Co-trimoxazole-resistant Shigella dysenteriae type 1 outbreak in a family in Bangladesh

Efficacy and potential of phage therapy against multidrug resistant Shigella spp

Shigella-infected bacillary dysentery or commonly known as Shigellosis is a leading cause of morbidity and mortality worldwide. The gradual emergence of multidrug resistant Shigella spp. has triggered the search for alternatives to conventional antibiotics. Phage therapy could be one such suitable alternative, given its proven long term safety profile as well as the rapid expansion of phage therapy research. To be successful, phage therapy will need an adequate regulatory framework, effective strategies, the proper selection of appropriate phages, early solutions to overcome phage therapy limitations, the implementation of safety protocols, and finally improved public awareness. To achieve all these criteria and successfully apply phage therapy against multidrug resistant shigellosis, a comprehensive study is required. In fact, a variety of phage-based approaches and products including single phages, phage cocktails, mutated phages, genetically engineered phages, and combinations of phages with antibiotics have already been carried out to test the applications of phage therapy against multidrug resistant Shigella. This review provides a broad survey of phage treatments from past to present, focusing on the history, applications, limitations and effective solutions related to, as well as the prospects for, the use of phage therapy against multidrug resistant Shigella spp. and other multidrug resistant bacterial pathogens.

The role of shigella spp. in childhood diarrhoea in Iran and their antibiotic resistance

The incidence of shigellae was measured in 445 children with diarrhoea in Sanandaj, Kordestan, and 715 in Tehran during a 1-year study. 18 (4%) patients in Sanandaj and 41 (5.7%) patients in Tehran were positive for various shigella species. Sh. boydii (7 strains) and Sh. sonnei (25 strains) were the commonest species in Sanandaj and Tehran respectively. Among the isolates from Sanandaj the highest resistance was to tetracycline (55.5%), whereas in Tehran it was to sulfamethoxazole/trimethoprim (68.3%).

Plasmid characterization of drug-resistant Shigella dysenteriae 1 from an epidemic in Central Africa

A widespread epidemic of severe dysentery in Zaire and neighbouring Central African countries was caused by a multiply drug-resistant strain of Shigella dysenteriae 1. Early isolations were resistant to ampicillin, chloramphenicol, streptomycin, sulphonamides and tetracyclines (R-type = ACSSuT). Later in the epidemic strains resistant to trimethoprim (Tm) became prevalent and a few strains resistant to kanamycin (K) or nalidixic acid were also isolated. All resistances except nalidixic acid were encoded by plasmids of incompatibility groups X (ACT) or I1 (ACSSuTTm) and the epidemic strain also carried an SSu plasmid and a number of cryptic plasmids. The Inc X plasmid from this epidemic is the same as that in Sh. dysenteriae 1 strains isolated in Somalia in 1976 whereas the epidemic strains from the Shiga outbreaks in Central America, 1969 to 1971, and Sri Lanka, 1979, carried plasmids of group B. This epidemic demonstrates that when a multiresistant strain includes resistance to trimethoprim, nalidixic acid is a suitable alternative therapeutic agent.

Treatment of severe bacillary dysentery with trimethoprim alone

Trimethoprim (300 mg twice daily for five days) and co-trimoxazole (two tablets twice daily for five days) were compared as treatment for adult patients with severe shigellosis in Rwanda. Excellent bacteriological and clinical results were obtained with both regimens, with the exception of patients infected with a trimethoprim-resistant strain of Shigella dysenteriae type 1. Since only 20 patients were investigated, the conclusions of our study do not reach statistical significance. Before recommending trimethoprim as standard therapy for shigellosis, the validity of our results should be tested in a larger trial and the long-term ecological consequences of monotherapy carefully monitored.

Drug resistance in Shigella dysenteriae, S flexneri and S boydii in England and Wales: increasing incidence of resistance to trimethoprim

A total of 2753 strains of shigella belonging to subgroups A, B, and C that were isolated from patients in England and Wales during the period from 1979 to mid-1983 were studied. Of these, 1690 (61%) were from patients recently returned from abroad or in contact with recent travellers, and 760 (45%) of these affected travellers from the Indian subcontinent. The number of strains resistant to sulphonamides and streptomycin remained at a high level throughout (average 76% and 72% respectively). Resistance to tetracyclines, ampicillin, and chloramphenicol rose, reaching 63%, 51%, and 48%, respectively, in 1982. Strains resistant to trimethoprim were seen in substantial numbers for the first time and increased from 1.3% of all strains in 1979 to 9.9% in 1982 and 16.8% in the first half of 1983. The proportion of patients with recent foreign contact was notably smaller among those with strains resistant to trimethoprim than among those with strains sensitive to trimethoprim. The increase in resistance to trimethoprim might partly result from the use in Britain of compounds containing trimethoprim for the treatment of shigellosis.