The intestinal microbiome represents a complex network of microbes that are important for human health and preventing pathogen invasion. Studies that examine differences in intestinal microbial communities across individuals with and without enteric infections are useful for identifying microbes that support or impede intestinal health. 16S rRNA gene sequencing was conducted on stool DNA from patients with enteric infections (n = 200) and 75 healthy family members to identify differences in intestinal community composition. Stools from 13 patients were also examined post-infection to better understand how intestinal communities recover. Patient communities had lower species richness, evenness, and diversity versus uninfected communities, while principle coordinate analysis demonstrated close clustering of uninfected communities, but not the patient communities, irrespective of age, gender, and race. Differences in community composition between patients and family members were mostly due to variation in the abundance of phyla Proteobacteria, Bacteroidetes, and Firmicutes. Patient communities had significantly more Proteobacteria representing genus Escherichia relative to uninfected communities, which were dominated by Bacteroides. Intestinal communities from patients with bloody diarrhea clustered together in the neighbor-joining phylogeny, while communities from 13 patients’ post-infection had a significant increase in Bacteroidetes and Firmicutes and clustered together with uninfected communities. These data demonstrate that the intestinal communities in patients with enteric bacterial infections get altered in similar ways. Furthermore, preventing an increase in Escherichia abundance may be an important consideration for future prevention strategies.

Antibiotic growth promoters have been used for growth promotion of chickens in poultry industry since 1940. Recently, concerns have been raised to th

Group B Streptococcus (GBS) is an opportunistic pathogen in both humans and bovines. Epidemiological and phylogenetic analyses have found strains belonging to certain phylogenetic lineages to be more frequently associated with invasive newborn disease, asymptomatic maternal colonization, and subclinical bovine mastitis. Pilus structures in GBS facilitate colonization and invasion of host tissues and play a role in biofilm formation, though few large-scale studies have estimated the frequency and diversity of the three pilus islands (PIs) across diverse genotypes. Here, we examined the distribution of pilus islands (PI) 1, 2a and 2b among 295 GBS strains representing 73 multilocus sequence types (STs) belonging to eight clonal complexes. PCR-based RFLP was also used to evaluate variation in the genes encoding pilus backbone proteins of PI-2a and PI-2b.

Shiga toxin-producing Escherichia coli (STEC) is an important foodborne pathogen that can cause hemorrhagic colitis and hemolytic-uremic syndrome. Cattle are the primary reservoir for STEC, and food or water contaminated with cattle feces is the most common source of infections in humans. Consequently, we conducted a cross-sectional study of 1,096 cattle in six dairy herds ( n = 718 animals) and five beef herds ( n = 378 animals) in the summers of 2011 and 2012 to identify epidemiological factors associated with shedding. Fecal samples were obtained from each animal and cultured for STEC. Multivariate analyses were performed to identify risk factors associated with STEC positivity. The prevalence of STEC was higher in beef cattle (21%) than dairy cattle (13%) (odds ratio [OR], 1.76; 95% confidence interval [CI], 1.25, 2.47), with considerable variation occurring across herds (range, 6% to 54%). Dairy cattle were significantly more likely to shed STEC when the average temperature was >28.9°C 1 to 5 days prior to sampling (OR, 2.5; 95% CI, 1.25, 4.91), during their first lactation (OR, 1.8; 95% CI, 1.1, 2.8), and when they were <30 days in milk (OR, 3.9; 95% CI, 2.1, 7.2). These data suggest that the stress or the negative energy balance associated with lactation may result in increased STEC shedding frequencies in Michigan during the warm summer months. Future prevention strategies aimed at reducing stress during lactation or isolating high-risk animals could be implemented to reduce herd-level shedding levels and avoid transmission of STEC to susceptible animals and people. IMPORTANCE STEC shedding frequencies vary considerably across cattle herds in Michigan, and the shedding frequency of strains belonging to non-O157 serotypes far exceeds the shedding frequency of O157 strains, which is congruent with human infections in the state. Dairy cattle sampled at higher temperatures, in their first lactation, and early in the milk production stage were significantly more likely to shed STEC, which could be due to stress or a negative energy balance. Future studies should focus on the isolation of high-risk animals to decrease herd shedding levels and the potential for contamination of the food supply.

Campylobacter jejuni is a zoonotic pathogen and the most common bacterial cause of human gastroenteritis worldwide. With the increase of antibiotic resistance to fluoroquinolones and macrolides, the drugs of choice for treatment, C. jejuni was recently classified as a serious antimicrobial resistant threat. Here, we characterized 94 C. jejuni isolates collected from patients at four Michigan hospitals in 2011 and 2012 to determine the frequency of resistance and association with phylogenetic lineages. The prevalence of resistance to fluoroquinolones (19.1%) and macrolides (2.1%) in this subset of C. jejuni isolates from Michigan was similar to national reports. High frequencies of fluoroquinolone-resistant C. jejuni isolates, however, were recovered from patients with a history of foreign travel. A high proportion of these resistant isolates were classified as multilocus sequence type (ST)-464, a fluoroquinolone-resistant lineage that recently emerged in Europe. A significantly higher prevalence of tetracycline-resistant C. jejuni was also found in Michigan and resistant isolates were more likely to represent ST-982, which has been previously recovered from ruminants and the environment in the U.S. Notably, patients with tetracycline-resistant C. jejuni infections were more likely to have contact with cattle. These outcomes prompt the need to monitor the dissemination and diversification of imported fluoroquinolone-resistant C. jejuni strains and to investigate the molecular epidemiology of C. jejuni recovered from cattle and farm environments to guide mitigation strategies.