Neutropenia induced in outbred mice by a simplified low-dose cyclophosphamide regimen: characterization and applicability to diverse experimental models of infectious diseases

BACKGROUND: For its low cost and ease of handling, the mouse remains the preferred experimental animal for preclinical tests. To avoid the interaction of the animal immune system, in vivo antibiotic pharmacodynamic studies often employ cyclophosphamide (CPM) to induce neutropenia. Although high doses (350–450 mg/kg) are still used and their effects on mouse leukocytes have been described, a lower dose (250 mg/kg) is widely preferred today, but the characteristics and applicability of this approach in outbred mice have not been determined. METHODS: Fifteen female ICR mice were injected intraperitoneally with 150 and 100 mg/kg of CPM on days 1 and 4, respectively. Blood samples (~160 μL) were drawn from the retro-orbital sinus of each mouse on days 1, 4, 5, 6, 7 and 11. Leukocytes were counted manually and the number of granulocytes was based on microscopic examination of Wright-stained smears. The impact of neutropenia induced by this method was then determined with a variety of pathogens in three different murine models of human infections: pneumonia (Klebsiella pneumoniae, Streptococcus pneumoniae, Staphylococcus aureus), meningoencephalitis (S. pneumoniae), and the thigh model (S. aureus, Escherichia coli, Bacteroides fragilis). RESULTS: The basal count of leukocytes was within the normal range for outbred mice. On day 4, there was an 84% reduction in total white blood cells, and by day 5 the leukopenia reached its nadir (370 ± 84 cells/mm(3)). Profound neutropenia (≤10 neutrophils/mm(3)) was demonstrated at day 4 and persisted through days 5 and 6. Lymphocytes and monocytes had a 92% and 96% decline between days 1 and 5, respectively. Leukocytes recovered completely by day 11. Mice immunosupressed under this protocol displayed clinical and microbiological patterns of progressive and lethal infectious diseases after inoculation in different organs with diverse human pathogens. CONCLUSION: A CPM total dose of 250 mg/kg is sufficient to induce profound and sustained neutropenia (<10 neutrophils/mm(3)) at least during 3 days in outbred mice, is simpler than previously described methods, and allows successful induction of infection in a variety of experimental models

Management and outcome of bloodstream infections: a prospective survey in 121 French hospitals (SPA-BACT survey)

Oliver Robineau,1 J&eacute;rome Robert,2 Christian Rabaud,3 Jean-Pierre Bedos,4 Emmanuelle Varon,5 Yves P&eacute;an,6 R&eacute;my Gauzit,7 Serge Alfandari8 On behalf of the Soci&eacute;t&eacute; de Pathologie Infectieuse de Langue Fran&ccedil;aise (SPILF), the Observatoire National de l&rsquo;&Eacute;pid&eacute;miologie de la R&eacute;sistance Bact&eacute;rienne aux Antibiotiques (ONERBA), and the Surveillance de la Prescription des Antibiotiques (SPA) Group 1Infectious Disease Department, Dron Hospital, Univ Lille, Tourcoing, 2Sorbonne University, UPMC Univ Paris 06, CR7, CIMI, Team E13 (Bacteriology), Paris, 3Infectious Disease Department, Nancy University Hospital, Nancy, 4Intensive Care Unit, Henri Mignot Hospital, Le Chesnay, 5Bacteriology Laboratory, HEGP, 6Observatoire National de L&rsquo;epid&eacute;miologie de la R&eacute;sistance Bact&eacute;rienne aux Antibiotiques (OneRBa), 7Intensive Care Unit, Cochin Hospital, APHP, Paris, 8Intensive Care Unit, Dron Hospital, Tourcoing, France Background: Bloodstream infections (BSIs) are severe infections that can be community or hospital acquired. Effects of time to appropriate treatment and impact of antimicrobial management team are discussed in terms of outcome of BSI. We sought to evaluate the impact of initial BSI management on short-term mortality. Patients and methods: A prospective, multicenter survey was conducted in 121 French hospitals. Participants declaring BSI during a 1-month period were included consecutively. Data on patient comorbidities, illness severity, BSI management, and resistance profile of bacterial strains were collected. Predictors of 10-day mortality were identified by multivariate regression for overall BSI, health care-related and hospital-acquired BSI. Results: We included 1,952 BSIs. More than a third of them were hospital acquired (39%). Multidrug resistance was identified in 10% of cases, mainly in health care-related BSI. Empirical therapy and targeted therapy were appropriate for 61% and 94% of cases, respectively. Increased 10-day mortality was associated with severe sepsis, septic shock, increasing age, and any focus other than the urinary tract. Decreased mortality was associated with receiving at least one active antibiotic within the first 48 hours. Intervention of antimicrobial management team during the acute phase of BSI was associated with a decreased mortality at day 10 in the overall population and in health care-related BSI. Conclusion: Optimizing BSI management by increasing rapidity of appropriate treatment initiation may decrease short-term mortality, even in countries with low rate of multidrug-resistant organisms. Early intervention of antimicrobial management team is crucial in terms of mortality. Keywords: mortality, bloodstream infections, antimicrobial management team, community-acquired infection, health care-related infectio

Antibiotics against Pseudomonas aeruginosa for COPD exacerbation in ICU: a 10-year retrospective study

Benjamin Planquette,1&ndash;4 Julien P&eacute;ron,2 Etienne Dubuisson,1 Ariane Roujansky,1 Virginie Laurent,1 Alban Le Monnier,3 Stephane Legriel,1 Alexis Ferre,4 Fabrice Bruneel,1 Peter G Chiles,5 Jean P Bedos1 1R&eacute;animation Polyvalente, Centre Hospitalier de Versailles, Le Chesnay, France; 2Unit&eacute; de Biostatistique M&eacute;dicale, H&ocirc;pital Lyon Sud, Lyon, France; 3Service de Microbiologie, Centre Hospitalier de Versailles, Le Chesnay, France; 4Service de Pneumologie et de Soins Intensifs, H&ocirc;pital Europ&eacute;en Georges Pompidou, Universit&eacute; Paris Ren&eacute; Descartes, Paris, France; 5Division of Pulmonary and Critical Care Medicine, University of California, San Diego, La Jolla, CA,&nbsp;USA Summary: Chronic obstructive pulmonary disease (COPD) is a frequent source of hospitalization. Antibiotics are largely prescribed during COPD exacerbation. Our hypothesis is that large broad-spectrum antibiotics are more and more frequently prescribed. Our results confirm this trend and highlight that the increase in large broad-spectrum use in COPD exacerbation is largely unexplained. Background: Acute COPD exacerbation (AECOPD) is frequently due to respiratory tract infection, and the benefit of antipseudomonal antibiotics (APA) is still debated. Health care&ndash;associated pneumonia (HCAP) was defined in 2005 and requires broad-spectrum antibiotherapy. The main objectives are to describe the antibiotic use for AECOPD in intensive care unit and to identify factors associated with APA use and AECOPD prognosis. Methods: We conducted a monocentric, retrospective study on all AECOPDs in the intensive care unit treated by antibiotics for respiratory tract infection. Treatment failure (TF) was defined by death, secondary need for mechanical ventilation, or secondary systemic steroid treatment. A multivariate analysis was used to assess factors associated with APA prescription and TF. Results: From January 2000 to December 2011, 111 patients were included. Mean age was 69&nbsp;years (&plusmn;12), mean forced expiratory volume 38% of theoretic value (&plusmn;13). Thirty-five (31%) patients were intubated, and 52 (47%) were treated with noninvasive ventilation. From 107&nbsp;patients, 8 (7%) cases of Pseudomonas aeruginosa were documented. APAs were prescribed in 21% of patients before 2006 versus 57% after (P=0.001). TF prevalence was 31%. Risk factors for P. aeruginosa in COPD and HCAP diagnosis did not influence APA, whereas the post-2006 period was independently associated with APA prescription (odds ratio 6.2; 95% confidence interval 1.9&ndash;20.3; P=0.0013). APA did not improve TF (odds ratio 1.09; 95% confidence interval 0.37&ndash;3.2). Conclusion: HCAP guidelines were followed by an increase in APA use in AECOPD, without an improvement in prognosis. HCAP prevalence cannot account for the increasing APA trend. Time effect reveals a drift in practices. The microbiological effect of such a drift must be evaluated. Keywords: COPD, exacerbation, Pseudomonas aeurginosa, antibiotics, IC

Factors associated with penicillin-nonsusceptible pneumococcal infections in Brazil

Resistance of Streptococcus pneumoniae is a worldwide, growing problem. Studies of factors associated with resistance to penicillin have not been conducted in Brazil. The objective of the present study was to evaluate factors associated with infection by S. pneumoniae not susceptible to penicillin. A prevalence study was conducted including all patients with a positive culture for S. pneumoniae in a hospital from July 1991 to December 1992 and the year 1994. Of 165 patients identified, 139 were considered to have clinically relevant infections and 88% of them had invasive infections. All infections were community acquired and consisted of pneumonia (44%) and of central nervous system (19%), pelvic or abdominal (12%), upper airway or ocular (12%), primary bloodstream (9%) and skin and soft tissue (5%) infections. Mortality was 25%. Susceptibility to penicillin was present in 77.6% of the isolates; 21.8% were relatively resistant, and one isolate was resistant (minimal inhibitory concentration = 4 µg/ml). Multivariate analysis showed that age below 4 years (odds ratio (OR): 3.53, 95% confidence interval (95%CI): 1.39-8.96) and renal failure (OR: 5.50, 95%CI: 1.07-28.36) were associated with lack of susceptibility to penicillin. Bacteremia occurred significantly less frequently in penicillin-nonsusceptible infections (OR: 0.34, 95%CI: 0.14-0.84), possibly suggesting that lack of penicillin susceptibility is associated with lower virulence in S. pneumoniae