Nkuchia M. M'ikanatha

Infectious disease surveillance.

The second edition portrays both the conceptual framework and practical aspects of infectious disease surveillance. It is a comprehensive resource designed to improve the tracking of infectious diseases and to serve as a starting point in the development of new surveillance systems. Infectious Disease Surveillance includes over 45 chapters from over 100 contributors, and topics organized into six sections based on major themes.

Multidrug-resistant Salmonella isolates from retail chicken meat compared with human clinical isolates.

AIM To examine the prevalence of antimicrobial-resistant Salmonella in chicken meat and correlate with isolates from ill humans. METHODS We isolated Salmonella from raw chicken purchased from a randomly selected sample of retail outlets in central Pennsylvania during 2006-2007. Salmonella isolates from meat were compared, using pulsed-field gel electrophoresis, to isolates in the PulseNet database of Salmonella recovered from humans. RESULTS Of 378 chicken meat samples, 84 (22%) contained Salmonella. Twenty-six (31%) of the Salmonella isolates were resistant to > or = 3 antimicrobials and 18 (21%) were resistant to ceftiofur. All ceftiofur-resistant isolates exhibited reduced susceptibility (minimum inhibitory concentration >2 microg/mL) to ceftriaxone and carried a bla(CMY) gene, as detected by polymerase chain reaction. Among the 28 Salmonella serovar Typhimurium isolates, 20 (71.4%) were resistant to > or = 3 antimicrobials and 12 (42.9%) were resistant to ceftiofur. One ceftiofur-resistant Salmonella serovar Typhimurium poultry isolate exhibited a rare pulsed-field gel electrophoresis pattern indistinguishable from a human isolate in PulseNet; both isolates carried the bla(CMY-2) gene. CONCLUSIONS These data demonstrate the presence of multidrug-resistant Salmonella in poultry meat, including bla(CMY) plasmid-mediated genes that confer resistance to both ceftiofur, used in poultry, and ceftriaxone, used for treating salmonellosis in humans. This study illustrates the potential for molecular subtyping databases to identify related Salmonella isolates from meat and ill humans, and suggests that chicken could be a source for multidrug-resistant salmonellosis in humans.

Prevalence of Salmonella cerro in laboratory-based submissions of cattle and comparison with human infections in Pennsylvania, 2005-2010.

The aim of this study was to identify Salmonella serotypes infecting cattle in Pennsylvania, to compare infection rates for the predominant serotype, Salmonella enterica serotype Cerro, with the infection rates for the same serotype in humans, and to study the clonal diversity and antimicrobial resistance for this serotype in cattle from 2005 to 2010. Clonal diversity among the selected isolates was studied using pulsed-field gel electrophoresis (PFGE) and repetitive (rep)-polymerase chain reaction (PCR). Salmonella Cerro showed the single largest increase as a cause of cattle infections over the study period. The proportional distribution of Salmonella Cerro serotype among laboratory-submitted Salmonella positive cases in cattle was 36.1% in the year 2010 compared to 14.3% in 2005. A simultaneous decrease in serotype Newport infections was also observed in cattle (25% in 2005, to 10.1% in 2010). Studies of clonal diversity for cattle and human isolates revealed a predominant PFGE type but showed some variability. All tested isolates (n = 60) were susceptible to sulfamethoxazole-trimethoprim, but 2% of cattle isolates (n = 1/50) and 20% of human isolates (n = 2/10) showed resistance to tetracycline and sulfisoxazole. One human isolate showed additional resistance to ampicillin and gentamicin. This study suggests an increase in Salmonella Cerro infections in the cattle population and a decrease in Salmonella Newport infections. The increase in Cerro infections appears to be restricted to the cattle population, but occasional human infections occur.

Sources of bioterrorism information among emergency physicians during the 2001 anthrax outbreak.

ONGOING COMMUNICATION BETWEEN public health officials and clinicians facilitates recognition of and response to emerging infections and deliberate attacks with biological agents.1 However, little is known about sources of bioterrorism information used by frontline responders, particularly emergency physicians. During the 2001 anthrax attacks, official bioterrorism updates were communicated through Health Alert Networks, the Epidemic Information Exchange (Epi-X), and the Centers for Disease Control and Prevention’s (CDC) Morbidity and Mortality Weekly Report (MMWR).2–4 Additional information was shared through MMWR reprints in medical journals and through the websites of medical associations, the CDC, and state and local health departments.5 To allow rapid dissemination of Health Alerts to key partners, state health departments started to use media such as e-mail and broadcast fax to strengthen links with hospitals, clinicians, and laboratories. In Pennsylvania, the development of a Health Alert Network had started in summer 2001 with the creation of an electronic database of e-mail addresses and fax numbers of hospital directors, emergency physician directors, and professional medical societies. The first Pennsylvania Health Alert was disseminated on September 11, 2001, shortly after the terrorist attack on the World Trade Center.6 The frequency of Health Alerts remained low until after the CDC announced an investigation of the index case of the 2001 bioterrorismrelated anthrax outbreak.7–8 During October and November, 21 alerts about bioterrorism were sent through the Pennsylvania Health Alert Network. These alerts primarily shared information derived from Epi-X, the eight MMWR updates released during the same period,4 and announcements of the CDC’s four satellite broadcasts targeted to clinicians.9 Health Alerts were sent to more than 300 fax machines and approximately 200 e-mail addresses in the Health Alert Network contact database. Public health communication during the 2001 anthrax attacks relied heavily on Health Alert Networks and other newly developed channels such as websites. However, it was unclear whether clinicians received official public health information disseminated through these newly developed electronic media and other sources. Specifically, we sought to determine whether physicians had been exposed to official Health Alerts and MMWR updates. We also wanted to assess physician-initiated contacts with public health agencies and physicians’ knowledge about bioterrorism. We report here results from a study conducted among Pennsylvania emergency physicians during the 2001 bioterrorism attacks.

Surveillance for Zoonotic Diseases

Zoonotic infections (zoonoses) involve pathogens that are sustained in animal populations but can be transmitted to and cause disease in humans. Zoonoses encompass some of the most ancient communicable diseases, such as rabies and plague, as well as newly recognized emerging infections, such as hantavirus pulmonary syndrome (HPS) and severe acute respiratory syndrome (SARS). A recent review of agents known to infect humans identified 61% (868/1415) as zoonotic in origin; furthermore, 75% (132/175) of human diseases classified as emerging were zoonotic [1]. The global distribution, diversity, clinical severity, and potential use as bioweapons all contribute to the importance of zoonotic pathogens in public health. In this chapter, we describe key host and transmission attributes of zoonotic infections and discuss some strategies for surveillance of zoonotic pathogens. We also discuss ongoing surveillance for rabies in the United States (US) and enhanced surveillance during a monkeypox outbreak.

Training Programs to Strengthen Pennsylvania's Public Health Response

This report describes Pennsylvanias 9-year experience in implementing training programs to strengthen public health response to emerging infectious diseases. During the biannual 3-5-day-long Pennsylvania Public Health Institute (PHI) events, which have been held since 2000, courses have covered topics such as emerging infectious disease outbreaks, monitoring of antimicrobial-resistant pathogens in retail food, and zoonotic diseases commonly associated with companion animals. Core competency courses include the legal basis for public health and epidemiology for nonepidemiologists. Emerging infectious disease seminars offered to clinicians since 2005 have focused on the emergence of community-associated methicillin-resistant Staphylococcus aureus and Clostridium difficile antibiotic-associated diarrhea. Complementing the PHI, the Pennsylvania Department of Healths monthly Epidemiology Journal Club offers additional interactions with presenters from academic institutions and federal agencies. Lunch-time forums also provide a venue for health department staff to share their work with colleagues. Innovative use of modern communication technology increases participation of frontline health workers in Journal Club events, and video conference capability offers flexibility in the selection of presenters. Pennsylvanias experience over the past 9 years demonstrates that with political will, commitment from content experts, and adequate administrative support, modest state and federal resources can be used to sustain public health training programs tailored to local needs.

Sharp-device injuries and perceived risk of infection with bloodborne pathogens among healthcare workers in rural Kenya.

To the Editor—Healthcare workers (HCWs) worldwide face the risk of occupational infection by bloodborne pathogens, including human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV). Guidelines exist for preventing injuries from sharp devices (hereafter, sharps), as well as for postexposure evaluation and prophylaxis, but HCWs working in limited-resource settings may not have adequate access to these recommended safety measures. This is especially of concern where the prevalence of bloodborne pathogens in the patient population may be relatively high. To guide interventions, in 2004 we conducted an anonymous, convenience-sample survey regarding occupational exposures to bloodborne pathogens among HCWs in Maua Methodist Hospital, a 250-bed rural mission hospital located on the eastern slopes of Mount Kenya. Of the estimated 320 employees, 200 were involved in direct patient care—the majority of these were nurses. Fifty-three (44.1%) of the 120 questionnaires distributed by unit managers were completed. Thirty-eight (71.7%) of the 53 who completed the survey were nurses. Twelve (22.6%) of the respondents recalled having at least 1 exposure to blood via percutaneous injury in the preceding year, for a total of 15 exposures. The 12 most recent sharps injuries experienced by these respondents were explored in further detail (Table), and only 4 (33.3%) of 12 respondents stated that they reported their injury to their supervisor or the infection control department. Eight (66.7%) of the injured HCWs did not know the HIV infection status of the source patient, and none knew the source patients HBV infection status. Concern about occupational HIV exposure was strong. Sixteen (41%) of the 39 respondents who provided estimates perceived that more than 25% of patients were infected with HIV, and 18 (47.4%) of 38 respondents perceived the risk of acquiring HIV infection from an HIV-contaminated needle stick to be greater than 10%. HCWs perceived the prevalences of HBV infection and HCV infection to be lower or answered that they did not know how prevalent they were. Twentyeight (87.5%) of 32 respondents estimated less than 11% of patients were infected with HBV, and 14 (77.8%) of 18 estimated that less than 1% of patients were infected with HCV. Perception of risk from contaminated needlestick injuries involving HBVor HCV-infected blood was mixed. Fifteen (44%) of 34 respondents believed the risk of HBV acquisition via a contaminated needlestick injury was greater than 25%; for HCV, 11 (52.4%) of 21 believed the risk was less than 1%. The availability and use of preventive measures to protect HCWs from bloodborne pathogens varied. Thirty-two (65.3%) of 49 respondents had received at least 1 dose of HBV vaccine (1 additional HCW did not receive vaccine because the HCW had already had blood tests positive for HBV surface antigen); only 12 (24.5%) of 49 respondents reported that they had received all 3 doses of vaccine. Forty-nine (92.0%) of 53 respondents reported that sharps disposal containers were always available when they performed their work, and 42 (82.3%) of 51 respondents reported that they always used them when indicated (Figure). Although 41 (82.0%) of 50 respondents reported that gloves were always available, 36 (72.0%) of these respondents reported using them at least most of the time when indicated, and 12 (24.0%) reported complete adherence to guidelines for glove use.

Surveillance for Travel and Domestically Acquired Multidrug-Resistant Human Shigella Infections—Pennsylvania, 2006-2014

Shigellosis is a leading cause of enteric infections in the United States. We compared antimicrobial resistance in Shigella infections related to overseas travel (travel-associated) and in those acquired domestically by analyzing antimicrobial resistance patterns, geographic distributions, and pulsed-field gel electrophoresis (PFGE) patterns. We tested samples (n = 204) from a collection of isolates recovered from patients in Pennsylvania between 2006 and 2014. Isolates were grouped into travel- and non-travel-associated categories. Eighty-one (79.4%) of the Shigella isolates acquired during international travel were resistant to multiple antibiotics compared to 53 (52.1%) of the infections transmitted in domestic settings. A majority (79.4%) of isolates associated with international travel demonstrated resistance to aminoglycosides and tetracyclines, whereas 47 (46.1%) of the infections acquired domestically were resistant to tetracycline. Almost all isolates (92.2%) transmitted in domestic settings were resistant to aminoglycosides, and 5 isolates from adult male patients were resistant to azithromycin, a drug often used for empiric treatment of severe shigellosis. Twenty (19.6%) isolates associated with illnesses acquired during overseas travel in 4 countries were resistant to quinolones. One S. sonnei PFGE pattern was traced to a multidrug-resistant isolate acquired overseas that had caused a multistate outbreak of shigellosis, suggesting global dissemination of a drug-resistant species. Resistance to certain drugs-for example, tetracycline-increased in both overseas- and domestic-acquired infections during the study period. The prevalence of resistance to macrolides (azithromycin) and third-generation cephalosporins (ceftriaxone) was less than 1%; however, efforts to better monitor changes in drug resistance over time combined with increased antimicrobial stewardship are essential at the local, national, and global levels.

Whole genome sequencing of antimicrobial-resistant Shigella sonnei associated with infection acquired from international and domestic setting reveals gene allelic variants that predict Global Lineages

Shigella spp. are a major cause of gastroenteritis worldwide, and S. sonnei is the most common species isolated within the United States. Recently, advancements in technology have made whole genome sequencing (WGS) readily available, and as such, laboratories are moving to implement WGS in outbreak analysis, surveillance, and antimicrobial resistance (AMR) monitoring of major foodborne pathogens. Accordingly, our study examined a collection of 22 antimicrobial resistant S. sonnei isolates from patients who either acquired the infections within the United States or when travelling to international locations between 2009 to 2014. We applied WGS to investigate both the relatedness of these isolates and the genetic determinants of AMR to address the phenotypic differences seen in previous observations. We analyzed the phylogeny of these strains and observed segmentation based on the previously described Global Lineages of S. sonnei. Following these results, 17 gene sequences with lineage specific single nucleotide polymorphisms (SNPs) were identified and developed into a lineage prediction test to determine the Global Lineage of uncharacterized S. sonnei, which accurately predicted phylogenetic segmentation and additionally showed specificity for S. sonnei genomes (97% accuracy, 38/39 genomes). Lastly, to determine differences between either the international or domestic isolates or between the Global Lineages, the AMR determinants were identified. We found a variety of AMR determinants within the genomes, and while the international and domestic S. sonnei carried similar resistance determinants, differences between Global Lineages were observed.

Retrospective whole-genome sequencing analysis distinguished PFGE and drug resistance matched retail meat and clinical Salmonella isolates

Non-typhoidal Salmonella are a leading cause of outbreak and sporadic-associated foodborne illnesses in the U.S. These infections have been associated with a range of foods, including retail meats. Traditionally, pulsed-field gel electrophoresis (PFGE) and antibiotic susceptibility testing (AST) have been used to facilitate public health investigations of Salmonella infections. However, whole-genome sequencing (WGS) has emerged as an alternative tool that can be routinely implemented. To assess its potential in enhancing integrated surveillance in Pennsylvania, WGS was used to directly compare the genetic characteristics of 7 retail meat and 43 clinical historic Salmonella isolates, subdivided into three subsets based on PFGE and AST results, to retrospectively resolve their genetic relatedness and identify antimicrobial resistance (AMR) determinants. Single nucleotide polymorphism (SNP) analyses revealed the retail meat isolates within S. Heidelberg, S. Typhimurium var. O5- subset 1, and S. Typhimurium var. O5- subset 2 were separated from each primary PFGE pattern-matched clinical isolate by 6-12, 41-96, and 21-81 SNPs, respectively. Fifteen resistance genes were identified across all isolates, including fosA7, a gene only recently found in a limited number of Salmonella and a ≥ 95% phenotype to genotype correlation was observed for all tested antimicrobials. Moreover, AMR was primarily plasmid-mediated in S. Heidelberg and S. Typhimurium var. O5- subset 2; whereas, AMR was chromosomally-carried in S. Typhimurium var. O5- subset 1. Similar plasmids were identified in both the retail meat and clinical isolates. Collectively, these data highlight the utility of WGS in retrospective analyses and enhancing integrated surveillance of Salmonella from multiple sources.