Multiyear Regional Evaluation of Foliar Fungicide Applications for Cotton Target Spot Management in the Southeastern United States.

Fungicide programs for managing target spot of cotton caused by Corynespora cassiicola were evaluated over 15 site-years in the southeastern United States between 2014 and 2016. Two cultivars, hypothesized to vary in target spot susceptibility, PhytoGen 499WRF (PHY499) and Deltapine 1137B2RF (DPL1137), and four fungicides (azoxystrobin, flutriafol, pyraclostrobin, pyraclostrobin + fluxapyroxad) plus nontreated control, were compared. Fungicide programs consisted of 1) a single application at first flower or disease onset and 2) the first application followed by a second 14 days later. Treatments were applied in a factorial, randomized complete block design. Target spot onset and severity varied among site-years. Except when severity was low, target spot-associated defoliation was greater on PHY499 than on DP1137. Fungicides delayed disease development and defoliation, but application number had little impact. Based on a meta-analysis of 15 site-years, pyraclostrobin-based applications resulted in a 4 to 6% yield preservation, and yield preservation was greater at site-years with early disease onset and >40% target spot associated defoliation. Results suggest a single well-timed application of a pyraclostrobin-based fungicide reduces defoliation and protects cotton yield at locations with high target spot severity. Additional research is needed to identify risk factors for target spot-associated yield losses in cotton production systems.

Fusarium verticillioides (Saccardo) Nirenberg associated with hardlock of cotton.

Boll rots of cotton (Gossypium hirsutum L.) are common in the humid areas of the Southeastern US. One type of boll damage that may be differentiated from others is hardlock, with symptoms that include compression of the fibers within individual locules of mature, open cotton bolls without further obvious disintegration of the lint or damage to the carpel wall. The principal economic effect is that the boll's lint is unharvestable by mechanical cotton pickers. This disease is endemic to the Southeast and can cause severe yield losses up to 70% in some fields. Scanning electron microscopy images of fibers from hardlocked bolls showed flattened and twisted tissue compared to fibers from healthy bolls. Fusarium verticillioides (Saccardo) Nirenberg was the fungus most commonly isolated from seeds of developing cotton bolls. Flowers inoculated with F. verticillioides on the day of bloom by spraying a spore suspension onto the flowers developed significantly (P < 0.05) more hardlock symptoms compared to untreated controls. The infection process was analyzed using a F. verticillioides isolate tagged with green fluorescent protein (GFP). When it was applied to cotton flowers on the day of bloom, the GFP-tagged F. verticillioides strain was detected in the stigma and style by 2 days after bloom (DAB) and in developing seeds at 4, 6, 8, 10, 16, 20, 40, and 60 (open bolls) DAB. By 8 DAB, the GFP F. verticillioides was isolated from over 80% of developing seeds.

Pyriproxyfen resistance of Bemisia tabaci (Homoptera: Aleyrodidae) biotype B: metabolic mechanism.

Juvenile hormone (JH) analog insecticides are relatively nontoxic to vertebrates and provide efficient control of key arthropod pests. One JH analog, pyriproxyfen, has provided over a decade of exceptional management of whiteflies in cotton of the southwestern United States. Thwarting resistance to pyriproxyfen in Bemisia tabaci (Gannadius) (a.k.a. Bemisia argentifolii Bellows and Perring) has been the focus of an integrated resistance management program because this insecticide was first registered for use in Arizona cotton in 1996. Resistance levels have increased slowly in field populations in recent years but have not demonstrably affected field performance of pyriproxyfen. Resistant strains have been isolated and studied in the laboratory to determine the mechanism of resistance and identify optimal strategies for controlling resistant whiteflies. Synergism bioassays showed that resistance in a laboratory-selected strain QC02-R, was partially suppressible with piperonyl butoxid (PBO) and diethyl maleate (DEM) but not with S, S, S-tributyl phosphorotrithioate (DEF). Consistent with the synergism bioassay results, enzymatic assays revealed that the enzyme activities of cytochrome P450 monooxygenases (P450) and glutathione S-transferases (GST) but not esterases were significantly higher in the pyriproxyfen-resistant QC02-R strain than in the susceptible strain. These results indicate that both P450 and GST are involved in whitefly resistance to pyriproxyfen.

The future of nematode management in cotton.

The importance of plant-parasitic nematodes as yield-limiting pathogens of cotton has received increased recognition and attention in the United States in the recent past. This paper summarizes the remarks made during a symposium of the same title that was held in July 2007 at the joint meeting of the Society of Nematologists and the American Phytopathological Society in San Diego, California. Although several cultural practices, including crop rotation, can be effective in suppressing the populations of the important nematode pathogens of cotton, the economic realities of cotton production limit their use. The use of nematicides is also limited by issues of efficacy and economics. There is a need for development of chemistries that will address these limitations. Also needed are systems that would enable precise nematicide application in terms of rate and placement only in areas where nematode population densities warrant application. Substantial progress is being made in the identification, characterization and mapping of loci for resistance to Meloidogyne incognita and Rotylenchulus reniformis. These data will lead to efficient marker-assisted selection systems that will likely result in development and release of nematode-resistant cotton cultivars with superior yield potential and high fiber quality.

Surgical wound infection.

Wound infections remain a major source of postoperative morbidity, accounting for about a quarter of the total number of nosocomial infections. Today, many of these infections are first recognized in the outpatient clinic or in the patient's home due to the large number of operations done in the outpatient setting. This leads to errors in establishing the true incidence of their occurrence but undoubtedly decreases the overall real cost and length of hospital stay. The pathogens implicated in the development of wound infections remain largely the human microorganisms from the exogenous environment and the endogenous organ microflora. Many perioperative factors have been identified that increase the incidence of the development of postoperative wound infection. Avoidance of these factors as well as the appropriate use of perioperative antibiotic prophylaxis has decreased the incidence of wound infection. During the last decade many studies have reported on the individual risk factors that favor the development of postoperative infectious complications in various surgical procedures. It is hoped that this knowledge may allow for prospective alterations in the preventative and therapeutic modalities in the high-risk patient in the studies designed in the 1990s. The use of effective infection surveillance both in the hospital and in the outpatient setting is mandatory in order to collect meaningful data. The use of computer technology will greatly facilitate the proper surveillance, analysis, and control of infections in the surgical patient.

Use of prophylactic antibiotics in surgical practice.

During the last decade great inroads have been made concerning the appropriate use of antibiotic prophylaxis in the surgical patient. Well-controlled, prospective, blinded studies have outlined many of the areas in which antibiotic prophylaxis is of benefit, as well as those clinical situations in which the risks of antibiotic prophylaxis outweighed the expected value. Historically, the most common errors in usage include the widespread use of antibiotic prophylaxis in clean surgery and the faulty timing of administration. The most common error today (in the use of prophylactic antibiotics in surgical practice) is continuation of the agents beyond the time necessary for maximal benefit. In order to appropriately administer prophylactic antibiotics in the various clinical settings on the surgical service, in which this practice has been of proved value, one must be aware of the following nuances including (1) choice of the antibiotic agent based on the type of organisms usually causing infection, (2) route of its administration, (3) the dosage necessary to attain efficacious tissue or serum levels, and (4) the timing of administration which offers the maximum benefits without risking the adverse effects.

Management of intra-abdominal sepsis.

Intra-abdominal sepsis most frequently follows penetrating or blunt abdominal trauma or perforated appendicitis or diverticulitis. The initial leakage of the endogenous gastrointestinal microflora into the peritoneal cavity results in peritonitis and secondary septicemia, which is frequently followed by localized intra-abdominal abscess. These infections are most frequently polymicrobial and relate directly to the unique endogenous microflora at the various levels of the gastrointestinal tract. The treatment of intra-abdominal sepsis is primarily centered around prompt, appropriate surgical intervention. Parenterally administered antibiotics are also required to decrease the chance of local bacterial infection or septicemia. The choice of the appropriate agent(s) to be used initially, before the results of culture and sensitivity reports are available, depends primarily on the clinical presentation and also on whether the intra-abdominal infection occurred in the community or within the hospital setting. Clinical and experimental studies of intra-abdominal sepsis have largely stressed the use of antibiotic agents that have a spectrum of activity effective against the aerobic coliforms and anaerobic Bacteroides fragilis.

Postoperative infections in the age of drug-resistant gram-positive bacteria.

Postoperative infection is a significant cause of surgical morbidity and mortality. The risk of infection after surgery depends on a number of factors, including the type and length of the surgical procedure; the age, underlying conditions, and previous history of the patient; the skill of the surgeon; the diligence with which infection control procedures are applied; and the type and timing of preoperative antibiotic prophylaxis. Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci, now implicated in many postoperative infections, have been joined most recently by strains of S. aureus that show intermediate levels of resistance to vancomycin. Postoperative infections caused by drug-resistant pathogens are more difficult to treat and are associated with a higher morbidity and mortality. New antibiotics that are effective against drug-resistant pathogens are urgently needed, as is renewed dedication to the prevention of postoperative infection and to the use of the principles of infection control.

Prevention of infection in high risk gastrointestinal surgery.

Postoperative infectious complications are a frequent cause of morbidity and mortality in the surgical patient. These septic events, which are usually confined to the surgical wound, may involve deeper structures or the bloodstream. The highest incidence of these complications in the patient undergoing elective operation occurs after gastrointestinal surgery, in which the endogenous bacterial populations are usually the causative microorganisms. The economic, physical, and psychological impact of postoperative infections mandates the use of preventive methods to decrease the incidence of such untoward events. In this clinical setting, sound surgical judgment and proper technique are most important. The use of appropriately chosen and administered prophylactic antibiotics also has proved of great benefit in many of these patients.

Comparison of oral fleroxacin with oral amoxicillin/clavulanate for treatment of skin and soft tissue infections.

Oral fleroxacin, 400 mg once a day, and oral amoxicillin/clavulanate potassium (AMX/CP), 400 mg/125 mg three times a day, administered for 4-21 days, were compared for efficacy and safety in the treatment of skin and soft tissue infections. A total of 113 patients were enrolled in a multicenter, randomized, double-blind trial; 57 were assigned to fleroxacin and 56 to AMX/CP. A total of 22 and 33 patients in the fleroxacin and AMX/CP groups, respectively, were evaluable for efficacy. The most common diagnoses were skin abscess (14; 62%) and wound infections (5; 23%) in the fleroxacin group and skin abscess (17; 52%) and skin ulcer (9; 27%) in the AMX/CP group. A total of 20 (91%) of the fleroxacin-treated patients and 29 (88%) of the AMX/CP-treated patients were bacteriologically cured (two fleroxacin- and one AMX/CP-treated patients developed super-infection). The eradication rate for Staphylococcus aureus was 100% (11 of 11) in the fleroxacin group and 89% (17 of 19) in the AMX/CP group; 18 (82%) of the fleroxacin group and 25 (76%) of the AMX/CP group were clinically cured. Adverse events were seen in 22% (12 of 54) of the fleroxacin group and 25% (13 of 53) of the AMX/CP group. None were serious. Bacteriologic and clinical cure rates and safety results for the two groups were similar. The small sample size precluded statistical analysis at the 95% confidence level.

Preventive antibiotic usage in traumatic thoracic injuries requiring closed tube thoracostomy.

OBJECTIVE: To evaluate the safety and effectiveness of antibiotics in reducing the infectious complications following closed tube thoracostomy for isolated chest trauma. DESIGN: Double-blind, randomized clinical trial. SETTING: Medical school affiliated large urban teaching hospital and trauma center. PATIENTS: One hundred nineteen of 159 patients over 18 years old presenting to the emergency department requiring closed tube thoracostomy for isolated chest injuries (113 penetrating, 6 blunt). INTERVENTION: Patients received either placebo or 1 g cefonicid daily intravenously started at chest tube insertion and stopped within 24 h of removal. MEASUREMENTS AND RESULTS: The development of wound infections, pneumonia (CDC criteria), or empyema; the incidence of adverse events; length of hospitalization. One nonspecific infection was seen in the cefonicid group (1.6 percent) and six respiratory tract infections (10.7 percent) in the placebo group (three empyema, one empyema with pneumonia, two pneumonia) (p = 0.0505; p = 0.0094 [excluding nonspecific infection]). No significant differences with antibiotic use were seen in the duration of chest tube use (p = 0.766), peak WBC counts (p = 0.108), lower peak temperatures (p = 0.063), or length of hospitalization (p = 0.165). Patients who developed infectious complications averaged approximately 8 days longer hospitalization than those without (p < 0.0001). CONCLUSION: This study showed that patients receiving antibiotics had a significantly reduced rate of infection than did patients administered placebo. No significant adverse events were seen in either group.

In vivo evaluation of ocular inserts of hydrogel impregnated with antibiotics for trachoma therapy.

Sustained release of antibiotics from hydrogel matrices in the eye was studied for the purpose of developing a new method for trachoma therapy. Copolymers of N-vinylpyrrolidone were moulded into an ocular insert and impregnated with erythromycin or erythromycin estolate. The antibiotic-hydrogel inserts completely suppressed the chlamydia trachomatis infection in the owl monkey eyes. The drug elution rates were a little lower in vivo than in vitro. By comparison of the drug elution rate in the human eye with that in the owl monkey eye, similar therapeutic effect is expected in the treatment of human trachoma.

Evaluation of the protective value of hospital gowns against blood strike-through and methicillin-resistant Staphylococcus aureus penetration.

BACKGROUND: Hospital gowns protect patients and health care workers from exposure to blood and other infectious materials. Previous studies have shown that certain gowns do allow blood strike-through. Because of worldwide increases in the incidence of Staphylococcus aureus infections, especially with methicillin-resistant strains, there is now increased concern regarding bacterial transmission through gowns. METHODS: This study evaluated six gown types used in hospitals (one disposable cover or isolation gown, three disposable operating room gowns, and new and washed reusable operating room gowns). Gowns were evaluated for dry spore and S. aureus filtration efficiencies and were subjected to 20 time-pressure combinations with methicillin-resistant S. aureus-spiked blood (10(4)/ml) to evaluate blood strike-through and passage of methicillin-resistant S. aureus. RESULTS: Blood strike-through was lowest with disposable operating room gowns 1 and 2 (polypropylene). Disposable operating room gown 3 (polyester-wood pulp) showed the greatest strike-through and overall passage of methicillin-resistant S. aureus. Operating room gowns 1 and 2 showed minimal bacterial passage, whereas the disposable cover (polypropylene) only allowed passage at pressures greater than 1 psi. Bacterial filtration efficiency testing showed operating room gowns 1 and 2 to be the most protective; operating room gown 3 and both reusable (cotton) gowns were the least protective. Dry spore passage was greatest for reusable gowns. CONCLUSION: Different hospital gowns offer varying degrees of protection against fluid strike-through or bacterial passage. Gowns therefore should be chosen according to the task performed and conditions encountered.

Isolation gowns: a false sense of security?

BACKGROUND: Isolation gowns have traditionally been used in health care situations to protect against microbial contamination. There is now concern over protection of the health care worker from contamination by patients' blood and body fluids. We quantitatively determined the effectiveness of commercially available isolation gowns against human blood leakage or strike through. METHODS: More than 1200 samples of 11 types of disposable gown and one type of reusable gown (new and washed 40 and 80 times) were tested at five different pressures (0.25 to 2 psi) and six durations (1 second to 2 minutes) by means of an apparatus designed to simulate pressures generated during gown usage. RESULTS: In all studied conditions, testing showed significant differences (p less than 0.0001) in the amount of strike through allowed by the gowns and demonstrated important differences in the gowns' protective capabilities. CONCLUSION: Although traditional thought assumes that isolation gowns protect the wearer from contamination, our data show this belief may provide a false sense of security.

Determination of surgeon-generated gown pressures during various surgical procedures in the operating room.

BACKGROUND: Patients' blood or other potentially infectious body fluids frequently pass through surgeons' gowns in the operating room. These fluids are absorbed by the scrub suit and can directly contaminate the surgeons' skin. Protective barriers remain an important method of exposure control for many blood-borne pathogens. The efficacy of surgical gowns in preventing this passage or strikethrough has therefore become the focus of much attention. Limited data are available concerning the magnitude and duration of pressure against surgeons' gowns. METHODS: A 32-sensor mat placed in the abdominal area was used to obtain pressure data for 15 surgeons of both sexes performing 20 procedures. RESULTS: The percentage of time any pressure was detected varied from 0% during knee reconstruction to 97.4% for excision of a stomach mass. In 16 procedures, more than 87.8% of pressure contacts were 2 N/cm2 (2.9 psi or less); in addition, more than 80% of the contacts were 15 seconds or less during 13 of the procedures. No correlation was found between the amount of pressure and sex of the surgeon, surgical service, or length of the procedure. CONCLUSIONS: Because pressure is related to the type of procedure, gowns should be chosen to afford protection against fluid strikethrough for the pressures and blood loss anticipated.

Barrier efficiency of surgical gowns. Are we really protected from our patients' pathogens?

Surgical gowns are traditionally worn to protect patients from contamination by the surgical team. Blood routinely covers gowns during surgery and often contaminates surgeons' undergarments and skin. Because of risks to the surgical team by blood-borne pathogens, disposable and reusable gowns were examined. To quantify "strike through," 1440 samples of gown fabric were tested against human blood in an apparatus designed to simulate abdominal pressure during surgery. Representative pressures (0.25 to 2.0 psi) and times (1 second to 5 minutes) were studied. Above 0.5 psi, spun-bond/melt-blown/spun-bond disposable products were more resistant than spun-lace cloth. New cloth gowns were better than those washed 40 times. Spun-bond/melt-blown/spun-bond fabric exposed to blood twice was more protective than spun-lace cloth challenged once. Gowns currently available exhibit varying resistance to strike through; only those with an impervious plastic reinforcement offer complete protection.

Contaminated street heroin. Relationship to clinical infections.

Thirty-one samples of street heroin were analyzed bacteriologically and chemically as to their microbial burden and chemical adulterants (fillers). Sixty-one percent of the samples were positive for microbial growth. Many species were isolated from the positive samples with Bacillus sp (79%) and Aspergillus sp (10%) predominating. The level of contamination ranged from 1.6 X 10(2) to 3.7 X 10(4) organisms per gram. We obtained cultures from 16 addicts from the Chicago area and 21 from the New Orleans area who had soft-tissue infections related to their habit. Infections in this group of patients were usually polymicrobial; however, there was no correlation between the organisms recovered from street heroin and the addicts' infections. Most drug-related infections appear to be related to the addicts' own oral and dermal microflora. No correlation was observed between the chemical fillers and the bacteria recovered from the heroin.

Inhibition of beta-lactamase-induced resistance in soft-tissue infections.

Sulbactam ([CP45,899] penicillanic acid sulfone) inhibits many of the beta-lactamases commonly found to be the cause of penicillin resistance. This agent was combined with either penicillin G potassium or ampicillin sodium in the treatment of 97 patients admitted with serious soft-tissue infections. Fifty-one of the infections were caused by at least one bacteria resistant to the antibiotic alone. Staphylococcus aureus was the most common pathogen (48 isolations) followed by the coliforms (30 isolations). Ninety percent of the isolates that were tested produced beta-lactamase. Susceptibility studies showed a high degree of resistance to the penicillin alone that was significantly lowered by the addition of sulbactam. The overall clinical results showed 81% of the infections to be either well controlled or cured. Three patients failed to show improvement. Thirteen patients showed transitory increases relatively safe and efficacious in the treatment of soft-tissue infection caused by penicillin-resistant and penicillin-susceptible organisms.

Prospective alterations in therapy for penetrating abdominal trauma.

In a double-blind, randomized study, 170 patients with traumatic perforation of the gastrointestinal tract were administered an advanced-generation cephalosporin. Patients were divided into infection risk groups (< or = 40%, low; 40% to 70%, mid; and > 70%, high) at surgical closure using a logistic regression formula based on four proved risk factors--age, blood replacement, ostomy, and the number of organs injured. Patients in the low group received 2 days of antibiotic therapy; those in the mid to high group received 5 days of antibiotic therapy. Those patients in the low to mid group had primary wound closure; those in the high group had their wounds packed open and closed later. Most of the patients (144 [85%]) were in the low group. Their major and minor infection rates (10% and 12%, respectively) were not significantly different from 145 historic control subjects receiving 5 days of antibiotic therapy (9% major; 14% minor). Patients in the mid to high group showed a greater incidence of major infections (46%) but a similar incidence of minor infections (12%). The results indicate that risk factors can be used to identify low-risk patients who require only short-term antibiotic therapy and primary wound closure. The remaining patients are at greater risk for infection despite prolonged antibiotic therapy and delayed wound closure.

The treatment of intraabdominal infections in surgery.

Intraabdominal sepsis is frequently seen following penetrating or blunt abdominal trauma as well as with perforated appendicitis or diverticulitis. The initial leakage of endogenous gastrointestinal microflora into the peritoneal cavity results in peritonitis and secondary septicemia, which often results in a localized intraabdominal abscess. These infections are commonly polymicrobial and correlate directly with the unique endogenous microflora at various levels of the gastrointestinal tract. The successful treatment of intraabdominal sepsis is primarily associated with prompt, appropriate surgical intervention. Parenterally administered antibiotics are also required to decrease the incidence of local bacterial infection or septicemia. The choice of the appropriate agent(s) to be used initially, before obtaining the results of culture and sensitivity tests, depends primarily on both the clinical presentation and on whether the intraabdominal infection occurred in the community or as a result of hospitalization. Clinical and experimental studies of intraabdominal sepsis have primarily emphasized the use of antibiotic agents that have a spectrum of activity effective against aerobic coliforms and the anaerobe Bacteroides fragilis.