A simple laboratory algorithm for diagnosis of melioidosis in resource-constrained areas: a study from north-central Vietnam.

OBJECTIVES: Melioidosis may be endemic in many tropical developing countries, but diagnosis of the disease is currently unreliable in resource-limited areas. We aimed to validate a simple and cheap laboratory algorithm for the identification of Burkholderia pseudomallei from clinical specimens in parts of Vietnam where the disease has not previously been reported. METHODS: In June 2015, we conducted training courses at five general hospitals in north-central provinces in order to raise awareness of the disease and to introduce a simple and cheap laboratory identification algorithm for B. pseudomallei including the three-antibiotic disc test. RESULTS: Until the end of the year (7 months later), 94 suspected B. pseudomallei strains resistant to gentamicin and colistin but sensitive to amoxicillin/clavulanic acid were detected in clinical specimens from 70 patients. All strains were further confirmed as B. pseudomallei by using a specific TTSS1 real-time PCR assay and recA sequencing analysis. Among positive blood cultures, positive rates with B. pseudomallei ranged from 3.4% (5/147) to 10.2% (32/312) in the various clinics. A total of 82.8% (58/70) patients were bacteraemic, with a mortality of 50% (18/36) among patients with known outcome. No death occurred in nonbacteraemic patients. CONCLUSIONS: Our results demonstrate that the introduction of a simple and easy-to-perform laboratory algorithm for the identification of B. pseudomallei from clinical samples, together with clinical awareness raising, can lead to the diagnosis of a significant number of melioidosis cases in resource-limited clinical laboratories which previously did not identify the pathogen.

Predictors of colonization with Staphylococcus species among patients scheduled for cardiac and orthopedic interventions at tertiary care hospitals in north-eastern Germany-a prevalence screening study.

As methicillin-resistant Staphylococcus aureus (MRSA) colonization and infection in humans are a global challenge. In Mecklenburg and Western Pomerania (Germany) 1,517 patients who underwent surgical interventions were systematically screened for MRSA and MSSA colonization on the day of hospital admission and discharge. Demographic data, risk factors and colonization status of the (i) nose, (ii) throat, (iii) groin, and (iv) thorax or site of surgical intervention were determined. Of the 1,433 patients who were included for further evaluation, 331 (23.1%) were colonized with MSSA, while only 17 (1.2%) were MRSA carriers on the day of hospital admission. A combination of nose, throat and groin swabs returned a detection rate of 98.3% for MSSA/MRSA. Trauma patients had lower prevalence of MRSA/MSSA (OR 0.524, 95% CI: 0.37-0.75; p < 0.001) than patients with intended orthopedic interventions. Males showed significantly higher nasal S. aureus carrier rates than females (odds ratio (OR) = 1.478; 95% CI: 1.14-1.92; p = 0.003). Nasal S. aureus colonization was less frequent among male smokers as compared to non-smokers (chi2 = 16.801; phi = 0.154; p < 0.001). Age, gender and smoking had a significant influence on S. aureus colonization. Combining at least three different swabbing sites should be considered for standard screening procedure to determine S. aureus colonization at patients scheduled for cardiac or orthopedic interventions at tertiary care hospitals.

Monitoring of abdominal Staphylococcus aureus infection using magnetic resonance imaging: a murine animal model for hepatic and renal abscesses.

To establish a routine workflow for in vivo magnetic resonance imaging (MRI) of mice infected with bacterial biosafety level 2 pathogens and to generate a mouse model for systemic infection with Staphylococcus aureus suitable for monitoring by MRI. A self-contained acrylic glass animal bed complying with biosafety level 2 requirements was constructed. After intravenous infection with 105 colony-forming units (CFU) (n = 3), 106 CFU (n = 11) or 107 CFU (n = 6) of S. aureus strain Newman, female Balb/c mice were whole-body scanned by 7T MRI. Abdominal infections such as abscesses were visualized using a standard T2-weighted scan. Infection monitoring was performed for each animal by measurements at 1, 3, and 7 days after infection. Intravenous pathogen application led to a dose-dependent decrease in survival probability (p = 0.03). In the group with the highest infectious dose the 7-day survival rate was 33 %. An intermediate S. aureus dose showed a survival rate of 80 %, whereas at the lowest infection dose, none of the animals died. All animals with the highest infection dose exhibited hepatic abscesses 4 days after inoculation, 80 % developed renal abscesses on the 3rd day. Mice obtaining the intermediate S. aureus load reached a plateau at day 4 with 72 % liver and 60 % renal abscess probability. No abscesses were observed in other abdominal organs at any time point. The implemented experimental setup provides a suitable and reliable in vivo MRI method to study murine abdominal infection models using BSL-2 pathogen. Systemic Staphylococcus aureus infection leads to a dose-dependent development of hepatic and renal abscesses.

Bartonella henselae induces NF-kappaB-dependent upregulation of adhesion molecules in cultured human endothelial cells: possible role of outer membrane proteins as pathogenic factors.

The endothelium is a specific target for Bartonella henselae, and endothelial cell infection represents an important step in the pathogenesis of cat scratch disease and bacillary angiomatosis. Mechanisms of Bartonella-endothelial cell interaction as well as signaling pathways involved in target cell activation were analyzed. B. henselae strain Berlin-1, isolated from bacillary angiomatosis lesions of a human immunodeficiency virus-infected patient, potently stimulated human umbilical cord vein endothelial cells (HUVEC), as determined by NF-kappaB activation and enhanced adhesion molecule expression. These effects were accompanied by increased PMN rolling on and adhesion to infected endothelial cell monolayers, as measured in a parallel-plate flow chamber assay. Monoclonal antibodies against E-selectin significantly reduced PMN rolling and adhesion. In our hands, B. henselae Berlin-1 was substantially more active than the typing strain B. henselae ATCC 49882. E-selectin and ICAM-1 upregulation occurred for up to 9 days, as verified by Northern blotting and cell surface enzyme-linked immunosorbent assay. Induction of adhesion molecules was mediated via NF-kappaB activation and could be blocked by a specific NF-kappaB inhibitor. Additional studies indicated that B. henselae-induced effects did not require living bacteria or Bartonella lipopolysaccharides. Exposure of HUVEC to purified B. henselae outer membrane proteins (OMPs), however, reproduced all aspects of endothelial cell activation. In conclusion, B. henselae, the causative agent of cat scratch disease and bacillary angiomatosis, infects and activates endothelial cells. B. henselae OMPs are sufficient to induce NF-kappaB activation and adhesion molecule expression followed by enhanced rolling and adhesion of leukocytes. These observations identify important new properties of B. henselae, demonstrating its capacity to initiate a cascade of events culminating in a proinflammatory phenotype of infected endothelial cells.