Tracking Antimicrobial Resistance Determinants in Diarrheal Pathogens: A Cross-Institutional Pilot Study

Infectious diarrhea affects over four billion individuals annually and causes over a million deaths each year. Though not typically prescribed for treatment of uncomplicated diarrheal disease, antimicrobials serve as a critical part of the armamentarium used to treat severe or persistent cases. Due to widespread over- and misuse of antimicrobials, there has been an alarming increase in global resistance, for which a standardized methodology for geographic surveillance would be highly beneficial. To demonstrate that a standardized methodology could be used to provide molecular surveillance of antimicrobial resistance (AMR) genes, we initiated a pilot study to test 130 diarrheal pathogens (Campylobacter spp., Escherichia coli, Salmonella, and Shigella spp.) from the USA, Peru, Egypt, Cambodia, and Kenya for the presence/absence of over 200 AMR determinants. We detected a total of 55 different determinants conferring resistance to ten different categories of antimicrobials: genes detected in ≥ 25 samples included bla_TEM, tet(A), tet(B), mac(A), mac(B), aadA1/A2, strA, strB, sul1, sul2, qacEΔ1, cmr, and dfrA1. The number of determinants per strain ranged from none (several Campylobacter spp. strains) to sixteen, with isolates from Egypt harboring a wider variety and greater number of genes per isolate than other sites. Two samples harbored carbapenemase genes, bla_OXA-48 or bla_NDM. Genes conferring resistance to azithromycin (ere(A), mph(A)/mph(K), erm(B)), a first-line therapeutic for severe diarrhea, were detected in over 10% of all Enterobacteriaceae tested: these included >25% of the Enterobacteriaceae from Egypt and Kenya. Forty-six percent of the Egyptian Enterobacteriaceae harbored genes encoding CTX-M-1 or CTX-M-9 families of extended-spectrum β-lactamases. Overall, the data provide cross-comparable resistome information to establish regional trends in support of international surveillance activities and potentially guide geospatially informed medical care.

Extragenital chlamydia infection among active-duty women in the United States Navy

BACKGROUND

Pharyngeal and anorectal reservoirs of gonorrhea (GC) and chlamydia (CT) are increasingly recognized among heterosexual women. While a number of studies performed at sexually transmitted disease (STD) clinics have found a high prevalence of extragenital GC/CT infection, such screening is typically not offered during routine primary care visits for women. We sought to define the prevalence of and factors associated with extragenital GC/CT among women in the U.S. Navy.

METHODS

We recruited servicewomen stationed in San Diego, California, between the ages of 18 and 25 who presented for an annual physical exam between January and September, 2017. Nucleic acid amplification testing was performed on swabs collected at endocervical, oropharyngeal and anorectal sites to assess the presence of GC/CT. An anonymous behavioral questionnaire was also administered to characterize sexual risk. Descriptive statistics were used to compare women with and without a prior history of any sexually transmitted infection (STI) (self-report) along with a current GC/CT diagnosis. This study was approved by the Institutional Review Board of the Uniformed Services University of Health Sciences.

RESULTS

Of the 75 patients who were approached, 60 subjects were enrolled in the study, including white 20 (33.3%), black/African American 18 (31.0%), Hispanic/Latina 13 (21.7%) and Asian/Pacific Islander 9 (15.5%) women. Among all the women, six (10.0%) were diagnosed with CT infection, all via endocervical exam. Of these, five (8.3%) had concurrent anorectal infection, including two cases (3.3%) accompanied by pharyngeal infection. Of the subjects, 15 (25.0%) reported anal intercourse in their most recent sexual encounter, most of which was condomless (13/15, 86.7%). A high number of women who reported sex with a casual male partner (19/45, 42.2%) reported rarely or never using condoms; last, 41.7% consuming at least 3 drinks on a typical drinking day, and one-third of the reported drinking more than once per week.

CONCLUSIONS

We found a high prevalence of anorectal CT infection, although no infections were detected without concurrent endocervical involvement. Nonetheless, the high prevalence of condomless anal intercourse reported by participants argues for further study and ongoing consideration of extragenital screening among high-risk patients. Behavioral interventions are also warranted given the high prevalence of sexual and related risk factors.

Prevalence of Staphylococcus aureus Colonization and Risk Factors for Infection Among Military Personnel in a Shipboard Setting

Staphylococcal skin and soft tissue infections (SSTIs), especially those due to methicillin-resistant Staphylococcus aureus (MRSA) are an important public health issue for the military. Limited data exist regarding the prevalence of S. aureus colonization in the shipboard setting. We conducted a cross-sectional, observational study to determine the point prevalence of S. aureus colonization among military personnel onboard a naval vessel. Asymptomatic active duty personnel completed a survey for risk factors associated with colonization and SSTIs. Culture specimens were obtained from the anterior nares, pharynx, groin, and perirectal regions. MRSA isolates underwent testing for antimicrobial resistance, virulence factors, and pulsed-field type. 400 individuals were enrolled, 198 (49.5%) of whom were colonized with S. aureus, with MRSA identified in 14 participants (3.5%). No significant risk factors were associated with MRSA colonization. USA800 was the most common colonizing MRSA strain in the cohort and was detected in 10 participants (71%). Two participants (14%) were colonized with USA300 MRSA. In this first report of S. aureus epidemiology in a shipboard setting, we observed high rates of S. aureus and MRSA colonization. Longitudinal studies are needed to document the incident rates of S. aureus colonization during shipboard deployment and its impact on SSTI risk.

The epidemiology of infectious gastroenteritis related reactive arthritis in U.S. military personnel: a case-control study

BACKGROUND

Reactive arthritis (ReA) is a recognized sequela of infectious gastroenteritis (IGE). However, the population-based incidence of IGE-related ReA is poorly defined, and the risk of disease has not previously been characterized in a military population. The intent of this study was to provide estimates of the incidence and morbidity associated with IGE-related ReA in the U.S. military population.

METHODS

Using active duty US military medical encounter data from the Defense Medical Surveillance System, we conducted a matched case-control study to assess the risk of ReA following IGE. Both specific and nonspecific case definitions were utilized to address ICD-9 coding limitations; these included specific ReA (Reiter's Disease or postdysenteric arthritis) and nonspecific arthritis/arthralgia (N.A.A) (which included several related arthropathy and arthralgia diagnoses). Incidence was estimated using events and the total number of active duty personnel for each year.

RESULTS

506 cases of specific ReA were identified in active duty personnel between 1999 and 2007. Another 16,365 cases of N.A.A. were identified. Overall incidence was 4.1 (95% CI: 3.7, 4.5) and 132.0 (95% CI, 130.0-134.0) per 100,000 for specific ReA and N.A.A, respectively. Compared to the youngest age category, the incidence of both outcomes increased 7-fold with a concurrent increase in symptom duration for cases over the age of 40. Specific IGE exposures were documented in 1.4% of subjects. After adjusting for potential confounders, there was a significant association between IGE and ReA (specific reactive arthritis OR: 4.42, 95% CI: 2.24, 8.73; N.A.A OR: 1.76, 95% CI: 1.49, 2.07).

CONCLUSIONS

Reactive arthritis may be more common in military populations than previously described. The burden of ReA and strong association with antecedent IGE warrants continued IGE prevention efforts.

Acute hepatitis E virus infection in an HIV-infected person in the United States

BACKGROUND

Hepatitis E virus (HEV) is an enterically transmitted cause of viral hepatitis rarely noted without international travel.

OBJECTIVE

To report the first case of an HIV-infected man with acute hepatitis due to HEV infection who had not traveled outside the United States.

Deconvolution of the factors contributing to the increase in global hurricane intensity

To better understand the change in global hurricane intensity since 1970, we examined the joint distribution of hurricane intensity with variables identified in the literature as contributing to the intensification of hurricanes. We used a methodology based on information theory, isolating the trend from the shorter-term natural modes of variability. The results show that the trend of increasing numbers of category 4 and 5 hurricanes for the period 1970-2004 is directly linked to the trend in sea-surface temperature; other aspects of the tropical environment, although they influence shorter-term variations in hurricane intensity, do not contribute substantially to the observed global trend.

Changes in tropical cyclone number, duration, and intensity in a warming environment

We examined the number of tropical cyclones and cyclone days as well as tropical cyclone intensity over the past 35 years, in an environment of increasing sea surface temperature. A large increase was seen in the number and proportion of hurricanes reaching categories 4 and 5. The largest increase occurred in the North Pacific, Indian, and Southwest Pacific Oceans, and the smallest percentage increase occurred in the North Atlantic Ocean. These increases have taken place while the number of cyclones and cyclone days has decreased in all basins except the North Atlantic during the past decade.

Intraneuronal Aβ, non-amyloid aggregates and neurodegeneration in a Drosophila model of Alzheimer’s disease

We have developed models of Alzheimer's disease in Drosophila melanogaster by expressing the Abeta peptides that accumulate in human disease. Expression of wild-type and Arctic mutant (Glu22Gly) Abeta(1-42) peptides in Drosophila neural tissue results in intracellular Abeta accumulation followed by non-amyloid aggregates that resemble diffuse plaques. These histological changes are associated with progressive locomotor deficits and vacuolation of the brain and premature death of the flies. The severity of the neurodegeneration is proportional to the propensity of the expressed Abeta peptide to form oligomers. The fly phenotype is rescued by treatment with Congo Red that reduces Abeta aggregation in vitro. Our model demonstrates that intracellular accumulation and non-amyloid aggregates of Abeta are sufficient to cause the neurodegeneration of Alzheimer's disease. Moreover it provides a platform to dissect the pathways of neurodegeneration in Alzheimer's disease and to develop novel therapeutic interventions.