Local Public Health Laboratories Research Articles

Laboratory-Based Surveillance of Non-typhoidalSalmonellaInfections in Guangdong Province, China

Salmonella is one of the most common foodborne pathogens in humans. Laboratory-based surveillance for non-typhoidal Salmonella infection was conducted in Guangdong Province, China to improve understanding about the disease burden and detection of dispersed outbreaks. Salmonella isolated from patients with diarrhea were sent from 16 sentinel hospitals to local public health laboratories for confirmation, serotyping, antimicrobial susceptibility testing, and pulsed-field gel electrophoresis (PFGE). PFGE patterns were analyzed to identify clusters representing potential outbreaks. Between September 2009 and October 2010, 352 (4%) Salmonella isolates were obtained from 9167 stool specimens. Salmonella enterica serotype Typhimurium (45%) and Salmonella enterica serotype Enteritidis (13%) were the most common serotypes, and multidrug resistance was high, especially in Salmonella Typhimurium isolates. PFGE patterns of obtained Salmonella isolates were found to be diverse, but a unique PFGE pattern comprising 53 Salmonella Typhimurium isolates were found to occur almost exclusively in infants. Epidemiologic studies are ongoing to determine whether a common exposure is the source of the Salmonella Typhimurium strain frequently isolated from infants.

Foodborne-associated Shigella sonnei, India, 2009 and 2010

Foodborne-associated Shigella sonnei, India, 2009 and 2010

Laboratory-Based Surveillance of NontyphoidalSalmonellaInfections in China

Foodborne infections are an important public health problem in China. In 2008, we conducted surveillance for laboratory-confirmed nontyphoidal Salmonella to monitor trends for this infection in China and to build capacity for rapid detection and response to foodborne outbreaks. Salmonella isolates from patients with diarrhea were sent from hospitals to local public health laboratories for confirmation, serotyping, and antimicrobial susceptibility testing. A total of 126 hospitals in 44 cities and counties from 8 provinces provided isolates and epidemiologic data for analysis. Of 23,140 stool specimens submitted to clinical laboratories, 662 (3%) grew Salmonella enterica. Salmonella were most commonly detected between April and October. The median age of infected patients was 27 years; 34% of infections occurred in patients <5 years old. Of the 662 isolates, we found 73 serotypes, of which serotype Enteritidis (31%) and serotype Typhimurium (26%) were the most common. The prevalence of resistance was high for clinically important antimicrobial agents, including ampicillin (41%) and ciprofloxacin (6%). More than 60% of isolates, including 35% of all Typhimurium, were resistant to three or more antimicrobial agents. In this first multiprovince surveillance report of laboratory-confirmed Salmonella infections in China, we found that Enteritidis and Typhimurium are the most common serotypes and that efforts to reduce antimicrobial resistance among Salmonella in China are needed. Although no outbreaks were detected using this system, efforts to improve this system's capacity to do so are underway.

Application of new assays for rapid confirmation and genotyping of isolates of Rubella virus

Rubella virus (RV) isolation is recommended by the WHO Measles and Rubella Labnet for studying the etiology and epidemiology of rubella. However, the absence of cytopathologic effects (CPE) in many of the cell lines used commonly makes it difficult to confirm RV growth. In this study, two assays amplifying RV cDNA were developed and validated in order to confirm and genotype RV isolates after cell culture. A SYBR Green I-based real-time PCR (Rtime-SGE317) was established for initial rapid detection of RV in Vero cells and a nested PCR (PCR-E860) was used for amplifying further the 739 nt window of the E1 gene for the identification of RV genotype as recommended by the WHO. Sensitivities of the two assays were evaluated using eight RV isolates, two from infants with the congenital rubella syndrome (CRS) and six from patients with acute rubella. All the isolates had cycle threshold (C(t)) values <37 after the third passage, which is recommended as the cut-off for the confirmation of a viable RV isolate. Phylogenetic analysis based on the 739 nt window generated by the PCR-E860 showed that the eight RV isolates belonged to genotypes 1E, 1G, and 2B. The Rtime-SGE317 assay can be carried out in local public health laboratories, which would extend the molecular surveillance of rubella and contribute to the WHO goal of eradicating rubella worldwide.

The role of local public health laboratories.

Local public health laboratories (PHLs) serve many of the same roles as state PHLs and often perform many or portions of the 11 Core Functions and Capabilities of State Public Health Laboratories; however, they differ in several important ways. First, many local laboratories provide testing at the site of patient care (e.g., sexually transmitted infection clinics) or address local environmental issues (e.g., water quality). Second, local PHLs support the missions of local public health departments, which may differ from those at the state level. Third, local PHLs often serve as conduits, collecting specimens for various state-level screening and disease-control programs; and while they may not perform the testing, local PHLs are responsible for tracking specimens, ordering tests, and reporting results. Fourth, local PHLs often serve as surge capacity for state PHLs, particularly for testing to support emergency response. Last, local PHLs work with and are typically co-located in the local public health agency with other public health programs. Local PHL professionals work as a team with investigators, inspectors, and community and public health medical professionals and, thus, are poised to provide rapid and relevant responses to community needs.

The Laboratory Response Network: Its role in times of disaster

The Laboratory Response Network (LRN) was established by the Centers for Disease Control and Prevention. Today, the LRN is charged with the task of maintaining an integrated network of state and local public health, federal, military, and international laboratories that can respond to bioterrorism, chemical terrorism, and other public health emergencies. The more than 150 laboratories that make up the current LRN are affiliated with federal agencies, military installations, international partners, and state and local public health departments. Laboratories in the network may accept samples from hospitals, clinics, the Federal Bureau of Investigation, other law enforcement groups, emergency medical services, and the military and other agencies. All of the LRN laboratories use the same protocols and validated methods to ensure rapid and certain identification of dangerous biologic agents that cause anthrax, botulism, plague, tularemia, brucellosis, and other illnesses.

Surveillance for human Salmonella infections in the United States.

Surveillance for human Salmonella infections plays a critical role in understanding and controlling foodborne illness due to Salmonella. Along with its public health partners, the Centers for Disease Control and Prevention (CDC) has several surveillance systems that collect information on Salmonella infections in the United States. The National Salmonella Surveillance System, begun in 1962, receives reports of laboratory-confirmed Salmonella infections through state public health laboratories. Salmonella outbreaks are reported by state and local health departments through the Foodborne Disease Outbreak Reporting System, which became a Web-based, electronic system (eFORS) in 2001. PulseNet facilitates the detection of clusters of Salmonella infections through standardized molecular subtyping (DNA "fingerprinting") of isolates and maintenance of "fingerprint" databases. The National Antimicrobial Resistance Monitoring System for Enteric Bacteria (NARMS) monitors antimicrobial resistance in Salmonella by susceptibility testing of every 20th Salmonella isolate received by state and local public health laboratories. FootNet is an active surveillance system that monitors Salmonella infections in sentinel areas, providing population-based estimates of infection rates. Efforts are underway to electronically link all of the Salmonella surveillance systems at CDC to facilitate optimum use of available data and minimize duplication.

High Prevalence of Antimicrobial Resistance among Shigella Isolates in the United States Tested by the National Antimicrobial Resistance Monitoring System from 1999 to 2002

Shigella spp. infect approximately 450,000 persons annually in the United States, resulting in over 6,000 hospitalizations. Since 1999, the National Antimicrobial Resistance Monitoring System (NARMS) for Enteric Bacteria has tested every 10th Shigella isolate from 16 state or local public health laboratories for susceptibility to 15 antimicrobial agents. From 1999 to 2002, NARMS tested 1,604 isolates. Among 1,598 isolates identified to species level, 1,278 (80%) were Shigella sonnei, 295 (18%) were Shigella flexneri, 18 (1%) were Shigella boydii, and 7 (0.4%) were Shigella dysenteriae. Overall, 1,251 (78%) were resistant to ampicillin and 744 (46%) were resistant to trimethoprim-sulfamethoxazole (TMP-SMX). Prevalence of TMP-SMX- or ampicillin- and TMP-SMX-resistant Shigella sonnei isolates varied by geographic region, with lower rates in the South and Midwest regions (TMP-SMX resistance, 27% and 30%, respectively; ampicillin and TMP-SMX resistance, 25% and 22%, respectively) and higher rates in the East and West regions (TMP-SMX resistance, 66% and 80%, respectively; ampicillin and TMP-SMX resistance, 54% and 65%, respectively). Nineteen isolates (1%) were resistant to nalidixic acid (1% of S. sonnei and 2% of S. flexneri isolates); 12 (63%) of these isolates had decreased susceptibility to ciprofloxacin. One S. flexneri isolate was resistant to ciprofloxacin. All isolates were susceptible to ceftriaxone. Since 1986, resistance to ampicillin and TMP-SMX has dramatically increased. Shigella isolates in the United States remain susceptible to ciprofloxacin and ceftriaxone.

Converging issues in veterinary and public health.

Converging issues in veterinary and public health.

Public Health Laboratory Preparedness; Bioterrorism the New Challenge

In the event of a bioterrorist attack, rapid screening, agent identification, and confirmatory diagnosis will be critical, so that prevention and treatment measures can be implemented quickly. However, because few biologic agents thought likely to be used as biological weapons represent major public health problems in the United States, we have limited capacity to diagnose them, either at the state and local or the federal level. to begin to address this new public health challenge the Laboratory Response Network for Bioterrorism (LRN) was established.The LRN is a multi-level system designed to link state and local public health laboratories, clinical, military, veterinary, agricultural, water and food-testing laboratories. Operational in August of 1999, the LRN was established as a consequence of Presidential Decision Directive 39, increased congressional awareness of the huge biological weapons program in the former Soviet Union, the high level of risk to national security and subsequent emergency funding to the Centers for Disease Control and Prevention under the DHHS Operating Plan for Anti- Bioterrorism Initiative.

PulseNet: The Molecular Subtyping Network for Foodborne Bacterial Disease Surveillance, United States

PulseNet, the national molecular subtyping network for foodborne disease surveillance, was established by the Centers for Disease Control and Prevention and several state health department laboratories to facilitate subtyping bacterial foodborne pathogens for epidemiologic purposes. PulseNet, which began in 1996 with 10 laboratories typing a single pathogen (Escherichia coli O157:H7), now includes 46 state and 2 local public health laboratories and the food safety laboratories of the U.S. Food and Drug Administration and the U.S. Department of Agriculture. Four foodborne pathogens (E. coli O157:H7; nontyphoidal Salmonella serotypes, Listeria monocytogenes and Shigella) are being subtyped, and other bacterial, viral, and parasitic organisms will be added soon.

Applications and Transfer of Technology to the Nations of the South: Biotechnology and the Control of Childhood Enteric Infections

The optimal use of biotechnology to address the health care needs of developing countries entails the formation of interdisciplinary working groups linking basic biomedical scientists with public health workers, epidemiologists, physicians, and social scientists. Their mission should be congruent with and guided by the public health goals and primary care program of the country or region. Moreover, their research and development activities should lead to products that address a specific need and which are evaluable, cost-effective, and readily transferred to the public health sector. With respect to the enteric infections of childhood, the essential components of an integrated control effort are a field site where infections of this kind are common and readily studied; a local public health laboratory where the performance of new products can be tested and where technology transfer can occur; a basic science laboratory where molecular pathogenicity studies lead to new diagnostic tests, vaccines, and drugs; and a production laboratory where these products can be refined and prepared in sufficient amounts for field testing. This strategy is now being evaluated for the control of infantile diarrhea through the combined use of epidemiologic investigations, DNA probe and amplification techniques, and molecular fingerprinting. Together, these methods are yielding new information about microbial reservoirs and transmission systems; in turn, this information should lead to highly focused public health interventions.

Serologic and Intradermal Tests for Parasitic Infections

For years, the diagnosis of most parasitic diseases has depended upon the direct demonstration of the parasite or its cysts, eggs, or larvae in specimens. In some infections, direct demonstration of the causative agent or its stages is almost impossible. In such cases, indirect techniques, such as serologic methods, have been found to be more practical and sensitive than are direct methods. Most serologic methods have been devised to detect antibodies. Tests for the detection of antigen are just beginning to be utilized; however, the practicality and under what situations antigen detection tests can be used await further testing. The majority of the serum antibody tests employ a heterogeneous mixture of antigens. Antigens derived from whole adult or larval stages usually result in tests with poor specificity and/or sensitivity. The necessity for better purified and standardized antigens cannot be over emphasized. Although there have been many major advances in the serodiagnosis of parasitic infections, a major drawback to routine use of parasitic serologies is the lack of commercially available reliable test kits. For the diagnosis of most parasitic diseases, one must rely upon specialty laboratories or public health laboratories. Before any laboratory begins to offer parasitic test serologies, they should contact their local or state public health laboratory or the Parasitic Serologic Section of the Centers for Disease Control to determine the pros and cons of these tests. Information of this type should be used to inform the physician of the limitations of the test in the differential diagnosis.

Local public health laboratory service in California.

Local public health laboratory service in California.

Every Nurse an Epidemiologist

After examining Tom, the resident physician made a tentative diagnosis of possible malaria, brucellosis, or nephritis and admitted Tom to the hospital. When he arrived on the ward, the nurse obtained the laboratory specimens the doctor had ordered and forwarded them to the local public health laboratory which served the hospital. A few days later, when the results of the agglutination test were reported positive for brucellosis, the local health officer requested the public health nurse to investigate the situation. She interviewed the patient and physician, visited the patient's home, and enlisted the aid of the local representative of the Department of Agriculture. She was able to establish that Tom's infection did not come from the two cows which supplied the family with milk, and that Tom had not used milk or butter away from home nor had he worked with animals on other farms. After repeated interviews she learned that to supplement his income, Tom worked each Monday at a slaughter house in a nearby town. Mrs. Lester (B.A., Grenada, Jackson, Miss.; Baptist Memorial, Memphis, Tenn.; M.P.H., University of Mirhignn, Ann Arbor) is chief of the Nursing Section, Epidemiology Branch of the U.S. Public Health Service, Department of Health, Education, and Welfare, Communicable Disease Center, Atlanta, Georgia.