Identification of Multidrug-Resistant Escherichia coli from Bovine Clinical Mastitis Using a Ceftiofur-Supplemented Medium.

Escherichia coli causes a significant number of clinical mastitis cases in dairy cattle worldwide. The antimicrobial susceptibility of E. coli is important for both human and animal health. Surveillance reports recorded that the efficacy of most antibiotics is substantially preserved but detection of E. coli from clinical mastitis cases producing extended-spectrum beta-lactamases and plasmid-encoded AmpC beta-lactamases has been reported. These resistance determinants have frequently been associated with multidrug resistance. The aim of this study was to determine if a MacConkey agar medium supplemented with 8 mg/L of ceftiofur (MC-CEF) could be a useful tool to identify cephalosporin-resistant and multidrug-resistant (MDR) E. coli among bovine mastitis isolates. During the period 2010-2011, 773 E. coli were isolated from bovine clinical mastitis milk samples collected in 80 dairy farms in Northern Italy. A total of 105 E. coli were selected and assigned either to group randomly selected E. coli (RSEC; n = 53), based on a random selection among the whole collection of 773 E. coli, or to group ceftiofur-resistant E. coli (CEFREC; n = 52). CEFREC isolates were identified by spreading the 773 E. coli isolates on MC-CEF. Minimum inhibitory concentration (MIC) was used to test the phenotypic antimicrobial susceptibility to 16 antibiotics. The MIC results confirmed the ceftiofur resistance in 73.1% (38/52) of CEFREC isolates, whereas all RSEC isolates were susceptible to ceftiofur. The comparison of MIC values for each antibiotic tested between the two groups revealed significantly higher frequencies of resistance to antimicrobials other than ceftiofur in the CEFREC group. Resistance profiles highlighted a significantly higher frequency of MDR isolates among CEFREC (73.1%) than RSEC (17%) E. coli. The results showed that MC-CEF may be a useful selective medium to identify cephalosporin-resistant and MDR E. coli on dairy farms, without performing MIC on all the isolates.

A Longitudinal Case Study on Dissemination of ST398 Methicillin-Resistant Staphylococcus aureus Within a Dairy Cow Herd.

The study was conducted to describe the dynamics of ST398 methicillin-resistant Staphylococcus aureus (MRSA) on a dairy herd in northeastern Italy. MRSA was first identified in this herd of 120 cows in 2016, after which the herd was sampled once every 3 months for 1 year (April 2016-May 2017). Samples collected included nasal swabs and milk samples from cows and nasal swabs from farmworkers. In addition, pen fencing and teat milk liners were swabbed and air samples from cow pens and the milking parlor were collected. All samples were tested for MRSA using a selective medium; positive isolates were confirmed by mecA PCR. A representative set of MRSA isolates was genotyped using spa typing and multilocus sequence typing. Overall, 34 (mean 23%, range 16-30%) milking cows were found harboring MRSA in the mammary gland and only 6 recovered from infection or colonization. The mean incidence rate was 14% (range 8-20%), mean cure rate was 23% (range 13-43%), and estimated basic reproduction number (R0) was 1.08. The average of positive quarters found was 35.1% and most of the positive quarters (82.4%) developed subclinical mastitis. The mean duration of MRSA colonization in quarters during the study was 247 days, but quarters affected by subclinical mastitis harbored MRSA for a longer time than healthy ones (285 days vs. 131 days). After the second sampling, the farmer segregated MRSA-positive cows from the uninfected cows and milked them last. Despite segregation, 25 newly infected or colonized cows were detected. MRSA isolates from cows, environment, and two farmworkers belonged to the same sequence type (ST398) and spa type (t034). This study highlights the ability of ST398 MRSA to cause a persistent infection of the mammary gland and to survive in the farm environment.

Circulating endothelial progenitor cells are reduced in peripheral vascular complications of type 2 diabetes mellitus.

OBJECTIVES: We sought to establish whether a reduction in endothelial progenitor cells (EPCs) has a putative role in peripheral vascular disease (PVD) of type 2 diabetic patients. BACKGROUND: Peripheral vascular disease is a common and severe complication of diabetes mellitus. Impaired collateralization of diabetic vasculopathy has been extensively shown, but causes leading to its pathogenesis are not fully understood. Recently, EPCs have been found to contribute to vascular repair and angiogenesis. Diabetes has been associated with low levels of circulating EPCs, but no data are available in the literature on the relationship between EPCs and PVD in diabetes. METHODS: Flow cytometric analysis was used to quantify circulating progenitor cells (CPCs, CD34+) and EPCs (CD34+KDR+) in 51 patients and 17 control subjects. RESULTS: The CPCs and EPCs from diabetic patients were reduced by 33% and 40%, respectively, compared with healthy subjects (p < 0.001). An inverse correlation was found between the number of EPCs and the values of fasting glucose (r = -0.49, p = 0.006). Peripheral vascular disease was associated with a 47% reduction in EPCs (p < 0.0001) and EPC levels directly correlated with the ankle-brachial index (r = 0.70, p = 0.01). The subgroup of diabetic patients with PVD also had reduced CPCs by 32% (p = 0.037), whereas patients with ischemic foot lesions had the lowest levels of both EPCs and CPCs (p = 0.02). CONCLUSIONS: Our data demonstrate decreased EPC levels in diabetic patients and, for the first time, show that PVD is associated with an extensively low number of EPCs. Depletion of circulating EPCs in diabetic patients may be involved in the pathogenesis of peripheral vascular complications.

Modulation of immune response by the acute and chronic exposure to high altitude.

PURPOSE: The chronic exposure at high altitude (HA) represents an ideal model for evaluating the in vivo effects of hypobaric hypoxia. Taking advantage of the EV-K2-CNR Pyramid, this study was designed to evaluate whether acute and chronic hypoxia differently modulates the in vivo immune responses. METHODS: The study includes 13 healthy female moderately active volunteers participating to the Italian HA project EV-K2-CNR. Peripheral blood lymphocytes, collected at sea level and at HA in the Pyramid Laboratory of CNR, Nepal (5050 m), were immunologically characterized by flow cytometry and a series of molecular and functional analyses. RESULTS: Flow cytometric analyses showed that: a) CD3+ T lymphocytes significantly decreased during both acute and chronic exposure to HA, b) T-cell fall was totally due to CD4+ T-cell reduction, c) B lymphocytes were not influenced by the exposure to HA, and d) natural killer (NK) cells significantly increased during acute and chronic exposure. The evaluation of the Th1/Th2 pattern demonstrated a significant decrease of the expression of the Th1 cytokine interferon-gamma (IFN-gamma) by circulating T cells during acute and chronic exposure to HA. The expression by T cells of CXCR3, a chemokine receptor typically expressed by Th1/Tc1 cells, paralleled the decrease of IFN-gamma. On the contrary, the expression of IL-4 was not conditioned by the exposure to HA. Finally, functional studies showed a significant reduction of the proliferative activity in response to mitogen (PHA) both in acute and chronic HA exposure. Despite the increased number of NK cells, NK cytotoxic activity was not influenced by the HA exposure. CONCLUSIONS: Our results indicate that the in vivo exposure to HA leads to an impairment of the homeostatic regulation of Th1/Th2 immune balance that potentially could favor long-term immunological alterations and increase the risk of infections.