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Sara Droz

Publications and source records attributed to Sara Droz.

7 recordsLinked to original sources
PubMed2006

Distribution and invasiveness of Streptococcus pneumoniae serotypes in Switzerland, a country with low antibiotic selection pressure, from 2001 to 2004.

To describe the serotype-specific epidemiology of colonizing and invasive Streptococcus pneumoniae isolates, which is important for vaccination strategies, we analyzed a total of 2,388 invasive and 1,540 colonizing S. pneumoniae isolates collected between January 2001 and December 2004 within two nationwide surveillance programs. We found that the relative rank orders of the most frequent serotypes (serotypes 1, 3, 4, 6B, 7F, 14, 19F, and 23F) differed among invasive and colonizing isolates. Serotypes 1, 4, 5, 7F, 8, 9V, and 14 had increased invasive potential, and serotypes/serogroups 3, 6A, 7, 10, 11, 19F, and 23F were associated with colonization. The proportion of pediatric serotypes was higher among children < 5 years old (48.5%) and persons > 64 years old (34.1%) than among other age groups (29.1%); it was also higher in West Switzerland (40.2%) than in other geographic regions (34.7%). Likewise, serotype-specific proportions of penicillin-resistant isolates for types 6B, 9V, 14, and 19F were significantly higher in West Switzerland. The relative frequency of pediatric serotypes corresponded with antibiotic consumption patterns. We conclude that the epidemiology of invasive and colonizing S. pneumoniae isolates is influenced by the serotype-specific potential for invasiveness, and therefore, surveillance programs should include colonizing and invasive S. pneumoniae isolates. Antibiotic selection pressure determines the serotype distribution in different age groups and geographic regions and therefore the expected direct and indirect effects of the 7-valent conjugate vaccine.

Adolescent↗
PubMed2005

Dynamics of hemodialysis catheter colonization by coagulase-negative staphylococci.

OBJECTIVES: Catheter colonization is a necessary but poorly characterized step in the pathogenesis of catheter-related infections. Colonization dynamics of central venous hemodialysis catheters were studied with emphasis on coagulase-negative staphylococci (CoNS) and their population genetics, antibiotic resistance, and biofilm formation. The homogeneity of CoNS colony morphotypes was evaluated. DESIGN: Prospective, longitudinal study during 1,158 catheter-days with microbiological analysis of skin swabs, weekly catheter blood and brush samples, and catheter tips. SETTING: Hemodialysis unit of a university hospital. PATIENTS: Twenty-six patients with 24 non-tunneled and 5 tunneled catheters. RESULTS: Nineteen (65.5%) of the catheters became colonized, 17 by CoNS. CoNS colonization of the inner lumen was observed in 17.2% of the catheters and was first detectable after 3 weeks. Colonization of the outer surface occurred in 44.8% of the catheters within a minimum of 2 weeks. PFGE of 53 CoNS revealed 10 clones and 20 unique isolates. Isolates from clones were more frequent in catheter blood and brush cultures than were unique isolates (41% vs 15%), were resistant to more antibiotics (median, 7 vs 2), and tended to more often carry the icaA gene (64.1% vs 40%). Four (23.5%) of the catheters showed colonization with a mixture of CoNS based on PFGE. The time from catheter insertion to such mixed CoNS colonization was longer than that for colonization with one CoNS PFGE pattern only (42 vs 25 days). CONCLUSIONS: Colonization of hemodialysis catheters is dominated by multidrug-resistant, icaA-positive CoNS clones. Mixed CoNS colonization occurs, but is delayed, suggesting a process of sequential superinfection.

Adult↗
PubMed2004

A family of variably expressed outer-membrane proteins (Vomp) mediates adhesion and autoaggregation in Bartonella quintana.

Bartonella species are fastidious, Gram-negative human pathogens that can persist in the host bloodstream for years and bind to and invade several types of host cells. For many pathogens, adhesion to host cells and extracellular matrix (ECM) components is a critical virulence determinant. Bacteria often vary expression of surface adhesins by phase or antigenic variation to subvert the host immune response and permit adaptive interaction with different host structures. We developed a macaque animal model for Bartonella quintana infection to detect changes in bacterial outer-membrane proteins (OMP) during prolonged bloodstream infection. We identified a gene family encoding four highly conserved, 100-kDa, variably expressed OMP (Vomp), two of which function as adhesins. The variable expression of Vomp family members appears to be mediated by deletion of one or more vomp genes during chronic bloodstream infection. vomp deletion was observed also in isolates from humans with chronic B. quintana infection. The Vomp are closely related to the afimbrial adhesin, YadA, a virulence factor of Yersinia enterocolitica. The surface-expressed Vomp contain conserved structural features of YadA, including collagen-binding motifs. We demonstrate that the B. quintana Vomp are multifunctional OMP involved in binding to collagen and autoaggregation: VompC confers the ability to bind collagen IV, and VompA is necessary and sufficient for autoaggregation. The B. quintana Vomp are members of the newly recognized family of YadA-like trimeric autotransporters; the Vomp constitute a multigene family, they are variably expressed, and different virulence properties are attributable to individual Vomp family members.

Adhesins, Bacterial↗
PubMed2003

Cefepime tissue penetration in experimental acute pancreatitis.

INTRODUCTION: Antibiotic treatment represents a cornerstone in the management of severe acute pancreatitis. However, different antibiotic substances are currently used. In this study, we analyzed penetration of cefepime into pancreatic tissue in two models of acute pancreatitis. AIMS AND METHODOLOGY: Following induction of acute pancreatitis, animals were treated with a single intravenous dose of cefepime (0.1 mg/g of body weight). At two different time points, blood and tissue samples were obtained for determination of cefepime concentration and microbiologic analysis. RESULTS: Mean pancreatic tissue concentrations +/- SEM 30 minutes after drug administration were significantly higher in animals with either mild acute pancreatitis (113 +/- 22 mg/kg) or severe acute pancreatitis (75 +/- 22 mg/kg) than in control animals (30 +/- 6 mg/kg) (p < 0.005). The minimal inhibitory concentrations (MIC90) for organisms usually isolated from infected pancreatic necrosis vary between 0.05 and 8 mg/L, which is between nine and 1,500 times lower than the mean peak concentration found in necrotic pancreatic tissue. Seven hours 30 minutes after antibiotic administration, pancreatic cefepime concentrations were still above the MIC90 in 100% and 83% of animals with mild and severe disease, respectively. The infection rate of pancreatic tissue was significantly lower after antibiotic treatment and was similar after imipenem/cilastatin or cefepime treatment. CONCLUSION: Because of its antibacterial coverage and proven tissue penetration in acute pancreatitis, cefepime should be studied in patients with severe acute pancreatitis.

Animals↗
PubMed2002

Experimental infection of domestic cats with Bartonella koehlerae and comparison of protein and DNA profiles with those of other Bartonella species infecting felines.

Bartonella koehlerae, a recently described feline Bartonella species, was isolated from two naturally infected cats in northern California. We experimentally infected domestic cats with B. koehlerae to establish the microbiological and immunological characteristics of this infection in cats and to compare it to infections with those caused by B. henselae and B. clarridgeiae. Four cats were inoculated intradermally with B. koehlerae (8.6 x 10(7) to 3.84 x 10(8) CFU/ml). None of the cats presented any obvious clinical signs, but all cats developed bacteremia, which peaked at 3.36 x 10(4) to 1.44 x 10(6) CFU/ml of blood between day 14 and day 36 postinoculation. B. koehlerae-inoculated cats had a bacteremia duration (mean, 74 days) shorter than did cats inoculated with B. clarridgeiae (mean, 324 days) (P = 0.03). None of the four cats inoculated with B. koehlerae had bacteremia relapse. As shown by enzyme-linked immunosorbent assay (ELISA) using B. koehlerae outer membrane protein (OMP) antigens, the four cats developed a species-specific antibody response, and ELISA testing using other feline Bartonella OMP antigens showed statistically lower optical density values. All four cats developed similar antibody reactivity patterns to B. koehlerae OMP antigens as seen by Western blotting, each with at least 20 seroreactive protein bands. Using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, protein profile differences were observed for both whole-cell lysate and OMPs from B. koehlerae, compared with B. henselae and B. clarridgeiae. B. koehlerae was more closely related to B. henselae than to B. clarridgeiae by protein profile, and this relatedness was also confirmed by analysis of the genomic DNA profiles by pulsed-field gel electrophoresis.

Animals↗