Multiresistant Shigella infections in Bangladesh

Prevalence and Antibiotic Resistant Shigellae among Primary School Children in Urban Calabar, Nigeria

In a recent study, involving the examination of 593 stool samples obtained from randomly selected children from three primary schools in Calabar, Shigella spp. were isolated from 123 (20.7%) of the samples. The infection rate was highest among the younger children with (64.2%) 79/123 of the isolates coming from children under 10 years of age. Infection rate was comparable among boys and girls ( p=0.1). Only two species of Shigella were isolated viz: Shigella flexneri 12.0% (71/593) and Shigella sonnei 8.8% (52/593), in this study. The infection rate was highest in the Government Public Primary school, which also had the highest ratio of pupils per toilet. In all, 24 (19.5%) of the isolates were sensitive to all of the nine antimicrobial agents tested while 67 (54.5%) were resistant to two or more antibiotics. The data generated from this study show that there is a high infection rate of shigellosis among primary school children in this study area and calls for better health education, improved and sustainable sanitation and provision of more functional toilets with running water in the primary schools. Asia Pac J Public Health 2004; 16(1): 41-44.

Changing species distribution and antimicrobial susceptibility pattern of Shigella over a 29-year period (1980-2008)

We studied changes in species distribution and antimicrobial resistance patterns of Shigella during 1980-2008, using the Diarrhoeal Diseases Surveillance system of Dhaka Hospital of ICDDR,B. In hospitalized patients Shigella prevalence decreased steadily from 8-12% in the 1980s to 3% in 2008. Endemic S. flexneri was the most commonly isolated species (54%). Epidemic S. dysenteriae type 1 had two peaks in 1984 and 1993, but was not found after 2000, except for one case in 2004. The therapeutic options are now limited: in 2008 a total of 33% of S. flexneri were resistant to ciprofloxacin and 57% to mecillinam. In the <5 years age group, severely underweight, wasted and stunted children were more at risk of shigellosis compared to well-nourished children (P<0·001). Although hospitalization for Shigella diarrhoea is decreasing, the high levels of antimicrobial resistance and increased susceptibility of malnourished children continue to pose an ongoing risk.

Treatment of infectious diarrhea in children

Diarrheal diseases remain an important cause of childhood morbidity and death in developing countries, although diarrheal deaths have significantly declined in recent years, mostly due to successes in the implementation of oral rehydration therapy (ORT), which is the principal treatment modality. Diarrhea may occur for varied reasons; however, most episodes of diarrhea in developing countries are infectious in origin. Three clinical forms of diarrhea (acute watery diarrhea, invasive diarrhea, and persistent diarrhea) have been identified to formulate a management plan. Acute diarrhea may be watery (where features of dehydration are prominent) or dysenteric (where stools contain blood and mucus). Rehydration therapy is the key to management of acute watery diarrhea, whereas antimicrobial agents play a vital role in the management of acute invasive diarrhea, particularly shigellosis and amebiasis. In persistent diarrhea, nutritional therapy, including dietary manipulations, is a very important aspect in its management, in addition to rehydration therapy. Rehydration may be carried out either by the oral or intravenous route, depending upon the degree of dehydration. Oral rehydration salts (ORS) solution (World Health Organization formula) is recommended for ORT. Intravenous fluid is recommended for initial management of severe dehydration due to diarrhea, followed by ORT with ORS solution for correction of ongoing fluid losses. Antimicrobial therapy is beneficial for cholera and shigellosis. Antiparasitic agents are indicated only if amebiasis and giardiasis are present. Appropriate feeding during diarrhea is recommended for nutritional recovery and to prevent bodyweight loss. Antidiarrheal agents do not provide additional benefit in the management of infectious diarrhea. Although some probiotics have been shown to be beneficial in the treatment of acute diarrhea due to rotavirus, their use in the treatment of diarrhea is yet to be recommended, even in developed countries. The children of developing countries might benefit from zinc supplementation during the diarrheal illness, but its mode of delivery and cost effectiveness are yet to be decided.

Treatment of infectious diarrhea in children

Diarrheal diseases remain an important cause of childhood morbidity and death in developing countries, although diarrheal deaths have significantly declined in recent years, mostly due to successes in the implementation of oral rehydration therapy (ORT), which is the principal treatment modality. Diarrhea may occur for varied reasons; however, most episodes of diarrhea in developing countries are infectious in origin. Three clinical forms of diarrhea (acute watery diarrhea, invasive diarrhea, and persistent diarrhea) have been identified to formulate a management plan. Acute diarrhea may be watery (where features of dehydration are prominent) or dysenteric (where stools contain blood and mucus). Rehydration therapy is the key to management of acute watery diarrhea, whereas antimicrobial agents play a vital role in the management of acute invasive diarrhea, particularly shigellosis and amebiasis. In persistent diarrhea, nutritional therapy, including dietary manipulations, is a very important aspect in its management, in addition to rehydration therapy. Rehydration may be carried out either by the oral or intravenous route, depending upon the degree of dehydration. Oral rehydration salts (ORS) solution (World Health Organization formula) is recommended for ORT. Intravenous fluid is recommended for initial management of severe dehydration due to diarrhea, followed by ORT with ORS solution for correction of ongoing fluid losses. Antimicrobial therapy is beneficial for cholera and shigellosis. Antiparasitic agents are indicated only if amebiasis and giardiasis are present. Appropriate feeding during diarrhea is recommended for nutritional recovery and to prevent bodyweight loss. Antidiarrheal agents do not provide additional benefit in the management of infectious diarrhea. Although some probiotics have been shown to be beneficial in the treatment of acute diarrhea due to rotavirus, their use in the treatment of diarrhea is yet to be recommended, even in developed countries. The children of developing countries might benefit from zinc supplementation during the diarrheal illness, but its mode of delivery and cost effectiveness are yet to be decided.

Antimicrobial susceptibilities and beta-lactamase production of Shigella isolates in Crete, Greece, during the period 1991-1995

The susceptibility to 11 antibiotics was determined for 52 strains of Shigella isolated from patients with diarrheal disease in Crete, Greece, during the period 1991-1995. Forty-six percent of the isolates were resistant to ampicillin, 48% to tetracycline, 44.2% to chloramphenicol, and 28.8% to cotrimoxazole. Shigella flexneri was more resistant than S. sonnei to ampicillin (82 vs 4.3%), to tetracycline (82 vs 8.7%) and to cotrimoxazole (42.8 vs 13%). Overall, 82% of all S. flexneri isolates were resistant to the three or four antimicrobial agents tested. The beta-lactamases produced by shigellae were identified by isoelectric focusing and were found to be OXA-1, TEM-1, and a low-level beta-lactamase with a pI>8. The results from the present study, which is the first carried out in Crete, emphasize the need for continuous surveillance of resistance and control of antibiotic usage.

Shigella infections

Shigella dysentery is a major public-health problem in many tropical areas. Despite improvements in water supplies and sanitation, it continues to be a disease of poor rural and urban communities and in populations affected by migration and crowding following disasters. Pathogenesis is due to colonic invasion, endotoxin, and, in Shigella dysenteriae 1, shiga toxin. As well as the local manifestations of dysentery, systemic complications include convulsions, haemolytic-uraemic syndrome, hyponatraemia and hypoglycaemia. The spread of shigella infection is most commonly person-person, although water and food-borne outbreaks have been reported. Since 1970, multiple antimicrobial resistance, particularly in Sh. dysenteriae 1, has complicated strategies for management. Multiply resistant strains have occurred in Latin America, Central Africa and southern and south-eastern Asia. No vaccines are currently available, and prevention and control will depend on public-health improvements and improved case management.

Shigellosis in Mozambique: the 1993 outbreak rehabilitation--a follow-up study

In this paper we describe a dysentery outbreak in Mozambique during 1993. A total of 47,483 cases and 199 deaths were reported, with an incidence rate of 292.5/100,000 and a fatality rate of 0.25% for the whole country. Of the 144 districts in the country 123 were affected: those situated along the principal communications routes and corridors had high incidence rates, up to 3308/100,000. All the provincial capitals were affected with incidence rates between 59.6 and 4381.8/100,000. Shigella dysenteriae type 1 was identified as the aetiological agent. This strain was sensitive to nalidixic acid, cephalosporins, gentamicin and kanamycin, and resistant to tetracyclines, trimethoprim, chloramphenicol, ampicillin, sulphisoxazole, cotrimoxazol and erythromycin. This is the first dysentery epidemic caused by S. dysenteriae type 1 reported in Mozambique. The epidemic still continues. Population movements after the war, poor levels of sanitation and poverty contributed to the gravity of the outbreak.

Water sources and environmental transmission of multiply resistant enteric bacteria in rural Bangladesh

The role of different water sources in the spread of multiply resistant enteric bacteria was investigated in rural Bangladesh. The prevalence of resistance to commonly used antimicrobial agents in the faecal flora of village children and the water quality and prevalence of resistance in village water sources were studied. Most of the children studied (81%) had multiply resistant faecal coliform bacteria, i.e. bacteria resistant to at least three antimicrobials. Although tubewells provided water with low faecal coliform counts, 62% of household storage pots contained water with moderate to high counts. Most of the storage pots (76%) and each of the river and pond sites tested contained multiply resistant isolates. Contamination of water within the household, and the widespread distribution of resistant coliforms in the environment, contribute to the high prevalence of multiply resistant enteric flora in the community. These findings are of importance in understanding the spread of multiply resistant enteric pathogens.

Increasing antimicrobial resistance of Shigella isolates in Israel during the period 1984 to 1992

Recent (1984 to 1992) trends in the antimicrobial resistance of Shigella isolates in Israel were studied by analyzing the results of 106,000 stool cultures, 3,511 of which yielded Shigella spp. Over the study period, resistance to trimethoprim-sulfamethoxazole (TMP-SMX) increased from 59 to 92% (P = 0.0038) and that to ampicillin increased from 13 to 86% (P < 0.0001). Resistances to nalidixic acid, chloramphenicol, and broad-spectrum cephalosporins remained low. Shigella sonnei, which currently accounts for 90% of Shigella infections, was more resistant than S. flexneri to TMP-SMX (81 versus 57%, P < 10(-6)), ampicillin (42 versus 32%, P < 10(-5)), and tetracycline (38 versus 28%, P < 10(-5)). S. boydii and S. dysenteriae were relatively rare. Seasonality in antimicrobial resistance was found, with summer isolates being less resistant to TMP-SMX, ampicillin, or both than isolates obtained over the rest of the year (P < 10(-5)). We conclude that the resistance of shigellae, especially S. sonnei, to TMP-SMX and ampicillin is increasing to approximately 90%. Resistance should be recorded locally, and empiric therapy for suspected shigellosis should be changed accordingly.

High frequency of strains multiply resistant to ampicillin, trimethoprim-sulfamethoxazole, streptomycin, chloramphenicol, and tetracycline isolated from patients with shigellosis in northeastern Brazil during the period 1988 to 1993

The occurrence and antimicrobial resistance pattern of Shigella isolates obtained from persons in community and hospital-based studies of diarrhea and matched controls in northeastern Brazil were studied. The isolation rate of Shigella spp. from patients with diarrhea during 1988 to 1993 varied from 4.5% (26 of 575) for the urban community of Gonçalves Dias to 6.7% (12 of 179) and 5.9% (7 of 119) for Hospital Infantil and Hospital Universitário, respectively. Of the 55 Shigella isolates (45 from patients with diarrhea, 8 from controls, and 2 undetermined) 73% (40 of 55) were Shigella flexneri, 16% (9 of 55) were S. sonnei, 7% (4 of 55) were S. boydii, and 4% (2 of 55) were S. dysenteriae. Of 39 S. flexneri strains, over half were resistant to ampicillin, trimethoprim-sulfamethoxazole, or both. Over 64% were resistant to streptomycin, chloramphenicol, and tetracycline. Overall, 82% of all S. flexneri isolates were resistant to four or more antimicrobial agents tested. As elsewhere, in the northeast of Brazil, ampicillin and trimethoprim-sulfamethoxazole are no longer reliable for treatment of S. flexneri infection. Most Shigella strains were resistant to four or more antimicrobial agents. Nalidixic acid was still useful for treatment of infections due to S. flexneri.

Acute bacterial diarrhoea in the emergency room: therapeutic implications of stool culture results

Empiric treatment with ciprofloxacin and norfloxacin has been recommended recently for patients with acute diarrhoeal disease. In a retrospective 6-month study period the results of stool cultures from 209 patients with acute diarrhoea admitted to the emergency room were analysed. Seventy-eight cultures (37%) were positive for one or more bacteria. Shigella was the most commonly isolated pathogen (68%). Shigella sonnei comprised 72% and Shigella flexneri 19% of all the bacterial isolates. While no antimicrobial resistance to ciprofloxacin was found for both Shigella species, only 36 and 26% of the Shigella isolates were sensitive to ampicillin and trimethoprim-sulfamethoxazole (TMP-SMZ), respectively. These findings point out to the emergence of drug resistance to commonly used antimicrobial drugs. Shigella's high sensitivity to the newer quinolones should make this the treatment of choice for the very sick patient, although physicians should be cautioned to the fact that indiscriminate use of this drug could result in the emergence of resistance similar to that noted with ampicillin and TMP-SMZ.

Comparison of pivmecillinam and nalidixic acid in the treatment of acute shigellosis in children

The efficacy of oral pivmecillinam was compared with nalidixic acid in the treatment of acute shigellosis in children 1-8 years of age. In a double-blind trial we studied 80 comparable children with bloody diarrhoea of less than 3 days' duration. Shigella spp. was isolated in 71 children. Patients were randomly assigned to receive either pivmecillinam, 50 mg/kg.day, or nalidixic acid, 60 mg/kg.day, both given orally for 5 days. The stool frequency decreased progressively in both treatment groups. Nalidixic acid failed to eradicate Shigella species in 10 patients, compared with three in the pivmecillinam group (p = 0.04). Similarly, clinical failure was observed in 11 of 37 patients receiving nalidixic acid and in 2 of 26 patients infected with nalidixic acid-susceptible strains as against none in the group receiving pivmecillinam. The results suggest that pivmecillinam given orally was, in fact, more effective than nalidixic acid in the treatment of acute shigellosis in children, particularly when the resistant strains are taken into account.

A randomized, double-blind study comparing cefixime and trimethoprim-sulfamethoxazole in the treatment of childhood shigellosis

We compared the clinical and bacteriologic response of 5-day treatment with cefixime, 8 mg/kg per day, with the response to trimethoprim-sulfamethoxazole (TMP-SMX), 10-50 mg/kg per day, the currently recommended therapy. Of the assessable children with acute, culture-proven shigellosis, 38 received cefixime and 39 received TMP-SMX. Pretreatment data on the two study groups were similar. In the first group, all isolates were susceptible to cefixime; in the TMP-SMX group, 32 isolates were resistant and 7 were susceptible to TMP-SMX. Clinical response (day 5) showed cure, improvement, and failure in 89%, 8%, and 3%, respectively, of the cefixime group, and in 25%, 44%, and 31%, respectively, of the TMP-SMX-resistant group (p < 0.001). Bacteriologic cure (day 3) occurred in 78% and 23% of the cefixime and TMP-SMX-resistant groups, respectively (p < 0.001). Clinical or bacteriologic relapse (day 12) was infrequent in both groups. The response to treatment of the cefixime and the TMP-SMX-susceptible groups was similar. No significant side effects were noted. We conclude that cefixime is superior to TMP-SMX in the treatment of suspected shigellosis in areas with a high rate of resistance to TMP-SMX.

The prevalence and genetics of resistance to commonly used antimicrobial agents in faecal Enterobacteriaceae from children in Bangladesh

The present study was undertaken to investigate the occurrence of antibiotic resistance in enteric flora in 64 children in rural Bangladesh over a 12-month period. The antibiotic resistance pattern of the isolates varied throughout the year and multiple resistance was highest during the post monsoon period. Seventy-three percent of children had isolates resistant to more than three antibiotics throughout the year. Resistance to streptomycin was highest (78%), followed closely by ampicillin (72%). Of 82 multiply resistant isolates, plasmid DNA was demonstrated in 75%. Plasmid sizes ranged between 3.7 and 110 MDa, the commonest plasmids were of 70, 98 and 110 MDa. Complete or partial resistance was transferred by conjugation from 52% of the isolates, most frequently by single plasmids. The commonest plasmid incompatibility group was F11-A (46%) followed by incompatibility group P (22%). Plasmids of molecular weight 98 MDa most often hybridized with F11-A probes and those of 110 MDa with H11 probes. Plasmids from 10 transconjugants were digested with restriction enzymes and digest patterns demonstrated the presence of common plasmids. The findings show that there is a diverse, and mobile, genetic pool of resistance genes in this rural community. This genetic reservoir is potentially transferable to enteric pathogens, with major implications for public health and diarrhoeal disease control.

Multiresistant Shigella species from African AIDS patients: antibacterial resistance patterns and application of the E-test for determination of minimum inhibitory concentration

The antibacterial resistance pattern and minimum inhibitory concentrations (MIC) of 25 Shigella flexneri, 5 S. boydii, 8 S. sonnei, and 3 strains of S. dysenteriae type 2 isolated from Kenyan prostitutes with bacillary dysentery and AIDS were determined, and the applicability of the E-test for MIC determination evaluated. All strains were resistant to > or = 3 of 9 different antibacterial agents tested. All strains were resistant to tetracycline and erythromycin, 95% to trimethoprim/sulfonamide, 93% to streptomycin, 54% to ampicillin, 39% to chloramphenicol, 2% to nalidixic acid and none to gentamicin and ciprofloxacin. Six different resistance patterns were observed. The most common pattern was resistance to tetracycline, erythromycin, trimethoprim/sulfa and streptomycin (39%). The E-test was shown to be well-suited for susceptibility testing of multiresistant Shigella spp.; the reproducibility was excellent and the correlation with the microtiter dilution method and the disk diffusion method were 98% in both instances. The MIC measured with E-test and the microdilution method were within +/- 1 dilution step for 94.4% of the combinations tested.

Comparative efficacy of ceftriaxone and ampicillin for treatment of severe shigellosis in children

In a prospective randomized open study, ceftriaxone, 50 mg/kg per day, was compared with ampicillin, 100 mg/kg per day, both given for a period of 5 days, for the treatment of 40 children whose mean (+/- SD) age was 4.5 +/- 3.2 years and who had severe dysentery caused by Shigella organisms. Twenty patients were treated with ceftriaxone and 20 with ampicillin. Both drugs were initially given intravenously for a period of 1 to 2 days and were continued intramuscularly, in the case of ceftriaxone, or orally, in the patients receiving ampicillin. All Shigella organisms isolated were susceptible to ceftriaxone; 28% were resistant to ampicillin. The diarrhea persisted for a mean (+/- SD) period of 2.5 +/- 1.0 days in the ceftriaxone-treated patients versus 6.8 +/- 6.3 days in the ampicillin-treated patients (p less than 0.005). At the end of the 5 days of therapy, stool cultures for Shigella organisms were negative in 12 (60%) of the 20 patients from the ampicillin group and in all the children (100%) from the ceftriaxone group (p less than 0.001). Bacteriologic relapses were observed in eight (40%) of the patients treated with ampicillin but in none of the children treated with ceftriaxone (p less than 0.001). In instances of clinical or bacteriologic failure in the ampicillin group, retreatment was instituted in most of the cases with ceftriaxone; persistent clearing of the Shigella organisms from the stool was finally achieved after a mean (+/- SD) period of 11.75 +/- 9.4 days after therapy was started, as compared with 1.85 +/- 0.6 days in the ceftriaxone-treated patients (p less than 0.001). We conclude that in children with severe shigellosis, treatment with ceftriaxone for 5 days is effective and better than use of ampicillin for clinical cure and eradication of the Shigella organisms from the stool.

Therapy for shigellosis. I. Randomized, double-blind trial of nalidixic acid in childhood shigellosis

We compared nalidixic acid, 55 mg/kg/day, with ampicillin, 100 mg/kg/day, both given orally for 5 days, in the treatment of children with dysentery caused by shigellosis. All patients entered into the study had illness of less than 72 hours' duration and no prior allopathic drug therapy. Treatment was randomized and administered in double-blind fashion. Patients initially treated with ampicillin who were infected with a Shigella strain resistant to ampicillin were considered as a separate group (ampicillin-R). All isolates were susceptible to nalidixic acid. Similar percentages of patients treated with nalidixic acid (26/32, 81%) and with ampicillin (17/22, 77%) were clinically cured by the end of therapy; the rate in ampicillin-R (3/14, 21%) patients was significantly lower (p less than 0.001). Stool frequency in patients treated with nalidixic acid was significantly less than for ampicillin-treated or ampicillin-R patients during the final 3 study days. All patients treated with nalidixic acid and ampicillin had Shigella eradicated from their stool by day 3, compared with 77% (10/13) of ampicillin-R patients (p less than 0.05, ampicillin-R vs nalidixic acid or ampicillin). We conclude that nalidixic acid is an effective alternative to ampicillin in the treatment of shigellosis caused by nalidixic acid-susceptible strains.

Comparison of norfloxacin and nalidixic acid for treatment of dysentery caused by Shigella dysenteriae type 1 in adults

A severe epidemic of dysentery began late in 1979 in northeast Zaire and spread to Rwanda, Burundi, and Tanzania. The epidemic strain is a multiply resistant Shigella dysenteriae type 1, which acquired resistance against trimethoprim and more recently against nalidixic acid in the course of the epidemic. A comparative open trial in Rwandan adults with Shiga dysentery involved 18 patients treated with norfloxacin at 400 mg twice daily and 12 patients treated with nalidixic acid at 1 g three times daily for 5 days. All isolates showed in vitro susceptibility to both drugs. Though norfloxacin eliminated Shigella organisms from stools more rapidly than nalidixic acid, its clinical superiority did not reach the level of significance. Norfloxacin is a promising drug and is more effective than nalidixic acid in the treatment of multiresistant shigellosis.