, Africa and India in the 1960's [33][34][35][36][37] and to Vietnam, Thailand, Indonesia and Malaysia in the 1970's [38][39][40][41].…”

Case Report: Near-Fatal Intestinal Hemorrhage and Acute Acalculous Cholecystitis due to Vi-Negative and Fluoroquinolone-Insensitive Salmonella enterica Serovar Typhi Infection: A Rare Entity

“…Vi capsular polysaccharide, which plays an important role in conferring resistance to the killing effect of serum, is a major virulence factor of S. Typhi (8). Despite the character of the Vi antigen as a distinguishing feature of S. Typhi, Vi-negative isolates have been reported in several countries (9,17). Furthermore, there have been reports of typhoid outbreaks caused by Vi-negative S. Typhi (17), but the clinical symptoms were not described.…”

“…Vi capsular polysaccharide is a major virulence factor and it is also a distinguishing feature of S. Typhi. It can increase the infectivity (7) of S. Typhi and the severity (8) of disease; however, Vi-negative isolates have been known for several decades (9). Antimicrobial-resistant S. Typhi has been a global threat with the wide spread of multidrugresistant (MDR) strains, defined as resistant to the traditional first-line antibiotics (ampicillin, chloramphenicol, and co-trimoxazole) since the early 1990s, and the emergence of extensively drug-resistant (XDR) strains, with resistance to the traditional first-line antibiotic fluoroquinolones and the third-generation antibiotic cephalosporins in the last 5 years (10).…”

Salmonella

“…Vi phage typing is now the internationally accepted method for differentiation of Typhi and the scheme is used in specialized WHO-approved reference centers world wide. The types most widespread and abundant throughout the world are E1 and A, followed by B2, C1, D1, and F1; other less common types are found that are prevalent temporarily or permanently in some countries only, or even within certain geographical areas within a country (Jegathesan 1983). The value of the Vi phage typing method was demonstrated, for example, by investigations of the sudden appearance in the UK in 1990 of multiresistant strains belonging to Vi phage type M1 and associated with patients recently returned from Pakistan ).…”