Characteristics of linezolid-resistant Enterococcus faecalis isolates from broiler breeder farms.

Linezolid is an oxazolidinone class antibiotic used for treatment infections caused by various multidrug-resistant gram-positive pathogens including enterococci. However, recently, linezolid-resistant isolates in animals are considered as a human health hazard. In a broiler operation system, antimicrobial resistance can be transferred to the environment and commercial broiler via the fecal-oral route. Therefore, this study was conducted to investigate the prevalence and characteristics of linezolid-resistant Enterococcus faecalis (E. faecalis) from broiler parent stock in a broiler operation system. Among 297 E. faecalis isolates from 85 flocks in 8 broiler breeder farms, the prevalence of chloramphenicol- and linezolid-resistant isolates was 0 to 12.1% and 0 to 8.0%, respectively; however, there were no significant differences between farms. Therefore, a total of 14 (4.7%) chloramphenicol- and/or linezolid-resistant E. faecalis showed resistance to 7 or more antimicrobial classes. The drug-resistance gene optrA, which can confer resistance to linezolid, tedizolid, and phenicols, was found in 8 (2.69%) isolates, and 7 (2.36%) of the 8 optrA-positive isolates co-carried the phenicol exporter gene fexA. However, E. faecalis isolates from 3 of 8 broiler breeder farms only carried the optrA and/or fexA genes. As linezolid is one of the last antimicrobial treatments of choice for multidrug-resistant gram-positive pathogens including E. faecalis, the presence of antibiotic-resistant E. faecalis in broiler breeder farms should be monitored to prevent the introduction of linezolid-resistant strains to the food chain.

Molecular characteristics of fluoroquinolone-resistant avian pathogenic Escherichia coli isolated from broiler chickens.

Avian pathogenic Escherichia coli (APEC) is a major pathogen in the poultry industry worldwide including Korea. In this study, the phenotypic and genotypic characteristics of 33 fluoroquinolone (FQ)-resistant APEC isolates from broilers were analyzed. All FQ-resistant APEC isolates showed amino acid exchanges at both gyrA and parC and high minimal inhibitory concentrations for FQs. A total of 11 (33.3%) isolates were positive for the plasmid-mediated quinolone resistance (PMQR) genes, qnrA (8 isolates) and qnrS (3 isolates), and showed multidrug resistance. Among the 11 PMQR-positive isolates, 1 and 2 isolates carried blaCTX-1 and blaCTX-15, respectively, as extended-spectrum ß-lactamase (ESBL) producers, and the non-ESBL gene, blaTEM-1, was found in 4 isolates. Among 3 aminoglycoside-resistant isolates, aac(3)-II was only detected in 1 isolate. All 8 APEC isolates with resistance to tetracycline carried the tetA gene. Overall, 6 of the 7 trimethoprim-sulfamethoxazole-resistant isolates carried the sul1 or sul2 genes, while only 2 of the 8 chloramphenicol-resistant isolates carried the catA1 gene. Although 9 isolates carried class I integrons, only 4 isolates carried the gene cassettes dfrA12-aadA2 (2 isolates), dfrA17-aadA5 (1 isolate), extX-psp-aadA2 (1 isolate), and dfrA27 (1 isolate). The most common plasmid replicon was FIB (8 isolates, 72.7%), followed by K/B (4 isolates, 36.4%). Antimicrobial resistance monitoring and molecular analysis of APEC should be performed continuously to surveil the transmission between poultry farms.

Antimicrobial resistance monitoring of commensal Enterococcus faecalis in broiler breeders.

Enterococcus faecalis (E. faecalis) has rapidly acquired resistance to multiple antimicrobials, and the antimicrobial resistance of E. faecalis from broiler breeders has been implicated in its vertical transmission to their offspring. The objective of this study was to investigate the antimicrobial resistance and genetic diversity of commensal E. faecalis isolated from the broiler breeder farms. Among a total of 229 E. faecalis isolates from 9 broiler breeder farms, the highest resistance rate was observed in tetracycline (78.2%), followed by doxycycline (58.1%) and erythromycin (43.7%), and the prevalence of antimicrobial resistance showed significant differences among the 9 broiler breeder farms (P < 0.05). The tetM gene (77.1%) and ermB gene (85.0%) were detected at the highest levels in 179 TE-and 100 E-resistant isolates, respectively. Twenty-four high-level gentamicin-resistant isolates carried aac(6″)Ie-aph(2″)-la gene, and 9 high-level ciprofloxacin-resistant isolates showed point mutations in both gyrA and parC genes. All high-level gentamicin-resistant or high-level ciprofloxacin-resistant isolates showed one of the two different virulence gene patterns, ace-asa1-efaA-gelE complex or ace-efaA-gelE complex. These results indicate that constant epidemiological monitoring at the breeder level is required to prevent the pyramidal transmission of antimicrobial-resistant E. faecalis.

Molecular characterization of avian pathogenic Escherichia coli from broiler chickens with colibacillosis.

Avian pathogenic Escherichia coli (APEC) causes extensive mortality in poultry flocks, leading to extensive economic losses. The aim of this study was to investigate the phenotypic and genotypic characteristics and antimicrobial resistance of recent APEC isolates. Of the 79 APEC isolates, the most predominant serogroup was O78 (16 isolates, 20.3%), followed by O2 (7 isolates, 8.9%) and O53 (7 isolates, 8.9%). Thirty-seven (46.8%) and six (7.6%) of the isolates belonged to phylogenetic groups D and B2, respectively, and presented as virulent extraintestinal E. coli. Among 5 analyzed virulence genes, the highest frequency was observed in hlyF (74 isolates, 93.7%), followed by iutA (72 isolates, 91.9%) gene. The distribution of the iss gene was significantly different between groups A/B1 and B2/D (P < 0.05). All group B2 isolates carried all 5 virulence genes. APEC isolates showed high resistance to ampicillin (83.5%), nalidixic acid (65.8%), tetracycline (64.6%), cephalothin (46.8%), and ciprofloxacin (46.8%). The ß-lactamases-encoding genes blaTEM-1 (23 isolates, 29.1%), blaCTX-M-1 (4 isolates, 5.1%), and blaCTX-M-15 (3 isolates, 3.8%); the aminoglycoside-modifying enzyme gene aac(3)-II (4 isolates, 5.1%); and the plasmid-mediated quinolone genes qnrA (10 isolates, 12.7%) and qnrS (2 isolates, 2.5%) were identified in APEC isolates. The tetA (37 isolates, 46.8%) and sul2 (20 isolates, 25.3%) were the most prevalent among tetracycline and sulfonamide resistant isolates, respectively. This study indicates that APEC isolates harbor a variety of virulence and resistance genes; such genes are often associated with plasmids that facilitate their transmission between bacteria and should be continuously monitored to track APEC transmission in poultry farms.

Prevalence and characterization of Salmonella in two integrated broiler operations in Korea.

BACKGROUND: Vertical integration of the broiler industry allows producers to combine different biosecurity and sanitation practices, housing technologies, and feeding regimens to improve food safety. The purpose of this study was to investigate the prevalence and distribution of Salmonella, to determine the source of Salmonella contaminants, and to reveal the relationships between isolates at each step in the vertically integrated broiler production system in two representative integrated broiler companies in Korea. RESULTS: A total of 2148 samples were collected from 2 broiler breeder hatcheries, 14 broiler breeder farms, 3 broiler hatcheries, 16 broiler farms, 8 broiler transporting trucks and 6 slaughterhouses belonging to representative integrated broiler companies, and 205 (9.5%) of these samples were positive for Salmonella. The Salmonella prevalence in broiler hatcheries (34.0%) and broiler transporting trucks (62.5%) was higher (P < 0.05) whereas that in the broiler breeder hatchery (0.8%) was lower (P < 0.05), than the overall prevalence. Nine and 13 different Salmonella serotypes were isolated from integrated companies A and B, and the predominant serotypes were S. Virchow (39.7%) and S. Hadar (59.2%), respectively. Pulsed field gel electrophoresis patterns of isolates from the two operations showed significant genetic relatedness within a single system. CONCLUSIONS: In a comparison of the two operations that participated in this study, the prevalence of Salmonella differed significantly between the broiler breeder hatchery, and broiler hatcheries and broiler farms.

Prevalence and characterization of Salmonella species in entire steps of a single integrated broiler supply chain in Korea.

The purpose of this study was to investigate the distribution of Salmonella species in an integrated broiler supply chain in Korea. A total of 1,214 samples from various steps of an integrated broiler production company including broiler breeder farms, broiler farms, broiler trucks, slaughterhouse, and retail chicken meats were collected and investigated. Salmonella was detected in 195 of the samples. The highest prevalence of Salmonella was observed in broiler transporting trucks (71.43%), followed by the slaughterhouse (63.89%) and broiler farms (16.05%). Salmonella Hadar was the most frequently isolated serotype (83.08%). All Salmonella Hadar isolates investigated in this study with pulsed-field gel electrophoresis showed the same XbaI pulsed-field gel electrophoresis pulsotype.

Association of T cells and eosinophils with Staphylococcus aureus exotoxin A and toxic shock syndrome toxin 1 in nasal polyps.

BACKGROUND: Staphylococcus aureus exotoxins (SEs) have been implicated in the pathogenesis of nasal polyps (NPs) in patients with chronic rhinosinusitis (CRS). The aim of this study was to identify the correlation between SEs and T cells in NPs. METHODS: After a nasal smear culture, the nasal lavage fluid and NP tissue were obtained from 30 CRS with NP (CRSwNP) patients. The control samples were taken from 10 normal individuals. The presence of S. aureus exotoxin A (SEA) and toxic shock syndrome toxin 1 (TSST-1) was verified through a polymerase chain reaction (PCR) analysis and immunohistochemical staining. Immunohistochemical staining for CD4(+) and CD8(+) T cells was performed, followed by hematoxylin and eosin (H&E) staining for eosinophils. RESULTS: The PCR analysis and immunohistochemical staining for SEA and TSST-1 showed a significantly higher expression in the NP group when compared with that in the control group. Furthermore, the number of T cells and eosinophils were notably increased in the NP group when compared with that in the control group. Significant correlation was observed between the results of the culture, PCR, and immunohistochemical staining in the NP group. Moreover, the number of T cells and eosinophils was significantly increased in the positive experimental groups, when compared with that in the control group. CONCLUSION: Our results indicate that there was, indeed, some correlation between the expression of SE in the nasal cavity and the increased number of T cells and eosinophils in NPs.

Clinical use of subjective visual horizontal and vertical in patients of unilateral vestibular neuritis.

OBJECTIVES: Subjective visual horizontal (SVH) and subjective visual vertical (SVV) used to assess otolith dysfunction and ipsilesional deviation of SVV and SVH in unilateral vestibular dysfunction is well known. The goal of this study was to investigate the clinical use of SVH/SVV and a dizziness scale in the clinical setting of acute unilateral vestibular neuritis. METHODS: Thirty-five patients with unilateral vestibular neuritis were investigated. Every patient was diagnosed by physical examination and electronystagmography. Subjective visual horizontal and SVV were assessed during the acute or subacute period; the Dizziness Handicap Inventory (DHI) and Vestibular Disorder Activities of Daily Living Scale (VADL) were used for a self-dizziness scale at the same time. All patients underwent rehabilitation therapy. Subjective visual horizontal/SVV and DHI/VADL were assessed again approximately 4 weeks later. Postrehabilitation SVH/SVV and DHI/VADL data were compared with initial data. RESULTS: Dizziness Handicap Inventory and VADL were improved after 4 weeks of rehabilitation, and the deviation toward ipsilesional side SVH and SVV was also improved. CONCLUSION: These results demonstrate that SVH and SVV correlated with clinical dizziness symptoms in patients with acute unilateral vestibular neuritis. Therefore, SVH and SVV would be useful tools for the evaluation of clinical manifestations of unilateral vestibular neuritis.

Effect of mitomycin C on the size of antrostomy after endoscopic sinus surgery.

OBJECTIVES: Mitomycin C (MMC) is an antibiotic-antineoplastic agent that decreases fibroblast proliferation and scar formation. We aimed to evaluate the effect of MMC on the size of antrostomy and the mucociliary clearance rate. METHODS: We selected 20 patients with chronic sinusitis on both sides. After middle meatal antrostomy, we selected one side, and a piece of Merocel soaked with 1.5 mL of MMC (0.4 mg/mL) was applied for 5 minutes. On the other side, normal saline solution was applied for a control. The size of the antrostomy was measured serially after surgery with a ruler. Mucociliary clearance was assessed by the saccharin test. RESULTS: The effect of MMC in maintaining the size of the antrostomy was only significant during the first month. The relative size (the ratio of the remaining antrostomy area compared to the area in the immediate postoperative period) in the first month was significantly greater on the MMC-treated side than on the control side. The results of the saccharin test were not different between the two sides. CONCLUSIONS: Topical MMC application may have a short-term effect in maintaining the patency of the antrostomy site. However, it does not seem to improve the relative size over an extended period of time.

Maple syrup urine disease encephalopathy: a follow-up study in the acute stage using diffusion-weighted MRI.

Neonatal maple syrup urine disease (MSUD) is associated with diffuse oedema and characteristic MSUD oedema. We present a newborn infant with two coexisting different types of oedema. The myelinated white matter showed a marked decrease in the water apparent diffusion coefficient (ADC) compatible with cytotoxic oedema. The unmyelinated white matter showed an increase in ADC, consistent with vasogenic-interstitial oedema. On follow-up studies, the cytotoxic oedema showed improvement, but the vasogenic-interstitial oedema progressed into brain atrophy.