Volume 8, Number 5—May 2002
http://wwwnc.cdc.gov/eid/article/8/5/01-0267_article.htm

Research

Excess Mortality Associated with Antimicrobial Drug-Resistant Salmonella Typhimurium

Morten Helms*, Pernille Vastrup*, Peter Gerner-Smidt*, and Kåre Mølbak* 

Author affiliations: *Statens Serum Institut, Copenhagen, Denmark;

Abstract

In a matched cohort study, we determined the death rates associated with drug resistance in Salmonella Typhimurium. We linked data from the Danish Surveillance Registry for Enteric Pathogens with the Civil Registration System and the Danish National Discharge Registry. By survival analysis, the 2-year death rates were compared with a matched sample of the general Danish population, after the data were adjusted for differences in comorbidity. In 2,047 patients with S. Typhimurium, 59 deaths were identified. Patients with pansusceptible strains of S. Typhimurium were 2.3 times more likely to die 2 years after infection than persons in the general Danish population. Patients infected with strains resistant to ampicillin, chloramphenicol, streptomycin, sulfonamide, and tetracycline were 4.8 times (95% CI 2.2 to 10.2) more likely to die, whereas quinolone resistance was associated with a mortality rate 10.3 times higher than the general population.

Foodborne Salmonella infections have become a major problem in most industrialized countries. Of particular concern is the increasing number of infections with antimicrobial drug-resistant Salmonella, including the recent emergence of drug-resistant Salmonella enterica serotype Typhimurium (S. Typhimurium) definitive phage type 104 (DT104). This strain is usually resistant to at least five drugs: ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline (R-type ACSSuT) and has become a predominant Salmonella type in many countries, including the United States, United Kingdom, Germany, and France (1–4). In spite of its rapid international dissemination (5) and the fact that antimicrobial drug-resistant Salmonella was associated with human infections before the recent spread of DT104, the available data are inconclusive regarding a possible increased virulence of DT104. Whether antimicrobial drug resistance in DT104 contributes to enhanced illness or death is unclear (5–7). Few studies have addressed the health impact of drug resistance in types of zoonotic Salmonella other than DT104 (8–10), and these studies suggest that drug resistance may be associated with increased illness and death rates.

Excess mortality associated with drug resistance in zoonotic Salmonella is difficult to quantify. Death is a relatively rare event and may not occur until months after the initial diagnosis. Furthermore, a number of factors, including chronic and malignant diseases, may contribute to death from salmonellosis. The objective of this study was to determine death associated with antimicrobial drug resistance in S. Typhimurium. The study was based on a large, unbiased sample of Danish patients registered in a national database. We linked these data with those in the Danish civil registry, which has complete information about survival status. Furthermore, by completing the data with information from hospital discharge registries, we were able to adjust for comorbidity.

Materials and Methods

Surveillance

In Denmark the diagnosis of human Salmonella infections is made at Statens Serum Institut (SSI) or at 10 clinical microbiology laboratories. The SSI receives notifications of positive findings as well as isolates from the microbiology laboratories. If a specific Salmonella serotype is found more than once from the same person during a period of up to 6 months, only the first positive sample is registered. As a part of this laboratory-based surveillance system, monitoring for antimicrobial resistance in S. Typhimurium was initiated in 1995. In 1995 and 1996, a sample of strains was tested, but from 1997 on, all S. Typhimurium strains received at SSI were tested for antimicrobial susceptibility. This study included all isolates of S. Typhimurium examined from January 1, 1995, through October 31, 1999.

Isolates were tested by tablet diffusion on Danish Blood Agar (SSI Diagnostica, Hillerød, Denmark) with the use of Rosco Neosensitabs (Rosco, Roskilde, Denmark). The panel included 13 drugs from the Danish Integrated Antimicrobial Resistance Monitoring and Research Programme (11). Because reduced susceptibility to ciprofloxacin is difficult to detect by the tablet diffusion test, the E-test (Biodisk, Solna, Sweden) was used as well whenever the tablet diffusion test identified nalidixic acid resistance. In this paper, quinolone resistance refers to strains resistant to the first-generation quinolone nalidixic acid (12).

Registry Linkage Study

All live-born children and citizens of Denmark are assigned a personal identification number, uniquely identifying every person the Danish Civil Registration System (13). Demographic data, including vital status, marriage status, emigration/immigration, and address of residence, are kept in this Civil Registration System.

The matched cohort study used the data from the Civil Registration System to compare the death rates of patients with culture-confirmed S. Typhimurium infections to the death rates of persons in the general Danish population. For each patient, we randomly selected 10 people matched by age, sex, and county of residence. People who were born during the same month and year as the patient and were alive on the date of sample receipt were eligible for the reference group. From the Danish Civil Registration System, we obtained information on vital status, date of change of vital status, (i.e., date of death or emigration) and area of residence (county level) for the patients and the persons included in the reference group.

Data on admissions to hospital and discharge diagnosis were obtained by using the data from the Danish National Patient Registry (14) and the Cancer Registry for all persons included in this study, thereby allowing us to control for preexisting illness (comorbidity). Danish National Patient Registry contains data on all patients discharged from non-psychiatric departments since January 1, 1977. Diagnoses and procedures are coded according to the International Classification of Diseases 8 or International Classification of Diseases 10 (from 1993). Diagnoses obtained during 10 years before infection were used to calculate the comorbidity index.

Statistical Methods

The comorbidity index used the principles described by Charlson et al. (15). This index is a sum of severity scores (weights) corresponding to the number and severity of comorbidity conditions. In the first step, we analyzed the data from the background population to calculate the relative rate associated with each of the diagnostic groups summarized in Table 1. These relative rates served as the weights in the further survival analyses. The index was calculated by adding log-transformed weights, thus taking into account multiple hospital discharges. Diagnostic groups associated with a relative mortality rate <1.2 were not included in the models. By comparing this index with the survival analyses, any difference between the death rates of Salmonella patients and the general population quantifies excess mortality beyond what is attributable to underlying illness.

To compare mortality rates of S. Typhimurium patients with those of the general population, the data were stratified so that each stratum contained 1 patient and 10 persons from the reference group. To control for age, sex, and county of residence, we used conditional proportional hazard regression. Death up to 2 years after infection was determined, after adjusting the data for comorbidity as described. To assess death rates associated with antimicrobial drug resistance, interaction by drug resistance on Salmonella deaths was determined. We used the Wald test to test for homogeneity of the rate ratios. The analyses were conducted by the use of the PHREG procedure of the SAS system (Version 6.12, SAS Inst. Inc., Cary, NC). Death rate ratios (RR) are expressed as the relative death rates of patients compared with the matched sample of the general Danish population, and the term “referents” refers to this unexposed matched sample.

Results

Of 4,075 cases of S. Typhimurium infections reported in Denmark from January 1995 to October 1999, the antimicrobial-drug susceptibility was determined in isolates from 2,059 cases, and a successful link to the Civil Registry System was obtained for 2,047 (99.4%). In the period up to 2 years after entry in the study, 59 deaths were identified in S. Typhimurium patients and 221 deaths among 20,456 referents. The median age of the 59 persons were 74.1 years (range 18.1 to 90.1). In the first 30 days after entry in the study, the cumulative mortality proportion (Kaplan-Meier estimate) was 0.73% for S. Typhimurium patients and 0.04% for the referents (RR 15.4, 95% confidence interval [CI] 6.1 to 39.2). In the period 30 to 720 days after entry, cumulative mortality was 2.75% in S. Typhimurium patients and 1.51% in referents (RR 1.8, 95% CI 1.3 to 2.6). On this basis, we used the period 0 to 720 days in the remaining analyses.

Overall, patients with S. Typhimurium were 3.0 times (95% CI 2.2 to 4.0) more likely to die than referents in the 2 years following infection. After the data were adjusted for comorbidity, the relative rate was 2.3 (95% CI 1.7 to 3.2). This relative death rate was independent of age (p=0.84).

A total of 631 (30.8%) patients were hospitalized in connection with the S. Typhimurium infection. In the reference group, 577 (2.8%) were hospitalized within 60 days of entry. Five of those had gastroenteritis as their primary diagnosis.

Two hundred seventeen (10.6%) of S. Typhimurium patients and 954 (4.7%) persons from the referent group had at least one of the diagnoses listed in Table 1, which summarizes the various diagnostic groups and their weights in relation to the comorbidity index. A total of five HIV infections were found, three among patients and two in the reference group. All five were still living at the end of the study.

In the 2,047 strains, 953 (46.6%) were pansusceptible, 1,094 (53.4%) resistant to at least one drug in the panel, and 639 (30.8%) were resistant to at least two drugs. Resistance to sulfonamides was found in 47.3% of the patient isolates, tetracycline in 25.1%, streptomycin in 22.4%, ampicillin in 19.2%, chloramphenicol in 17.0%, kanamycin in 9.6%, quinolone in 4.1%, trimethoprim in 3.0%, gentamicin in 2.2%, and ceftriaxon in 1.4%. No ciprofloxacin-resistant strains were found. The MIC of ciprofloxacin in the quinolone-resistant isolates ranged from 0.06 to 0.38 mg/L (median 0.09 mg/L).

R-type ACSSuT was found in 283 (13.8%) isolates, and patients infected with this type were 6.9 times more likely to die than the general population, compared with a RR of 2.6 in patients with strains of other R-types (p =0.02). Also, chloramphenicol (7.4 vs. 2.4, p=0.003), quinolones (9.9 versus 2.8, p=0.05), and ampicillin (5.1 versus 2.7, p=0.09) were associated with higher death rates in resistant than sensitive strains.

Table 2 shows the relative death rate associated with antimicrobial resistance after the data was adjusted for coexisting diseases. Infections with pansusceptible strains were 2.3 times (95% CI 1.5 to 3.5) more likely to die than the general population, whereas infection with R-type ACSSuT was associated with 4.8 times (95% CI 2.2 to 10.5) higher mortality. Patients infected with quinolone-resistant strains (R-type Nx) were 10.3 times (95% CI 2.8 to 37.8) more likely to die, and R-type ACSSuTNx was associated with 13.1 times (95% CI 3.3 to 51.9) higher mortality. Three other antimicrobial drugs (trimethoprim, gentamicin, and ceftriaxone) were examined, but because of a low number of resistant strains, valid statistical inference could not be carried out. All the strains resistant to these drugs exhibited R-type ACSSuT. Most (82%) of the chloramphenicol-resistant strains and 72% of the ampicillin-resistant strains were also R-type ACSSuT.

A total of 270 of the isolates with R-type ACSSuT were phage-typed, and 217 (80.4%) were DT104, 18 (6.7%) DT12, 11 (4.1%) DT120, and the rest were other or unknown phage types. Strains with other R-types were distributed over a number of different phage types. A total of 1,667 were examined, and the three most common were DT12 (46.8%), DT66 (6.0%), and U288 (4.9%). Thirty-nine (2.3%) were DT104. In the patients with R-type ACSSuT, no difference in the death rate between persons infected with DT104 (relative death rate 4.4, 95% CI 1.7 to 11.6) and other phage types (relative death rate 6.4, 95% CI 1.3 to 32.4) was found; both estimates were adjusted for comorbidity.

No difference in age and sex distribution between patients infected with R-type ACSSuT and other antibiograms were found. The median age in both groups was 33 years (range 1 to 87 and 0 to 95, respectively, p=0.89).

Figure

Figure. Survival comparison of patients infected with Salmonella Typhimurium (by resistance level) to referents. The patients and referents were matched by age, gender, and county of residence.

Finally, we analyzed a model with three levels of resistance: non-ACSSuT, R-type ACSSuT (Nx-sensitive), and R-type ACSSuTNx. The figure shows the survival curve of the referents and patients according to these three groups. In the group of 40 cases with R-type ACSSuTNx, we identified five deaths within the 2-year period after infection, one of those within the first month of infection, three within 6 months, and one within 18 months. The relative risk associated with an infection with R-type ACSSuTNx was 12.4 without adjusting the data for comorbidity. After adjustment, the RR associated with this resistance pattern was 13.1. The median age in this group was 43 years (range 1 to 89), 10 years higher than the R-type ACSSuT quinolone-sensitive group.

Discussion

Since the 1990s, the frequency of antimicrobial drug resistance in zoonotic Salmonella and the number of drugs to which the strains are resistant has increased, primarily as a consequence of antimicrobial use in food production (1,9,16–18). The recent development of fluoroquinolone resistance is of particular concern (16–21). At present, a fluoroquinolone is the drug of first choice for extraintestinal and serious intestinal Salmonella infections in adults, and resistance to this drug may potentially reduce the efficacy of early empirical treatment. The health impact of antimicrobial drug resistance in zoonotic Salmonella needs to be determined (21,22). We used data from registries created for other purposes to avoid bias and were able to explore long-term death rates and adjust the data for comorbidity.

The comorbidity index was based on discharge diagnoses from patients admitted to hospitals in Denmark and to a lesser degree on data from outpatient clinics but did not include data from general practitioners. Any patient with a coexisting disease severe enough to alter the outcome of a Salmonella infection is likely to have had contact with a hospital or an outpatient clinic within the 10-year period before infection. The backbone for the construction of the comorbidity index was the National Discharge Registry. A validation of this registry showed that there was agreement between the registry and hospital records of 75% to 90%, using 3-digit level International Classification of Diseases diagnoses (14).

In general, patients with S. Typhimurium infections were 2.3 times more likely to die than the matched sample of the Danish population during a 2-year follow-up. This figure is likely to reflect both long-term consequences of S. Typhimurium as well as underlying diseases and conditions not fully described by our comorbidity score based on hospital discharge diagnosis. The excess mortality was independent of age, a finding which warrants further studies. The cumulative mortality in the first 30 days, 0.7%, is comparable with the case-fatality rate of 0.8% for all nontyphoidal Salmonella serotypes found in data from FoodNet 1996-97 (23).

We found that S. Typhimurium with R-type ACSSuT was associated with higher death rates than other strains. Similar tendencies were found for chloramphenicol and ampicillin, both being markers for R-type ACSSuT. Patients infected with R-type ACSSuT were seven times more likely to die than the general population, but when the data were adjusted for underlying illness, this figure was reduced to fivefold higher mortality. This reduction was expected; a part of the excess mortality associated with R-type ACSSuT was attributable to underlying illness. However, the excess mortality still tended to be elevated after adjustment. Patients with quinolone-resistant strains had a marked and substantial excess mortality, which could not be explained by imbalances in comorbidity. All the quinolone-resistant strains in this study were designated as fluoroquinolone-susceptible by NCCLS cut-offs for ciprofloxacin. Several patients in the study were part of an outbreak of S. Typhimurium DT104 R-type ACSSuTNx traced back to swine herds in the Danish island of Zealand (17).

Most deaths occurred in relation to infections with S. Typhimurium DT104, and we were not able to demonstrate any statistically significant variation among different phage types. In our initial model we took age into account, expecting a relatively higher mortality among the elderly. But again, we could not demonstrate such an effect. In other words, no additive effect was found between age and drug resistance compared with age and being infected by sensitive strains of S. Typhimurium.

A study from England suggests that the isolation rates of drug-resistant DT104 from blood cultures are not higher than those of other S. Typhimurium phage types and that the frequency is comparable with the incidence of blood culture isolates of Salmonella Enteritidis (7). The study suggests that S. Typhimurium of R-type ACSSuT does not cause invasive disease more often than Salmonella Enteritidis. However, the overall mortality in relation to S. Typhimurium infection is higher. Two studies based on outbreaks of resistant Salmonella in the United States and the United Kingdom have found case fatality rates of 4.2% and 3.0% respectively (6,8). Even though they were based on outbreak investigations, the cumulative death rate is comparable to our results (2.9% after 6 months of infection).

Antimicrobial drug resistance in zoonotic Salmonella may be associated with adverse consequences in several ways, including treatment failures. However, treatment failures have, until now, been infrequently reported (17,21). We had no data on treatment with antimicrobial drugs. Therefore, exploring the extent to which the excess mortality of patients infected with quinolone-resistant strains was caused by reduced efficacy of drugs was impossible. We estimate that approximately 20% of the patients were prescribed empiric treatment in connection with the collection of specimens and that some of the deaths may have been associated with reduced efficacy of flouroquinolones, as described in Mølbak et al. (17).

Resistant bacteria have a selective advantage in ecosystems where antimicrobial drugs are used. Studies have shown that treatment with antimicrobial drugs (for any reason) is a major risk factor for infections with antimicrobial drug-resistant bacteria, and that this association may result in increased incidence and illness severity (9,24,25). Infection with drug-resistant S. Typhimurium in patients treated for other infections may contribute to the excess mortality we found.

Infections with resistant Salmonella may be associated with increased severity for reasons that are poorly understood. An increased virulence of drug-resistant Salmonella has not been well characterized. Two earlier studies found increased rates of hospitalizations (10) and death (8), but these studies had limitations. Lee et al. (10) were only able to control for comorbidity in a limited way, and none of the earlier studies were restricted to a single serotype and able explore the impact of specific resistance patterns as we did.

The use of antimicrobial drugs in food production is one of the major factors in the emergence and dissemination of antimicrobial drug-resistance in foodborne bacterial pathogens. We were able to determine death rates in a large sample of patients with S. Typhimurium and to control for confounding factors in the analyses. We associated resistance in S. Typhimurium with excess mortality, and the demonstration of a hazard to human health underscores the need for restrictions in the use of antimicrobial drugs in the production of food from animals. A particular risk was associated with quinolone resistance, indicating that the use of fluoroquinolones for food production animals should be discontinued.

Dr. Helms is a research fellow at the Department of Epidemiology Research, Statens Serum Institut, studying health outcomes in relation to foodborne bacterial infections, in particular the hazards associated with drug-resistant bacteria in our food supply.

Acknowledgments

We thank Per Krag Andersen for his statistical advice, the Salmonella Laboratory of The Danish Veterinary Laboratory for phage typing, and the 10 microbiology laboratories in Denmark for reporting findings of Salmonella Typhimurium to the SSI. We also thank the two reviewers for helpful suggestions.

The study was funded by The Danish Research Center for Environmental Health.

References

Figure

• Figure. Survival comparison of patients infected with Salmonella Typhimurium (by resistance level) to referents. The patients and referents were matched by age, gender, and county of residence.

Tables

• Table 1. The distribution of comorbidity diagnosis of 2,047 patients with S. Typhimurium infection and a sample of the general Danish population of 20,456 persons
  
• Table 2. Two-year relative death rate of patients infected with Salmonella Typhimurium, by antimicrobial susceptibility pattern. Registry linkage study including 2,047 patients and a random matched sample of 20,456 people from the Danish…

Suggested citation: Helms M, Vastrup P, Gerner-Smidt P, and Mølbak K. Excess Mortality Associated with Antimicrobial Drug-Resistant Salmonella Typhimurium. Emerg Infect Dis. [serial on the Internet]. 2002 May [date cited]. Available from http://wwwnc.cdc.gov/eid/article/8/5/01-0267.htm

DOI: 10.3201/eid0805.010267

미국의 동물용 항생제 사용량 증가

2011년 미국에서 사용된 동물용 항생제는 총 2990만 파운드.
2011년 미국에서 사용된 인체용 항생제는 총 730만 파운드.

가축에 사용된 항생제가 인체용 항생제에 비해 3.9배나 더 많아
(미국 내 항생제의 80%를 가축에 사용, 인체용은 20%에 불과)

니실린 및 테트라사이클린
2009년  1150만 파운드 –> 2011년 1440만 파운드

미국 내 페니실린 판매량 중 38%와 테트라사이클린 판매량 중 98%가 동물에서 사용됨
(인체 치료용 항생제 포함한 통계)

Animal Antibiotic Use Continues Upwards, FDA Keeps Blinders on

http://www.huffingtonpost.com/david-wallinga-md/animal-antibiotic-use_b_2654385.html

With legislation in 2008, Congress for the first time asked the Food and Drug Administration (FDA) to collect and report to the public the overall sales of antibiotics used in food animals. February 6 marked the release of a third year’s worth of data.

Penicillins and tetracyclines sold for animal use increased for the second year in a row. From 11.5 million pounds in 2009, sales rose to 14.4 million pounds in 2011. The two classes of antibiotics remain the most commonly used antibiotics in livestock and poultry, despite their obvious import for treating infections in people as well. In 2011, animal sales accounted for 38 percent of total penicillin sales and 98 percent of total tetracycline sales, including in humans.

Use of antibiotics in animals overall also continues to rise, to 29.9 million pounds in 2011. That compares with at least 7.3 million pounds (according to FDA data, comparing to 7.7 million according to Pew) sold for use in humans. The fact that 3.9 times more antibiotics are used in animals than humans, as this new infographic illustrates from the PEW Charitable Trusts, may shock most Americans.

For 34 years, the FDA considered the routine use of penicillins and tetracyclines in animal feed, for purposes like growth promotion, a public health threat. The agency had moved in 1977 to withdraw its approval for these animal feed products on the grounds that such use had not been shown to be safe for people. That official stance remained on the books until 2011.

IATP produced a recent bibliography listing 147 studies comprising a compelling body of evidence that this routine use antibiotics at nontherapeutic levels in animal feed helps drive an epidemic of expensive, hard-to-treat superbug infections in people, including those coming from a meat supply replete with bacteria resistant to multiple antibiotics.

In December 2011, FDA backtracked from its 1977 proposal claiming the move to protect public health by ending addition of penicillins and tetracyclines to animal feed was now outdated. Instead, said FDA, it was changing focus, by asking pharmaceutical companies to voluntarily to reduce the sales of their antibiotic products sold for use in animal feed.

So, if the success of FDA’s approach strikes you as unlikely, you’re not alone. Along with my partners in Keep Antibiotics Working, I have been quite skeptical of this voluntary approach, but apparently there’s been skepticism within the FDA as well.

Last March, a Federal judge ordered the FDA to reverse its decision and withdraw the animal products after all. In effect, the judge said that the stand first taken by the FDA in 1977 had been right. The FDA has appealed the judge’s decision.

“In the face of the antibiotic resistance crisis, we cannot afford to be standing still. We need strong action to combat the overuse of antibiotics in animal agriculture,” said Steven Roach, Public Health Program Director at Food Animal Concerns Trust (FACT) and a member of Keep Antibiotics Working.

Nothing less will suffice for the public’s health. The World Economic Forum recently reported that overuse and misuse of antibiotics has created the real and immediate threat that once easily treatable infections will rage, and be unresponsive to treatment with any existing antibiotics.

As a parent of young children who get bacterial bronchitis, ear infections and skin infections, that keeps me awake at night.

물고기들에게 약 먹였습니까?

슈퍼박테리아, 성인 여성한테 피해 집중
[한겨레] 이정애 기자   
 

출처 : 한겨레 등록 : 20110601 20:36 | 수정 : 20110602 09:15  
http://www.hani.co.kr/arti/international/europe/480836.html
             
유럽 질병통제센터 ‘사망사례중 여성비율 높아 이례적’
“특정 유전형질에 반응 가능성”…사망자 17명으로 늘어

‘슈퍼박테리아는 도대체 어디서 왔을까?’
독일 당국의 발표로 스페인산 오이는 ‘누명’을 벗었지만, 거꾸로 유럽의 공포감은 더 커져가고 있다. 슈퍼박테리아로 불리는 장출혈성 대장균(EHEC)에 의한 사망자가 처음 발생한 지 2주가 넘도록 정확한 오염경로 파악은커녕 더 미궁으로 빠져드는 모양새다. 장출혈성 대장균에 의한 일반적 사망 사례와는 달리 이번 피해가 ‘성인 여성’에게 집중되고 있어, 여성에만 반응하는 특정한 유전 형질이 있는 게 아니냐는 의문도 높아지고 있다.

현재까지 파악된 피해자 대부분은 성인 여성이다. 장출혈성 대장균에 의한 사망 사고가 대체로 면역체계가 약한 어린이에게서 많이 나타난다는 점에 비춰보면 이례적이다.

31일 독일 밖에서 처음으로 나온 스웨덴 사망자 역시 50대 여성이었다. 영국 <비비시>(BBC) 방송은 유럽질병예방통제센터의 설명을 인용해 “그동안 장출혈성 대장균에 의한 ‘용혈성 요독증 증후군’ (사망) 사례는 대체로 5살 미만의 어린이들에게서 주로 관찰됐는데, 이번 사태의 경우 피해자의 87%가 성인이었으며 이 중에서도 여성(68%)의 비율이 높게 나타났다”고 전했다. 드물게도, 1994년 미국에서도 평균 36살의 여성에게 피해가 집중되는 장출혈성 대장균이 발견된 바 있다.

과학자들은 이런 현상에 대해 아직까지 정확한 답을 내놓지 못하고 있다. 여성들이 주로 오이 등 낮은 칼로리의 유기농 건강식을 선호하기 때문이 아니냐는 가설도 있지만, 그런 결론은 성급하다는 지적이 나온다. 이와 관련해 베를린 소재 샤리테 대학의 울프 괴벨 박사는 “특정 유전형질이 일부 인종에게만 나타나듯 (슈퍼박테리아 안의) 특정한 유전형질이 여성 신체에서만 반응을 보이는 것일 수 있다”고 말했다.

현재 슈퍼박테리아에 대한 디엔에이(DNA) 분석 등 광대한 작업이 벌어지고 있지만, 오염경로 규명은 진전이 없다. 특히 “슈퍼박테리아는 스페인에서 수입된 오이에서 발견됐다”던 독일 보건당국이 “오이가 스페인에서 감염된 건지 운반 도중 문제가 생기거나 독일로 들여온 뒤 발생했는지는 확실하지 않다”고 발표하면서, 스페인과의 외교적 논란으로까지 비화되고 있다. 이미 각국이 스페인산 농산물에 대한 수입금지 조처를 내려 피해를 입은 스페인 쪽은 “이번 사태로 입은 막대한 손실을 보상하기 위해 특별조처를 유럽연합에 요구할 것”이라고 밝혔다.

한편, 1일에도 84살 독일 여성이 슈퍼박테리아에 희생된 것으로 보고됐다. 이에 따라 2주 전 독일 북부에서 유사 식중독 사례가 처음 알려진 이래, 이날까지 17명이 목숨을 잃었고 감염자 수는 1500명까지 불어났다.

이정애 기자 hongbyul@hani.co.kr

유럽식품안전청(The European Food Safety Authority)에서 돼지의 MRSA(메티실린내성포도상구균) 조사를 최초로 시행했다는 소식입니다. 유럽연합 회원국 24개국에서 수행된 조사에 사육돼지들은 따르면 17개의 MRSA type을 보유하고 있었고, 7개의 MRSA type은 가지고 있지 않은 것으로 나타났다고 합니다. 평균적으로 사육돼지의 1/4에서 서로 다른 type의 MRSA가 발견되었다고 하는데, 회원 국가들 간의 통계수치는 많은 차이가 있었다고 합니다. 가장 흔하게 발견되는 type은 MRSA ST398이었습니다.

MRSA(메티실린내성포도상구균)은 인간의 공중보건 상 커다란 위협이 되고 있으며, 병원 내 감염의 가장 중요한 원인 중의 하나이며, 많은 다양한  MRSA type이 보고되고 있습니다.

돼지농장 내에서 확인된 MRSA(메티실린내성포도상구균)는 농장주, 농장노동자, 수의사, 그리고 그 가족들에게 건강 상 위해를 끼칠 수 있으며, 축산식품을 통해 소비자들에게도 건강 상 위해를 끼칠 수 있습니다.

조사를 수행한 패널들은 현재까지 MRSA ST398가 항생제 내성세균에 오염된 동물로부터 인간에게 전염된다는 과학적 증거는 없다고 밝혔습니다.


=======================

EFSA publishes results of the first survey on MRSA in pigs in the EU

출처 : 24 November 2009
http://www.efsa.europa.eu/EFSA/efsa_locale-1178620753812_1211903070258.htm

The European Food Safety Authority (EFSA) has published the first EU-wide survey on MRSA (Methicillin-resistant Staphylococcus aureus) in breeding pigs. The results indicate that MRSA, a bacterium resistant to many antibiotics, is commonly detected in holdings with breeding pigs in some EU Member States. The survey provides estimates of its occurrence and makes recommendations for further monitoring and investigation of the causes and implications of MRSA findings in pig holdings in the EU.

The survey was carried out in 24 Member States[1], 17 of which found some type of MRSA in their holdings with breeding pigs and 7 none at all. On average, different types of MRSA were found in 1 out of 4 holdings with breeding pigs across the EU, but the survey also says that figures vary greatly between Member States. MRSA ST398 was the most reported type of MRSA among the holdings with breeding pigs in the EU; some Member States also reported other types, but their prevalence was much lower[2].

MRSA is a major concern for public health and its various types are recognised as an important cause of hospital-acquired (or nosocomial) infections in humans. The specific type MRSA ST398 has been identified in some domestic animals and is considered an occupational health risk for farmers, veterinarians and their families, who may become exposed to it through direct or indirect contact with these animals. In an opinion published earlier this year, EFSA’s Biological Hazards (BIOHAZ) Panel assessed the public health significance of MRSA in animals and food[3] and concluded that the MRSA ST398[4] strain is less likely to contribute to the spread of MRSA in hospitals than other types carried by humans. The Panel also said that there is currently no evidence that MRSA ST398 can be transmitted to humans by eating or handling contaminated food.

In the survey published today, EFSA recommends monitoring of pigs and other food producing animals for MRSA. It also says further research should be carried out, so that the reasons for differences in the prevalence of MRSA in the various Member States can be identified and used to propose options on possible control measures.

_________________________________________
Note to editors:

The Staphylococcus aureus is a bacterium that can be persistently or intermittently carried by healthy humans and is a very common cause of minor skin infections that usually do not require treatment. In patients in hospitals, Staphylococcus aureus is a common cause of hospital-acquired infections. Its variant Methicillin-Resistant Staphylococcus aureus (MRSA) emerged in the 1970s and is now often found in hospitals in many European Member States. MRSA is resistant to many commonly used antibiotics. In recent years, clones of MRSA have evolved outside the hospitals, causing infections among people who have no connection with hospitals. Most recently MRSA has also been detected in several farm animal species.

EFSA’s Zoonoses Unit monitors and analyses the situation on zoonoses, zoonotic agents, antimicrobial resistance, microbiological contaminants and food-borne outbreaks across Europe. The Unit is supported by a Task Force on Zoonoses Data Collection consisting of a pan-European network of national representatives of Member States, other reporting countries, as well as World Health Organisation (WHO) and World organisation for animal health (OIE). They gather each year data in their respective countries.

EFSA’s BIOHAZ Panel provides scientific advice on biological hazards in relation to food safety and food-borne diseases. This covers food-borne zoonoses (animal diseases transmissible to humans), Transmissible spongiform Encephalopathies (BSE/TSEs), food microbiology, food hygiene and associated waste management issues. The Panel’s risk assessment work helps to provide a sound foundation for European policies and legislation and supports risk managers in taking effective and timely decisions.

• Analysis of the baseline survey on the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in holdings with breeding pigs, in the EU, 2008 [1] – Part A: MRSA prevalence estimates
  

EFSA’s previous work on MRSA:

• EFSA’s BIOHAZ Panel “Assessment of the Public Health significance of Methicillin-resistant Staphylococcus aureus (MRSA) in animals and foods”
  
• Joint scientific report of ECDC, EFSA and EMEA on Methicillin-resistant Staphylococcus aureus (MRSA) in livestock, companion animals and food
  
  
• Joint Opinion of ECDC, EFSA, EMEA and SCENIHR on antimicrobial resistance (AMR) focused on zoonotic infections

[1] The sampling took place during 2008. Dust samples were taken in the environment of pigs in a total of 5,073 holdings from 24 EU Member States and two non-Member States. The pooled sample of each holding was tested for the presence of the various MRSA strains.
[2] Only six Member States and one non-Member State reported MRSA non-ST398 in the holdings with breeding pigs. The prevalence of MRSA non-ST398 in holdings with breeding pigs across the participating Member States was substantially lower than the prevalence of MRSA and MRSA ST398.
[3] EFSA’s BIOHAZ Panel opinion on the “Assessment of the Public Health significance of Methicillin-resistant Staphylococcus aureus (MRSA) in animals and foods” of March 2009
[4] In its opinion the BIOHAZ Panel refers to CC398 which corresponds to MRSA ST398.