Cefalexin is a first generation cephalosporin, and although it is effective against gram negative bacilli, it would not be a good choice for treating typhoid fever. Salmonella enterica serotypes are usually treated with fluoroquinolones, but there are many reports of resistance in some parts of Africa and Asia. Depending on sensitivity, a cephalosporin may be used as an alternative or in some cases, in combination with a fluoroquinolone. Third generation cephalosporins are preferred, e.g., Cefotaxime, Ceftriaxone, etc.

Typhus is usually caused by rickettsial organisms and the treatment of choice is doxycycline ± chloramphenicol.

Current Trends in the Management of Typhoid Fever

Introduction

Typhoid (cloudy) fever is a systemic infection, caused mainly by Salmonella typhi found only in man. It is characterized by a continuous fever for 3-4 weeks, relative bradycardia, with involvement of lymphoid tissue and considerable constitutional symptoms. In western countries, the disease has been brought very close to eradication levels. In the UK, there is approximately one case per 100,000 population per year. Each year, the world over, there are at least 13-17 million cases of typhoid fever, resulting in 600,000 deaths. 80% of these cases and deaths occur in Asia alone. In South East Asian nations, 5% or more of the strains of the bacteria may already be resistant to several antibiotics [1]. Antibiotics resistance, particularly emergence of multidrug resistant (MDR) strains among Salmonellae is also a rising concern and has recently been linked to antibiotic use in livestock. Many S typhi strains contain plasmids encoding resistance to chloramphenicol, ampicillin and co-trimoxazole, the antibiotics that have long been used to treat enteric fever. In addition, resistance to ciprofloxacin also called nalidixic-acidresistant S typhi (NARST) strain either chromosomally or plasmids encoded, has been observed in Asia. A significant number of strains from Africa and the Indian subcontinent are MDR type. A small percentage of strains from Vietnam and the Indian subcontinent are NARST strains [2]. The changing pattern of multi drug resistance in typhoid fever was studied in Delhi in 1993 [3]. Out of 76 patients, 12 patients responded to a combination of chloramphenicol and gentamicin, 51 to ciprofloxacin while the remaining 9 responded to combination of cefotaxime and amikacin. This study re-emphasizes the changing pattern, and role of quinolone especially ciprofloxacin in the management of drug resistant typhoid fever, but at the same time indicates that ciprofloxacin is not the drug of choice in all cases of typhoid fever and resistance to it may be seen in some cases, where other drugs have to be used. 100 children (consecutive) with positive blood culture for S typhi were studied for clinical profile in Ahmedabad in 2000. 80% Salmonella isolates were resistant to amoxycillin, chloramphenicol and cotrimoxazole, but all were sensitive to ciprofloxacin and ceftriaxone [4]. In another study from Rourkela in 2000, out of 5410 blood samples 715 samples, were found positive for S typhi. The number of MDR strains of S typhi constituted almost 16.1% of the total isolates. In this study, chloramphenicol sensitivity was found quite high (86.5%) and ceftriaxone showed 100% sensitivity. Resistance to ciprofloxacin was found in 2.5% cases [5]. In the extended typhoid epidemic that affected more than 24,000 people in Tajikistan from 1996 through 1998, more than 90% of the organisms were MDR and 82% were resistant to ciprofloxacin. This is the first reported epidemic of quinolones-resistant typhoid fever [6]. Atypical and varied presentations often confuse the picture in enteric fever. Neuropsychiatric manifestations in particular, often may be mistaken for encephalitis, meningitis, cerebral malaria, psychosis, etc [7]. Recurrent salmonellosis (usually S typhimurium) is an AIDS defining criterion in HIV positive patients, though for reasons unknown this is rarely due to S typhi. HIV positive patients are more prone to develop enteric fever and its frequent relapses. Diagnosis Laboratory diagnosis of typhoid fever is based on three principles : Isolation of organism Detection of microbial antigen Titration of antibody against causative organism Definitive diagnosis of enteric fever requires the isolation of S typhi or S paratyphi. Cultures of blood, stool, urine, rose spots, the blood mononuclear cellplatelet fraction, bone marrow, and gastric or intestinal secretions may each be useful in establishing the diagnosis. The duodenal string test is especially useful as a noninvasive technique to sample duodenalsecretions. A positive culture for S typhi or S paratyphi is obtained in more than 90% of patients if blood, bone marrow and intestinal secretions are all performed [8]. The sensitivity of blood culture alone is only 50 to 70% [9] probably because small quantities of S typhi (i.e.

Cephalexin is contraindicated in typhoid fever.It cause typhoid fever vaccy deactivation. Therefore, never use in cephalexin in typhoid fever.

Cephalexin has no indication in typhoid fever.

As far as the action of the drug target cell wall of the bacteria, it may have no action against salmonella and generally first generation cephalosporin have poor action against g-ve