Characterization of multidrug resistant Salmonella recovered from diseased animals.

Three hundred and eighty Salmonella isolates recovered from animal diagnostic samples obtained from four state veterinary diagnostic laboratories (AZ, NC, MO, and TN) between 2002 and 2003 were tested for antimicrobial susceptibilities and further characterized for bla(CMY) beta-lactamase genes, class 1 integrons and genetic relatedness using PFGE. Forty-seven serovars were identified, the most common being S. Typhimurium (26%), S. Heidelberg (9%), S, Dublin (8%), S. Newport (8%), S. Derby (7%), and S. Choleraesuis (7%). Three hundred and thirteen (82%) isolates were resistant to at least one antimicrobial, and 265 (70%) to three or more antimicrobials. Resistance was most often observed to tetracycline (78%), followed by streptomycin (73%), sulfamethoxazole (68%), and ampicillin (54%), and to a lesser extent chloramphenicol (37%), kanamycin (37%), amoxicillin-clavulanic acid (20%), and ceftiofur (17%). With regards to animal of origin, swine Salmonella isolates displayed the highest rate of resistance, being resistant to at least one antimicrobial (92%), followed by those recovered from turkey (91%), cattle (77%), chicken (68%), and equine (20%). Serovars commonly showing multidrug resistance (MDR) to > or =9 antimicrobials were S. Uganda (100%), S. Agona (79%), and S. Newport (62%), compared to S. Heidelberg (11%) and S. Typhimurium (7%). Class-1 integrons were detected in 43% of all isolates, and were found to contain aadA, aadB, dhfr, cmlA and sat1 gene cassettes alone or in various combinations. All ceftiofur resistant isolates (n=66) carried the bla(CMY) beta-lactamase gene. A total of 230 PFGE patterns were generated among the 380 isolates tested using XbaI, indicating extensive genetic diversity across recovered Salmonella serovars, however, several MDR clones were repeatedly recovered from different diseased animals.

Characterization of antimicrobial-resistant Salmonella isolated from imported foods.

Two-hundred eight Salmonella isolates recovered from over 5,000 imported foods entering the United States in 2001 were tested for antimicrobial susceptibilities and further characterized for quinolone resistance mechanisms, integron carriage, and genetic relatedness. Salmonella Weltevreden (20%), Salmonella Newport (6%), Salmonella Lexington (5%), and Salmonella Thompson (4%) were the four most common serotypes recovered. Twenty-three (11%) isolates were resistant to at least one antimicrobial, and seven (3.4%) to three or more antimicrobials. Resistance was most often observed to tetracycline (9%), followed by sulfamethoxazole (5%), streptomycin (4%), nalidixic acid (3%), and trimethoprim/sulfamethoxazole (2%). One Salmonella Schwarzengrund isolate recovered from squid imported from Taiwan exhibited resistance to eight antimicrobials, including ampicillin, chloramphenicol, gentamicin, kanamycin, nalidixic acid, sulfamethoxazole, tetracycline, and trimethoprim/sulfamethoxazole. Six isolates (Salmonella Bareilly, Salmonella Derby, Salmonella Ohio and three Salmonella Schwarzengrund) contained class 1 integrons, which carried several resistance genes including dhfrI/dhfrXII, aadA, pse-1, and sat1, conferring resistance to trimethoprim/sulfamethoxazole, streptomycin, ampicillin, and streptothricin, respectively. Five of six nalidixic acid-resistant isolates possessed DNA point mutations at either Ser83 or Asp87 in DNA gyrase. One ciprofloxacin-resistant isolate possessed double mutations in DNA gyrase at positions Ser83 and Asp87 as well as a single mutation at Ser80 in parC. The top three serotypes identified, Salmonella Weltevreden (n = 41), Salmonella Newport (n = 13), and Salmonella Lexington (n = 11), were further characterized for genetic relatedness by pulsed-field gel electrophoresis. Fifty-five distinct pulsed-field gel electrophoresis patterns were observed among the 65 isolates, indicating extensive genetic diversity among these Salmonella serotypes contaminating imported foods.

Characterization of Salmonella Typhimurium of animal origin obtained from the National Antimicrobial Resistance Monitoring System.

Salmonella Typhimurium remains one of the most common causes of salmonellosis in animals and humans in the United States. The emergence of multi-drug resistant Salmonella reduces the therapeutic options in cases of invasive infections, and has been shown to be associated with an increased burden of illness. In this study, 588 S. Typhimurium (including var. Copenhagen) isolates obtained from either animal diagnostic specimens (n = 199) or food animals after slaughter/processing (n = 389) were examined for antimicrobial susceptibility, presence of class-1 integrons, and characterized using pulsed-field gel electrophoresis and phage typing. Seventy-six percent (448/588) of isolates were resistant to at least one antimicrobial. Salmonella isolates displayed resistance most often to streptomycin (63%), tetracycline (61%), ampicillin (61%), and to a lesser extent, chloramphenicol (36%), ceftiofur (15%), gentamicin (9%), and nalidixic acid (4%), with more resistance observed among diagnostic isolates. Salmonella recovered from turkeys (n = 38) exhibited the highest rates of resistance, with 92% of isolates resistant to least one antimicrobial, and 58% resistant to > or =10 antimicrobials. Class 1 integrons were present in 51% of all isolates. Five integron associated resistance genes (aadA, aadB, pse-1, oxa-2 and dhfr) were identified. A total of 311 PFGE patterns were generated using XbaI, indicating a genetically diverse population. The largest PFGE cluster contained 146 isolates, including DT104 isolates obtained from all seven animal species. Results demonstrated a varied spectrum of antimicrobial resistance, including several multidrug resistant clonal groups, among S. Typhimurium and S. Typhimurium var. Copenhagen isolates recovered from both diagnostic and slaughter/processing samples.

Characterization of Salmonella enterica serotype newport isolated from humans and food animals.

Salmonella enterica serotype Newport isolates resistant to at least nine antimicrobials (including extended-spectrum cephalosporins), known as serotype Newport MDR-AmpC isolates, have been rapidly emerging as pathogens in both animals and humans throughout the United States. Resistance to extended-spectrum cephalosporins is associated with clinical failures, including death, in patients with systemic infections. In this study, 87 Salmonella serotype Newport strains were characterized by pulsed-field gel electrophoresis (PFGE) and antimicrobial susceptibility testing and examined for the presence of class 1 integrons and bla(CMY) genes. Thirty-five PFGE patterns were observed with XbaI, and three of these patterns were indistinguishable among isolates from humans and animals. Fifty-three (60%) Salmonella serotype Newport isolates were identified as serotype Newport MDR-AmpC, including 16 (53%) of 30 human isolates, 27 (93%) of 29 cattle isolates, 7 (70%) of 10 swine isolates, and 3 (30%) of 10 chicken isolates. However, 28 (32%) Salmonella serotype Newport isolates were susceptible to all 16 antimicrobials tested. The bla(CMY) gene was present in all serotype Newport MDR-AmpC isolates. Furthermore, the plasmid-mediated bla(CMY) gene was transferable via conjugation to an Escherichia coli strain. The transconjugant showed the MDR-AmpC resistance profile. Thirty-five (40%) of the isolates possessed class 1 integrons. Sequence analyses of the integrons showed that they contained aadA, which confers resistance to streptomycin, or aadA and dhfr, which confer resistance to trimethoprim-sulfamethoxazole. One integron from a swine isolate contained the sat-1 gene, which encodes resistance to streptothricin, an antimicrobial agent that has never been approved for use in the United States. In conclusion, Salmonella serotype Newport MDR-AmpC was commonly identified among Salmonella serotype Newport isolates recovered from humans and food animals. These findings support the possibility of transmission of this organism to humans through the food chain.

Antimicrobial susceptibility and genetic relatedness of Salmonella serovars isolated from animal-derived dog treats in the USA.

OBJECTIVES: The objectives of this study were to determine the potential risk of dog treats in transmitting Salmonella to humans in the USA, and to characterize genetic relatedness and antimicrobial resistance among the isolates. METHODS: A total of 158 dog treats derived from pig ears and other animal parts were randomly collected nationwide and assayed for the presence of Salmonella. The Salmonella isolates were characterized using serotyping, pulsed-field gel electrophoresis (PFGE) and antimicrobial susceptibility testing. RESULTS: Forty-one percent (65/158) of samples were positive for Salmonella. Eighty-four Salmonella isolates, comprising 24 serotypes, were recovered from the 65 positive samples. Fourteen samples were contaminated with more than one Salmonella serotype. PFGE analysis of 78 Salmonella isolates yielded 64 patterns. S. Infantis with PFGE patterns indistinguishable from those of strains identified in Canadian outbreaks in 1999 were recovered in several dog treat products. The majority of Salmonella isolates were susceptible to the antimicrobials tested; however, resistance was observed to tetracycline (26%), streptomycin (23%), sulfamethoxazole (19%), chloramphenicol (8%) and ampicillin (8%). Twenty-eight (36%) Salmonella isolates were resistant to at least one antimicrobial and 10 (13%) isolates displayed resistance to four or more antimicrobials. Two isolates were identified as S. Typhimurium DT104 with the characteristic penta-resistance phenotype (ampicillin, chloramphenicol, streptomycin, sulfamethoxazole and tetracycline). One S. Brandenburg isolate was resistant to eight antimicrobials. Seven Salmonella isolates also contained class I integrons encoding resistance genes to aminoglycosides, beta-lactam and streptothricin antimicrobials. CONCLUSIONS: The study indicates that animal-derived dog treats in the USA could be a potential source of animal and human infections with Salmonella, including multidrug-resistant Salmonella strains.

Prevalence of streptogramin resistance genes among Enterococcus isolates recovered from retail meats in the Greater Washington DC area.

The prevalence of streptogramin resistance genes in enterococci recovered from retail poultry in the Greater Washington DC area was examined. Forty-three chicken and 32 turkey retail samples were analysed. Thirty-one non-Enterococcus faecalis enterococcal strains were isolated that displayed MICs of quinupristin-dalfopristin and virginiamycin of > or = 4 mg/L. These included Enterococcus faecium (turkey n = 4, chicken n = 23), Enterococcus gallinarum (turkey n = 2, chicken n = 1) and Enterococcus hirae (chicken n = 1). The presence of streptogramin resistance genes was examined by PCR in all non-E. faecalis isolates. The vat(E) gene was detected in 10/23 chicken E. faecium and from 2/4 turkey E. faecium. No other streptogramin resistance genes were detected by PCR. In addition, erm(B) was detected in all the E. faecium and E. gallinarum found in turkeys and in 7/23 E. faecium found in chickens. The vat(E) gene was transferable by conjugation from only two of the 12 E. faecium isolates (one from chicken and one from turkey). This study suggests that there is a high prevalence of low-level streptogramin resistance among enterococci found in retail poultry and that other, yet to be identified, mechanisms operate in these isolates that confer streptogramin resistance in enterococci.

Identification of vat(E) in Enterococcus faecalis isolates from retail poultry and its transferability to Enterococcus faecium.

Sixteen isolates of Enterococcus faecalis were recovered from retail poultry samples (seven chickens and nine turkeys) purchased from grocery stores in the greater Washington, D.C., area. PCR for known streptogramin resistance genes identified vat(E) in five E. faecalis isolates (three isolates from chickens and two isolates from turkeys). The vat(E) gene was transmissible on a ca. 70-kb plasmid, along with resistance to erythromycin, tetracycline, and streptomycin, by conjugation to E. faecalis and Enterococcus faecium recipient strains. DNA sequencing showed little variation between E. faecalis vat(E) genes from the chicken samples; however, one E. faecalis vat(E) gene from a turkey sample possessed 5 nucleotide changes that resulted in four amino acid substitutions. None of these substitutions in the vat(E) allele have previously been described. This is the first report of vat(E) in E. faecalis and its transferability to E. faecium, which indicates that E. faecalis can act as a reservoir for the dissemination of vat(E)-mediated streptogramin resistance to E. faecium.

An episodic outbreak of genetically related Burkholderia cepacia among non-cystic fibrosis patients at a university hospital.

OBJECTIVE: To investigate an outbreak of Burkholderia cepacia. DESIGN: Observational study and chart review. PATIENTS: Adult non-cystic fibrosis (CF) patients. SETTING: Intensive care units (ICUs) at a university-affiliated teaching hospital. METHODS: As part of the epidemiological investigation, we conducted a chart review and collected environmental samples. A review of work schedules of healthcare workers also was performed. We used B. cepacia selective agar for preliminary screening for all isolates, which subsequently were confirmed as members of the B. cepacia complex by polyphasic analysis employing conventional biochemical reactions and genus- and species-specific polymerase chain reaction assays. Pulsed-field gel electrophoresis, randomly amplified polymorphic DNA typing, and automated ribotyping were used to genotype the isolates. As part of the intervention, contact isolation precautions were initiated for all patients identified as having had a culture positive for B. cepacia. RESULTS: Between September 1997 and September 1999, B. cepacia was isolated from 31 adult patients without CF in ICUs at a university-affiliated teaching hospital. Based on geographic clustering and genotypic analysis, three distinct clusters were observed involving 20 patients. Isolates from 17 of these patients were available for testing and were found to be of the same strain (outbreak strain). Further taxonomic analysis indicated that the outbreak strain was B. cepacia complex genomovar III. Twelve (71%) of the 17 patients were judged to be infected, and 5 (29%) were colonized with this strain. Six of 200 environmental cultures from multiple sources in the hospital's ICUs yielded B. cepacia. Two of these isolates, both recovered from rooms of colonized patients, were the same genotype as the outbreak strain recovered from patients. CONCLUSION: Despite an extensive investigation, the source of the B. cepacia clone involved in this outbreak remains unknown. The spatial and temporal pattern of cases suggests that cross-transmission of a genetically related strain contributed to clustering among patients. The initiation of contact isolation may have limited the extent of this transmission. Additional studies are needed to elucidate better the epidemiology of nosocomial B. cepacia infection among non-CF adult patients.

Vancomycin-resistant enterococci colonization in patients at seven hemodialysis centers.

BACKGROUND: Vancomycin-resistant enterococci (VRE) are increasing in prevalence at many institutions, and are often reported in dialysis patients. We studied the prevalence of and risk factors for VRE at seven outpatient hemodialysis centers (three in Baltimore, MD, USA, and four in Richmond, VA, USA). METHODS: Rectal or stool cultures were performed on consenting hemodialysis patients during December 1997 to April 1998. Consenting patients were recultured during May to July 1998 (median 120 days later). Clinical and laboratory data and functional status (1 to 10 scale: 1, normal function; 9, home attendant, not totally disabled; 10, disabled, living at home) were recorded. RESULTS: Of 478 cultures performed, 20 (4.2%) were positive for VRE. Among the seven centers, the prevalence of VRE-positive cultures varied from 1.0 to 7.9%. Independently significant risk factors for a VRE-positive culture were a functional score of 9 to 10 (odds ratio 6.9, P < 0.001), antimicrobial receipt within 90 days before culture (odds ratio 6.1, P < 0.001), and a history of injection drug use (odds ratio 5.4, P = 0.004). CONCLUSIONS: VRE-colonized patients were present at all seven participating centers, suggesting that careful infection-control precautions should be used at all centers to limit transmission. In agreement with previous studies, VRE colonization was more frequent in patients who had received antimicrobial agents recently, underscoring the importance of judicious antimicrobial use in limiting selection for this potential pathogen.

High-frequency recovery of quinupristin-dalfopristin-resistant Enterococcus faecium isolates from the poultry production environment.

The occurrence of resistance to the streptogramin quinupristin-dalfopristin in Enterococcus faecium isolates from chickens on the Eastern Seaboard, was evaluated. Quinupristin-dalfopristin resistance was found in 51 to 78% of E. faecium isolates from the food production environment. The high level of resistance in this organism suggests that this reservoir of resistance may compromise the therapeutic potential of quinupristin-dalfopristin.

A randomized trial of surgical antimicrobial prophylaxis with and without vancomycin in organ transplant patients.

BACKGROUND: Gram-positive organisms, including vancomycin-resistant enterococci (VRE), have emerged as major pathogens on the organ transplant service at our institution. We hypothesized that our use of vancomycin as part of routine surgical prophylaxis increased the risk of VRE colonization and infection; conversely, there was concern that failure to use vancomycin prophylaxis would increase peri-operative morbidity due to gram-positive organisms. METHODS: Renal transplant recipients (n = 88) were randomized to receive either a) vancomycin/ceftriaxone or b) cefazolin; and pancreas transplants (n = 24) to receive either a) vancomycin/gentamicin or b) cefazolin/gentamicin. Stool samples or rectal swabs were obtained for culture for enterococci within 24 h of transplantation and weekly while hospitalized. RESULTS: Enterococci were isolated on stool culture from 38 (34%) of 102 patients at the time of transplantation; 4 (11%) of the isolates were VRE. The percentage of patients who subsequently acquired VRE was low (1-7% per wk) but remained constant during hospitalization. There was no association between new VRE detection and vancomycin use for either prophylactic or therapeutic purposes. Forty-four patients (39%) had a post-operative infection with 46% of these infections due to gram-positive organisms; rates were unaffected by prophylactic vancomycin use. Pancreas transplant patients who did not receive vancomycin prophylaxis had a significantly longer initial hospitalization (p = 0.03); however, differences were not statistically significant when total length of stay (LOS) within the first 90 d of transplantation was compared. CONCLUSIONS: Vancomycin surgical prophylaxis does not appear to have an effect on VRE colonization or infection, or on rates of infection with gram-positive bacteria. Elimination of vancomycin prophylaxis in renal transplant patients may be a reasonable part of an overall program to limit vancomycin usage, although as a single measure, its impact may be minimal. Vancomycin surgical prophylaxis may be of greater importance in pancreas transplants.

The effect of application of aquaphor on skin condition, fluid requirements, and bacterial colonization in very low birth weight infants.

OBJECTIVE: To determine the effects of repeated application of an occlusive ointment on the skin of very low birth weight infants. STUDY DESIGN: Nineteen neonates of 26 to 30 weeks gestational age were randomly assigned to receive topical Aquaphor ointment twice daily for 2 weeks or to receive standard skin care. Skin quality, fluid requirements, and skin bacterial colonization counts were assessed. RESULTS: Infants treated with Aquaphor had significantly improved skin condition scores versus controls (p = 0.002). Aquaphor improved skin scores over time (p = 0.012) in treated infants, whereas skin scores of untreated infants worsened before eventually healing. There were no significant differences in total fluid requirements, urine output, serum sodium concentrations, skin bacterial counts, fungal counts, or colonization patterns between treated and control infants in either gestational age cohort. CONCLUSION: Aquaphor ointment, used during the first two postnatal weeks, improved skin condition in infants of 26 to 30 weeks' gestation without changing skin bacterial flora. We speculate that improved skin condition may limit transepidermal water loss and decrease portals of entry for pathogens, thereby potentially decreasing fluid and electrolyte imbalances and sepsis in very low birth weight infants.

In vitro activity of LY333328, an investigational glycopeptide antibiotic, against enterococci and staphylococci.

The in vitro activities of LY333328 were compared with those of vancomycin, teicoplanin, and quinupristin-dalfopristin (Synercid) against 219 strains of enterococci and staphylococci, including vancomycin-resistant enterococci and methicillin-resistant Staphylococcus aureus. MICs and MBCs were determined by a microtiter dilution protocol. LY333328 demonstrated superior activity against vancomycin-resistant enterococci and was the only antibiotic which was bactericidal. Its potency was comparable or superior to those of other antibiotics tested against methicillin-resistant staphylococci.

Stimulus-inadequate sensations in cochlear implant patients.

From August 1984 to April 1987 the Department of Otolaryngology at the Medizinische Hochschule in Hannover implanted the NUCLEUS 22 channel cochlear implant system (CI) in their first 56 adults. Since implantation, 27 (51%) patients have described undesirable sensations from their implant. These were defined as stimulus-inadequate sensations (SIS) and were classified into three types: 1) pain-like sensations; 2) high-frequency sensations; and 3) non-stimulation. Twenty-three patients were radiographically investigated by polytomography. All of the intracochlear electrodes were visualised and a correlation between SIS and the radiological findings was established. It was found that i) SIS similar to pain are caused by electrical stimulation of the mucous membranes and periosteum of the tympanic cavity; ii) the high-frequency SIS seemed to be due to non-physiological electrical stimulation of the basal ganglion cells; and iii) the reason for non-stimulation is probably damaged electrodes and fibrosis around the electrode. Conventional tomography is the method of choice for estimating the number and configuration of intracochlear electrodes.

[The therapeutic value of ambulatory extracorporeal shockwave lithotripsy of salivary calculi. Results of a prospective study]. / Die therapeutische Wertigkeit der ambulanten extrakorporalen Stosswellenlithotripsie von Speichelsteinen. Ergebnisse einer prospektiven Studie.

In a prospective study, results of the extracorporeal shock wave lithotripsy of salivary stones were evaluated. The study was performed with the currently available technical possibilities of electromagnetic systems to get indication criteria for this procedure. Using the Modulith SL 20-lithotripter of Storz Medical AG, 33 concrements in 25 patients were treated in 89 lithotripsy sections. The stone sizes, localized by ultrasound, ranged from 3 to 13 mm diameter (phi 6.9 mm). After application of local anaesthesia, per session on an average 1300 shock waves with raising energy levels were applied, the succession of shocks fixed to 1 MHz. With the help of ultrasound localisation, a therapeutic success with complete emission of the concrement or an adequate disintegration of these stones could be achieved in 82% of the parotid gland stones (n = 11) and in 14% of the submandibular gland stones (n = 22). Since the unhampered functioning of these salivary glands is an inevitable pre-condition for the spontaneous emission of the disintegrated fragments, the status of function of salivary glands should be established by a scintigraphy before performing the ESWL. Even though complete emission of the stone could be achieved in only 4 patients, all patients were clinically free of symptoms after the treatment. In 3 of 25 patients, discrete bleeding of a passing nature occurred coming from the salivary duct. In 2 patients, formation of haematoma of varying dimensions could be visualized by ultrasound. 3 patients showed petechial skin bleeding. The tinnitus aurium which affected one patient eased after 3 days. In our patients collective a facial nerve damage did not occur.2+ longterm prognosis after this procedure.

[Postoperative conventional tomography of the temporal bone in the assessment of inadequate perception in patients with cochlear implants]. / Postoperative konventionelle Schläfenbeintomographie in der Beurteilung von reizinadäquaten Empfindungen (RIE) bei Cochlear-Implant-Patienten.

Between August 1984 and August 1990, 166 patients received a 22-channel cochlear implant (Nucleus) in the ENT clinic in Hannover. Some of these patients who were able to understand speech nevertheless complained of inadequate perception. To study this further a phantom skull with a cochlear implant was examined by CT and by conventional tomography of the petrous bone in various image planes. The method of choice for evaluating the position and appearance of the cochlear implant proved to be conventional tomography of the petrous bone in the frontal transorbital plane. In 7/23 patients examined it was possible to demonstrate dislocation of the electrodes; this is evidently responsible for the faulty perception.