Travel Destinations and Sexual Behavior as Indicators of Antibiotic Resistant Shigella Strains--Victoria, Australia

BACKGROUND

Knowledge of relationships between antibiotic susceptibility of Shigella isolates and travel destination or other risk factors can assist clinicians in determining appropriate antibiotic therapy prior to susceptibility testing. We describe relationships between resistance patterns and risk factors for acquisition in Shigella isolates using routinely collected data for notified cases of shigellosis between 2008 and 2012 in Victoria, Australia.

METHODS

We included all shigellosis patients notified during the study period, where Shigella isolates were tested for antimicrobial sensitivity using Clinical and Laboratory Standards Institute breakpoints. Cases were interviewed to collect data on risk factors, including recent travel. Data were analyzed using Stata 13.1 to examine associations between risk factors and resistant strains.

RESULTS

Of the 500 cases of shigellosis, 249 were associated with overseas travel and 210 were locally acquired. Forty-six of 51 isolates of Indian origin displayed decreased susceptibility or resistance to ciprofloxacin. All isolates of Indonesian origin were susceptible to ciprofloxacin. Twenty-six travel-related isolates were resistant to all tested oral antimicrobials. Male-to-male sexual contact was the primary risk factor for 80% (120/150) of locally acquired infections among adult males, characterized by distinct periodic Shigella sonnei outbreaks.

CONCLUSIONS

Clinicians should consider travel destination as a marker for resistance to common antimicrobials in returning travelers, where severe disease requires empirical treatment prior to receipt of individual sensitivity testing results. Repeated outbreaks of locally acquired shigellosis among men who have sex with men highlight the importance of prevention and control measures in this high-risk group.

Foodborne and waterborne infections in elderly community and long-term care facility residents,Victoria, Australia

We calculated rates of foodborne and waterborne infections reported to the health department in Victoria, Australia, during 2000-2009 for elderly residents of long-term care facilities (LTCFs) and the community. We used negative binomial regression to estimate incidence rate ratios, adjusting for age, sex, and reporting period. We analyzed 8,277 infections in elderly persons. Rates of campylobacteriosis, legionellosis, listeriosis, toxigenic Escherichia coli infections, and shigellosis were higher in community residents, and rates of Salmonella infection were higher in LTCF residents. Each year, 61.7 Campylobacter infections were reported per 100,000 LTCF residents, compared with 97.6 per 100,000 community residents. LTCF residents were at higher risk for S. enterica serotype Typhimurium associated with outbreaks. Rates of foodborne infections (except salmonellosis) were similar to or lower for LTCF residents than for community residents. These findings may indicate that food preparation practices in LTCFs are safer than those used by elderly persons in the community.

A multistate outbreak of hepatitis A associated with semidried tomatoes in Australia, 2009

BACKGROUND

A large outbreak of hepatitis A affected individuals in several Australian states in 2009, resulting in a 2-fold increase in cases reported to state health departments compared with 2008. Two peaks of infection occurred (April-May and September-November), with surveillance data suggesting locally acquired infections from a widely distributed food product.

METHODS

Two case-control studies were completed. Intensive product trace-back and food sampling was undertaken. Genotyping was conducted on virus isolates from patient serum and food samples. Control measures included prophylaxis for close contacts, public health warnings, an order by the chief health officer under the Victorian Food Act 1984, and trade-level recalls on implicated batches of semidried tomatoes.

RESULTS

A multijurisdictional case-control study in April-May found an association between illness and consumption of semidried tomatoes (odds ratio [OR], 3.0; 95% CI 1.4-6.7). A second case-control study conducted in Victoria in October-November also implicated semidried tomatoes as being associated with illness (OR, 10.3; 95% CI, 4.7-22.7). Hepatitis A RNA was detected in 22 samples of semidried tomatoes. Hepatitis A virus genotype IB was identified in 144 of 153 (94%) patients tested from 2009, and partial sequence analysis showed complete identity with an isolate found in a sample of semidried tomatoes.

CONCLUSIONS

The results of both case-control studies and food testing implicated the novel vehicle of semidried tomatoes as the cause of this hepatitis A outbreak. The outbreak was extensive and sustained despite public health interventions, the design and implementation of which were complicated by limitations in food testing capability and complex supply chains.

Food- and waterborne disease outbreaks in Australian long-term care facilities, 2001-2008

Abstract Food- or waterborne diseases in long-term care facilities (LTCF) can result in serious outcomes, including deaths, and they are potentially preventable. We analyzed data collected by OzFoodNet on food- and waterborne disease outbreaks occurring in LTCF in Australia from 2001 to 2008. We compared outbreaks by the number of persons affected, etiology, and implicated vehicle. During 8 years of surveillance, 5.9% (55/936) of all food- and waterborne outbreaks in Australia occurred in LTCF. These LTCF outbreaks affected a total of 909 people, with 66 hospitalized and 23 deaths. The annual incidence of food- or waterborne outbreaks was 1.9 (95% confidence intervals 1.0-3.7) per 1000 facilities. Salmonella caused 17 outbreaks, Clostridium perfringens 14 outbreaks, Campylobacter 8 outbreaks, and norovirus 1 outbreak. Residents were at higher risk of death during outbreaks of salmonellosis than for all other outbreaks combined (relative risk 7.8, 95% confidence intervals 1.8-33.8). Of 15 outbreaks of unknown etiology, 11 were suspected to be due to C. perfringens intoxication. Food vehicles were only identified in 27% (14/52) of outbreaks, with six outbreak investigations implicating pureed foods. Dishes containing raw eggs were implicated as the cause of four outbreaks. Three outbreaks of suspected waterborne disease were attributed to rainwater collected from facility roofs. To prevent disease outbreaks, facilities need to improve handling of pureed foods, avoid feeding residents raw or undercooked eggs, and ensure that rainwater tanks have a scheduled maintenance and disinfection program.

Serogroup-specific risk factors for Shiga toxin-producing Escherichia coli infection in Australia

BACKGROUND

Shiga toxin-producing Escherichia coli (STEC) is an important cause of foodborne illness. In Australia, risk factors for STEC infection have not been examined at a national level.

METHODS

We conducted a case-control study in 6 Australian jurisdictions from 2003 through 2007. A case patient was defined as a person from whom STEC was isolated or toxin production genes were detected in stool. Case patients were recruited from notifiable disease registers, and 3 control subjects frequency matched by age were selected from databases of controls. Using structured questionnaires, interviewers collected data on clinical illness, foods consumed, and exposures to potential environmental sources.

RESULTS

We recruited 43 case patients infected with STEC serogroup O157, 71 case patients infected with non-O157 serogroups, and 304 control subjects. One patient infected with serogroup O157 and 7 infected with non-O157 serogroups developed hemolytic uremic syndrome. Compared with control subjects, case patients infected with STEC O157 were more likely to eat hamburgers, visit restaurants, have previously used antibiotics, or have family occupational exposure to red meat. Case patients infected with non-O157 STEC were more likely to eat sliced chicken meat or corned beef from a delicatessen, camp in the bush, eat catered meals, or have family occupational exposure to animals. Negative associations were observed for certain foods, particularly homegrown vegetables, fruits, or herbs.

CONCLUSION

This study of risk factors for STEC infection by serogroup highlights risks associated with eating hamburgers and occupational handling of raw meat. To prevent infection, hamburgers must be cooked thoroughly, and people handling raw meat or who have close contact with animals must ensure adequate hygiene.

Frequency of infectious gastrointestinal illness in Australia, 2002: regional, seasonal and demographic variation

To estimate the frequency of infectious gastroenteritis across Australia, and to identify risk factors, we conducted a national telephone survey of 6087 randomly selected respondents in 2001-2002. The case definition was three or more loose stools and/or two or more vomits in a 24-hour period in the last 4 weeks, with adjustment to exclude non-infectious causes and symptoms secondary to a respiratory infection. Frequency data were weighted to the Australian population. Multivariate logistic regression was used to assess potential risk factors including season, region, demographic and socioeconomic status. Among contacted individuals, 67% responded. The case definition applied to 7% of respondents (450/6087) which extrapolates to 17.2 million (95% CI 14.5-19.9 million) cases of gastroenteritis in Australia in one year, or 0.92 (95% CI 0.77-1.06) cases/person per year. In the multivariate model, the odds of having gastroenteritis were increased in summer and in the warmest state, in young children, females, those with higher socioeconomic status and those without health insurance.

Estimating foodborne gastroenteritis, Australia

An estimated 4.0–6.9 million episodes of foodborne gastroenteritis occur in Australia each year.

We estimated for Australia the number of cases, hospitalizations, and deaths due to foodborne gastroenteritis in a typical year, circa 2000. The total amount of infectious gastroenteritis was measured by using a national telephone survey. The foodborne proportion was estimated from Australian data on each of 16 pathogens. To account for uncertainty, we used simulation techniques to calculate 95% credibility intervals (CrI). The estimate of incidence of gastroenteritis in Australia is 17.2 million (95% confidence interval 14.5–19.9 million) cases per year. We estimate that 32% (95% CrI 24%–40%) are foodborne, which equals 0.3 (95% CrI 0.2–0.4) episodes per person, or 5.4 million (95% CrI 4.0–6.9 million) cases annually in Australia. Norovirus, enteropathogenic Escherichia coli, Campylobacter spp., and Salmonella spp. cause the most illnesses. In addition, foodborne gastroenteritis causes ≈15,000 (95% CrI 11,000–18,000) hospitalizations and 80 (95% CrI 40–120) deaths annually. This study highlights global public health concerns about foodborne diseases and the need for standardized methods, including assessment of uncertainty, for international comparison.