Population genetics of the Asian tiger mosquito Aedes albopictus, an invasive vector of human diseases.

The Asian tiger mosquito Aedes albopictus is currently one of the most threatening invasive species in the world. Native to Southeast Asia, the species has spread throughout the world in the past 30 years and is now present in every continent but Antarctica. Because it was the main vector of recent Dengue and Chikungunya outbreaks, and because of its competency for numerous other viruses and pathogens such as the Zika virus, A. albopictus stands out as a model species for invasive diseases vector studies. A synthesis of the current knowledge about the genetic diversity of A. albopictus is needed, knowing the interplays between the vector, the pathogens, the environment and their epidemiological consequences. Such resources are also valuable for assessing the role of genetic diversity in the invasive success. We review here the large but sometimes dispersed literature about the population genetics of A. albopictus. We first debate about the experimental design of these studies and present an up-to-date assessment of the available molecular markers. We then summarize the main genetic characteristics of natural populations and synthesize the available data regarding the worldwide structuring of the vector. Finally, we pinpoint the gaps that remain to be addressed and suggest possible research directions.

Pollution gradients shape microbial communities associated with ae. albopictus larval habitats in urban community gardens.

The Asian tiger mosquito Aedes albopictus is well adapted to urban environments and takes advantage of the artificial containers that proliferate in anthropized landscapes. Little is known about the physicochemical, pollutant and microbiota compositions of Ae. albopictus-colonized aquatic habitats and whether these properties differ with noncolonized habitats. We specifically addressed this question in French community gardens by investigating whether pollution gradients (characterized either by water physicochemical properties combined with pollution variables or by the presence of organic molecules in water) influence water microbial composition and then the presence/absence of Ae. albopictus mosquitoes. Interestingly, we showed that the physicochemical and microbial compositions of noncolonized and colonized waters did not significantly differ, with the exception of N2O and CH4 concentrations, which were higher in noncolonized water samples. Moreover, the microbial composition of larval habitats covaried differentially along the pollution gradients according to colonization status. This study opens new avenues on the impact of pollution on mosquito habitats in urban areas and raises questions on the influence of biotic and abiotic interactions on adult life history traits and their ability to transmit pathogens to humans.

French invasive Asian tiger mosquito populations harbor reduced bacterial microbiota and genetic diversity compared to Vietnamese autochthonous relatives.

The Asian tiger mosquito Aedes albopictus is one of the most significant pathogen vectors of the twenty-first century. Originating from Asia, it has invaded a wide range of eco-climatic regions worldwide. The insect-associated microbiota is now recognized to play a significant role in host biology. While genetic diversity bottlenecks are known to result from biological invasions, the resulting shifts in host-associated microbiota diversity has not been thoroughly investigated. To address this subject, we compared four autochthonous Ae. albopictus populations in Vietnam, the native area of Ae. albopictus, and three populations recently introduced to Metropolitan France, with the aim of documenting whether these populations display differences in host genotype and bacterial microbiota. Population-level genetic diversity (microsatellite markers and COI haplotype) and bacterial diversity (16S rDNA metabarcoding) were compared between field-caught mosquitoes. Bacterial microbiota from the whole insect bodies were largely dominated by Wolbachia pipientis. Targeted analysis of the gut microbiota revealed a greater bacterial diversity in which a fraction was common between French and Vietnamese populations. The genus Dysgonomonas was the most prevalent and abundant across all studied populations. Overall genetic diversities of both hosts and bacterial microbiota were significantly reduced in recently established populations of France compared to the autochthonous populations of Vietnam. These results open up many important avenues of investigation in order to link the process of geographical invasion to shifts in commensal and symbiotic microbiome communities, as such shifts may have dramatic impacts on the biology and/or vector competence of invading hematophagous insects.

Visceral protein response to enteral versus parenteral nutrition and sepsis in patients with trauma.

BACKGROUND: Sepsis and the route of nutrient administration are clearly related to visceral protein levels; however, the mechanisms and amount of influence are not completely defined. METHODS: Constitutive and acute-phase protein levels were measured on days 1, 4, 7, and 10 in 68 severely injured patients with abdominal trauma indexes of 15 or more randomized to enteral or parenteral feeding. Groups were matched for age, abdominal trauma index, injury severity score, and length of stay. RESULTS: Significantly higher levels of constitutive proteins and lower levels of acute-phase proteins were found in patients randomized to enteral feeding. Although some "hepatic protein reprioritization" appeared to be caused by nutrient route, this appeared only in the less severely injured patients. A more important factor in visceral protein levels is a reduction in septic morbidity associated with enteral feeding. CONCLUSIONS: Enteral feeding produces greater increase in constitutive proteins and greater decreases in acute-phase proteins after severe trauma primarily caused by reduced septic morbidity with enteral feeding.

Duration of antibiotic therapy for penetrating abdominal trauma: a prospective trial.

BACKGROUND: The optimal duration of antibiotic use in penetrating abdominal trauma is incompletely defined. It is generally accepted that short-term antibiotics are appropriate for low-risk wounds. However, with colon injury and significant degree of injury, abdominal trauma index (ATI) more than 25, concern exists that short-term treatment is not adequate. METHODS: The study was a prospective double-blind trial of 24-hour treatment (cefoxitin or cefotetan) compared with 5-day treatment in 515 patients. Major abdominal infections (MAI) included abscess, necrotizing fasciitis, and diffuse peritonitis. RESULTS: MAI occurred in 8% of those patients with 1-day therapy and 10% with 5-day therapy. Subgroup analysis of high-risk groups (colon wounds and ATI of more than 25) showed the following MAI rates: colon, 1-day therapy, 14%; 5-day therapy, 15%; ATI of more than 25, 1-day therapy, 17%; 5-day therapy, 30%. CONCLUSIONS: Regardless of contamination and degree of injury, 24-hour antibiotic therapy is satisfactory for all penetrating abdominal trauma.

Risk of abdominal septic complications after feeding jejunostomy placement in patients undergoing splenectomy for trauma.

Compared with total parenteral nutrition, enteral feeding via jejunostomy reduces septic complications in patients with severe trauma. However, violation of the bowel with insertion of a jejunostomy tube may increase the risk of intra-abdominal abscess (IAA), particularly if no simultaneous gastrointestinal tract injury exists. The records of 123 patients requiring splenectomy for trauma at a level I trauma center during a 6-year period (1986 to 1992) were reviewed to examine the incidence of IAA in patients with and without simultaneous jejunostomy placement in the presence and absence of gastrointestinal tract injuries. Thirty patients had jejunostomies placed (J), and 93 did not (NoJ). There were no significant differences between the groups in age, Abdominal Trauma Index, Injury Severity Score, or transfusion requirements. The incidence of IAA was not significantly different between the J and NoJ groups in the presence or absence of gastrointestinal tract injuries. Thus, jejunostomy placement does not increase the incidence of IAA after splenectomy regardless of the presence of a gastrointestinal tract injury.

Is resection with primary anastomosis following destructive colon wounds always safe?

Resection with primary anastomosis was associated with a 14% anastomotic leak rate in this review of 60 patients with destructive colon wounds. The presence of an underlying medical illness or massive blood transfusion was associated with anastomotic complications. In the high-risk subset of patients who had one or both of these risk factors, the anastomotic leak rate was 42%. The incidence of anastomotic leak in previously healthy patients without massive transfusion was 3%. Ileocolostomies were no safer than colocolostomies. We conclude that resection with anastomosis should not be performed on all patients with destructive colon injuries, as the risk of anastomotic leak is prohibitive in those with either massive blood loss or underlying medical illness. We continue to perform primary anastomosis in healthy patients without excessive blood loss.

Early versus delayed feeding with an immune-enhancing diet in patients with severe head injuries.

BACKGROUND: Although early enteral feeding clearly reduces septic morbidity after blunt and penetrating trauma, data for head-injured patients are conflicting. This study examines the effects of early vs delayed enteral feedings on outcome in patients with severe closed-head injuries with a Glasgow Coma Scale (GCS) score greater than 3 and less than 11. METHODS: Thirty patients were prospectively randomized to receive an immune-enhancing diet (Impact with fiber) early (initiated < 72 hours after trauma) delivered via an endoscopically placed nasoenteric tube (Stay-Put) or late (administered after gastric ileus resolved). This formula was continued for 14 days or until the patient tolerated oral feeding. Goal rate of nutrition was 21 nonprotein cal/kg/d and 0.3 g N/kg/d. RESULTS: Two patients in the early group were excluded due to inability to place the tube, and one patient in the late group died before 72 hours. Five of the remaining 27 died, 1 in the early group and 4 in the late group. There were no significant differences between the groups in length of stay, intensive care unit (ICU) days, significant infection, or GCS score. However, major infection correlated inversely with admission GCS score (R = -0.6, p < .003). Time to reach a GCS score of 14 was significantly longer in patients with significant infections compared with those without (p < .02). CONCLUSIONS: No difference in length of stay or infectious complications is shown in patients with severe closed-head injury when they are given early vs delayed feeding using an immune-enhancing formula. Severity of the head injury is closely associated with significant infection.

Rectal trauma: management based on anatomic distinctions.

Principles of rectal wound management, including routine diversion, injury repair, presacral drainage and distal washout, evolved from World War II and the Vietnam conflict and have been questioned in recent years. We believe significant confusion arises because of imprecise definition of injury location relative to retroperitoneal involvement. Our 5-year experience with penetrating rectal injuries at a Level I trauma center was analyzed. Injuries to the anterior and lateral surfaces of the upper two-thirds of the rectum were classified as intraperitoneal (IP, serosalized), and those of the posterior surface extraperitoneal (EP, no serosa); injuries to the lower one-third were EP. A total of 58 injuries were managed (92% gunshot wounds). Of these, 16 were IP, and 42 had some EP component. Ten patients underwent repair without diversion (6 IP, 4 EP); there were no leaks. Ten septic complications occurred in the remaining population: 2 necrotizing fasciitis, 5 abdominal abscess, and 3 presacral infections (PIs) (2 presacral abscesses and 1 wound tract infection). PI is the only complication that can be specifically associated with EP rectal injuries relative to management; as associated injury confounds interpretation of the other complications. The operative management in the 38 patients with diverted EP wounds with respect to presacral infection (PI) demonstrated the following: repair injury (n = 10), 0 PI versus no repair (n = 28), 3 PI (P = 0.55); washout (n = 33), 2 PI versus no washout (n = 5), 1 PI (P = 0.35); presacral drain (n = 30), 1 PI versus no drain (n = 8), 2 PI (P = 0.11). We conclude that most IP injuries can be managed with primary repair. EP wounds to the upper two-thirds of the rectum should usually be repaired. EP wounds to the lower one-third, which are explored and repaired, do not require drainage. EP wounds that are not explored should be managed with presacral drainage to minimize the incidence of presacral abscess.

Shotgun wounds to the abdomen.

In 1963 Sherman and Parrish (Sherman RT, Parrish RA. Management of shotgun Injuries: A Review of 152 Cases. J Trauma 1963;3:76-86) classified shotgun wounds into three types based upon distance and penetration. Because distances are often unknown, we redefined Sherman's groups by pellet scatter. Type I patients had > 25 cm of scatter, Type II had < 25 cm but > 10 cm, and Type III had < 10 cm. Seventy-one abdominal shotgun wound patients were admitted over 8 years. Eight tangential wounds were managed by local wound care. Of the remaining 63, 27 were Type I, 10 were Type II, and 26 Type III. Two Type II and six Type III patients died within 24 hours. All required laparotomy. Nine of the Type I patients required laparotomy; eight had peritoneal signs and one had progressive abdominal tenderness, hypotension, and intra-abdominal pellets. Eighteen Type I patients without peritoneal signs were observed without complications. Type III patients suffered more vascular injuries and presented more frequently with hypotension than Type II patients. Of the patients surviving greater than 24 hours, Type IIIs received more transfusions and stayed longer in the intensive care unit and hospital than Type IIs. They also suffered more complications than Type IIs. Seven Type III patients required complicated reconstruction of the abdominal wall. Classification of abdominal shotgun injuries using pellet spread is a more useful system in determining patient management and prognosis compared to systems based on distance. Type II and III abdominal shotgun injuries require laparotomy, debridement of soft tissue injuries and frequently reconstruction of abdominal wall defects. Type I injuries can be managed effectively using signs of peritoneal irritation or progressive abdominal tenderness as the best indicator of the need for operation.

Laryngotracheal trauma.

Laryngotracheal trauma (LTT) is a rare but clinically important injury that may be missed without a high index of suspicion. Forty patients with LTT admitted to the University of Tennessee, Memphis from 1984 through 1989 were retrospectively reviewed. Twenty-six patients sustained penetrating (P)-LTT and 14 had blunt (B)-LTT. Three patients with P-LTT and one with B-LTT arrived in full arrest. Sixty-five per cent of blunt injuries, and 100 per cent of penetrating injuries had neck tenderness or overlying evidence of trauma. A combination of angiography, barium swallow, esophagoscopy, CT scan, bronchoscopy and/or laryngoscopy was used for evaluation, depending on the mechanism. Twenty-two of the 23 surviving P-LTT patients underwent surgery; 11 (50%) had concomitant esophageal injury. All patients with complications from P-LTT were in the group with esophageal injury. B-LTT was classified as either mild5, moderate3, or severe6; all 6 severely injured patients had preoperative airway compromise. All complications of B-LTT occurred in the severely injured group. The following conclusions were reached: LTT usually presents with symptoms and/or signs, but they may be minimal and nonspecific. Emergency tracheostomy should not be delayed if ventilation is compromised. Concomitant esophageal injuries are frequent in P-LTT and predispose the patient to postoperative complications. Airway compromise frequently correlates with severity of injury in B-LTT and these patients are also at high risk for complications.

Stress ulceration requiring definitive surgery after severe trauma.

Despite antiulcer prophylaxis 19 severely injured patients at our institution developed stress ulceration (SU) between 1989 and 1999 requiring surgery for perforation (n = 4) or bleeding (n = 15). A herald bleed (HB) 10.7 +/- 1.2 days after admission, 7.2 +/- 1.2 days before definitive operative therapy, and requiring 7.1 +/- 0.9 units of blood occurred in 93 per cent of patients operated on for bleeding. Bleeding preceded perforation in one patient. Central nervous system damage was part of the injury pattern in 68 per cent of the patients including spinal cord (42%), severe head injury (16%), or both (10%). Forty-two per cent had acalculous cholecystitis found at surgery. Eight patients had vagotomy and antrectomy (VA), and 11 patients had vagotomy and pyloroplasty (VP). VA required more time than VP (255 +/- 41 vs 158 +/- 13 minutes; P = 0.02). One patient (12.5%) rebled after VA versus two (18%) after VP; one patient in each group required reoperation. There was no difference in mortality, length of stay, or intensive care unit stay. A herald bleed preceded recurrent hemorrhage of SU by one week. Spinal cord or head injury increase the risk of SU. More than 40 per cent of patients with SU had acalculous cholecystitis found at operation. VA provides no benefit on rebleeding or reoperation over VP, so anatomical considerations and not rebleed rates should determine the surgical procedure.

Enteral access.

The enteral route is the preferred method of nutrition support in patients with functional gastrointestinal tracts. Many techniques for obtaining enteral access are available, and the decision regarding which one to use depends on several issues, including anticipated duration of support, aspiration risk, and local expertise. Using laparotomy, laparoscopy, fluoroscopy, or endoscopy, tubes can be placed into the stomach, the duodenum, and the jejunum. Nasogastric and nasoenteric tubes are useful for short-term supplementation; however, patients needing support for more than 6 weeks may be better served with a more permanent tube. In this review, specific methods for obtaining enteral access are discussed along with their advantages and disadvantages.

Postoperative nutrition in surgery for major trauma.

Research in the area of the nutritional support of trauma patients has continued to focus on a few main areas: the effect that the route, timing and type of feeding has on patient outcome, nutritional assessment and mucosal immunity. This year a nutritional conference has released a paper, summarizing the current state of research in this area, that generated some controversy.

Management of nutrition in the critically ill patient.

Many recent clinical studies focus on the critically ill or injured hypermetabolic patient and investigate nutritional factors and regimens that can potentially reduce septic complications and improve clinical outcome. In addition to better defining the amount and type of nutrients appropriate for this population, these studies provide insight into important variables such as route of nutrient administration, supplementation of formulas with immune-enhancing (or nonimmunosuppressive) nutrients, and anabolic agents that promote increased nitrogen retention and lean body mass accumulation.

Is early feeding beneficial? How early is early?

Nutritional support is a vital part of the therapy of most hospitalized patients. Early initiation, particularly via the enteral route, has a significant effect on septic complications in a wide variety of patients. Early enteral feeding may also attenuate the hypercatabolic response that follows burn injury, although the evidence is somewhat conflicting. The mechanisms for the benefit of early nutrition have not been fully elucidated. However, preservation of gut mass, prevention of increased gut permeability to bacteria and other toxins, and maintenance of the gut-associated lymphoid tissue all probably play a role. The question "How early is early?" is important, since maintenance of early feeding requires time, patience, and dedication. It appears that starting nutrition within 24 hrs of major surgery, injury, or burn is ideal, but within 48 hours is acceptable. However, hemodynamic stability is a prerequisite to initiation of enteral feeding. Although labor intensive, the provision of early feeding, particularly via the enteral route, is a worthwhile goal for all clinicians.

Effect of route of feeding on the incidence of septic complications in critically ill patients.

The increased risk of septic complications accompanying severe illness and injury is compounded by the presence of malnutrition. Total parenteral nutrition (TPN) has been used extensively to prevent or rectify this problem. Although enteral nutrition is frequently more difficult to administer, a growing body of laboratory and clinical research shows a significant reduction in the incidence of secondary infection with its use. The mechanism proposed is that the enteral route helps maintain the gut barrier, decreasing passage of bacteria and other toxins. Translocation of these products has been implicated as a cause of nosocomial infection and organ failure. Therefore, when possible, the use of the enteral route of nutrition should be part of the overall approach to the care of the critically ill or injured patient.

Nutritional support and infection: does the route matter?

Questions regarding the effects of the route of nutrition began to surface shortly after the introduction of total parenteral nutrition (TPN). Although TPN has become a life-saving therapy for patients who cannot tolerate enteral nutrition, it is not the panacea it was hoped to be. It appears that the enteral route of nutrition decreases rates of infectious complications compared with parenteral feeding. Reasons for this phenomenon are not clear, but it seems that enteral nutrition supports the gut barrier and gut-associated lymphoid tissue, which may have effects on infections at distant sites such as the lung. These effects do not appear to be due solely to prevention to malnutrition, as the infectious complications develop early after injury or illness. However, the lack of understanding of the mechanisms does not negate the fact that in many clinical studies the enteral route of nutrition is superior to the parenteral route in terms of reducing infectious complications in critically ill or injured patients.

Correlation of abdominal trauma index and injury severity score with abdominal septic complications in penetrating and blunt trauma.

The Abdominal Trauma Index (ATI) was designed to stratify patients with penetrating injuries, and has been used to classify patients with blunt trauma. The Injury Severity Score (ISS) was originally designed to stratify victims of blunt trauma, and it has also been used for victims of penetrating trauma. We attempted to validate the use of ISS and ATI for both penetrating and blunt trauma. A total of 592 penetrating and 334 blunt trauma patients who underwent laparotomy over a 5-year period were evaluated. The overall rate of abdominal sepsis was 7.5% for blunt trauma and 7.6% for penetrating trauma. Mortality (excluding deaths within 48 hours) was 7% for blunt trauma and 1% for penetrating trauma. In the penetrating injury population, an ATI value greater than 15 and an ATI value greater than 25 were significantly associated with abdominal septic complications (ASCs) (p less than 0.001, both comparisons). An ISS greater than or equal to 16 was also associated with ASCs (p less than 0.001). The ASC rate for gunshots was higher than that for stab wounds (11% vs. 2%; p less than 0.001). In the blunt group, an ATI value greater than 15 and an ATI value greater than 25 were associated with ASCs (p less than 0.01 and p less than 0.001, respectively). The association of ASCs and ISS was linear with increasing ISS in patients with blunt abdominal trauma.(ABSTRACT TRUNCATED AT 250 WORDS)