Titratable transmembrane residues and a hydrophobic plug are essential for manganese import via the Bacillus anthracis ABC transporter MntBC-A.

All extant life forms require trace transition metals (e.g., Fe2/3+, Cu1/2+, and Mn2+) to survive. However, as these are environmentally scarce, organisms have evolved sophisticated metal uptake machineries. In bacteria, high-affinity import of transition metals is predominantly mediated by ABC transporters. During bacterial infection, sequestration of metal by the host further limits the availability of these ions, and accordingly, bacterial ABC transporters (importers) of metals are key virulence determinants. However, the structure-function relationships of these metal transporters have not been fully elucidated. Here, we used metal-sensitivity assays, advanced structural modeling, and enzymatic assays to study the ABC transporter MntBC-A, a virulence determinant of the bacterial human pathogen Bacillus anthracis. We find that despite its broad metal-recognition profile, MntBC-A imports only manganese, whereas zinc can function as a high-affinity inhibitor of MntBC-A. Computational analysis shows that the transmembrane metal permeation pathway is lined with six titratable residues that can coordinate the positively charged metal, and mutagenesis studies show that they are essential for manganese transport. Modeling suggests that access to these titratable residues is blocked by a ladder of hydrophobic residues, and ATP-driven conformational changes open and close this hydrophobic seal to permit metal binding and release. The conservation of this arrangement of titratable and hydrophobic residues among ABC transporters of transition metals suggests a common mechanism. These findings advance our understanding of transmembrane metal recognition and permeation and may aid the design and development of novel antibacterial agents.

A novel host-protein assay outperforms routine parameters for distinguishing between bacterial and viral lower respiratory tract infections.

Bacterial and viral lower respiratory tract infections (LRTIs) are often clinically indistinguishable, leading to antibiotic overuse. We compared the diagnostic accuracy of a new assay that combines 3 host-biomarkers (TRAIL, IP-10, CRP) with parameters in routine use to distinguish bacterial from viral LRTIs. Study cohort included 184 potentially eligible pediatric and adult patients. Reference standard diagnosis was based on adjudication by an expert panel following comprehensive clinical and laboratory investigation (including respiratory PCRs). Experts were blinded to assay results and assay performers were blinded to reference standard outcomes. Evaluated cohort included 88 bacterial and 36 viral patients (23 did not fulfill inclusion criteria; 37 had indeterminate reference standard outcome). Assay distinguished bacterial from viral LRTI patients with sensitivity of 0.93±0.06 and specificity of 0.91±0.09, outperforming routine parameters, including WBC, CRP and chest x-ray signs. These findings support the assay's potential to help clinicians avoid missing bacterial LRTIs or overusing antibiotics.

A novel host-proteome signature for distinguishing between acute bacterial and viral infections.

Bacterial and viral infections are often clinically indistinguishable, leading to inappropriate patient management and antibiotic misuse. Bacterial-induced host proteins such as procalcitonin, C-reactive protein (CRP), and Interleukin-6, are routinely used to support diagnosis of infection. However, their performance is negatively affected by inter-patient variability, including time from symptom onset, clinical syndrome, and pathogens. Our aim was to identify novel viral-induced host proteins that can complement bacterial-induced proteins to increase diagnostic accuracy. Initially, we conducted a bioinformatic screen to identify putative circulating host immune response proteins. The resulting 600 candidates were then quantitatively screened for diagnostic potential using blood samples from 1002 prospectively recruited patients with suspected acute infectious disease and controls with no apparent infection. For each patient, three independent physicians assigned a diagnosis based on comprehensive clinical and laboratory investigation including PCR for 21 pathogens yielding 319 bacterial, 334 viral, 112 control and 98 indeterminate diagnoses; 139 patients were excluded based on predetermined criteria. The best performing host-protein was TNF-related apoptosis-inducing ligand (TRAIL) (area under the curve [AUC] of 0.89; 95% confidence interval [CI], 0.86 to 0.91), which was consistently up-regulated in viral infected patients. We further developed a multi-protein signature using logistic-regression on half of the patients and validated it on the remaining half. The signature with the highest precision included both viral- and bacterial-induced proteins: TRAIL, Interferon gamma-induced protein-10, and CRP (AUC of 0.94; 95% CI, 0.92 to 0.96). The signature was superior to any of the individual proteins (P<0.001), as well as routinely used clinical parameters and their combinations (P<0.001). It remained robust across different physiological systems, times from symptom onset, and pathogens (AUCs 0.87-1.0). The accurate differential diagnosis provided by this novel combination of viral- and bacterial-induced proteins has the potential to improve management of patients with acute infections and reduce antibiotic misuse.

Leukemoid reaction: spectrum and prognosis of 173 adult patients.

BACKGROUND: The prognosis of patients with leukemoid reaction (LR) depends mainly on their underlying illness. Our aim was to investigate the etiologies and prognosis of a mixed group of patients with LR. METHODS: We identified 173 patients who had ≥30.0 × 10(9) leukocytes/µL without hematologic malignancies. Causes of LR and factors contributing to death were analyzed. RESULTS: Patients with LR constituted 0.59% of all admitted adults. The median age was 75 years, but 20 patients were aged <40 years. There was no difference in LR prevalence by gender (female/male = 88/85). Average white blood cell (WBC) count was 37.7 × 10(9)/µL. Fourteen patients (8.0%) had a WBC count of >50.0 × 10(9)/µL. The median duration of LR was 1 day, but 39 patients had prolonged LR (>1 day). Infection was the most common cause of LR (n = 83, 47.9%; 95% confidence interval, 40.7-55.4), followed by ischemia/stress (27.7%), inflammation (6.9%), and obstetric diagnoses (6.9%). Higher WBC counts were significantly associated with positive blood cultures (P = .017) or a positive Clostridium difficile toxin (P = .001). Antibiotics were prescribed for 140 patients (80.9%). Sixty-six patients (38.1%) died during hospitalization. Those with prolonged LR had an in-hospital mortality rate of 61.5%. Factors found to be highly correlated with death were age (odds ratio [OR] = 1.051, P < .001), any infectious diagnosis (OR = 2.574, P = .014), and sepsis (OR = 3.752, P = .001). CONCLUSIONS: LR carries a grave prognosis, especially among the elderly and those with sepsis. LR was found to have multiple etiologies including infections, stress, inflammation, and obstetric diagnoses.

Impact of a computerized integrated antibiotic authorization system.

BACKGROUND: Overuse and abuse of antibiotics is a major cause of microbial resistance. Within the hospital setting such overuse necessitates real-time supervision by infectious diseases (ID) specialists. OBJECTIVES: To evaluate the impact of a recently introduced computerized antibiotic authorization system on the pharmacy budget. METHODS: The study was performed in a 400 bed university hospital. With the new system, antibiotic requests are entered electronically by the ward physician and reviewed within minutes to hours by ID specialists. The feedbacks are seen in the wards and pharmacy. Successive years, one before and the other after introduction of the system, were compared. RESULTS: During the first year with the new system 7167 antibiotic requests were entered; 20% of them were rejected, mainly for improper indication (43% of the rejections). During that year the antibiotic expenditure was reduced by 17%, compared to the previous year (approximately equal to 200,000 US$), and was against the trend of the last 5 years. Of the 35 antibiotics under the control of the ID team, the use of 7 was probably curtailed by the supervision. Pareto analysis revealed that four drugs constituted > 50% of the pharmacy's expenses. The mortality rate (per 1000 hospitalization days) during those 2 years fell from 4.0 to 3.8. CONCLUSIONS: Computerized antibiotic control by ID specialists is a feasible cost-saving new modality that may help reduce unnecessary antibiotic prescriptions.

Pregnancy course and outcome in women traveling to developing countries.

BACKGROUND: The issue of travel to developing countries during pregnancy has not been sufficiently studied. The aim of this study is to investigate the rate, course, and outcome of pregnancies in women who traveled to developing countries while pregnant, or became pregnant during such travel. METHODS: Women visiting two major travel clinics in Israel for consultation within the years 2004 to 2009, who were pregnant or declared an intention of becoming pregnant during travel were contacted. This was followed by a telephone interview by an obstetrician with those women who were actually pregnant. Background characteristics, morbidity during travel, and pregnancy course and outcome were collected. RESULTS: Overall 52,430 travelers' records had been screened. Of these, we identified 49 women who were pregnant during their trip, but 3 declined participation. Of the remaining 46 women, 33 were pregnant at departure, and 13 conceived during travel. The incidence of pregnancy during travel was thus 0.93/1000 travelers. Thirty-three women traveled to East Asia, 8 to South and Central America, 5 to Africa. More than two thirds of women received pretravel vaccinations. Adherence to the World Health Organization recommendations regarding food and drink was high (87%) and travelers' diarrhea occurred in only 11% of women. Five of 22 women traveling to malarious areas had taken antimalarial prophylaxis. Six women required medical therapy during travel. Pregnancy outcome was not different from the normal population except for an unusually low rate of preterm delivery. CONCLUSIONS: In this cohort, travel to developing countries was not associated with adverse pregnancy outcome. Larger studies are needed to support these findings.

When uncommon uncovers: mucosal tuberculosis in a medical tourist from Burundi.

Tuberculosis confined to the mucus membranes is a rare presentation in the era of effective chemotherapy. We describe a case of mucosal tuberculosis in a "medical tourist" from Burundi that went undiagnosed for 6 years. Starting as conjunctivitis, the disease has spread to involve the nose and larynx as well. The clinical, pathophysiological, and epidemiological aspects are discussed.

Assessment of rabies exposure risk among Israeli travelers.

BACKGROUND: The decision whether or not to administer rabies pre-exposure prophylaxis (PEP) to travelers visiting endemic areas is a complex one. Paramount for making that decision is knowledge of the risk of animal bites during travel. This study attempts to estimate the risk of bites in travelers, and study the action they took before and after the incident. METHODS: Travelers presenting for pre-travel immunizations during the period of August through December 2004, who planned a travel of >or= 1 month's duration were retrospectively identified, contacted and interviewed by a structured questionnaire. These travelers did not receive specific advice concerning rabies. RESULTS: The study cohort comprised of 815 travelers (median age=25), of who 13 (1.6%) were injured by a potentially rabid animal (mainly, dog=6; monkey=4). The incidence of potential rabies exposure was found to be of 2.66 per 1000 travelers per month. Those injured had significantly longer trips than the non-injured (6.9+/-3.8 vs. 4+/-5.0 months, p=0.037); notably, the injuries occurred after a median of 5 weeks from departure. Although seven travelers noted blood at the site of injury, only four (31%) of the injured sought medical attention following the exposure, and all four received post-exposure prophylaxis. CONCLUSIONS: An injury by potentially rabid animals is not rare among long-term travelers. As the injury may occur early in the itinerary, rabies PEP should be considered for this population. Educational efforts are required in light of the lack of understanding of the dismal consequences of rabies among travelers.

Ischemic stroke, aortic dissection, and thrombolytic therapy--the importance of basic clinical skills.

Aortic dissection masquerading as ischemic stroke is particularly challenging in the era of thrombolysis as a result of narrow diagnostic time window and severe hemorrhagic potential. We describe a case of a 77-year-old patient with a presumed ischemic cerebral infarct, in whom planned treatment with tissue plasminogen activator therapy (TPA) was withheld because of partial spontaneous improvement in his condition. Shortly afterwards, newly elicited clues in the medical history and physical examination led to timely diagnosis and treatment of ascending thoracic aorta dissection, which was the underlying disorder. Analysis of the features of this case and similar previously published cases illustrates the importance of using and mastering basic diagnostic skills.

Emphysematous cystitis: illustrative case report and review of the literature.

Emphysematous cystitis is a rare disease characterized by primary infection of the urinary bladder with gas-producing pathogens. There is a paucity of information on this entity in the English-language literature covering the last 45 years, and the clinical picture is poorly outlined. We carried out a comprehensive, retrospective review of the English-language literature from 1986 to 2006, searching for reports describing cases of emphysematous cystitis. The demographic, clinical, laboratory, imaging, and outcome characteristics of every eligible patient were excerpted. In the present report, we describe a typical case of emphysematous cystitis, followed by an analysis of the literature. Of the 53 eligible cases, most were elderly women with diabetes mellitus (62.2%). Classic symptoms of urinary tract infection were present in only 53.3% of cases. Abdominal tenderness and hematuria were noted in 65.6% and 82.3% of cases, respectively. Plain abdominal X-ray was highly sensitive (97.4%), while abdominal computerized tomography was the most sensitive and specific diagnostic tool. A complicated course attributable to emphysematous cystitis was described in 18.8% of cases. The exact mechanism contributing to the formation of gas in such cases is unknown. Various theories have been suggested, including fermentation of glucose in urine, with emphasis on disequilibrium between gas formation and clearance. Emphysematous cystitis has a highly variable presentation and course, with a considerable potential for complications. Further diagnostic imaging is highly recommended in diabetic patients with urinary tract infection who present with abdominal pain and hematuria. Knowledge of this rare entity may lead to early diagnosis and appropriate management.

Proteinuria on dipstick urine analysis after sexual intercourse.

OBJECTIVE: To examine the role of sexual intercourse as a cause of proteinuria, and establishes its duration, as a knowledge of benign causes of proteinuria is required to avoid unnecessary testing. SUBJECTS AND METHODS: Twenty-four married couples were instructed to produce a urine sample before and after sexual intercourse; their urine was tested for proteinuria by dipstick analysis. RESULTS: Samples were assayed from 22 men and 11 women. Whereas none of the 24 men originally assessed for the study had proteinuria before sexual intercourse, six of the 22 who were eventually enrolled had proteinuria after intercourse (27.3%, 95% confidence interval, 10-50%; P = 0.008). None of the women had proteinuria after sexual intercourse (95% confidence interval, 70-100%). The time to disappearance of proteinuria was <12 h. CONCLUSION: Sexual intercourse is confirmed as a benign cause of proteinuria in men. Whenever possible, it is wise to avoid sexual intercourse at least 12 h before urinary dipstick testing.