Isolated Medial Maxillary Buttress Displacement in Naso-Orbito-Ethmoid Fractures: A Surgical Indication to Resolve Nasal Airway Obstruction.

PURPOSE: The aim of this study was to present a case series emphasizing low medial maxillary (pyriform) buttress displacement in naso-orbito-ethmoid (NOE) fractures as an operative indication, in the absence of the typical NOE surgical indications (medial canthus displacement, midface bony comminution, nasal bone collapse, and orbital indications), to prevent nasal airway obstruction. METHODS: Five cases of minor NOE fractures are reviewed, where only the low medial maxillary buttress was displaced. The typical surgical indications for NOE repair were absent. RESULTS: In each case, the pyriform buttress was medially and posteriorly displaced, creating nasal airway obstruction in each patient. The medial canthal tendons were all nondisplaced, there was no diplopia, and the other 2 cardinal buttresses (infraorbital rim and nasofrontal junction) were minimally displaced or greensticked. In the acute setting, patients were treated with open reduction and internal fixation. With delayed presentation, septorhinoplasty or osteotomy and fixation were used. Among the patients who had adequate follow-up, nasal airway obstruction was resolved. CONCLUSIONS: This series suggests that, in NOE fractures with isolated displacement at the medial maxillary buttress, nasal airway obstruction should be considered an operative indication (independent of the classical indications) in order to prevent or resolve nasal airway obstruction.

Neutralizing and Neuraminidase Antibodies Correlate With Protection Against Influenza During a Late Season A/H3N2 Outbreak Among Unvaccinated Military Recruits.

BACKGROUND: Antibodies that inhibit hemagglutination have long been considered a correlate of protection against influenza, but these antibodies are only a subset of potentially protective antibodies. Neutralizing and neuraminidase antibodies may also contribute to protection, but data on their associations with protection are limited. METHODS: We measured preoutbreak hemagglutinin pseudovirus neutralization (PVN) and neuraminidase inhibition (NAI) antibody titers in unvaccinated military recruits who experienced an H3N2 influenza outbreak during training. We conducted a case-control study to investigate the association between titers and protection against influenza illness or H3N2-associated pneumonia using logistic regression. RESULTS: With every 2-fold increase in PVN titer, the odds of medically attended polymerase chain reaction-confirmed H3N2 infection (H3N2+) decreased by 41% (odds ratio [OR], 0.59; 95% confidence interval [CI], .45 to .77; P < .001). Among those who were H3N2+, the odds for pneumonia decreased by 52% (OR, 0.48; CI, .25 to .91; P = .0249). With every 2-fold increase in NAI titer, the odds of medically attended H3N2 infection decreased by 32% (OR, 0.68; 95% CI, .53 to .87; P = .0028), but there was no association between NAI titers and H3N2-associated pneumonia. There was also no synergistic effect of PVN and NAI antibodies. CONCLUSIONS: PVN and NAI titers were independently associated with reduced risk of influenza illness. NAI titers associated with protection had greater breadth of reactivity to drifted strains than PVN titers. These findings show that PVN and NAI titers are valuable biomarkers for assessing the odds of influenza infection.

Respiratory Infections in the U.S. Military: Recent Experience and Control.

This comprehensive review outlines the impact of military-relevant respiratory infections, with special attention to recruit training environments, influenza pandemics in 1918 to 1919 and 2009 to 2010, and peacetime operations and conflicts in the past 25 years. Outbreaks and epidemiologic investigations of viral and bacterial infections among high-risk groups are presented, including (i) experience by recruits at training centers, (ii) impact on advanced trainees in special settings, (iii) morbidity sustained by shipboard personnel at sea, and (iv) experience of deployed personnel. Utilizing a pathogen-by-pathogen approach, we examine (i) epidemiology, (ii) impact in terms of morbidity and operational readiness, (iii) clinical presentation and outbreak potential, (iv) diagnostic modalities, (v) treatment approaches, and (vi) vaccine and other control measures. We also outline military-specific initiatives in (i) surveillance, (ii) vaccine development and policy, (iii) novel influenza and coronavirus diagnostic test development and surveillance methods, (iv) influenza virus transmission and severity prediction modeling efforts, and (v) evaluation and implementation of nonvaccine, nonpharmacologic interventions.

Management of deeply infiltrating endometriosis involving the rectum.

BACKGROUND: Rectal endometriosis can cause debilitating symptoms. Rectal resection in this setting has been shown to improve symptoms; however, there remain some reservations about this intervention because of the risk of complications such as anastomotic leak and rectovaginal fistula. OBJECTIVE: The aim of this study is to review our experience with rectal resection in patients with rectal endometriosis. DATA SOURCES: Hospital records and prospectively maintained electronic databases of an endogynecologist and colorectal surgeon were reviewed. STUDY SELECTION: This is a retrospective study of consecutive patients who underwent rectal resection for endometriosis from 2001 to 2010. INTERVENTIONS: All patients underwent either disc or segmental resection of the rectum. MAIN OUTCOME MEASURES: Outcomes of interest were operative complications and recurrence requiring surgical reintervention. RESULTS: Ninety-one patients underwent 92 resections for endometriosis. Sixty-five (71%) were disc resections, 25 (27%) were segmental resections, and 1 patient underwent both disc and segmental resections. Eighty-one (88%) procedures were completed laparoscopically. Patients requiring segmental resection had more extensive disease, and this was associated with open conversion (p ≤ 0.0001). Average duration of procedure was 209 minutes. Three patients (3%) required defunctioning ileostomies. Intramural endometriosis was confirmed in 96.7% of specimens. Complications occurred in 13 patients (15%); 4 were minor. Three patients had small pelvic collections treated with antibiotics, 5 patients required transfusion for bleeding (3 intraoperative, 2 anastomotic bleeds that settled conservatively), and 1 patient sustained ureteric injury that was reimplanted with no sequelae. None had anastomotic leak or rectovaginal fistula. Ten patients (11%) required reintervention for recurrent symptoms. Of these, 8 (8.8%) patients were found to have recurrent endometriosis. No correlation could be found between involved margins on pathology and need for redo surgery. LIMITATIONS: : This study is limited by its retrospective nature. CONCLUSIONS: Laparoscopic rectal resection for deeply infiltrative endometriosis is feasible and safe, and it provides durable symptom control with acceptable recurrence rates.

Multidisciplinary response to the Escherichia coli 0104 outbreak in Europe.

The 2011 outbreak of Escherichia coli (E. coli) O104 in northern Germany resulted in over 4,100 illnesses, 900 cases of hemolytic uremic syndrome, and 50 deaths. The U.S. Army's Public Health Command Region-Europe established a multidisciplinary advisory team to prevent E. coli O104 exposure in the Department of Defense (DoD) population. This decentralized, interagency team engaged European public health authorities and coordinated control measures including risk communication. Following German public health investigations, the DoD advisory team compiled information from available official reports, assessed risk, and published guidance to halt the local procurement and supply of suspect foods for all DoD installations in Europe. Advisory team members processed outbreak information, adjusted advisories, and coordinated response efforts. The advisory team quickly identified authoritative information sources, coordinated case definitions, and streamlined potential case reporting. Timely and accurate risk assessment, management, and communication were vital in protecting the DoD population during this outbreak. There were no cases in DoD-related personnel.

A growing global network's role in outbreak response: AFHSC-GEIS 2008-2009.

A cornerstone of effective disease surveillance programs comprises the early identification of infectious threats and the subsequent rapid response to prevent further spread. Effectively identifying, tracking and responding to these threats is often difficult and requires international cooperation due to the rapidity with which diseases cross national borders and spread throughout the global community as a result of travel and migration by humans and animals. From Oct.1, 2008 to Sept. 30, 2009, the United States Department of Defense's (DoD) Armed Forces Health Surveillance Center Global Emerging Infections Surveillance and Response System (AFHSC-GEIS) identified 76 outbreaks in 53 countries. Emerging infectious disease outbreaks were identified by the global network and included a wide spectrum of support activities in collaboration with host country partners, several of which were in direct support of the World Health Organization's (WHO) International Health Regulations (IHR) (2005). The network also supported military forces around the world affected by the novel influenza A/H1N1 pandemic of 2009. With IHR (2005) as the guiding framework for action, the AFHSC-GEIS network of international partners and overseas research laboratories continues to develop into a far-reaching system for identifying, analyzing and responding to emerging disease threats.

Department of Defense influenza and other respiratory disease surveillance during the 2009 pandemic.

The Armed Forces Health Surveillance Center's Division of Global Emerging Infections Surveillance and Response System (AFHSC-GEIS) supports and oversees surveillance for emerging infectious diseases, including respiratory diseases, of importance to the U.S. Department of Defense (DoD). AFHSC-GEIS accomplishes this mission by providing funding and oversight to a global network of partners for respiratory disease surveillance. This report details the system's surveillance activities during 2009, with a focus on efforts in responding to the novel H1N1 Influenza A (A/H1N1) pandemic and contributions to global public health. Active surveillance networks established by AFHSC-GEIS partners resulted in the initial detection of novel A/H1N1 influenza in the U.S. and several other countries, and viruses isolated from these activities were used as seed strains for the 2009 pandemic influenza vaccine. Partners also provided diagnostic laboratory training and capacity building to host nations to assist with the novel A/H1N1 pandemic global response, adapted a Food and Drug Administration-approved assay for use on a ruggedized polymerase chain reaction platform for diagnosing novel A/H1N1 in remote settings, and provided estimates of seasonal vaccine effectiveness against novel A/H1N1 illness. Regular reporting of the system's worldwide surveillance findings to the global public health community enabled leaders to make informed decisions on disease mitigation measures and controls for the 2009 A/H1N1 influenza pandemic. AFHSC-GEIS's support of a global network contributes to DoD's force health protection, while supporting global public health.

Relevance of gastrointestinal symptoms in endometriosis.

BACKGROUND: Endometriosis commonly presents with a range of symptoms none of which are particularly specific for the condition, often resulting in misdiagnosis or delay in diagnosis. AIM: To investigate gastrointestinal symptoms in women with endometriosis and compare their frequency with that of the classical gynaecological symptoms. METHODS: Systematic exploration of symptoms in a consecutive series of 355 women undergoing operative laparoscopy for suspected endometriosis. RESULTS: Endometriosis was confirmed by histology in 290 women (84.5%). Bowel lesions were present in only 7.6%. Ninety per cent of women had gastrointestinal symptoms, of which bloating was the most common (82.8%), but 71.3% also had other bowel symptoms. All gastrointestinal symptoms were similarly predictive of histologically confirmed endometriosis. Seventy-six women (21.4%) had previously been diagnosed with irritable bowel syndrome and 79% of them had endometriosis confirmed. CONCLUSION: Gastrointestinal symptoms are nearly as common as gynaecological symptoms in women with endometriosis and do not necessarily reflect bowel involvement.

Bowel resection for severe endometriosis: an Australian series of 177 cases.

BACKGROUND: Colorectal resection for severe endometriosis has been increasingly described in the literature over the last 20 years. AIMS: To describe the experiences of three gynaecological surgeons who perform radical surgery for colorectal endometriosis. METHODS: The records of three surgeons were reviewed. Relevant information was extracted and complied into a database. RESULTS: One hundred and seventy-seven women were identified as having undergone surgery between February 1997 and October 2007. The primary reason for presentation was pain in the majority of women (79%). Eighty-one segmental resections were performed, 71 disc excisions, ten appendicectomies and multiple procedures in ten women. The majority of procedures (81.4%) were performed laparoscopically. Histology confirmed the presence of disease in 98.3% of cases. A further 124 procedures to remove other sites of endometriosis were conducted, along with an additional 44 procedures not primarily for endometriosis. A total of 16 unintended events occurred. CONCLUSIONS: Our study adds to the growing body of literature describing colorectal resection for severe endometriosis. Overall, the surgery appeared to be well tolerated, demonstrating the role for this surgery.

Fertility and pain outcomes following laparoscopic segmental bowel resection for colorectal endometriosis: a review.

Intestinal involvement in endometriosis is thought to occur in up to 12% of all endometriosis cases. While colorectal resection is being increasingly advocated as a feasible management option in patients with severe disease, there still remains significant resistance towards this surgery. This article aims to review the current literature to determine the pain and fertility outcomes following segmental bowel resection for colorectal endometriosis.

The Effects of Birth Year, Age and Sex on Hemagglutination Inhibition Antibody Responses to Influenza Vaccination.

The first exposure to influenza is thought to impact subsequent immune responses later in life. The consequences of this can be seen during influenza epidemics and pandemics with differences in morbidity and mortality for different birth cohorts. There is a need for better understanding of how vaccine responses are affected by early exposures to influenza viruses. In this analysis of hemagglutination inhibition (HI) antibody responses in two cohorts of military personnel we noticed differences related to age, sex, prior vaccination, deployment and birth year. These data suggest that HI antibody production, in response to influenza vaccination, is affected by these factors. The magnitude of this antibody response is associated with, among other factors, the influenza strain that circulated following birth.

Treatment Delay Impact on Open Reduction Internal Fixation of Mandibular Fractures: A Systematic Review.

BACKGROUND: The impact of mandible fracture treatment delay has been contested in the literature for decades, with conventional wisdom favoring earlier surgical treatment to prevent postoperative complications, primarily infection. Through a systematic review of all available evidence, this study aims to determine whether delay to open reduction and internal fixation of traumatic mandibular fractures influences outcomes. METHODS: MEDLINE, EMBASE, CINAHL, and Web of Science were systematically searched for English language literature pertaining to the above research question and screened in duplicate. Methodological quality scoring was performed using MINORS criteria. Qualitative and quantitative findings from relevant studies are presented. RESULTS: Twenty eligible studies including 2,671 patients had open reduction internal fixation, with or without adjunct mandibulomaxillary fixation. All studies were observational cohort or case-control studies of low methodological quality with a mean MINORS score of 6.5 of 16 (40.6%) for noncomparative studies and 11.2 of 24 (46.7%) for comparative studies. Only 5 of 20 (25%) studies recommended earlier treatment. Due to insufficient reporting of data and study heterogeneity, the impact of treatment delay on complications could not be quantitatively analyzed. CONCLUSIONS: There is substantial heterogeneity and no consensus on the definition of "early" versus "delayed" surgical treatment for patients with traumatic mandibular fractures. The majority of included studies do not make a recommendation for earlier treatment. Future, well-designed prospective studies are essential to determine if there is an optimal surgical treatment delay of mandibular fractures that mitigates the risk of infectious and noninfectious complications.

Outbreak of influenza and rhinovirus co-circulation among unvaccinated recruits, U.S. Coast Guard Training Center Cape May, NJ, 24 July-21 August 2016.

Military and Coast Guard recruits are particularly susceptible to respiratory infections. Although seasonal influenza vaccinations are mandatory for recruits, the vaccine expires annually in June. On 29 July 2016, the U.S. Coast Guard Training Center Cape May, NJ, identified an increase in febrile respiratory illness (FRI) among recruits. During 24 July-21 August, a total of 115 recruits reported symptoms. A total of 74 recruits tested positive for respiratory infections: influenza A (H3) (n=34), rhinovirus (n=28), influenza/rhinovirus co-infection (n=11), and adenovirus/rhinovirus co-infection (n=1), while 41 recruits had no laboratory-confirmed specimen but were considered suspected cases. Only one recruit reported receiving the seasonal influenza vaccine within the previous 12 months. Influenza predominated during 24 July-6 August, whereas rhinovirus predominated during 7 August-20 August. Most (92.2%) cases were identified in four of 10 recruit companies; incidence rates were highest among recruits in weeks 2-4 of an 8-week training cycle. Key factors for outbreak control included rapid detection through routine FRI surveillance, quick decision-making and streamlined response by using a single chain of command, and employing both nonpharmaceutical and pharmaceutical interventions.

Different Repeat Annual Influenza Vaccinations Improve the Antibody Response to Drifted Influenza Strains.

Seasonal influenza vaccine formulas change almost every year yet information about how this affects the antibody repertoire of vaccine recipients is inadequate. New vaccine virus strains are selected, replacing older strains to better match the currently circulating strains. But even while the vaccine is being manufactured the circulating strains can evolve. The ideal response to a seasonal vaccine would maintain antibodies toward existing strains that might continue to circulate, and to generate cross-reactive antibodies, particularly towards conserved influenza epitopes, potentially limiting infections caused by newly evolving strains. Here we use the hemagglutination inhibition assay to analyze the antibody repertoire in subjects vaccinated two years in a row with either identical vaccine virus strains or with differing vaccine virus strains. The data indicates that changing the vaccine formulation results in an antibody repertoire that is better able to react with strains emerging after the vaccine virus strains are selected. The effect is observed for both influenza A and B strains in groups of subjects vaccinated in three different seasons. Analyses include stratification by age and sex.

A prospective multi-centre study of major complications experienced during excisional laparoscopic surgery for endometriosis.

OBJECTIVE: To clarify the rate of major intra-operative and post-operative complications experienced during excisional surgery for endometriosis. DESIGN: Prospective multi-centre observational study set in two University teaching hospitals and three private hospitals in Sydney, Australia. All consecutive subjects undergoing laparoscopic excisional surgery for minimal to severe endometriosis were recruited (790 subjects). Complications were recorded intra-operatively or post-operatively on a secure computerised patient database. Major intra- and post-operative complications i.e. inadvertent visceral or vascular injury or other complications directly related to surgery that either significantly prolonged the operating time, delayed discharge or necessitated re-admission. RESULTS: Seven hundred and ninety subjects were recruited over a 3-year period. Seven major complications were experienced (8.8/1000); four bowel injuries, one cystotomy, one ureteric transection, and one major vascular injury. All visceral or vascular injuries were diagnosed prior to completion of the surgery. No significant longterm sequelae were experienced. CONCLUSION: The incidence of major complications in this study of 8.8/1000 compares favourably with other similar reports. In view of the potential symptom relief obtained, the authors continue to believe the benefits of such surgery significantly outweigh the risks of subsequent operative-related morbidity.

Risk factors for severe outcomes among members of the United States military hospitalized with pneumonia and influenza, 2000-2012.

BACKGROUND: The progression from hospitalization for a respiratory infection to requiring substantial supportive therapy is a key stage of the influenza severity pyramid. Respiratory infections are responsible for 300,000-400,000 medical encounters each year among US military personnel, some of which progress to severe acute respiratory infections. METHODS: We obtained data on 11,086 hospitalizations for pneumonia and influenza (P&I) among non-recruit US military service members during the period of 1 January 2000 through 31 December 2012. From these, we identified 512 P&I hospitalizations that progressed to severe episodes using standard case definitions. We evaluated the effect of demographic and occupational characteristics, co-morbid conditions, and history of influenza vaccination on the risk of a hospitalized P&I case becoming a severe case. We also evaluated the risk of a severe outcome and the length of time since influenza vaccination (within 180, 60, and 30 days). RESULTS: The median age of subjects at the time of the P&I episode was 32 years (range, 28-40) and subjects were predominantly male (89.5%). In a univariate analysis, demographic risk factors for a severe episode included service in the US Air Force (RR=1.6 relative to US Army, 95%CI 1.3-2.1), US Coast Guard (RR=2.1, 1.2-3.7) or US Navy (RR=1.4, 1.1-1.8). Being born in the US and recent influenza vaccination (within 180 days of episode) were protective against developing severe disease. Among co-morbid conditions, univariate risk factors for severe disease included chronic renal or liver disease (RR=4.98, 95%CI 4.1-6.1), diseases of the circulatory system (RR=3.1, 95%CI 2.6-3.7), diabetes mellitus (RR=2.3, 95%CI 1.5-3.6), obesity (RR=1.6, 95%CI 1.2-2.1), cancer (RR=1.6, 95%CI 1.3-2.0), and chronic obstructive pulmonary disease (RR=1.4, 95%CI 1.1-1.7). Although many of the risk factors found to be significant in univariate analysis were no longer significant under a multivariate analysis, receipt of any influenza vaccine within 180 days of episode remained protective (RR=0.81, 95%CI 0.67-0.99), while serving in the US Coast Guard (RR=1.9, 95%CI 1.1-3.4) or US Air Force (RR=1. 5, 95%CI 1.2-2.0), presence of renal or liver disease (RR=3.6, 95%CI 2.9-4.6), and diseases of the circulatory system (RR=2.2, 95%CI 1.8-2.8), remained significantly associated with a higher risk of developing severe disease. CONCLUSIONS: In a large cohort, after adjusting for many possible risk factors, influenza vaccination was protective against severe episodes among P&I hospitalizations. The service-specific (US Coast Guard or US Air Force) increased risk may represent some differences in data (e.g., coding or reporting practices) as opposed to genuine differences in physiological outcome. Our findings suggest that renal and liver disease as well as diseases of the circulatory system may contribute to influenza severity in this population independently of age and other potential comorbidities. These findings provide additional evidence for the prioritization of specific risk groups within the US military for influenza vaccination.

Tuberculosis as a force health protection threat to the United States military.

Tuberculosis (TB) is a communicable disease that poses a threat to force health protection to the U.S. military. The rate of TB disease in the military is low; however, there are unique challenges for its control in this setting. As a low-risk population, TB testing in the U.S. military can be scaled back from the universal testing approach used previously. Reactivation of latent TB infection (LTBI) present at accession into service is the most important factor leading to TB disease; therefore, its diagnosis and treatment among recruits should be given a high priority. Deployment and overseas military service is an uncommon but important source of TB infection, and rigorous surveillance should be ensured. Case management of TB disease and LTBI can be improved by the use of cohort reviews at the service and installation levels and case finding and delays in the diagnosis of TB disease can be improved by education of providers, as well as increased use of molecular diagnostic tests. Program outcomes can be improved by making LTBI treatment compulsory, offering shorter treatment regimens, and increasing accountability through oversight and evaluation. The diagnosis of LTBI can be improved by implementing targeted testing in all settings and reducing confirmatory interferon-gamma release assay testing.

Meta-analysis of antibiotic prophylaxis in breast reduction surgery.

BACKGROUND: Breast reduction surgery is a very common procedure; however, there is still no consensus as to whether antibiotics should be used perioperatively. OBJECTIVE: To review the world literature and perform a meta-analysis of studies comparing wound infection rates with antibiotic use in breast reduction surgery. METHODS: A literature search was performed using the MEDLINE, Cochrane Database of Systematic Reviews, Cochrane Database of Clinical Trials, Embase and CINAHL databases. Subject headings and relevant subheadings for "Breast", "Breast Reduction", "Reduction Mammaplasty", "Mammaplasty" were combined with "Antibiotics" and "Antibacterial Agents". The list of titles was assessed by the study's authors and abstracts were reviewed. All relevant articles were then independently reviewed by the two primary authors, and Jadad scoring was used to assess the quality of the included articles. RESULTS: From the original search, three randomized controlled trials were included in the meta-analysis of preoperative antibiotics. The meta-analysis revealed a 75% reduction in wound infections with preoperative antibiotics (OR 0.25 [95% CI 0.09 to 0.72]). Because only one randomized controlled trial analyzed postoperative antibiotics, no meta-analysis could be performed. CONCLUSIONS: Preoperative antibiotics should routinely be used before breast reduction surgery. The use of postoperative antibiotics remains controversial. Additional randomized studies investigating postoperative antibiotics are needed.

HISTORIQUE: La chirurgie de réduction mammaire est une intervention très courante. On ne s'entend toutefois pas sur l'utilisation d'antibiotiques pendant la période périopératoire. OBJECTIF: Examiner les publications mondiales et effectuer une méta-analyse des études comparant le taux d'infection des plaies malgré l'utilisation des antibiotiques en cas de chirurgie de réduction mammaire. MÉTHODOLOGIE: Les chercheurs ont effectué une analyse bibliographique dans les bases de données de MEDLINE, de la Cochrane Database of Systematic Reviews, de la Cochrane Database of Clinical Trials, d'Embase et de CINAHL. Les rubriques et les sous-rubriques pour Breast, Breast Reduction, Reduction Mammaplasty, Mammaplasty ont été combinées à Antibiotics et Antibacterial Agents. Les auteurs de l'étude ont évalué la liste des titres et révisé les résumés. Les deux auteurs principaux ont également fait une évaluation indépendante de tous les articles pertinents, puis l'échelle de Jadad a été utilisée pour déterminer la qualité des articles inclus. RÉSULTATS: À partir de la recherche originale, trois essais aléatoires et contrôlés ont été inclus dans la méta-analyse des antibiotiques préopératoires. La méta-analyse a révélé une réduction de 75 % des infections des plaies grâce aux antibiotiques préopératoires (RC 0,25 [95 % IC 0,09 à 0,72]). Puisque seulement un essai aléatoire et contrôlé a porté sur les antibiotiques postopératoires, aucune méta-analyse n'a pu être effectuée. CONCLUSIONS: Il faudrait toujours utiliser des antibiotiques préopératoires avant une chirurgie de réduction mammaire. L'utilisation d'antibiotiques postopératoires demeure controversée. Il faudra effectuer d'autres études aléatoires sur les antibiotiques postopératoires.