Authors' reply

LETTER TO THE EDITOR

Authors' reply

Mireille Ângela Bernardes Sousa^I; Maria do Rosário Conceição Moura Nunes^II; Edilberto Nogueira Mendes^III; Luciano Amedée Péret-Filho^IV; Francisco José Penna^IV; Paula Prazeres Magalhães^V

^IPhD, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (UFMG) e Hermes Pardini, Belo Horizonte, MG, Brazil

^IIPhD, Departamento de Parasitologia e Microbiologia, Instituto de Ciências da Saúde, Universidade Federal do Piauí, Teresina, PI, Brazil

^IIIMD, PhD, Departamento de Propedêutica Complementar, Faculdade de Medicina, UFMG, Belo Horizonte, MG, Brazil

^IV MD, Departamento de Pediatria, Faculdade de Medicina, UFMG, Belo Horizonte, MG, Brazil

^VPhD, Departamento de Microbiologia, Instituto de Ciências Biológicas, UFMG, Belo Horizonte, MG, Brazil

Dear Editor,

There is a consensus that, although shigellosis is often self-limited and successfully treated with fluid and electrolyte replacement therapy only, more severe cases of dysentery require the administration of antimicrobials, especially undernourished patients or those with a compromised immune system. In fact, the World Health Organization recommends early establishment of antibiotic therapy directed against Shigella for individuals with inflammatory diarrhea.¹

In Brazil, the Ministry of Health still recommends the trimethoprim-sulfamethoxazole association as the first choice treatment for patients with shigellosis whenever the use of antimicrobial drugs is indicated. In cases of bacterial resistance, quinolones should be used, but these are non indicated for pregnant women and children.²

Carrari et al.³ described the use of ceftriaxone for the treatment of patients hospitalized with dysentery, given the high rates of trimethoprim-sulfamethoxazole resistance found by those authors. Indeed, a high prevalence of Shigella samples that are resistant to this association of antimicrobials has been observed in different regions of Brazil.^4-8 Thus, considering the great possibility of therapy failure when trimethoprim-sulfamethoxazole association is employed for patients with Shigella dysentery, other options should be considered.

In Brazil, S. sonnei and S. flexneri are almost exclusively observed. Our results corroborate data found in the literature, which show that the distribution of Shigella species in different Brazilian regions is uneven. We observed a predominance (≈ 80%) of S. flexneri among children with shigellosis in Teresina,⁹ while in Belo Horizonte, S. sonnei was associated with almost 90% of the cases.¹⁰

In addition, our experience points to differences in the antimicrobial susceptibility profiles of S. sonnei and S. flexneri. All samples included in our study groups were susceptible to nalidixic acid, ceftriaxone, and ciprofloxacin. Regarding trimethoprim-sulfamethoxazole and ampicillin, rates of about 85 and 100% were observed for S. sonnei, and of 50 and 70% for S. flexneri, in southeastern and northeastern Brazil, respectively. Ampicillin resistance, in turn, was not found in any sample of S. sonnei and in approximately 65% of S. flexneri strains in the state of Piauí; in Minas Gerais, resistance rates of approximately 15 and 100% were observed for S. sonnei and S. flexneri, respectively.^9,10

According to the recommendation of the Brazilian Ministry of Health, antimicrobial drugs should be indicated for the treatment of patients with shigellosis regardless of diagnostic confirmation via coproculture and antibiogram.² Taking into consideration that, in most cases, treatment is initiated prior to a result of a coproculture – a poorly sensitive, expensive and time-consuming test – and thus without the establishment of the antimicrobial susceptibility profile of the etiologic agent in question, safe treatment options, based on local epidemiological data, should be adopted.

In this scenario, nalidixic acid, ceftriaxone, and ciprofloxacin emerge as suitable options; treatment definition should be based on the particularities of each patient. Ceftriaxone is available only in an parenteral formulation, and therefore it is more suitable for hospitalized patients; however, the high cost of this antimicrobial and the scarcity of data pointing to its efficacy limit its use.¹ Moreover, nalidixic acid and ciprofloxacin are recommended for outpatient treatment. With regard to ciprofloxacin, although there is not a consensus,¹ the Brazilian Ministry of Health imposes restrictions on its use in children.² Finally, nalidixic acid has been shown to have a low therapeutic efficacy, even when susceptibility of the etiologic agent is confirmed in vitro.¹

In view of the above, as mentioned by Nunes et al.,⁹ indeed the use of sulfamethoxazole-trimethoprim for the empirical treatment of patients with dysentery in Brazil is not appropriate and should be restricted to cases for which antimicrobial susceptibility results are available. These data also suggest that the recommendation of the Ministry of Health regarding the use of this antimicrobial for the treatment of patients with shigellosis should be revised.

References

• 1. World Health Organization. Guidelines for the control of shigellosis, including epidemics due to Shigella dysenteriae 1. Geneva: World Health Organization; 2005. 64p.
• ²
  Brasil. Ministério da Saúde. Secretaria de Vigilância em Saúde. Departamento de Vigilância Epidemiológica. Doenças infecciosas e parasitárias: guia de bolso. 8ª ed. rev. Brasília: Ministério da Saúde; 2010. Série B. Textos Básicos de Saúde. p. 370-2.
• 3. Carrari MH, Tahan S, Morais MB. Antibiotic therapy in acute diarrhea associated with Shigella: what is the best option? J Pediatr (Rio J). 2012;88:366-7.
• 4. Bastos FC, Loureiro EC. Antimicrobial resistance of Shigella spp. isolated in the State of Pará, Brazil. Rev Soc Bras Med Trop. 2011;44:607-10.
• 5. Diniz-Santos DR, Santana JS, Barretto JR, Andrade MG, Silva LR. Epidemiological and microbiological aspects of acute bacterial diarrhea in children from Salvador, Bahia, Brazil. Braz J Infect Dis. 2005;9:77-83.
• 6. de Paula CM, Geimba MP, Amaral PH, Tondo EC. Antimicrobial resistance and PCR-ribotyping of Shigella responsible for foodborne outbreaks occurred in southern Brazil. Braz J Microbiol. 2010;41:966-77.
• 7. Peirano G, Souza FS, Rodrigues DP; Shigella Study Group. Frequency of serovars and antimicrobial resistance in Shigella spp. from Brazil. Mem Inst Oswaldo Cruz. 2006;101:245-50.
• 8. Silva T, Nogueira PA, Magalhães GF, Grava AF, Silva LH, Orlandi PP. Characterization of Shigella spp. by antimicrobial resistance and PCR detection of ipa genes in an infantile population from Porto Velho (Western Amazon region), Brazil. Mem Inst Oswaldo Cruz. 2008;103:731-3.
• 9. Nunes MR, Magalhães PP, Penna FJ, Nunes JM, Mendes EN. Diarrhea associated with Shigella in children and susceptibility to antimicrobials. J Pediatr (Rio J). 2012;88:125-8.
• 10. Sousa MA. Shigella e Salmonella enterica em crianças com diarreia aguda em Belo Horizonte/MG: pesquisa de fatores de virulência e perfil de suscetibilidade a antimicrobianos. Belo Horizonte: Universidade Federal de Minas Gerais, 2005.

Publication Dates

• Publication in this collection
  18 Sept 2012
• Date of issue
  Aug 2012