Bacterial inhibition by linatine and other hydrazino acids

Target Product Profile and Development Path for Shigellosis Treatment with Antibacterials

Enteric infection with Shigella spp. can lead to symptoms ranging from acute watery diarrhea to sudden, severe dysentery. Approximately 212 000 diarrheal deaths annually are attributed to Shigella with a disproportionate impact in low-resource countries. The impact in under-resourced countries was illustrated by a reanalysis of the Global Enteric Multicenter Study which found that Shigella was the leading pathogen associated with moderate-to severe diarrhea in children under 5 years old. While recent studies have highlighted the burden of the disease, there has been a concurrent reduction in therapeutic options for the treatment of shigellosis as drug resistant strains increase in prevalence. In addition, increasing reports of drug resistant shigellosis cases in the men who have sex with men community confirm that the impact is not limited to low-resource countries. Despite the urgent need for new treatments, a target product profile (TPP) has not been established, and there is no clear development path for antibacterial treatments. To address this troubling concern, this manuscript describes a TPP for antishigellosis small molecule therapeutics and a development path that integrates currently available preclinical and clinical models of Shigella infection.

Options for treating resistant Shigella species infections in children

Infection due to Shigella species remains an important public health problem, especially in developing countries where it remains the most common cause of bloody diarrhea. In the United States (US), 10,000 to 15,000 cases of shigellosis are reported each year in both children and adults. US surveillance data from 2004 has demonstrated increased resistance in Shigella species to first-line antibiotics such as ampicillin and trimethoprim-sulfamethoxazole, with approximately 37% of isolates demonstrating resistance to both ampicillin and trimethoprim-sulfamethoxazole. Since approximately 69% of Shigella infections occur in children younger than 5 years of age, it is important that alternative antibiotics other than typical first-line agents such as ampicillin and trimethoprim-sulfamethoxazole be available to treat Shigella infections in this population. The American Academy of Pediatrics (AAP) recommends cefixime, ceftriaxone, azithromycin, and fluoroquinolones as alternative antibiotics for the treatment of Shigella species infections in children. This paper will review the microbiology, susceptibility, efficacy and safety data of these alternative antibiotics with regard to the treatment of Shigella species infections in children, and will attempt to define the role of each of these agents in the pediatric population.

Antibiotic therapy for Shigella dysentery

BACKGROUND

Shigella dysentery is a relatively common illness and occasionally causes death, worldwide. Mild symptoms are self-limiting but in more severe cases, antibiotics are recommended for cure and preventing relapse. The antibiotics recommended are diverse, have regional differences in sensitivity, and have side effects.

OBJECTIVES

To evaluate the efficacy and safety of antibiotics for treating Shigella dysentery.

SEARCH STRATEGY

In June 2009 we identified all relevant trials from the following databases: Cochrane Infectious Diseases Group Specialized Register; Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2008, issue 4), MEDLINE, EMBASE, LILACS and the metaRegister of Controlled Trials (mRCT). We also checked conference proceedings for relevant abstracts, and contacted researchers, organizations, and pharmaceutical companies.

SELECTION CRITERIA

Randomized controlled trials of antibiotics for Shigella dysentery.

DATA COLLECTION AND ANALYSIS

Four authors, working in pairs, independently assessed trial eligibility, methodological quality, and extracted data. We calculated risk ratios (RR) with 95% confidence intervals (CI) for dichotomous data, and used the random-effects model for significant heterogeneity. We explored possible sources of heterogeneity, when present, in subgroup analyses of participant age and percentage of participants with confirmed Shigella infection.

MAIN RESULTS

Sixteen trials (1748 participants), spanning four decades and with differing sensitivity to Shigella isolates, met the inclusion criteria. Seven were judged to be at risk of bias due to inadequate allocation concealment or blinding, and 12 due to incomplete reporting of outcome data. Limited data from one three-armed trial of people with moderately severe illness suggest that antibiotics reduce the episodes of diarrhoea at follow-up (furazolidone versus no drug RR 0.21, 95% CI 0.09 to 0.48, 73 participants; cotrimoxazole versus no drug RR 0.30, 95% CI 0.15 to 0.59, 76 participants).There was insufficient evidence to consider any class of antibiotic superior in efficacy in treating Shigella dysentery, but heterogeneity for some comparisons limits confidence in the results. All the antibiotics studied were safe. There was inadequate evidence regarding the role of antibiotics in preventing relapses.

AUTHORS' CONCLUSIONS

Antibiotics reduce the duration of Shigella dysentery.Regularly updated local or regional antibiotic sensitivity patterns to different species and strains of Shigella are required to guide empiric therapy. More trials adhering to standard guidelines are required to evaluate the role of antibiotics in the treatment of severe forms of Shigella dysentery and in groups who are at high risk of complications.

Antibiotic therapy for Shigella dysentery

BACKGROUND

Shigella dysentery is a relatively common illness and occasionally causes death, worldwide. Mild symptoms are self-limiting but in more severe cases, antibiotics are recommended for cure and preventing relapse. The antibiotics recommended are diverse, have regional differences in sensitivity, and have side effects.

OBJECTIVES

To evaluate the efficacy and safety of antibiotics for treating Shigella dysentery.

SEARCH STRATEGY

In June 2009 we identified all relevant trials from the following databases: Cochrane Infectious Diseases Group Specialized Register; Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2008, issue 4), MEDLINE, EMBASE, LILACS and the metaRegister of Controlled Trials (mRCT). We also checked conference proceedings for relevant abstracts, and contacted researchers, organizations, and pharmaceutical companies.

SELECTION CRITERIA

Randomized controlled trials of antibiotics for Shigella dysentery.

DATA COLLECTION AND ANALYSIS

Four authors, working in pairs, independently assessed trial eligibility, methodological quality, and extracted data. We calculated risk ratios (RR) with 95% confidence intervals (CI) for dichotomous data, and used the random-effects model for significant heterogeneity. We explored possible sources of heterogeneity, when present, in subgroup analyses of participant age and percentage of participants with confirmed Shigella infection.

MAIN RESULTS

Sixteen trials (1748 participants), spanning four decades and with differing sensitivity to Shigella isolates, met the inclusion criteria. Seven were judged to be at risk of bias due to inadequate allocation concealment or blinding, and 12 due to incomplete reporting of outcome data. Limited data from one three-armed trial of people with moderately severe illness suggest that antibiotics reduce the episodes of diarrhoea at follow-up (furazolidone versus no drug RR 0.21, 95% CI 0.09 to 0.48, 73 participants; cotrimoxazole versus no drug RR 0.30, 95% CI 0.15 to 0.59, 76 participants).There was insufficient evidence to consider any class of antibiotic superior in efficacy in treating Shigella dysentery, but heterogeneity for some comparisons limits confidence in the results. All the antibiotics studied were safe. There was inadequate evidence regarding the role of antibiotics in preventing relapses.

AUTHORS' CONCLUSIONS

Antibiotics reduce the duration of Shigella dysentery.Regularly updated local or regional antibiotic sensitivity patterns to different species and strains of Shigella are required to guide empiric therapy. More trials adhering to standard guidelines are required to evaluate the role of antibiotics in the treatment of severe forms of Shigella dysentery and in groups who are at high risk of complications.

Antibiotic therapy for Shigella dysentery

BACKGROUND

Shigella dysentery is a relatively common illness and occasionally causes death, worldwide. Mild symptoms are self-limiting but in more severe cases, antibiotics are recommended for cure and preventing relapse. The antibiotics recommended are diverse, have regional differences in sensitivity, and have side effects.

OBJECTIVES

To evaluate the efficacy and safety of antibiotics for treating Shigella dysentery.

SEARCH STRATEGY

In June 2009 we identified all relevant trials from the following databases: Cochrane Infectious Diseases Group Specialized Register; Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2008, issue 4), MEDLINE, EMBASE, LILACS and the metaRegister of Controlled Trials (mRCT). We also checked conference proceedings for relevant abstracts, and contacted researchers, organizations, and pharmaceutical companies.

SELECTION CRITERIA

Randomized controlled trials of antibiotics for Shigella dysentery.

DATA COLLECTION AND ANALYSIS

Four authors, working in pairs, independently assessed trial eligibility, methodological quality, and extracted data. We calculated risk ratios (RR) with 95% confidence intervals (CI) for dichotomous data, and used the random-effects model for significant heterogeneity. We explored possible sources of heterogeneity, when present, in subgroup analyses of participant age and percentage of participants with confirmed Shigella infection.

MAIN RESULTS

Sixteen trials (1748 participants), spanning four decades and with differing sensitivity to Shigella isolates, met the inclusion criteria. Seven were judged to be at risk of bias due to inadequate allocation concealment or blinding, and 12 due to incomplete reporting of outcome data. Limited data from one three-armed trial of people with moderately severe illness suggest that antibiotics reduce the episodes of diarrhoea at follow-up (furazolidone versus no drug RR 0.21, 95% CI 0.09 to 0.48, 73 participants; cotrimoxazole versus no drug RR 0.30, 95% CI 0.15 to 0.59, 76 participants).There was insufficient evidence to consider any class of antibiotic superior in efficacy in treating Shigella dysentery, but heterogeneity for some comparisons limits confidence in the results. All the antibiotics studied were safe. There was inadequate evidence regarding the role of antibiotics in preventing relapses.

AUTHORS' CONCLUSIONS

Antibiotics reduce the duration of Shigella dysentery.Regularly updated local or regional antibiotic sensitivity patterns to different species and strains of Shigella are required to guide empiric therapy. More trials adhering to standard guidelines are required to evaluate the role of antibiotics in the treatment of severe forms of Shigella dysentery and in groups who are at high risk of complications.

Treatment of shigellosis with cefixime: two days vs. five days

BACKGROUND

Although the recommended standard course of therapy for shigellosis is 5 days of oral ampicillin or trimethoprim-sulfamethoxazole therapy, successful outcome has been reported in adults treated with abbreviated courses of antibiotics. The purpose of this study was to compare short course (2-day) vs. 5-day therapy with cefixime for treatment of diarrheal disease caused by Shigella sonnei in children.

METHODS

This was a prospective, randomized, double blind, placebo-controlled study. Patients were eligible if they were at least 6 months of age and presented to the Children's Hospital of Pittsburgh during an outbreak of diarrhea caused by S. sonnei, with (1) a history of fever and diarrhea (at least three loose or watery stools per day), (2) bloody diarrhea or (3) diarrhea and known exposure to an individual with documented shigellosis. Patients were randomized to receive either 2 days of cefixime (8 mg/kg(day) given once daily followed by 3 days of placebo or 5 days of cefixime. Telephone follow-up was performed on Days 3, 7 and 14 after enrollment. Follow-up stool cultures were obtained on Day 7 to assess bacteriologic cure. There were standardized definitions for cure, improvement, failure and relapse.

RESULTS

Forty-seven patients were enrolled. Eleven were eliminated from analysis because their stool cultures were not positive for S. sonnei. There were 36 evaluable patients, 21 in the 2-day group and 15 in the 5-day group. Patients ranged in age from 6 months to 17 years. Forty-four percent of the subjects were male. Symptoms were improved or had resolved by Day 3 of therapy in all patients. There were 8 patients who experienced a clinical relapse: 5 of 21 (24%) patients in the 2-day treatment group and 3 of 15 (20%) in the 5-day group. There were 13 patients who experienced a bacteriologic failure (defined as the occurrence of a positive culture at the Day 7 follow-up visit), 11 of 20 (55%) in the 2-day group and 2 of 14 (14%) in the 5-day group (P < 0.02).

CONCLUSION

Two- and 5-day treatment courses with cefixime for treatment of diarrheal disease caused by S. sonnei result in similar rates of clinical cure and clinical relapses; however, there was a higher rate of bacteriologic failure with shorter course therapy.

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.

Comparative efficacies of single intravenous doses of ceftriaxone and ampicillin for shigellosis in a placebo-controlled trial

To evaluate ceftriaxone for the treatment of shigellosis, 94 adult males with acute dysentery were randomly assigned to receive ceftriaxone (1 g), ampicillin (4 g), or saline placebo intravenously in single doses in a double-blind design. Stool cultures were positive for Shigella dysenteriae in 52 patients, S. flexneri in 38 patients, and other species in 4 patients. Both ceftriaxone and ampicillin caused reductions in the mean duration of fever and the means of daily stool frequency 2 to 4 days after therapy versus placebo (P less than 0.05). The ability of ceftriaxone to reduce stool frequency during 6 days after treatment was significant in patients with S. flexneri infections (P less than 0.05), whereas S. dysenteriae infections were relatively refractory to improvement by both antibiotics. Neither drug had a significant effect on overall duration of diarrhea, blood in stool, or tenesmus. Ampicillin reduced the mean duration of positive stool cultures after treatment from 2.6 days in the placebo group to 1.1 days (P less than 0.05), whereas ceftriaxone did not affect the duration of Shigella sp. excretion. These results indicate that single intravenous doses of ceftriaxone and ampicillin caused some clinical improvement in acute shigellosis but only ampicillin exerted a bacteriological effect on Shigella sp. excretion.

Antibiotic treatment of acute shigellosis: failure of cefamandole compared with trimethoprim/ sulfamethoxazole and ampicillin

Intravenously administered ampicillin (AMP), trimethoprim-sulfamethoxazole (TMP-SMX) and cefamandole (CEF) were evaluated in 30 children with shigellosis: 11 children received AMP, 10 TMP-SMX, and 9 CEF for a maximum of five days. Discharge criteria included; afebrile greater than 12 hrs, less than 9 stools/day, absence of seizures, and adequate oral intake. AMP or TMP-SMX patients required significantly fewer median days to meet discharge criteria than those who received CEF. AMP and TMP-SMX patients had fewer median days with fever (one day each) compared with CEF (five days). On day five, 7 of 8 CEF, 3 of 10 AMP and 2 of 9 TMP-SMX treated patients remained culture positive. Inhibitory concentrations against all Shigella isolates from CEF patients all were less than or equal to 0.4 microgram CEF/ml. Intravenous TMP-SMX was equivalent to AMP in treatment of children with shigellosis, while CEF was ineffective despite in vitro activity. Clinical and bacteriologic responses were achieved with AMP and TMP-SMX in the majority of patients with less than 5 days of intravenous therapy.

Comparison of trimethoprim-sulfamethoxazole and ampicillin theraphy for shigellosis in ambulatory

One-hundred seventy-four infants and children with acute diarrhea were treated as ambulatory patients with either ampicillin (100 mg/kg/day orally in four divided doses) or trimethoprim sulfamethoxazole (10 mg TMP and 50 mg SMX/KG/day orally in two divided doses). There were 65 patients with shigellosis. Responses of those treated with TMP/SMX and of those with susceptible Shigella treated with ampicillin were comparable. Patients with resistant organisms failed to respond to ampicillin. All Shigella, including ampicillin-resistant strains, were suseptible in vitro to TMP/SMX, and patients with ampicillin-resistant strains responded favorably to treatment with TMP/SMX. TMP/SMX appears to be the best, currently available drug for the treatment of shigellosis.