Invasive Infection with Multidrug‐ResistantSalmonella entericaSerotype Typhimurium Definitive Type 104 among HIV‐Infected Adults

Estimated Incidence of Antimicrobial Drug-Resistant Nontyphoidal Salmonella Infections, United States, 2004-2012

Salmonella infections are a major cause of illness in the United States. The antimicrobial agents used to treat severe infections include ceftriaxone, ciprofloxacin, and ampicillin. Antimicrobial drug resistance has been associated with adverse clinical outcomes. To estimate the incidence of resistant culture-confirmed nontyphoidal Salmonella infections, we used Bayesian hierarchical models of 2004–2012 data from the Centers for Disease Control and Prevention National Antimicrobial Resistance Monitoring System and Laboratory-based Enteric Disease Surveillance. We based 3 mutually exclusive resistance categories on susceptibility testing: ceftriaxone and ampicillin resistant, ciprofloxacin nonsusceptible but ceftriaxone susceptible, and ampicillin resistant but ceftriaxone and ciprofloxacin susceptible. We estimated the overall incidence of resistant infections as 1.07/100,000 person-years for ampicillin-only resistance, 0.51/100,000 person-years for ceftriaxone and ampicillin resistance, and 0.35/100,000 person-years for ciprofloxacin nonsusceptibility, or ≈6,200 resistant culture-confirmed infections annually. These national estimates help define the magnitude of the resistance problem so that control measures can be appropriately targeted.

A meta-analysis of the proportion of animal Salmonella isolates resistant to drugs used against human salmonellosis in Ethiopia

Background

The emergence and spread of drug resistant Salmonellae of both human and animal origins are global concerns and worrisome in countries where the risk of infection is high and treatment options are limited. The objective of this study was to estimate the proportions of animal isolates resistant to antimicrobials used against human salmonellosis in Ethiopia.

Methods

Published studies on the antimicrobial resistance features of Salmonellae isolated from food animals of Ethiopia were searched in Medline, Google Scholar and the lists of references of articles. Eligible studies were selected by using inclusion and exclusion criteria and data were extracted. The extracted data included the host species, the numbers of isolates and the numbers of ampicillin, co-trimoxazole, chloramphenicol, ceftriaxone and ciprofloxacin resistant isolates. The risks of bias were assessed and the percentages of the variations of the estimates attributable to heterogeneities were quantified. Pooled proportions were estimated by the DerSimonian and Laird random effects model.

Results

Five hundred and fifty four Salmonellae isolated from cattle, camels, sheep, goats and pigs were tested with a variety of antimicrobials. The percentages of the variations attributable to heterogeneities were low for chloramphenicol and ceftriaxone (I² = 0) and high for ampicillin, co-trimoxazole and ciprofloxacin resistance estimates (I² > 75%). The pooled estimate of ampicillin resistant isolates was higher in slaughtered ruminants (17.28%) than in pigs (3.95%), (p < 0.001). The pooled estimates of co-trimoxazole resistant isolates in true ruminants (4.35%) and pigs (1.12%) were not significantly different (p > 0.05). The overall pooled estimates of chloramphenicol and ceftriaxone resistant isolates were 2.24% and 1.25%, respectively. Seven serotypes have been reported to be resistant to antimicrobials uncommonly used in veterinary clinical practice in Ethiopia.

Conclusions

Among Salmonellae of farm animals, there exist strains that are resistant to drugs used in the therapeutic management of human salmonellosis in Ethiopia. Intervention measures should be taken to ensure the prudent use of antimicrobials and curb the spread of high risk strains across the country.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-0835-x) contains supplementary material, which is available to authorized users.

A meta-analysis of the prevalence of Salmonella in food animals in Ethiopia

BACKGROUND

The globalization of the food supply and the increased movements of people, animals and goods have increased the threat of Salmonella infections in several countries. The objective of this study was to estimate the prevalence of Salmonella in food animals in Ethiopia by using meta-analytical methods.

RESULTS

The prevalence of Salmonella in slaughtered cattle, sheep, goats and pigs were 7.07%, 8.41%, 9.01% and 43.81% respectively. The occurrence of Salmonella was significantly higher in pigs than in slaughtered true ruminants (p <0.001) but not significantly different between cattle, sheep and goats (p >0. 05). S. Mishmarhaemek, S. Infantis and S. Hadar were the predominant isolates in cattle, small ruminants and pigs respectively. S. Typhimurium was isolated from all host species.

CONCLUSIONS

All food animals are considerable reservoirs of Salmonella and pose a significant risk to public health. Safety measures in slaughter houses and butcheries and education of the public could reduce the risk of transmission of Salmonella from animals to humans.

A meta-analysis of the proportion of antimicrobial resistant human Salmonella isolates in Ethiopia

BACKGROUND

Antimicrobial resistant Salmonella is a global problem and recently, a strain on the verge of pan-resistance was reported. In Ethiopia, the therapeutic management of Salmonellosis is difficult because drug sensitivity tests are not routinely carried out and treatment alternatives are not available in most health care facilities. The objectives of this study were to estimate the temporal changes and proportions of drug resistant isolates in Ethiopia.

METHODS

Published studies on drug resistant Salmonella isolates were searched in Medline, Google Scholar and the lists of references of articles. Eligible studies were selected by using inclusion and exclusion criteria. Generic, methodological and statistical information were extracted from the eligible studies. The extracted data included the proportions of ampicillin, co-trimoxazole, chloramphenicol, ceftriaxone, ciprofloxacin and multi-drug resistant isolates. Pooled proportions were estimated by a random effects model.

RESULTS

The odds of multi-drug resistant isolates in the 2000s was higher than before the 1990s (OR =18.86, 95% CI = 13.08, 27.19). The pooled proportions of ampicillin, co-trimoxazole, chloramphenicol, ciprofloxacin and multi-drug resistant isolates in the 2000s were 86.01%, 68.01%, 62.08%, 3.61% and 79.56% respectively. S. Concord (>97%) was resistant to ampicillin, co-trimoxazole, chloramphenicol and ceftriaxone.

CONCLUSION

The proportion of drug resistant isolates has increased since the 1970s. All drugs currently used for the treatment of Salmonellosis but ciprofloxacin are not reliable for an empirical therapy. Alternative drugs should be included in the essential drug list and measures should be taken to re-enforce the drug use policy.

Prevalence of human Salmonellosis in Ethiopia: a systematic review and meta-analysis

BACKGROUND

Human Salmonellosis is one of the major diseases in Ethiopia and several factors including under and mal-nutrition and HIV-AIDS may substantially contribute to its occurrence. Despite its importance, surveillance and monitoring systems are not in place and a comprehensive picture of its epidemiology is not available. The objectives of this study were to systematically review and estimate the prevalence of the disease and identify the dominant serogroups and serotypes in Ethiopia.

METHODS

Published studies on Salmonellosis in Ethiopia were electronically and manually searched. Eligible studies were selected by using inclusion and exclusion criteria. Generic, methodological and statistical information were extracted from the eligible studies. The extracted data included sample sizes, the numbers of Salmonella positive samples, serogroups and serotypes. The variations in prevalence estimates attributable to heterogeneities were assessed and pooled prevalence was estimated by the random effects model.

RESULTS

Twenty studies carried out between 1974 and 2012 were eligible. The pooled prevalence estimates of Salmonella in stool samples of diarrheic children, diarrheic adults and carriers were 8.72%, 5.68%, and 1.08% respectively. Invasive infections in children (5.71%) and adults (0.76%) were significantly different (p < 0.001). Non-typhi isolates accounted for 57.9% of the isolates from patients. Serogroup D occurred more frequently than serogroups C and B. S. Concord, S. Typhi, S. Typhimurium and S. Paratyphi were dominant and accounted for 82.1% of the serotypes isolated from patients.

CONCLUSION

The prevalence of Salmonellosis is considerable and most infections are due to four serotypes. The results imply the need for a policy to promote public hygiene and regularly screen individuals in contact with food items for public consumption.

Increase in resistance to ceftriaxone and nonsusceptibility to ciprofloxacin and decrease in multidrug resistance among Salmonella strains, United States, 1996-2009

BACKGROUND

Salmonella is a major bacterial pathogen transmitted commonly through food. Increasing resistance to antimicrobial agents (e.g., ceftriaxone, ciprofloxacin) used to treat serious Salmonella infections threatens the utility of these agents. Infection with antimicrobial-resistant Salmonella has been associated with increased risk of severe infection, hospitalization, and death. We describe changes in antimicrobial resistance among nontyphoidal Salmonella in the United States from 1996 through 2009.

METHODS

The Centers for Disease Control and Prevention's National Antimicrobial Resistance Monitoring System conducts surveillance of resistance among Salmonella isolated from humans. From 1996 through 2009, public health laboratories submitted isolates for antimicrobial susceptibility testing. We used interpretive criteria from the Clinical and Laboratory Standards Institute and defined isolates with ciprofloxacin resistance or intermediate susceptibility as nonsusceptible to ciprofloxacin. Using logistic regression, we modeled annual data to assess changes in antimicrobial resistance.

RESULTS

From 1996 through 2009, the percentage of nontyphoidal Salmonella isolates resistant to ceftriaxone increased from 0.2% to 3.4% (odds ratio [OR]=20, 95% confidence interval [CI] 6.3-64), and the percentage with nonsusceptibility to ciprofloxacin increased from 0.4% to 2.4% (OR=8.3, 95% CI 3.3-21). The percentage of isolates that were multidrug resistant (resistant to ≥3 antimicrobial classes) decreased from 17% to 9.6% (OR=0.6, 95% CI 0.5-0.7), which was driven mainly by a decline among serotype Typhimurium. However, multidrug resistance increased from 5.9% in 1996 to a peak of 31% in 2001 among serotype Newport and increased from 12% in 1996 to 26% in 2009 (OR=2.6, 95% CI 1.1-6.2) among serotype Heidelberg.

CONCLUSIONS

We describe an increase in resistance to ceftriaxone and nonsusceptibility to ciprofloxacin and an overall decline in multidrug resistance. Trends varied by serotype. Because of evidence that antimicrobial resistance among Salmonella is predominantly a consequence of antimicrobial use in food animals, efforts are needed to reduce unnecessary use, especially of critically important agents.

Risk of Recurrent Nontyphoid Salmonella Bacteremia in HIV-Infected Patients in the Era of Highly Active Antiretroviral Therapy and an Increasing Trend of Fluoroquinolone Resistance

BACKGROUND

Risk of recurrent nontyphoid Salmonella (NTS) bacteremia and trends of antimicrobial resistance of NTS remain unknown in human immunodeficiency virus (HIV)-infected patients receiving highly active antiretroviral therapy (HAART).

METHODS

Ninety-three patients who received a diagnosis of NTS bacteremia from June 1994 through June 2006 were prospectively followed up. Incidence of recurrent NTS bacteremia was compared between the pre-HAART era (June 1994-March 1997) and the HAART era (April 1997-June 2006). Prevalence of antimicrobial resistance was compared among the NTS isolates obtained in the pre-HAART era, the early HAART era (April 1997-June 2002), and the late HAART era (July 2002-June 2006).

RESULTS

Compared with patients enrolled in the pre-HAART era, patients who received HAART had an incidence of recurrent NTS bacteremia that was significantly reduced by 96%; the incidence of recurrent NTS bacteremia was 2.56 cases per 100 person-years in the HAART era, compared with 70.56 cases per 100 person-years in the pre-HAART era (rate ratio, 0.036; 95% confidence interval, 0.012-0.114; P<.001). In the HAART era, the incidence of recurrent NTS bacteremia did not increase among patients receiving fluoroquinolone prophylaxis for <or=30 days (1.69 cases per 100 person-years), compared with among patients receiving fluoroquinolones for >30 days (3.95 cases per 100 person-years), with a rate ratio of 0.43 (95% confidence interval, 0.07-2.58). Although resistance to ampicillin, cotrimoxazole, and chloramphenicol decreased, the proportion of NTS isolates resistant to fluoroquinolones increased from 0% in the pre-HAART era to 6.2% in the early HAART era and 34.2% in the late HAART era (P=.002).

CONCLUSIONS

The risk of recurrent NTS bacteremia decreased significantly in the HAART era, although NTS isolates obtained from HIV-infected patients were increasingly resistant to fluoroquinolones.

Emerging microbiological food safety issues related to meat

Avian influenza viruses and antibiotic-resistant pathogens have become topics of current public health interest. This paper will focus on the significance of these pathogens to the meat industry as well as other emerging microbiological food safety topics likely to impact the meat industry. These include surveillance of foodborne pathogens, microbial source tracking, risk assessment, and human populations at increased risk of infection by foodborne microbes. These emerging issues will likely lead to even greater challenges to producing microbiologically safe meat products than the industry has ever experienced. However, accompanying such challenges will be innovative solutions that provide even greater public health protection to meat-containing foods.