Pharmacokinetics of ciprofloxacin as a tool to optimise dosage schedules in community patients

OBJECTIVE

To evaluate the dosage regimens of ciprofloxacin prescribed for outpatients by applying the principles of antibacterial therapy.

DESIGN

Retrospective analysis of prescription and demographic data.

SETTING

Community pharmacy in Valladolid, Spain.

PATIENTS

Fifty male and female patients aged 18-93 years and with bodyweight 41-95kg.

METHODS

Prescribed dosage regimen, age, weight, height, type of infection, comorbidity and coadministered drugs were recorded for each patient. Plasma concentration curves were simulated from literature values of the pharmacokinetic parameters of the drug and the age and weight of the patients. Urine concentrations were estimated from simulated plasma concentrations, literature values of renal clearance and an average urinary flow rate of 2 L/day. The potential efficacy of the prescribed treatment was evaluated from the ratio of the simulated peak plasma concentration (C(max)) to the literature value of the minimum inhibitory concentration (MIC) for the bacterium most probably responsible for the infection (C(max) /MIC). The ratio of area under the plasma concentration-time curve over 24 hours to MIC (AUC24 /MIC) was also estimated for non-urinary infections.

RESULTS

Demographic variables such as age or bodyweight do not seem to be taken in consideration when ciprofloxacin is prescribed, at least in the patients considered here, leading to wide interindividual variability in plasma concentrations. This may not be relevant for urinary infections, since ciprofloxacin concentrates in the urine, leading to high Cmax /MIC ratios in all patients. Simulated plasma concentration-time curves revealed consistent underdosing for systemic infections in young patients over 60kg, for whom the plasma concentrations achieved led to Cmax /MIC and AUC24 /MIC ratios lower than those associated with clinical efficacy and minimal spread of bacterial resistance.

CONCLUSIONS

The standard regimen of ciprofloxacin 250mg every 12 hours prescribed for urinary infections may not be the best choice, since a more convenient regimen of 500mg once daily leads to a higher Cmax /MIC ratio, which is associated with a more significant postantibiotic effect and higher efficacy of fluoroquinolones. For non-urinary infections, the age and weight of patients should be taken into account to achieve optimum plasma concentrations.

Transient hypophosphataemia associated with acute infectious disease in paediatric patients

The aim of this study was to investigate the prevalence of hypophosphataemia in children with acute infection and the relationship between serum phosphate and C-reactive protein (CRP) concentration. Serum phosphate and CRP levels were measured on admission in 238 patients (aged 1 month to 14 y) with: pneumonia (n = 51), upper respiratory tract-related bacterial infection (n = 70), urinary tract infection (n = 50) and viral infection (n = 67). Patients were classified according to CRP value (0-50, 51-100, 101-150, > or = 151 mg/l) and type of infection. The prevalence of hypophosphataemia was calculated for each group. 30 children with hypophosphataemia on admission had serial measurements of serum phosphate and CRP levels. A significant negative correlation between serum phosphate and CRP levels was found (r = -0.41, p < 0.0001). Patients with CRP > or = 151 mg/l on admission had a lower mean serum phosphate value than those with CRP < or = 50 mg/l (1.17 vs 1.50 mmol/l, p < 0.0001). The overall prevalence of hypophosphataemia for patients with pneumonia, upper respiratory tract bacterial infection, urinary tract and viral infections was 45%, 35.7%, 18% and 4.4%, respectively. Hypophosphataemia occurred during the phase of rising of CRP level and resolved soon after CRP reached a plateau. In conclusion, hypophosphataemia is a relatively frequent but transient phenomenon in children with acute infectious disease. It is associated with an increase in CRP concentration and resolves before the normalization of CRP levels.

Protein S declines during winter respiratory infections

There is an increase in cardiovascular and cerebrovascular morbidity and mortality in the older adult population during the winter that could be related to prothrombotic changes caused by seasonal effects or acute respiratory tract infections. Therefore, a prospective cohort study was conducted to assess the effect of acute winter respiratory infection on hemostatic parameters including complement 4b-binding protein (C4-BP), functional protein S, total protein S, free protein S, and the inflammatory marker, interleukin-6 (IL-6), in younger and older adults. The changes in the levels of hemostatic and inflammatory markers during winter respiratory infections in the younger and older adults were compared with matched, non-infected controls. In younger and older adults (combined), total protein S increased from 83% [95% confidence interval (CI); 77-88] to 98% (95% CI; 91-106, P < 0.001) while free protein S decreased from 100% (95% CI; 95-105) to 70% (95% CI; 66-75, P < 0.001). There were no significant changes in C4-BP (P = 0.622), functional protein S (P = 0.061) or IL-6 (P = 0.651) from baseline. In a multivariate analysis, only total protein S and free protein S showed significant association with seasonal change after adjusting for the effect of infection. The estimated effect of season on total protein S was 15 +/- 4%, P < 0.001 and on free protein S was -27 +/- 3%, P < 0.001. After adjusting for seasonal effect, only functional protein S showed a significant association with infection, with the estimated effect of -17 +/- 5%, P < 0.001. The results in the younger and older adults were similar to those in the combined groups. Seasonal and infection-related changes in hemostatic parameters including an increase in fibrinogen and a decrease in free protein S, observed in this study, may contribute to thrombotic risk and excess vascular disease morbidity and mortality in older populations in the winter season.

Dysfunction of peripheral blood granulocyte oxidative metabolism in children with recurrent upper respiratory tract infections

Granulocytes play a key role in the defence against bacterial infections. Their dysfunction may both predispose to and result from infections. The oxidative metabolism of peripheral blood granulocytes was studied in 50 children aged from 1 to 10 years, with recurrent upper respiratory tract infections and/or tonsillar hypertrophy. Four groups of patients were recruited: 15 healthy controls, seven patients with idiopathic tonsillar hypertrophy, 12 patients with upper respiratory tract infections and 16 patients with upper respiratory tract infections with concurrent tonsillar hypertrophy. The ability of granulocytes to produce reactive oxygen species was assessed by nFMLP-induced chemiluminescence. Both increased and depressed granulocyte activity was observed in all studied groups, with the exception of controls. Altered granulocyte function was observed in 30% of patients in the idiopathic tonsillar hypertrophy group. In children with recurrent infections abnormal chemiluminescence results were found in from 75% to nearly 90% of patients. This preliminary study demonstrates the possible relationship between recurrent upper respiratory tract infections, tonsillar hypertrophy and impaired peripheral blood granulocyte chemiluminescence.

White blood cell count can aid judicious antibiotic prescribing in acute upper respiratory infections in children

Fifty percent or more of children with upper respiratory infections (URIs) and nonspecific febrile illnesses (e.g., children febrile, anorexic, decreased activity, irritable) receive unnecessary antibiotics from community-based physicians. This study was undertaken to show that white blood cell (WBC) count testing can aid physicians in avoiding antibiotic prescribing when managing children with URIs, and nonspecific febrile illnesses. A prospective, 3-year study was conducted in a community-based pediatric practice. A weekly convenience sample (Tuesdays) of acute URI and febrile patients ages 3 months to 21 years was studied. Data collected on enrollment included: age, gender, duration of illness, recent/current antibiotic use, temperature, symptoms, signs, laboratory testing (WBC count, cultures), diagnosis and treatment. Similar data on any illness visits in the previous 2 weeks and the subsequent 2 weeks after enrollment were collected. Viral culture specimens were obtained on a subset. The use of the WBC count was assessed, including obviating antibiotic prescription, frequency of related follow-up visits, and the occurrence of subsequent bacterial infections. Of 1,956 patients with respiratory or febrile illness enrolled, 1,219 (62%) had a diagnosis established by history and examination (e.g., acute otitis media) and 737 (38%) did not. Of the 737 patients without an established diagnosis, 386 (52%) did not receive an antibiotic because they did not appear particularly ill, their temperature was less than 101 degrees F, and parents were not demanding antibiotics, leaving 351 (48%) patients who appeared ill, had a temperature greater than 101 degrees F, and parents were demanding an antibiotic or physicians were inclined to give an antibiotic. A WBC count was performed on these 351 children; 337 children (96%) had a WBC count less than 15,000/mm3, and 14 (4%) had a WBC 15,000/mm3 or greater. An antibiotic was prescribed for 13 of the 14 children with a WBC count greater than 15,000/mms. With this approach, return office visits in the following 2 weeks were infrequent (13% of 737 patients), and no child had significant bacterial illness that was missed. With selective use of WBC count testing

Adenovirus DNA in serum of children hospitalized due to an acute respiratory adenovirus infection

Serum samples from 68 immunocompetent infants (mean age, 12.6 months) with an acute adenovirus infection of the respiratory tract (39 experiencing their first adenovirus infection) were tested for the presence of adenovirus DNA, to investigate whether viral dissemination via the blood is usually present in the immunocompetent patient. Using a nested polymerase chain reaction assay, adenovirus DNA could be detected in acute-phase serum samples from 28 (41%) children. Adenovirus DNA was never found in follow-up serum samples, indicating a short period ( approximately 1 week) of viral dissemination. In children experiencing their first adenovirus infection, viral DNA could be detected in 72% of the acute-phase serum samples collected within the first week after onset of symptoms. Adenovirus DNA could also be detected in 25% of the acute-phase serum samples from patients with reinfection.

Respiratory infection in asthma

Ever since the first decades of the 20th century, some authors have given respiratory infection triggered by bacteria an etiologic role in bronchial asthma, focusing on infection and the asthmatic response. In 1995 our group already presented a study in this sense on nasal secretion cultures and the relationship between IgE and sensitization to allergens. There is a significant association between patients with sensitization to Dermatophagoides, high levels of total IgE, and positive culture to Staphylococcus aureus. Following studies by Norn, we performed a study with 40 children, aged 2-14 years, where we observed that children with sensitization to mites and a positive culture had higher levels of histamine release than did children with negative culture and controls, the differences being significant. We also found, like other authors, that the joint presence of Staphylococcus aureus and Derrmatophagoides pteronyssinus potentiates antigen-specific histamine release. In recent years, with the increasing prevalence of bronchial asthma being studied, the role that infection could play in this increase is being considered again among other factors. As participants of the ISAAC project and using the same methods as in this study, we performed a simultaneous questionnaire with questions related with triggering and contributing factors, etc., including respiratory infection. We found an association between having had more than three episodes of "bronchitis" with fever and lasting for longer than seven days in the last year and having ever had asthma (OR 29.09). This association is still greater with having had wheezing in the last 12 months (OR 43.26), a finding that it is also associated with requiring attention in an emergency room (OR 30.65). From these results, we concluded that respiratory infection is an aggravating factor of asthma, something we already knew. In order to have our own experience, we studied serum interleukin 4 (IL-4) and interferon gamma (IFNgamma) in a sample of 41 children aged 3 to 17 years. The most frequent values of IL-4 ranged between 0.25 and 0.40 ng, and very low dispersion was found in the sample, which did not allow correlation with other parameters. Regarding IFNgamma, we found values between < 5 pg/ml and 605 pg/ml. When we studied children under treatment with antigen-specific immunotherapy, we observed mean values of IFNgamma of 115.86 pg/ml, whereas the ones who did not follow this treatment or had followed it for less than one year had a mean of 66.06 pg/ml, these differences being significant (p = 0.035), and proving a Th1 response to immunotherapy. This significance is not found if children who have been under immunotherapy for less than one year are included. When we studied children with bacterial immunotherapy, we found that the mean IFNgamma value in children under immunotherapy for longer than one year was 56.4 pg/ml, whereas in children with no immunotherapy it was 101.75 pg/ml (p = 0.034). We conclude that bacterial immunotherapy modifies the Thl response, inhibiting it in those children with greater susceptibility to infections.

Etiology of acute lower respiratory tract infection

OBJECTIVE

To identify pathogens responsible for acute severe lower respiratory tract infection (ALRTI) in under five children by non-invasive methods.

METHOD

95 children hospitalized with acute severe lower respiratory tract infection were investigated for identification of viruses, bacteria, chlamydia or mycoplasma by nasopharyngeal aspirates, blood culture and serology.

RESULT

Etiological agents could be identified in 94% of the patients. Viruses from NP aspirate could be isolated in 36 (38%), bacterial isolates from blood cultures in 15 (16%); mycoplasma was identified in 23 (24%) and chlamydia in 10 (11%) by serological tests; mixed infections were present in 8 (8%) patients.

CONCLUSION

Noninvasive methods can be useful in identifying etiological agents in severe ALRTI.

Pharmacokinetic aspects of levofloxacin 500 mg once daily during sequential intravenous/oral therapy in patients with lower respiratory tract infections

Levofloxacin is considered an effective antibiotic in the treatment of community-acquired lower respiratory tract infections (LRTIs). A study was carried out on 17 in-patients to assess the pharmacokinetics of a 500 mg once-daily switch intravenous (i.v.)/oral regimen of levofloxacin in the treatment of LRTI patients. Blood samples were collected under steady-state conditions at appropriate intervals. Levofloxacin plasma concentrations were analysed by means of HPLC and pharmacokinetic parameters were estimated using the WinNonlin pharmacokinetic software package. A lower clearance of levofloxacin (<2 mL/min/kg), conditioning both a longer elimination half-life (approximately 9 h) and a larger AUC(0-tau) (approximately 80 mg/L x h), was observed for both routes in our patients than in healthy volunteers. These differences may be explained considering that levofloxacin is excreted mainly as unchanged drug by the renal route, and most of our patients (71%) were very elderly subjects whose renal function physiologically declines with age. The almost complete (> or =99%) absolute oral bioavailability suggests that a comparable exposure to the iv regimen may be achieved after oral administration. The overall clinical success rate was 94.1%.

Serum transferrin receptor in children with respiratory infections

OBJECTIVE

To study the effect of infection on iron status in children suffering from acute, mild or severe respiratory infections and to determine the nature of anemia in infection using serum transferrin receptor (sTfR) levels.

DESIGN

Forty-three children aged between 3 and 5 y with no evidence of infection and receiving iron supplements in the preceding 100 days served as controls. Twenty-one children with mild upper respiratory infection and 94 children hospitalized for acute pneumonia constituted the experimental group. Hemoglobin (Hb), sTfR and serum ferritin were estimated in all the children at the time of diagnosis and again on the 15th and 30th days after the infection in those who were available for follow-up.

RESULTS

Mean (95% CI) sTfR was 6.08 (5.1-7.1) mg/l in healthy non-anemic children. Upper respiratory infection had no impact on Hb or sTfR but it significantly elevated serum ferritin levels. Eighty-three percent of the children with pneumonia had Hb less than 110 g/l at the time of diagnosis and had elevated mean sTfR, 18.0 (15.7-20.3) mg/l. There was a decline in mean sTfR by the 15th day of infection to 14.3 (11.3-17.4) mg/l with further rise to 22.9 (13.0-31.9) mg/l by 30 days. Serum ferritin was significantly elevated at the time of diagnosis (85.9; 71.1-100.8 micro g/l) as well as at 15 days (89.1; 68-110.1 micro g/l) with a decline by 30 days.

CONCLUSIONS

Severe lower respiratory infection exaggerates iron-deficient erythropoiesis by blocking release of iron from the storage pools. sTfR may not be a sensitive and specific tool of assessing true iron status of children exposed to severe infections.

[Acute respiratory tract infections and mannose-binding lectin insufficiency in small children]

INTRODUCTION

According to hospital-based studies, increased susceptibility to certain infections is associated with genotypes that cause low serum levels of the protein mannose-binding lectin (MBL). However, the contribution of MBL insufficiency to the incidence of common childhood infections on a population basis is unknown. To investigate the effect of MBL insufficiency on the risk of acute respiratory infections (ARI) in unselected children, we performed a prospective population-based study of ARI in young children in Sisimiut, Greenland.

MATERIAL AND METHODS

An open cohort of children aged 0-2 years was formed in 1996, and followed up with weekly morbidity surveillance visits for a two-year period. Episodes of ARI were diagnosed on medical history and clinical examinations. MBL genotypes were determined from blood samples according to the presence of structural alleles and promoter alleles.

RESULTS

Altogether 294 children participated and 44 refused. Blood samples were taken from 252 participants. A 2.1-fold (95% confidence interval 1.4-3.1) increased risk of ARI was found in MBL-insufficient children compared with MBL-sufficient children (p < 0.001). The risk association was largely restricted to the period 6 to 17 months of age, whereas less or no effect could be shown in younger and older children.

DISCUSSION

These population-based data suggest that genetic factors such as MBL insufficiency play an important role in host defence, particularly during the vulnerable period of infancy between 6 and 17 months of age, when the adaptive immune system is immature.

Viral infection and allergy: lower airway

Acute asthma exacerbations in adults and children are triggered commonly by viral upper respiratory infections. The main culprits are respiratory syncytial virus and parainfluenza virus in young children and rhinovirus in older children and adults. Recent investigations in multiple laboratories have increased our understanding of the nature of this relationship. Postulated mechanisms include a viral modulation of airway epithelial and inflammatory cell function with the release of proinflammatory cytokines and mediators, airway microvascular endothelial cell function leading to airway wall edema, airway smooth muscle cell functions, and neural regulation of airway tone via either enhanced parasympathetic efferent neuronal activity, activation of the release of bronchoactive neuropeptides from sensory c-fibers in the airways, or modulation of the influence of the nonadrenergic/noncholinergic neuronal system on airway tone. There also is evidence that rhinoviruses may directly infect the lower airways. These potential mechanisms likely relate to, are superimposed on, and potentiate preexisting inflammatory and immune responses that are characteristic of the atopic asthmatic airway. Undoubtedly, future efforts will be aimed at the prevention of asthma exacerbations via well-targeted and well-conceived strategies for prevention and/or treatment of upper respiratory infections.

The level of magnesium in the serum of children hospitalized for severe respiratory infections

The objective of the studies was evaluation of the level of magnesium in children hospitalized for severe respiratory infections (mainly pneumonia and bronchitis). The criterion for the evaluation of the magnesium level in the serum of the children hospitalized for severe respiratory infections were the following parameters: general condition of the child at the time of admittance, feeding pattern and psychosomatic development in the children with respiratory infection. The level of magnesium in the serum of the children admitted with median general condition was higher than that of the children admitted with poor general condition. The level of magnesium in the serum of breastfed children and those with correct psychosomatic development was higher than the level of magnesium in children fed artificially and representing backward psychosomatic development.

[Microcirculation, hemostasis, and hemorheology in influenza and acute respiratory viral infections in patients with hypertension]

AIM

To study microcirculation (MC), hemostasis (HS) and blood viscosity (BV) in influenza and acute respiratory viral infection (ARVI) in hypertensive patients.

MATERIAL AND METHODS

The study group consisted of 67 hypertensive patients with influenza or ARVI. 45 influenza and ARVI normotensive subjects served control. HS and BV tests were made, conjunctival biomicroscopy was performed.

RESULTS

Patients with influenza and ARVI in the acute period had distinct perivascular and vascular abnormalities, sludge phenomenon in the majority of postcapillary venules and capillaries. In convalescence microcirculation improved. HS in the acute stage of infections was characterized by fast coagulation, depression of fibrinolysis; in convalescence, a significantly enhanced platelet aggregation was seen. The highest BV occurred at low shift speeds. Hypertensive patients had higher vascular permeability and more severe intravascular changes which presented with disseminated intravascular red cell aggregation, slowing down of blood flow, its partial block. In hypertension there was also significantly higher platelet aggregation, lower disaggregation, higher BV increase in convalescence.

CONCLUSION

Hypertensive patients with influenza or ARVI had serious disorders of microcirculation, HS and BV threatening cardiovascular complications in such patients.

Respiratory infections with Pseudomonas aeruginosa in children with cystic fibrosis: early detection by serology and assessment of risk factors

CONTEXT

Patients with cystic fibrosis (CF) are susceptible to lower respiratory tract infections with Pseudomonas aeruginosa and typically acquire this organism in early childhood. Once P aeruginosa infection is established, eradication may be impossible, and progressive lung disease often aggravates morbidity and mortality risks. The ability to diagnose CF by genetic testing at birth makes it possible to determine the temporal sequence of events that result in P aeruginosa-associated pulmonary infections.

OBJECTIVE

To evaluate the longitudinal relationship between the production of an antibody response against P aeruginosa and clinical factors associated with P aeruginosa pulmonary infections in patients with CF diagnosed in early life.

DESIGN, SETTING, AND PATIENTS

Serum samples and oropharyngeal cultures (protocol cultures) were obtained at 6-month intervals from April 15, 1985, to April 15, 2000 (or for up to 180 months depending on their enrollment date) from 68 patients at 2 centers in Madison and Milwaukee, Wis, diagnosed through the Wisconsin CF Neonatal Screening Project, a longitudinal cohort study. Additional cultures were obtained at examining physicians' discretion (all cultures).

MAIN OUTCOME MEASURES

Time to serum IgG, IgA, and IgM antibody titer of at least 1:256 against P aeruginosa, assessed by enzyme-linked immunosorbent assay using cell lysate, exotoxin A, and elastase as antigens; time to organism isolation from respiratory samples; time to Wisconsin Cystic Fibrosis Radiograph (WCXR) score of 5 or more.

RESULTS

The median time to an antibody titer of at least 1:256 was 17.8, 24.2, and 70.9 months for cell lysate, exotoxin A, and elastase, respectively. The rise of anti-cell lysate and anti-exotoxin A titers to 1:256 or more occurred a mean of 11.9 (P<.001) and 5.6 (P =.04) months, respectively, before the isolation of P aeruginosa for all cultures and 18.2 (P<.001) and 11.9 (P =.006) months, respectively, before protocol cultures. There was no significant difference between the rise of anti-cell lysate and anti-exotoxin A titer and a WCXR score of 5 or more (P =.24 and.32, respectively). Treatment with long-term, non-Pseudomonas oral antibiotics and integration of CF infants with older, chronically infected patients were associated with a significantly increased risk of P aeruginosa pulmonary infection.

CONCLUSIONS

In CF patients diagnosed through neonatal screening, P aeruginosa pulmonary infections occurred 6 to 12 months before the organism was isolated from respiratory secretions. The longitudinal monitoring of P aeruginosa antibody titers, in concert with WCXR score, should facilitate diagnosis and treatment of P aeruginosa pulmonary infections in young children with CF.

Vancomycin-induced neutropenia in a patient positive for an antineutrophil antibody

A 48-year-old man, hospitalized after experiencing subarachnoid hemorrhage secondary to a basilar aneurysm, received vancomycin for methicillin-resistant Staphylococcus aureus sepsis. He developed neutropenia 16 days after the start of vancomycin therapy, and his white blood cell count decreased to a nadir of 1200 cells/mm3. Vancomycin was discontinued, and granulocyte-colony stimulating factor (G-CSF) therapy was begun. The patient was rechallenged with a single dose of vancomycin 1 g in preparation for intraarterial aneurysm coiling. His white blood cell count dropped to 600 cells/mm3 but returned to normal with continued G-CSF therapy. A diagnosis of vancomycin-induced neutropenia was considered. Subsequent testing by granulocyte agglutination and granulocyte immunofluorescence assays revealed that his serum was positive for an antigranulocyte antibody. A test for HLA antibody reactivity was negative. Monoclonal antibody immobilization of granulocyte antigens assay failed to determine the antigen specificity of his granulocyte antibody.

[Evaluation of amixine reactivity and efficacy for prophylaxis of acute respiratory tract infections]

Amixine reactivity and tolerability were evaluated in controlled trial at the risk group of medical personal at the period of flu and respiratory viral infection season. Drugs safety was estimated according to anamnesis, direct observation and hemogram. High efficacy of the drug for the infections prophylaxis and treatment was demonstrated. The drug was well tolerated and had no side effects. Amixine unreactivity was proved.

Rapid diagnostic evaluation of bronchial washings in patients with suspected coccidioidomycosis

Coccidioidomycosis is a regionally common fungal infection, primarily affecting the lung. While in the majority of cases the tempo of the disease allows for a more leisurely diagnostic plan, including multiple serologic tests and culture of respiratory secretions, occasionally, patients will present with rapidly progressive, life-threatening pulmonary illness, in whom there is an urgent need for rapid diagnosis. Evaluation of respiratory secretions including expectorated sputum as well as bronchial washings are frequently available or obtained for diagnosing pulmonary infiltrates. We compared the sensitivity of the Papanicolaou stain with 10% potassium hydroxide digestion (10% KOH) and with calcofluor white (cw). The Papanicolaou test performed the best and should be used in the evaluation of suspected patients with coccidioidomycosis.

Streptococcus pneumoniae causes experimental meningitis following intranasal and otitis media infections via a nonhematogenous route

Using two different animal models of Streptococcus pneumoniae infection, we have demonstrated that this organism is able to spread to the central nervous system and cause meningitis by bypassing the bloodstream. Following respiratory tract infection induced via intranasal inoculation, bacteria were rapidly found in the bloodstream and brains in the majority of infected mice. A similar pattern of dissemination occurred following otitis media infection via transbullar injection of gerbils. However, a small percentage of animals infected by either route showed no bacteria in the blood and yet did have significant numbers of bacteria in brain tissue. Subsequent experiments using a galU mutant of S. pneumoniae, which is impaired in its ability to disseminate to the bloodstream following infection, showed that this organism is able to spread to the brain and cerebrospinal fluid. These results demonstrate that, unlike many bacterial pathogens that cause meningitis, S. pneumoniae is able to do so independent of bloodstream involvement upon different routes of infection. This may address the difficulty in treating human infections caused by this organism.

Predicting antibacterial response from pharmacodynamic and pharmacokinetic profiles

The aim of antibacterial chemotherapy is to achieve sufficient drug concentrations at the site of infection for an adequate length of time to ensure bacterial eradication and optimize clinical success. Whether the desired outcome is achieved or not depends on a number of pathogen-, drug- and patient-related factors. Neither microbiologic activity nor antibacterial pharmacokinetic data alone can adequately describe the complex interaction between pathogen, host and antibacterial during the disease process. A relatively new discipline - pharmacodynamics - seeks to integrate both microbiologic and pharmacokinetic data. The particular model that best predicts clinical outcome depends on the pattern of microbial killing and the persistence of antibacterial effects after plasma concentrations have fallen below the minimum inhibitory concentration (MIC) for the target pathogen (post-antibiotic effect [PAE]). The beta-lactams, for example, exhibit time-dependent bacterial killing with minimal persistent effects. Time above MIC (T(MIC)) is therefore the parameter that best correlates with clinical efficacy for these agents and that, in turn, necessitates multiple daily dosing to optimize the duration of exposure. The macrolides erythromycinA and clarithromycin exhibit a similar pharmacokinetic/pharmacodynamic relationship to that of the beta-lactams, although for clarithromycin the area under the concentration-time curve (AUC) also correlates with clinical outcome (reflecting the more prolonged PAE of this agent). Azithromycin, ketolides, such as telithromycin (HMR 3647), streptogramins and fluoroquinolones exhibit concentration-dependent killing and have prolonged persistent effects, such that the AUC:MIC or Cmax:MIC ratio correlates most closely with clinical efficacy. For these agents the aim is to maximize drug concentrations to which the target pathogen is exposed and this may require higher doses and hence enable longer dosing intervals to be used. In summary, pharmacodynamic models provide a unique approach to determining likely in vivo activity of individual antibacterial agents and prediction of clinical outcomes.

Clinical presentation of inhalational anthrax following bioterrorism exposure: report of 2 surviving patients

The use of anthrax as a weapon of biological terrorism has moved from theory to reality in recent weeks. Following processing of a letter containing anthrax spores that had been mailed to a US senator, 5 cases of inhalational anthrax have occurred among postal workers employed at a major postal facility in Washington, DC. This report details the clinical presentation, diagnostic workup, and initial therapy of 2 of these patients. The clinical course is in some ways different from what has been described as the classic pattern for inhalational anthrax. One patient developed low-grade fever, chills, cough, and malaise 3 days prior to admission, and then progressive dyspnea and cough productive of blood-tinged sputum on the day of admission. The other patient developed progressively worsening headache of 3 days' duration, along with nausea, chills, and night sweats, but no respiratory symptoms, on the day of admission. Both patients had abnormal findings on chest radiographs. Non-contrast-enhanced computed tomography of the chest showing mediastinal adenopathy led to a presumptive diagnosis of inhalational anthrax in both cases. The diagnoses were confirmed by blood cultures and polymerase chain reaction testing. Treatment with antibiotics, including intravenous ciprofloxacin, rifampin, and clindamycin, and supportive therapy appears to have slowed the progression of inhalational anthrax and has resulted to date in survival.

Death due to bioterrorism-related inhalational anthrax: report of 2 patients

On October 9, 2001, a letter containing anthrax spores was mailed from New Jersey to Washington, DC. The letter was processed at a major postal facility in Washington, DC, and opened in the Senate's Hart Office Building on October 15. Between October 19 and October 26, there were 5 cases of inhalational anthrax among postal workers who were employed at that major facility or who handled bulk mail originating from that facility. The cases of 2 postal workers who died of inhalational anthrax are reported here. Both patients had nonspecific prodromal illnesses. One patient developed predominantly gastrointestinal symptoms, including nausea, vomiting, and abdominal pain. The other patient had a "flulike" illness associated with myalgias and malaise. Both patients ultimately developed dyspnea, retrosternal chest pressure, and respiratory failure requiring mechanical ventilation. Leukocytosis and hemoconcentration were noted in both cases prior to death. Both patients had evidence of mediastinitis and extensive pulmonary infiltrates late in their course of illness. The durations of illness were 7 days and 5 days from onset of symptoms to death; both patients died within 24 hours of hospitalization. Without a clinician's high index of suspicion, the diagnosis of inhalational anthrax is difficult during nonspecific prodromal illness. Clinicians have an urgent need for prompt communication of vital epidemiologic information that could focus their diagnostic evaluation. Rapid diagnostic assays to distinguish more common infectious processes from agents of bioterrorism also could improve management strategies.

Mutational analysis of early region 4 of bovine adenovirus type 3

The primary objective of characterizing bovine adenovirus type 3 (BAV3) in greater detail is to develop it as a vector for gene therapy and vaccination of humans and animals. A series of BAV3 early region 4 (E4) deletion-mutant viruses, containing deletions in individual E4 open reading frames (Orf) or combinations of Orfs, were generated by transfecting primary fetal bovine retinal cells with E4-modified genomic DNA. Each of these mutants was further analyzed for growth kinetics, viral DNA accumulation, and early-late protein synthesis. Mutant viruses carrying deletions in Orf1, Orf2, Orf3, or Orf4 showed growth characteristics similar to those of the E3-deleted BAV3 (BAV302). DNA accumulation and early/late protein synthesis were also indistinguishable from those of BAV302. However, mutant viruses carrying a deletion in Orf5, Orfs 1-3 (BAV429), or Orfs 3-5 (BAV430) were modestly compromised in their ability to grow in bovine cells and express early/late proteins. E4 mutants containing larger deletions, Orfs 1-3 (BAV429) and Orfs 3-5 (BAV430), were further tested in a cotton rat model. Both mutants replicated as efficiently as BAV3 or BAV302 in the lungs of cotton rats. BAV3-specific IgA and IgG responses were detected in serum and at the mucosal surfaces in cotton rats inoculated with mutant viruses. In vitro and in vivo characterization of these E4 mutants suggests that none of the individual E4 Orfs are essential for viral replication. Moreover, successful deletion of a 1.5-kb fragment in the BAV3 E4 region increased the available insertion capacity of replication-competent BAV3 vector (E3-E4 deleted) to approximately 4.5 kb and that of replication-defective BAV3 vector (E1a-E3-E4 deleted) to approximately 5.0 kb. This is extremely useful for the construction of BAV3 vectors that express multiple genes and/or regulatory elements for gene therapy and vaccination.

Administration of aerosolized antibiotics in cystic fibrosis patients

High rates of colonization and the challenge of managing Pseudomonas aeruginosa infections in patients with cystic fibrosis (CF) have necessitated a search for safe and effective antibiotics. Currently, therapy with an aminoglycoside in combination with a beta-lactam or a quinolone antibiotic is the standard. Unfortunately, it is difficult to deliver high doses of these antibiotics via the IV route without significant systemic adverse events (AEs) (eg, ototoxicity and nephrotoxicity). Recently, a reformulation of the aminoglycoside antibiotic tobramycin has become available in a preservative-free, pH-adjusted solution for inhalation by jet nebulizer. A 96-week series of clinical studies including 520 patients, aged > or = 6 years, with moderate-to-severe CF has evaluated the long-term safety and effectiveness of this formulation. Patients received tobramycin solution for inhalation (TSI) or placebo, which was administered in alternating cycles of 28-days-on and 28-days-off therapy, plus their usual CF care for 6 months with open-label follow-up extended to 2 years. Most AEs declined in frequency with increasing TSI exposure. Patients receiving TSI spent 25 to 33% fewer days in the hospital. Following the initiation of TSI treatment, patients experienced significant increases in FEV(1). FEV(1) values were maintained above baseline for the duration of the study series. Antibiotic susceptibility of the bacterial isolates did not predict clinical response. TSI was safe, well-tolerated, and effective for long-term treatment (96 weeks) of P aeruginosa colonization and infection in CF patients.