Multidrug-resistant Salmonella typhi in Pakistani children: clinical features and treatment

Genome Analysis and Therapeutic Evaluation of a Novel Lytic Bacteriophage of Salmonella Typhimurium: Suggestive of a New Genus in the Subfamily Vequintavirinae

Salmonella Typhimurium, a foodborne pathogen, is a major concern for food safety. Its MDR serovars of animal origin pose a serious threat to the human population. Phage therapy can be an alternative for the treatment of such MDR Salmonella serovars. In this study, we report on detailed genome analyses of a novel Salmonella phage (Salmonella-Phage-SSBI34) and evaluate its therapeutic potential. The phage was evaluated for latent time, burst size, host range, and bacterial growth reduction in liquid cultures. The phage stability was examined at various pH levels and temperatures. The genome analysis (141.095 Kb) indicated that its nucleotide sequence is novel, as it exhibited only 1-7% DNA coverage. The phage genome features 44% GC content, and 234 putative open reading frames were predicted. The genome was predicted to encode for 28 structural proteins and 40 enzymes related to nucleotide metabolism, DNA modification, and protein synthesis. Further, the genome features 11 tRNA genes for 10 different amino acids, indicating alternate codon usage, and hosts a unique hydrolase for bacterial lysis. This study provides new insights into the subfamily Vequintavirinae, of which SSBI34 may represent a new genus.

Persistence of Salmonellae in blood and bone marrow: randomized controlled trial comparing ciprofloxacin and chloramphenicol treatments against enteric fever

We performed a randomized controlled trial involving 55 adult patients with enteric fever to compare ciprofloxacin and chloramphenicol. Blood and bone marrow cultures and cytokine profiles during therapy were done to compare the clinical and bacteriological efficacies of these drugs. All patients were randomly assigned to receive chloramphenicol (500 mg four times a day orally) for 14 days or ciprofloxacin (500 mg twice a day orally) for 7 days. In each treatment group, patients were subsequently randomized to have blood and bone marrow cultured after either 3 or 5 days of treatment. Twenty-seven patients received chloramphenicol, and 28 received ciprofloxacin. The two groups were similar in terms of baseline characteristics. No significant differences in clinical cure and time to defervescence were found. All strains isolated were susceptible to both antibiotics. Although ciprofloxacin was more effective in the elimination of Salmonella enterica serovars Typhi and Paratyphi A from bone marrow than chloramphenicol, there was still an impressive persistence of Salmonella in the bone marrow culture (67%). In the ciprofloxacin-treated patients the suppressed cytokine production capacity showed a trend to normalize earlier than in patients treated with chloramphenicol.

Treatment of typhoid fever in children with a flexible-duration of ceftriaxone, compared with 14-day treatment with chloramphenicol

Although the efficacy of ceftriaxone in typhoid fever is well documented, the precise duration of ceftriaxone therapy in children with typhoid fever is not established and varies from 3 to 14 days in the literature. In a prospective, randomized study ceftriaxone was compared with chloramphenicol for treatment of 72 children who had bacteriologically confirmed typhoid fever. Ceftriaxone was given at a dose of 75 mg/kg per day (maximally 2 g/day) intravenously, in two doses until defervescence and continued 5 days after that time. Chloramphenicol was given at a dose of 75 mg/kg per day (maximally 2 g/day) in four doses for 14 days. Mean defervescence time was in 5.4 days in the ceftriaxone group and 4.2 days in the chloramphenicol group (P=0.04). Clinical cure without complications was achieved in all patients in both groups. No patient relapsed in the ceftriaxone group, and four patients relapsed in the chloramphenicol group (P=0.048). The overall results of this study suggest that a flexible-duration of ceftriaxone therapy given until defervescence time, followed by an additional 5 days of therapy is a reasonable alternative to conventional 14-day chloramphenicol treatment in children with typhoid fever.

Clinical use of fluoroquinolones in children

OBJECTIVE

To review the pharmacokinetics, efficacy, and safety of fluoroquinolones in children.

DATA SOURCES

A MEDLINE search (January 1966-March 1998) was conducted for relevant literature.

STUDY SELECTION AND DATA EXTRACTION

Data from compassionate use and published studies were reviewed for the assessment of pharmacokinetics, efficacy, and safety of fluoroquinolones in children.

DATA SYNTHESIS

Fluoroquinolones have a broad spectrum coverage of gram-positive and gram-negative bacteria, including Pseudomonas aeruginosa and intracellular organisms. Fluoroquinolones are well absorbed from the gastrointestinal tract, have excellent tissue penetration, low protein binding, and long elimination half-lives. These antibiotics are effective in treating various infections and are well tolerated in adults. However, the use of fluoroquinolones in children has been restricted due to potential cartilage damage that occurred in research with immature animals. Fluoroquinolones have been used in children on a compassionate basis. Ciprofloxacin is the most frequently used fluoroquinolone in children, most often in the treatment of pulmonary infection in cystic fibrosis as well as salmonellosis and shigellosis. Other uses include chronic suppurative otitis media, meningitis, septicemia, and urinary tract infection. Safety data of fluoroquinolones in children appear to be similar to those in adults. Fluoroquinolones are associated with tendinitis and reversible arthralgia in adults and children. However, direct association between fluoroquinolones and arthropathy remains uncertain.

CONCLUSIONS

Fluoroquinolones have been found to be effective in treating certain infections in children. Additional research is needed to define the optimal dosage regimens in pediatric patients. Although fluoroquinolones appear to be well tolerated, further investigations are needed to determine the risk of arthropathy in children. However, their use in children should not be withheld when the benefits outweigh the risks.