Salmonella enterica Serovar Agbeni, British Columbia, Canada, 2011

TO THE EDITOR: Infection with Salmonella enterica serovar Agbeni is rare. In Canada, it was reported 8 times during 2000-2010 and never in the province of British Columbia (2011 population?4.5 million) (Public Health Agency of Canada, unpub. data). In June 2011, an outbreak of S. enterica ser. Agbeni affecting 8 persons was identified in British Columbia; pulsed-field gel electrophoresis patterns for all isolates were identical. Although no specific source was identified, 2 features were noted: 1) diagnosis through urine specimens for 3 of 8 persons and 2) a longer than typical incubation period for Salmonella spp. infection.     

Typhoid Fever and Invasive Nontyphoid Salmonellosis, Malawi and South Africa

To determine the prevalence of invasive nontyphoid salmonellosis and typhoid fever in Malawi and South Africa, we compared case frequency and patient age distribution. Invasive nontyphoid salmonellosis showed a clear bimodal age distribution; the infection developed in women at a younger age than in men. Case frequency for typhoid fever was lower than for salmonellosis.     

Emergence of multidrug-resistant Salmonella Paratyphi B dT+, Canada

We document an increase in the number of multidrug-resistant Salmonella enterica serovar Paratyphi B dT+ identified in Canada. Most of these strains harbor Salmonella genomic island 1 (SGI1). Further studies are needed to determine factors contributing to the observed emergence of this multidrug-resistant strain.     

Evaluation of safety and protection efficacy on cpxR and lon deleted mutant of Salmonella Gallinarum as a live vaccine candidate for fowl typhoid

We evaluated a recently developed live fowl typhoid (FT) vaccine candidate, JOL916, the cpxR/lon mutant of Salmonella Gallinarum (SG), for safety and protection efficacy in 5-week-old layer chickens. Intramuscular vaccination with JOL916 revealed no or very few lesions in livers and spleens of the animals until the fourth week post-vaccination (wpv). This candidate clearly induced cellular immune responses in 5 of 5 chickens on the first and second wpv based on the peripheral lymphocyte proliferation assay. Systemic IgG responses were observed in 5 of 5 chickens from the first wpv and dramatic elevations were observed on the second and third wpv. Vaccination of chickens offered efficient protection against challenge by a wild-type SG; only slight anorexia and depression were temporarily observed after challenge in the vaccinated group while 100% mortality was observed in the positive control group. Body weight increases per day were slightly reduced between the 3rd and 6th day post challenge (dpc) compared to the negative control group; it was recovered from the 6th dpc. Collectively, these results demonstrate the safety and protective efficacy of JOL916 as a live vaccine for systemic FT.     

Poor potential coverage for 7-valent pneumococcal conjugate vaccine,Malawi

Streptococcus pneumoniae infections can be prevented by using new conjugate vaccines, but these vaccines have limited serogroup coverage. We report the first serogrouping data from carried and invasive isolates obtained from children and adults in Malawi. The 7-valent vaccine would cover 41% of invasive isolates from children and 25% from adults. A 9-valent vaccine, including types 1 and 5, would cover 66% of invasive isolates from children and 55% from adults.     

Plasmid-mediated quinolone resistance among non-Typhi Salmonella enterica isolates, USA

We determined the prevalence of plasmid-mediated quinolone resistance mechanisms among non-Typhi Salmonella spp. isolated from humans, food animals, and retail meat in the United States in 2007. Six isolates collected from humans harbored aac(6')Ib-cr or a qnr gene. Most prevalent was qnrS1. No animal or retail meat isolates harbored a plasmid-mediated mechanism.     

Emergence of Salmonella enterica serotype Paratyphi A as a major cause of enteric fever in Kathmandu, Nepal

We performed pulsed-field gel electrophoresis (XbaI) on 114 bloodstream isolates of Salmonella enterica serotype Paratyphi A and S. enterica serotype Typhi collected from febrile patients in Kathmandu, Nepal. Of the 56 S. Paratyphi A isolates, 51 (91%) were indistinguishable, which suggests the emergence of a single clone. In contrast, only 21 (36%) of the 58 S. Typhi isolates exhibited a common genotype, which is consistent with endemic disease from multiple sources.     

Vi-CRM 197 as a new conjugate vaccine against Salmonella Typhi

An efficacious, low cost vaccine against typhoid fever, especially for young children, would make a major impact on disease burden in developing countries. The virulence capsular polysaccharide of Salmonella Typhi (Vi) coupled to recombinant mutant Pseudomonas aeruginosa exoprotein A (Vi-rEPA) has been shown to be highly efficacious. We investigated the use of carrier proteins included in infant vaccines, standardized the conjugation process and developed key assays required for routine lot release at production scale. Vi from a BSL1 organism, Citrobacter freundii, strain WR7011, was used as an alternative to Vi from S. Typhi. We showed that Vi conjugated to CRM₁₉₇, a non-toxic mutant of diphtheria toxin, widely used in commercial vaccines, was produced at high yield. Vi-CRM₁₉₇ proved immunogenic in animal studies, even without adjuvant. Thus, Vi-CRM₁₉₇ appears to be a suitable candidate for the development of a commercially viable, effective typhoid vaccine for developing countries.     

Estimate of illnesses from Salmonella enteritidis in eggs, United States, 2000

Results from our model suggest that eating Salmonella enterica serovar Enteritidis-contaminated shell eggs caused 182,060 illnesses in the United States during 2000. Uncertainty about the estimate ranged from 81,535 (5th percentile) to 276,500 illnesses (95th percentile). Our model provides but 1 approach for estimating foodborne illness and quantifying estimate uncertainty.     

Extended-Spectrum Cephalosporin-Resistant Salmonella enterica serovar Heidelberg Strains,the Netherlands

Extended-spectrum cephalosporin-resistant Salmonella enterica serovar Heidelberg strains (JF6X01.0022/XbaI.0251, JF6X01.0326/XbaI.1966, JF6X01.0258/XbaI.1968, and JF6X01.0045/XbaI.1970) have been identified in the United States with pulsed-field gel electrophoresis. Our examination of isolates showed introduction of these strains in the Netherlands and highlight the need for active surveillance and intervention strategies by public health organizations.     

Potential international spread of multidrug-resistant invasive Salmonella enterica serovar enteritidis

In developing countries, Salmonella enterica serovar Enteritidis causes substantial illness and death, and drug resistance is increasing. Isolates from the United Kingdom containing virulence-resistance plasmids were characterized. They mainly caused invasive infections in adults linked to Africa. The common features in isolates from these continents indicate the role of human travel in their spread.     

Room temperature stabilization of oral, live attenuated Salmonella enterica serovar Typhi-vectored vaccines

Foam drying, a modified freeze drying process, was utilized to produce a heat-stable, live attenuated Salmonella Typhi ‘Ty21a’ bacterial vaccine. Ty21a vaccine was formulated with pharmaceutically approved stabilizers, including sugars, plasticizers, amino acids, and proteins. Growth media and harvesting conditions of the bacteria were also studied to enhance resistance to desiccation stress encountered during processing as well as subsequent storage at elevated temperatures. The optimized Ty21a vaccine, formulated with trehalose, methionine, and gelatin, demonstrated stability for approximately 12 weeks at 37 °C (i.e., time required for the vaccine to decrease in potency by 1 log₁₀ CFU) and no loss in titer at 4 and 25 °C following storage for the same duration. Furthermore, the foam dried Ty21a elicited a similar immunogenic response in mice as well as protection in challenge studies compared to Vivotif™, the commercial Ty21a vaccine. The enhanced heat stability of the Ty21a oral vaccine, or Ty21a derivatives expressing foreign antigens (e.g. anthrax), could mitigate risks of vaccine potency loss during long-term storage, shipping, delivery to geographical areas with warmer climates or during emergency distribution following a bioterrorist attack. Because the foam drying process is conducted using conventional freeze dryers and can be readily implemented at any freeze drying manufacturing facility, this technology appears ready and appropriate for large scale processing of foam dried vaccines.     

Salmonella enterica serotype Uganda infection in New York City and Chicago

Outbreaks associated with distinct strains of Salmonella enterica serotype Uganda, a rare serotype, occurred in New York City and Chicago during the summer of 2001. Both outbreaks were linked to eating ready-to-eat pork products. This serotype may emerge as a more frequent cause of human infections.     

Life-threatening infantile diarrhea from fluoroquinolone-resistant Salmonella enterica typhimurium with mutations in both gyrA and parC

Salmonella Typhimurium DT12, isolated from a 35-day-old infant with diarrhea, was highly resistant to ampicillin, tetracycline, chloramphenicol, streptomycin, gentamycin, sulfamethoxazole/trimethoprim, nalidixic acid, and fluoroquinolones. The patient responded to antibiotic therapy with fosfomycin. Multidrug-resistance may become prevalent in Salmonella infections in Japan, as shown in this first case of a patient infected with fluoroquinolone-resistant Salmonella.