Reduced fluoroquinolone susceptibility in Salmonella enterica isolates from travelers, Finland

Travel-Related Antimicrobial Resistance: A Systematic Review

There is increasing evidence that human movement facilitates the global spread of resistant bacteria and antimicrobial resistance (AMR) genes. We systematically reviewed the literature on the impact of travel on the dissemination of AMR. We searched the databases Medline, EMBASE and SCOPUS from database inception until the end of June 2019. Of the 3052 titles identified, 2253 articles passed the initial screening, of which 238 met the inclusion criteria. The studies covered 30,060 drug-resistant isolates from 26 identified bacterial species. Most were enteric, accounting for 65% of the identified species and 92% of all documented isolates. High-income countries were more likely to be recipient nations for AMR originating from middle- and low-income countries. The most common origin of travellers with resistant bacteria was Asia, covering 36% of the total isolates. Beta-lactams and quinolones were the most documented drug-resistant organisms, accounting for 35% and 31% of the overall drug resistance, respectively. Medical tourism was twice as likely to be associated with multidrug-resistant organisms than general travel. International travel is a vehicle for the transmission of antimicrobial resistance globally. Health systems should identify recent travellers to ensure that adequate precautions are taken.

Antimicrobial investigation on the multi-state outbreak of salmonellosis and shigellosis in Iran

Background: Foodborne diseases are caused by indigestion of contaminated food. In some cases they may result in either hospitalization or death. The Centers for Disease Control (CDC) and Prevention in 2017 stated that 10% reduction in foodborne illness would prevent nearly five million illnesses every year. Approximately one out of six Americans become ill from contaminated foods or beverages every year. Another problem is drug resistance which is responsible for approximately 2 million illnesses and around 23000 dead every year. Nearly 400,000 Americans acquire antibiotic-resistant Salmonella or Campylobacter each year. The aim of this study was to evaluate the outbreak of salmonellosis and shigellosis along with their antibiotic susceptibility patterns in different provinces of Iran.

Methods: Over a period of 2 years from 2015 to 2016, a total of 1055 cases in 249 outbreaks reported in 20 provinces of Iran, as a part of surveillance by the National Institute of Health (NIH). The stool samples of patients were taken and tested for Salmonella spp. and Shigella spp. by conventional standard techniques. Disk diffusion was used for the antibiotic sensitivity test.

Results: Of 1055 cases, 118 (11.2%) contained Shigella and 74 (7%) contained Salmonella. Antibiotic susceptibility tests showed that entirely 100% of Salmonella and Shigella isolates were susceptible to ciprofloxacin; whereas 12.2% of Salmonella and 98.2% of Shigella were resistant to cotrimoxazole.

Conclusion: Our results show that there is a need for more food handling practices to minimize the exposure of consumers to Salmonella and Shigella , at all points along the distribution chain.

Risk factors of stillbirths in Victoria (Australia): A case-control study

Stillbirth is one of the most adverse pregnancy outcomes. The rate of stillbirth in high income countries has remained stagnant in recent decades. This study aimed to determine the incidence and risk factors of stillbirths specific to hospital-based deliveries in a secondary level hospital in Melbourne, Australia, over a 5-year period. We conducted a case-control study from January 2007 to December 2011. Univariate and multivariate analyses were conducted in STATA 12.1. The 5-year cumulative incidence of still-birth was 5.3 per 1000 total births (95% CI 4.3, 6.5). Univariate analysis revealed that higher body-mass index, smoking during pregnancy, haemoglobin level (≥14.5 g/dl), previous stillbirth, primiparity, marital status, previous caesarean section and reduced foetal movement in the 2 weeks prior to delivery were associated with increased risk of stillbirth. However, after adjustment for confounders in a multiple-regression model, only previous caesarean section (p = 0.006), unmarried (p = 0.004), high haemoglobin level (p = 0.007) and reduced foetal movement in the 2 weeks prior to delivery (p < 0.001) remained significantly associated with increased risk of stillbirth. The characteristics of our study population was similar to the population of state-wide survey in 2009, however, the incidence in our study was slightly lower. We concluded that previous caesarean section, pregnancy while being unmarried, higher haemoglobin level and reduced foetal movement in the 2 weeks before delivery were significant predictors of stillbirth. The identified risk factors were similar to other studies and the obstetric practice at the hospital or the demographics of the study population did not add to additional risk.

Enteropathogens and antibiotics

Infectious gastroenteritis remains a public health problem. The most severe cases are of bacterial origin. In Spain, Campylobacter and Salmonella are the most prevalent bacterial genus, while Yersinia and Shigella are much less frequent. Most cases are usually self-limiting and antibiotic therapy is not generally indicated, unless patients have risk factors for severe infection and shigellosis. Ciprofloxacin, third generation cephalosporins, azithromycin, ampicillin, cotrimoxazole and doxycycline are the most recommended drugs. The susceptibility pattern of the different bacteria determines the choice of the most appropriate treatment. The aim of this review is to analyse the current situation, developments, and evolution of resistance and multidrug resistance in these 4 enteric pathogens.

Cefotaxime-resistant Salmonella enterica in travelers returning from Thailand to Finland

During 1993–2011, cefotaxime resistance among Salmonella enterica isolates from patients in Finland increased substantially. Most of these infections originated in Thailand; many were qnr positive and belonged to S. enterica serovar Typhimurium and S. enterica monophasic serovar 4,[5],12:i:-. Although cefotaxime-resistant salmonellae mainly originate in discrete geographic areas, they represent a global threat.

Revised Ciprofloxacin Breakpoints for Salmonella: Is it Time to Write an Obituary?

OBJECTIVES

To determine the minimum inhibitory concentration of ciprofloxacin among 50 blood stream isolates of Salmonella enterica.

MATERIAL AND METHODS

A total of 50 consecutive isolates of Salmonella enterica were tested for susceptibility to antimicrobials using the Kirby Bauer disk diffusion method. Minimum inhibitory concentrations were determined using Hi-Comb strips. All results were interpreted according to the CLSI guidelines.

RESULTS

Of the 50 isolates 70%were Salmonella Typhi, 4% Salmonella paratyphi A, 2% Salmonella paratyphi B and the remaining 10% were identified only as Salmonella species. Using the CLSI 2011 breakpoints for disc diffusion, 86% (43/50) were resistant to nalidixic acid(NA), 22% (11/50) to ciprofloxacin, 12% to azithromycin, 6% to cotrimoxazole, 4% to ampicillin and 1% to chloramphenicol. The MIC50 and MIC90 of ciprofloxacin for S.Typhi were 0.181 μg/mL and 5.06 μg/mL respectively. While the same for S. paratyphi A was 0.212μg/mL and 0.228μg/mL respectively. None of the isolates were multi drug resistant and all were susceptible to ceftriaxone. Using the CLSI 2012 revised ciprofloxacin breakpoints for disc diffusion (>31mm) & MIC (<0.06 μg/mL), 90% (45/50) of these isolates were found to be resistant.

CONCLUSION

MIC's of ciprofloxacin should be reported for all salmonella isolates and should be used to guide treatment. Blindly following western guidelines for a disease which is highly endemic in the subcontinent will spell the death knell of a cheap and effective drug in our armamentarium. Therefore it will be too premature to declare that "the concept of using ciprofloxacin in typhoid fever is dead!"

Molecular characterization showed limited genetic diversity among Salmonella Enteritidis isolated from humans and animals in Malaysia

Salmonella enterica serovar Enteritidis (S. Enteritidis) is the most common causative agent of non-typhoidal salmonellosis in Malaysia. We aimed to characterize S. Enteritidis isolated from humans and animals by analyzing their antimicrobial resistance profiles and genotypes. A total of 111 strains were characterized using multiple-locus variable-number tandem repeat analysis, pulsed-field gel electrophoresis, and antimicrobial susceptibility testing. Both typing methods revealed that genetically similar S. Enteritidis strains had persisted among human and animal populations within the period of study (2003-2008). Only 39% of the strains were multi-drug resistant (i.e., resistant to 3 or more classes of antimicrobial agents), with a majority (73%) of these in low-risk phase (multiple antibiotic resistant index <0.20). Limited genetic diversity among clinical and zoonotic S. Enteritidis suggested that animals are possible sources of human salmonellosis. The degree of multi-drug resistance among the strains was generally low during the study period.

Trends of etiology and drug resistance in enteric fever in the last two decades in Nepal: a systematic review and meta-analysis

Prospective time-trend analyses on shifting etiology and trends of drug resistance in enteric fever are scarce. Using published and unpublished datasets from Nepal, we performed a systematic review and meta-analysis to understand the trends in etiology and resistance to antimicrobials that have occurred since 1993. Thirty-two studies involving 21 067 Salmonella enterica serotype Typhi (ST) and S. enterica serotype Paratyphi A (SPA) isolates were included. There was an increasing trend in enteric fever caused by SPA during the last 2 decades (P < .01). We observed sharply increasing trends in resistance to nalidixic acid and ciprofloxacin for both ST and SPA. In contrast, multi-drug resistance (MDR), resistance to traditional first-line antibiotics such as chloramphenicol and co-trimoxazole have significantly decreased for both organisms. The resistance to ceftriaxone has remained low, suggesting it is likely to remain useful as a reserve antibiotic for treatment. Trends in decreasing resistance to traditional first-line antibiotics and decreasing MDR provide an opportunity to reconsider these first-line antimicrobials as therapeutic options.

In vitro susceptibility testing of fluoroquinolone activity against Salmonella: recent changes to CLSI standards

Fluoroquinolone (FQ) resistance in Salmonella enterica is a significant clinical concern. Recognition of resistance by the clinical laboratory is complicated by the multiple FQ resistance mechanisms found in Salmonella. The Clinical Laboratory Standards Institute (CLSI) recently addressed this issue by revising the ciprofloxacin break points for Salmonella species. It is critical for clinicians and laboratory workers to be aware of the multiple technical issues surrounding these revised break points. In this article, we review FQ resistance mechanisms in Salmonella, their clinical significance, and data supporting the revised ciprofloxacin break points. We encourage clinical laboratories to adopt the revised CLSI ciprofloxacin break points for all Salmonella isolates in which susceptibility testing is indicated and discuss the technical issues for laboratories using commercial antimicrobial susceptibility systems.

In vitro synergism of ciprofloxacin and cefotaxime against nalidixic acid-resistant Salmonella enterica serotypes Paratyphi A and Paratyphi B

Paratyphoid fever is considered an emerging systemic intracellular infection caused by Salmonella enterica serotypes Paratyphi A, B, and C. We performed in vitro time-kill studies on three clinical isolates of nalidixic acid-resistant Salmonella serotype Paratyphi (NARSP) with different concentrations of ciprofloxacin and cefotaxime to identify combinations of antibiotics with synergistic activity against paratyphoid fever. Furthermore, we identify the frequency of mutations to ciprofloxacin, cefotaxime, and rifampin resistance and also sequenced the gyrA, gyrB, parC, and parE genes to identify the cause of resistance in NARSP. When the activity of ciprofloxacin at 0.75x MIC (0.012 to 0.38 microg/ml) with cefotaxime at the MIC (0.125 to 0.25 microg/ml) against all three NARSP isolates was investigated, synergy was observed at 24 h, and the bacterial counts were reduced by >3 log(10) CFU/ml. This synergy was elongated for up to 72 h in two out of three isolates. When ciprofloxacin at 0.75x MIC (0.012 to 0.38 microg/ml) was combined with cefotaxime at 2x MIC (0.25 to 0.50 microg/ml), synergy was prolonged for up to 72 h in all three isolates. Both Salmonella serotype Paratyphi A isolates carried single mutations in codon 83 of the gyrA gene and codon 84 of the parC gene that were responsible for their reduced susceptibility to ciprofloxacin, while no mutations were found in the gyrB or parE gene. The ciprofloxacin-plus-cefotaxime regimen was very effective in reducing the bacterial counts at 24 h for all three isolates, and this combination therapy may be helpful in reducing the chance of the emergence of fluoroquinolone-resistant mutants in patients with severe paratyphoid fever.

In vitro activity of azithromycin against nontyphoidal Salmonella enterica

The in vitro activity of azithromycin against 1,237 nontyphoidal Salmonella enterica isolates collected from Finnish patients between 2003 and 2008 was investigated. Only 24 (1.9%) of the isolates tested and 15 (5.1%) of the 294 isolates with reduced fluoroquinolone susceptibility had azithromycin MICs of >or=32 microg/ml. These data show that azithromycin has good in vitro activity against nontyphoidal S. enterica, and thus, it may be a good candidate for clinical treatment studies of salmonellosis.

Travellers' diarrhoea - pros and cons of different prophylactic measures

Travellers' diarrhoea is the most likely cause for disturbing travel arrangements. At an average, 30-40% of tourists are concerned, depending on the travel destination. Due to the high impact on the travellers' health this topic is still of utmost importance in travel medicine. A wide spectrum of enteropathogens can be accountable, with enterotoxigenic Escherichia coli being the major causing pathogen among other bacteria, parasites and viruses. Here we discuss advantages and disadvantages of different prophylactic measures against travellers' diarrhoea. The effectiveness but also the relevance of hygiene education, vaccination and antibiotic or probiotic application will be discussed in the context of the travellers' different risk profiles.

Mechanisms of resistance in nontyphoidal Salmonella enterica strains exhibiting a nonclassical quinolone resistance phenotype

Nontyphoidal Salmonella enterica strains with a nonclassical quinolone resistance phenotype were isolated from patients returning from Thailand or Malaysia to Finland. A total of 10 isolates of seven serovars were studied in detail, all of which had reduced susceptibility (MIC > or = 0.125 microg/ml) to ciprofloxacin but were either susceptible or showed only low-level resistance (MIC < or = 32 microg/ml) to nalidixic acid. Phenotypic characterization included susceptibility testing by the agar dilution method and investigation of efflux activity. Genotypic characterization included the screening of mutations in the quinolone resistance-determining regions (QRDR) of gyrA, gyrB, parC, and parE by PCR and denaturing high-pressure liquid chromatography and the amplification of plasmid-mediated quinolone resistance (PMQR) genes qnrA, qnrB, qnrS, qnrD, aac(6')-Ib-cr, and qepA by PCR. PMQR was confirmed by plasmid analysis, Southern hybridization, and plasmid transfer. No mutations in the QRDRs of gyrA, gyrB, parC, or parE were detected with the exception of a Thr57-Ser substitution within ParC seen in all but the S. enterica serovar Typhimurium strains. The qnrA and qnrS genes were the only PMQR determinants detected. Plasmids carrying qnr alleles were transferable in vitro, and the resistance phenotype was reproducible in Escherichia coli DH5alpha transformants. These data demonstrate the emergence of a highly mobile qnr genotype that, in the absence of mutation within topoisomerase genes, confers the nontypical quinolone resistance phenotype in S. enterica isolates. The qnr resistance mechanism enables bacteria to survive elevated quinolone concentrations, and therefore, strains carrying qnr alleles may be able to expand during fluoroquinolone treatment. This is of concern since nonclassical quinolone resistance is plasmid mediated and therefore mobilizable.