Ertapenem combined with metronidazole for treatment of complex abdominal infections: Efficacy and impact on serum inflammatory indicators and T lymphocyte subsets

BACKGROUND

Complex intra-abdominal infections (cIAIs), often associated with abdominal trauma, have a complex etiology, are acute and severe, and have a high risk. They are an important cause of death in patients with abdominal trauma. Safe and effective treatment strategies are the factors affecting the prognosis of such patients.

AIM

To investigate the efficacy and safey of ertapenem combined with metronidazole in the treatment of cIAIs as well as the impact on serum inflammatory markers and T lymphocyte subsets, recovery status, and treatment costs.

METHODS

A total of 92 patients with cIAIs treated at our hospital from June 2021 to January 2023 were randomly divided into a control group and a study group, with 46 cases in each group. After admission, both groups received puncture drainage, continuous double-cannula irrigation, anti-infection therapy, organ function support, nutritional support, and other treatments. On this basis, the control group was treated with piperacillin/tazobactam combined with metronidazole, while the study group was treated with ertapenem combined with metronidazole. The therapeutic effects, recovery conditions, treatment costs, serum inflammatory indicators [procalcitonin (PCT), Toll-like receptor 4 (TLR-4), tumor necrosis factor-α (TNF-α), and C-reactive protein (CRP)], T lymphocyte subsets (CD3⁺, CD4⁺, and CD4⁺/CD8⁺ ratio), acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ) score, sequential organ failure assessment (SOFA) score, adverse reactions, and bacterial culture results were compared between the two groups.

RESULTS

The total effective rate of the study group was 93.48%, significantly higher than that of the control group (78.26%; P < 0.05). After 3 d and 7 d of treatment, the levels of serum PCT, TLR-4, TNF-α, and CRP in the study group were significantly lower and the levels of serum CD3⁺ and CD4⁺ T lymphocytes and CD4⁺/CD8⁺ ratio were significantly higher than those of the control group (P < 0.05). The APACHEⅡ score and SOFA score of the study group were significantly lower than those of the control group after 3 d and 7 d of treatment (P < 0.05). The time to fever resolution, ICU stay duration, and hospital stay in the study group were significantly shorter than those of the control group, and the costs of drugs and other resources were less than those of the control group (P < 0.05). The incidence of adverse reactions in the study group was 4.35%, significantly lower than that of the control group (17.39%; P < 0.05). There was no significant difference in the distribution of pathogenic bacteria between the two groups before and after treatment (P > 0.05).

CONCLUSION

Ertapenem combined with metronidazole is effective in the treatment of cIAIs, which can reduce inflammation, improve immune function, control disease progression, reduce the risk of organ failure, reduce the economic burden of patients, and improve treatment safety.

Carrilizumab for treatment of advanced colorectal cancer: Short-term efficacy and impact on immune function and PD-1/PD-L1 signaling pathway

BACKGROUND

Colorectal cancer is one of the most prevalent malignant tumours in China, and chemotherapy is the main treatment modality for patients with advanced colorectal cancer, which results in toxic side effects and reduces patients' quality of life. Since the occurrence of toxic side effects is related to patients' immunity and other factors, it is important to study whether the combined injection of carrilizumab with chemotherapy can positively affect patients' conditions by influencing the programmed cell death protein 1 (PD-1)/programmed death ligand 1 (PD-L1) signalling pathway.

AIM

To investigate the possible mechanism of carrilizumab for injection to improve immune function in advanced colorectal cancer, and to analyze its regulatory effect on the PD-1/ PD-L1 signaling pathway.

METHODS

A prospective randomised controlled study (RCT) was performed to include 127 patients with advanced colorectal cancer admitted to our hospital from January 2019 to October 2021, and they were divided into a control group (n = 63) and a study group (n = 64) using the computerised random number method. The control group was given oxaliplatin + capecitabine, and the study group was given oxaliplatin + capecitabine + carrilizumab for injection. The therapeutic effect, toxicity and side effects, survival status, PD-1/PD-L1 signaling pathway, tumor markers [carbohydrate antigen 125 (CA125), carbohydrate antigen 242 (CA242), thymidine kinase 1 (TK1), and carcinoembryonic antigen (CEA)], and nutritional status indicators [albumin (ALB), hemoglobin (HGB), prealbumin (PA), transferrin (TF), and patient-generated subjective global assessment (PG-SGA)] before and after treatment were compared between the two groups.

RESULTS

After four cycles of treatment, the disease control rate of the study group was higher than that of the control group (P < 0.05); the mRNA and protein levels of PD-1 and PD-L1 in the study group were lower than those in the control group (P < 0.05); serum ALB, PA, and TF levels and PG-SGA scores in the study group were higher than those in the control group (P < 0.05); and serum CA125, CA242, TK1, and CEA in the study group were lower than those in the control group (P < 0.05). There was no significant difference in the incidence of toxic and side effects or survival rate between the two groups (P > 0.05).

CONCLUSION

Camrelizumab for injection combined with oxaliplatin and capecitabine in the treatment of advanced colorectal cancer can improve the disease control rate, may reduce the impact of chemotherapy drugs on the nutritional status of the body by inhibiting the activation of PD-1/PD-L1 signal pathway, thus improving the immune function of the body, and has good safety.

Astragalus injection improves inflammatory response in lung injury in acute hemorrhagic necrotizing pancreatitis by regulating the mTOR/p70S6K signal pathway

BACKGROUND

Acute hemorrhagic necrotic pancreatitis is a clinically common digestive system emergency. Lung injury is a common complication and cause of death. Astragalus injection can regulate endocrine balance, enhance immunity, inhibit virus, and exert anti-inflammatory and antioxidant effects. However, there has been no relevant study on Astragalus injection in lung injury caused by severe acute pancreatitis.

AIM

To analyze the effect of Astragalus injection on the inflammatory response in lung injury secondary to acute hemorrhagic necrotic pancreatitis (AHNP) with regard to regulating the target protein of rapamycin/ribosomal 70S small subunit S6 protein kinase (mTOR/p70S6K).

METHODS

Forty-eight adult SD rats were randomly divided into a control group, a model group, low, medium, and high dosage Astragalus injection groups, and a positive control group, with 8 rats in each group. The histopathological changes of pancreas and lung tissues were recorded. Schmidt score, serum amylase (AMS), Hofouaer score, arterial blood carbon dioxide partial pressure (PaCO2), arterial oxygen partial pressure (PaO2), inflammatory factors [tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6)], and mTOR/p70S6K signaling pathway protein (mTOR, p70S6K, p-p70S6K, p-mTOR, and 4EBP1) levels were assessed.

RESULTS

There were no abnormal changes in the pancreas and lung tissues in the control group. The pancreatic parenchyma of mice in the model group showed flaky necrosis, congestion, and edema, massive destruction of pancreatic acinar cells and interstitial cells, disordered lobular structure, infiltration of inflammatory cells and red blood cell overflow, and disordered alveolar structure, interstitial edema, inflammatory cell infiltration, alveolar septum widening, focal or flaky atelectasis, and hemorrhage. Compared with the model group, the low, medium, and high dosage Astragalus injection groups showed different degrees of improvement in a dose dependent manner. The histopathology of the high dosage Astragalus injection group and the positive control group showed similar characteristics. The Schmidt score, AMS, Hofouaer score, and PaCO2 in the model group were higher than those in the control group, and PaO2 was lower than that of the control group (P < 0.05). Schmidt score, AMS, Hofouaer score, and PaCO2 decreased, and PaO2 increased in the low, medium, and high dosage Astragalus injection groups compared with the model group (P < 0.05). TNF-α and IL-6 in the model group were higher than those of the control group (P < 0.05); TNF-α and IL-6 decreased in the low, medium, and high dosage Astragalus injection groups compared with the model group (P < 0.05). mTOR, p70S6K, p-p70S6K, p-mTOR, and 4EBP1 were higher in the model group than in the control group (P < 0.05), while the low, medium, high dosage Astragalus injection groups had lower mTOR, p70S6K, p-p70S6K, p-mTOR, and 4EBP1 than the model group (P < 0.05).

CONCLUSION

Astragalus injection can improve blood gas indexes, inflammatory response, pancreas and lung pathological state in AHNP in a dose dependent manner. Such effects may be achieved by regulating the mTOR/p70S6K signaling pathway, and inhibiting the mTOR/p70S6K signaling pathway may provides a new idea for the treatment of lung injury in AHNP.

Preventing Soil Inoculum of Calonectria pseudonaviculata from Splashing onto Healthy Boxwood Foliage by Mulching

Boxwood blight, caused by Calonectria pseudonaviculata, is an emerging disease of great concern to horticulturists in the United States and other affected countries. The objective of this study was to evaluate the efficacy of mulching as a physical barrier to prevent soil inoculum from splashing onto healthy boxwood foliage. A field trial consisting of two treatments, mulched and nonmulched, was conducted under field conditions in Lowgap, North Carolina, and in a residential landscape setting near Richmond, Virginia, for 2 years at each site. Mulching efficacy was assessed by monitoring and comparing boxwood blight development on detector plants: containerized 'Justin Brouwers' boxwood, which were rotated through mulched and nonmulched plots at 1- and 2-week intervals in the Lowgap and Richmond sites, respectively. Boxwood blight was observed on detector plants in a combined 55 of the 88 monitoring periods during this study at the two sites. Mulching provided complete protection of Justin Brouwers boxwood from infection by C. pseudonaviculata soil inoculum during 33 of the 55 positive monitoring periods (60%) and good to excellent protection during 13 monitoring periods (24%). The potential applications of mulching for boxwood blight mitigation are discussed.

Effects of Inoculum Dose, Temperature, Cultivar, and Interrupted Leaf Wetness Period on Infection of Boxwood by Calonectria pseudonaviculata

Boxwood blight is an emerging disease of great concern for the ornamental horticulture industry, historic garden managers, landscapers, and homeowners. Controlled-environment experiments were conducted to determine the effects of conidial concentration, temperature, interrupted leaf wetness period, cultivar, and leaf age on infection of boxwood leaves by Calonectria pseudonaviculata. Boxwood blight incidence (BBI) increased with increasing concentration up to 2.0 × 10⁴ spores/ml. BBI also increased as temperature increased from 18 to 25°C, then declined gradually to zero at 29°C. Similar infection effects of inoculum concentration were observed in an experiment with four boxwood cultivars ('Justin Brouwers', 'John Baldwin', 'Green Mound', and 'Nana') of various degrees of susceptibility. The hypothesis that younger leaves are more susceptible than older leaves was supported for Justin Brouwers and Nana but not for Green Mound; and younger leaves of John Baldwin were less susceptible than older leaves. When inoculated plants ('Suffruticosa') were exposed to dry interruptions of 3 h or longer between 5 or 8 h of initial wetness and 12 h of additional wetness, these plants had significantly lower BBI compared with those exposed to continuous wetness for 20 h, and similar or at most slightly more infection than plants exposed to only the 5- or 8-h initial wetness. Continuous wetness durations beyond 20 h did not increase infection in these experiments. These results advanced our understanding of the environmental requirements of the infection process in boxwood blight development and they are essential for refining disease forecasting models.

Root and Stem Rot of Begonia Caused by Phytopythium helicoides in Virginia

In the summer of 2011, severe root and stem rot of begonia (Begonia × semperflorens-cultorum cv. Vodka Dark Red) was observed during a field trial. Seventy-eight percent of the plants had symptoms included foliar blight, blackened and rotting roots, rotting stems, and collapsing crown, often leading to plant death. Isolation from the diseased plant roots consistently recovered a Pythium-like species and 41 isolates were subcultured for identification. These isolates produced very similar single-strand conformation polymorphism (SSCP) fingerprints (2), which were distinct from those of other oomycete pathogens known to attack begonia (1). These isolates produced proliferous, ovoid to globose, terminal, and papillate sporangia which were 30.6 to 45.4 μm (av. 38.7 μm) in length and 20.5 to 35.4 μm (av. 28.2 μm) in width. Oogonia were produced in single culture grown in clarified V8 juice agar. These smooth-walled oogonia were mostly aplerotic and 28.9 to 36.8 μm (av. 33.1 μm) in diameter. Each contained a single oospore with a diameter of 23.7 to 34.4 μm (av. 26.9 μm). Single to multiple antheridia were attached lengthwise to each oogonium. These morphological characteristics match the description of Phytopythium helicoides (= Pythium helicoides) (3). The identity of these isolates was confirmed by sequencing the rDNA internal transcribed spacer (ITS) 1 and 2 regions. ITS sequence of the representative isolate 55C7 (GenBank Accession No. KC907734) had 97 to 99% homology with P. helicoides sequences in GenBank. Two isolates, 55C7 and 56A7, were tested for pathogenicity to begonia in the summer of 2012. Twelve plants per isolate were inoculated by injecting ground P. helicoides-colonized rice grains into the root soil using a long-neck funnel. Sterile rice grains were used on control plants. Aboveground symptoms including foliar blight, stem rot, and collapsing crown were observed 7 days after inoculation and the disease progressed for additional 6 weeks. At 7 weeks, all inoculated plants showed different symptom levels. Four and 10 plants inoculated with 55C7 and 56A7, respectively, were already dead. Begonia roots showed severe symptoms including blackening, stunted growth, and rotting. Seven of 12 control plants also had notable symptoms due to cross contamination. Isolates recovered from all symptomatic plants had identical SSCP fingerprints to those of isolates 55C7 and 56A7. To our knowledge, this is the first report of P. helicoides attacking begonia plants. The avenue of this pathogen entering the 2011 field trial remains unknown. The field trial in 2011 and pathogenicity test in 2012 indicate that this pathogen is potentially destructive to begonia. Additional research is warranted to identify the origin and dissemination of this pathogen to mitigate the risk to begonia production. References: (1) C. X. Hong et al. Plant Dis. 92: 1201, 2008. (2) P. Kong et al. FEMS Microbiol. Lett. 240:229, 2003. (3) A. J. van der Plaats-Niterink. Monograph of the Genus Pythium. Centraalbureau voor Schimmelcultures, Baarn, the Netherlands, 1981.

Prevalence of IL-28B and ITPA genotypes in Chinese Han population infected persistently with hepatitis C virus genotype 6 or HCV-1

The geographic distribution, demographics, epidemiology, host factors, and clinical characteristics of persistent HCV-6 infection in China need further characterization. This multicenter study enrolled 63 patients with persistent HCV-6 infection and 63 patients with persistent HCV-1 infection as controls. Blood biochemistry, quantitation of HCV RNA levels, and identification of host IL-28B genotypes (rs12979860, rs8099917, and rs12980275) and ITPA genotype (rs1127354) were performed to estimate potential variability in host factors that may affect response to treatment. The mean HCV-6 RNA level (3.8E6 IU/ml) was significantly higher than that in patients infected with HCV-1 (1.7E6 IU/ml; P < 0.001). Patients persistently infected with HCV-6 had a high prevalence of IL-28B rs12979860 CC genotype (92.1%), rs8099917 TT genotype (93.7%), and rs12980275 AA genotype (90.5%). Their prevalence in patients infected with HCV-1 was only modestly lower (82.5%, 84.1%, and 82.5%, respectively; P > 0.05). The inosine triphosphate pyrophosphatase (ITPA) SNP rs1127354 CC genotype was present in 66.7% of patients infected with HCV-6, comparable to that of patients infected with HCV-1 (65.1%; P > 0.05). There were no differences in the liver function, proportion of hepatic cirrhosis patients or patients with increased serum glucose between these two groups. Persistent HCV-6 infection in Chinese Han is found mainly in the southern China. Chinese Han with chronic HCV-1 or HCV-6 infection have IL-28B genotypes, suggesting responsiveness to interferon-based pharmacotherapy. Most patients (67%) possess the ITPA genotype associated with susceptibility to ribavirin-induced hemolysis. The routes of transmission for HCV-6 genotype were more diversified than HCV-1 genotype. The outbreak of HCV-6 infection through blood transfusion progressed faster than HCV-1.

Diversity and Mefenoxam Sensitivity of Phytophthora spp. Associated with the Ornamental Horticulture Industry in the Southeastern United States

Phytophthora isolates associated with ornamental plants or recovered from irrigation water in six states in the southeastern United States (Georgia, North Carolina, South Carolina, Tennessee, Texas, and Virginia) were identified and screened for sensitivity to mefenoxam. Isolates from forest and suburban streams in Georgia and Virginia were included for comparison. A new in vitro assay, utilizing 48-well tissue culture plates, was used to screen for mefenoxam sensitivity; this assay allowed high throughput of isolates and used less material than the traditional petri plate assay. In total, 1,483 Phytophthora isolates were evaluated, and 27 species were identified with Phytophthora nicotianae, P. hydropathica, and P. gonapodyides, the most abundant species associated with plants, irrigation water, and streams, respectively. Only 6% of isolates associated with plants and 9% from irrigation water were insensitive to mefenoxam at 100 μg a.i./ml. Approximately 78% of insensitive isolates associated with plants were P. nicotianae, and most of these (67%) came from herbaceous annual plants. Most of the insensitive isolates recovered from irrigation water were P. gonapodyides, P. hydropathica, P. megasperma, and P. pini, and 83% of the insensitive isolates from streams were P. gonapodyides. Overall, this study suggests that mefenoxam should continue to be a valuable tool in the management of Phytophthora diseases affecting ornamental plants in the southeastern United States.

Phytophthora hedraiandra Detected from Irrigation Water at a Perennial Ornamental Plant Nursery in Virginia

Water survey for Phytophthora spp. by baiting with rhododendron leaves in April 2006 at a perennial ornamental plant nursery in Virginia detected five isolates showing a unique, previously unknown single-strand conformation polymorphism (SSCP) fingerprint (1). These cultures were isolated from two reservoirs at different depths of water column from surface to 2 m. They were homothallic and produced smooth-surfaced spherical oogonia with an average diameter of 27 μm on 10% V8 agar. Oospores were aplerotic. The paragynous antheridia were averaging 12 μm in diameter. Sporangia were papillate, spherical to ovoid, averaging 39 by 28 μm (length by width). They were caducous with short (<4 μm) pedicels. Chlamydospores and hyphal swellings were not observed. Two isolates were sequenced for rDNA internal transcribed spacer (ITS) 1 and 2 regions and cytochrome oxidase subunit 1 (Cox 1) gene. ITS sequences of both isolates (GenBank Accession Nos. JN376065 and JN376066) were identical to that of Phytophthora hedraiandra type culture (GenBank Accession No. AY707987). Also, the Cox 1 sequence of an isolate (Accession No. JN376067) had 99% homology with that of the type culture (GenBank Accession No. AY69115). Pathogenicity of both isolates was tested on Rhododendron catawbiense and Viburnum tinus, two known hosts of P. hedraiandra (2). For each isolate and host, five leaves and stems on potted plants were wounded by needles and then inoculated by placing over each wound a 5-mm² mycelial plug from a 7-day-old culture and securing with Parafilm. V8 agar was used instead of mycelial plugs on control plants. After inoculation, each plant was enclosed in a plastic bag for 1 day and then incubated at 22°C with a 12-h photoperiod. Distilled water was sprayed daily for 5 days postinoculation (dpi) until disease symptoms were observed. At 15 dpi, 3 of the 10 inoculated rhododendron leaves and 6 of the 10 stems showed leaf lesions, wilting, dieback, and cankers, eventually leading to rhododendron death. Two of the 10 viburnum leaves and 4 of the 10 stems showed similar symptoms. Leaf lesions were approximately 3 to 5 cm in diameter. P. hedraiandra was recovered from diseased tissues and all resulting cultures showed an identical SSCP fingerprint to tested isolates as well as a P. hedraiandra isolate from Minnesota (3). No symptom developed on control plants. To our knowledge, this is the first report of P. hedraiandra in Virginia. Considering neither host plant has been grown or bought for resale by this nursery, this study indicates that P. hedraiandra may have a wider host range than is currently known. This possibility and the importance of water dispersal for P. hedraiandra in disease epidemiology warrant further investigation. References: (1) P. Kong et al. Fungal Genet. Biol. 39:238, 2003. (2) W. A. Man in't Veld et al. Eur. J. Plant Pathol. 117:25, 2007. (3) B. W. Schwingle et al. Plant Dis. 90:109, 2006.

Population Structure, Mating Type, and Mefenoxam Sensitivity of Phytophthora nicotianae in Virginia Tobacco Fields

Black shank is an important disease of tobacco (Nicotiana tabacum) caused by the fungus-like organism, Phytophthora nicotianae. Three physiological races (0, 1, and 3) have been documented in the United States. Shifts in the pathogen population structure have become a concern due to the widespread use of cultivars possessing resistance to race 0 arising from a single gene (Ph_p or Ph_l). A comprehensive statewide survey conducted throughout major tobacco-growing areas during summer 2006 and supplemented by additional isolates in 2007 and 2008 yielded 217 isolates from flue-cured, burley, and dark fire-cured tobacco fields. After determining species identity using a single-strand conformational polymorphism fingerprinting technique, the race identity of isolates was assessed via greenhouse tests using three differential cultivars (Hicks, L8, and NC1071). Approximately 76% of the isolates belonged to race 1, 21% to race 0, and the remaining 3% were race 3. This race structure was comparable with those in the other tobacco-producing states in the United States. Approximately 94% of isolates belonged to A² mating type and merely 6% were A¹. These data suggest that it is unlikely that sexual recombination serves as a major mechanism enhancing the genetic diversity of the pathogen in Virginia. All isolates were also evaluated against mefenoxam at 5 μg/ml. None were insensitive; 98% of isolates were either highly sensitive or sensitive and the remaining 2% were intermediately sensitive. These results indicate that mefenoxam remains effective for control of black shank in Virginia. The results of this study can assist breeders to develop cultivars possessing the most appropriate set of disease resistance traits, as well as extension specialists, county agents, and tobacco growers in their decision-making process to manage tobacco black shank in Virginia.

Foliar Blight of Annual Vinca (Catharanthus roseus) Caused by Phytophthora tropicalis in Virginia

Annual vinca (Catharanthus roseus), also known as Madagascar periwinkle, has been cultivated as a major color crop for landscape and as an herbal medicine. This plant performs well in dry, warm locations with full sun or partial shade. Two-month-old diseased plants (cv. First Kiss Blueberry) with blighted leaves and stems were received from a local nursery in Suffolk, VA in May 2009. The disease began with dark, greenish black lesions on young leaves. Lesions gradually became tan or brown and leaves wilted and curled and finally turned necrotic. Brown, sunken lesions beginning at the branching points were typical symptoms on blighted stems and shoots. Blighted areas and spots were approximately 30 to 90 mm long and 20 to 40 mm wide on leaves and 40 mm long on stems. A Phytophthora species previously unknown to attack this plant was consistently isolated from diseased leaves and stems, and resultant isolates were grown on PARP-V8 agar. These isolates produced papillate sporangia on umbellate sympodium. Sporangia were mostly ellipsoid with a length/breadth ratio of >1.8 and tapered base; they were caducous with a long pedicel (usually >50 μm). These isolates also produced chlamydospores that averaged 31 μm in diameter. The isolates were identified as Phytophthora tropicalis by morphology. The identity was confirmed by DNA fingerprinting (1) and sequence analysis of ribosomal DNA internal transcribed spacers (GenBank Accession No. GQ478707). For pathogenicity studies, a zoospore suspension of 1,100 spores per milliliter was sprayed onto the foliage of 50-day-old healthy plants of the same cultivar grown in pine bark medium in six 10-cm-diameter plastic containers with a hand mister in the evening until runoff. Control plants were sprayed with tap water. Plants were placed in a tray containing a small amount of water and enclosed in plastic tents overnight to facilitate infection. The tents were removed the following morning, and plants were kept in a greenhouse under natural light and watered as needed. Within 4 days, all six inoculated plants developed foliar symptoms similar to what was observed on the diseased plant samples from the production nursery. The pathogen was reisolated from infected leaves and stems and its identity was confirmed by colony PCR-single-strand conformation polymorphism (3). The pathogenicity test was repeated once with the same results. Phytophthora aerial blight is a common destructive disease of annual vinca, which is usually caused by P. nicotianae. To our knowledge, this is the first report of foliar blight caused by P. tropicalis on annual vinca in Virginia. According to the head grower who submitted the disease samples, this new disease caused 10% crop loss of annual vinca this past spring. P. tropicalis was previously reported to attack ornamental shrubs, including Pieris japonica and Rhododendron catawbiense (2). This study indicates that P. tropicalis could be a potential threat to herbaceous annual crops as well. References: (1) M. E. Gallegly and C. X. Hong. Phytophthora: Identifying Species by Morphology and DNA Fingerprints. The American Phytopathological Society, St. Paul, MN, 2008. (2) C. Hong et al. Plant Dis. 90:525, 2006. (3) P. Kong et al. J. Microbiol. Methods 61:25, 2005.

The avocado subgroup of Phytophthora citricola constitutes a distinct species, Phytophthora mengei sp. nov

Isolates from avocado tree cankers have been recognized as a distinct subgroup within the P. citricola complex since 1974, both morphologically and molecularly (isozyme and amplified fragment length polymorphism [AFLP] analyses). This subgroup is formally separated from P. citricola after comparative DNA fingerprinting and sequence analyses of the ITS region, as well as by morphological examinations. This new taxon is homothallic, produces plerotic oospores with paragynous antheridia and noncaducous semipapillate sporangia. Morphologically it differs from other species of Waterhouse group III by producing many large bizarre-shaped sporangia and smaller oogonia with asymmetric capitate antheridia. It belongs to clade 2 and is phylogenetically closer to P. siskiyouensis, P. capsici and P. tropicalis than to P. citricola. P. mengei can be easily differentiated from its relatives in the same clade and other species of this morpho-group by DNA fingerprints and sequence analysis. This new taxon is named Phytophthora mengei sp. nov.

Downy Mildew of Rudbeckia fulgida cv. Goldsturm by Plasmopara halstedii in Virginia

A severe foliage disease was observed on black-eyed Susan (Rudbeckia fulgida cv. Goldsturm) at a commercial nursery in Virginia Beach, VA in early June of 2005 and 2006. In both years, disease symptoms began after plants were transferred from 1-liter (1quart) to 4-liter (1-gallon) containers. Several hundred 'Goldsturm' plants were grown at this nursery but none was marketable because of this disease. Typical symptoms were dark, blotchy necrotic areas on the upper leaf surface. Fuzzy, grayish white zoosporangiophores and zoosporangia were commonly produced on the underside of affected leaves. These disease signs also were observed on both sides of new leaves in severely affected plants. Zoosporangiophores were monopodially branched at right angles with acutely tapering termini. Zoosporangia were ovoid to elliptical, hyaline, and measured 19 to 28 × 17 to 21 μm. On the basis of these morphological characters and host specificity, the organism was identified as Plasmopara halstedii (Farl.) Berl. & De Toni in Sacc. Inoculum at 1.4 × 10⁴ zoosporangia/ml was prepared by washing diseased leaves with deionized reverse osmosis water and applied with a hand sprayer onto the foliage of test plants until runoff. Control plants were treated with deionized reverse osmosis water only. Inoculated and control plants were placed in plastic bags to keep moist for 48 h at 20°C. The inoculated plants developed the same symptoms with fresh crops of the zoosporangiophores and zoosporangia of P. halstedii on the underside of leaves, while the control plants remained healthy 14 days after treatment. The source of the primary inoculum is not known. Interestingly, none of 12 other Rudbeckia spp. and cultivars (R. hirta cvs. Autumn Colors, Becky, Cherokee Sunset, Indian Summer, Irish Eye, Prarie Sun, and Sonora, R. laciniata, R. maxima, R. missouriensis, R. occidentalis cv. Green Wizard, and R. speciosa cv. Viette's Little) grown at the same nursery adjacent to those severely diseased 'Goldsturm' plants was affected. Although downy mildew was reported on rudbeckias in north Florida previously (1), to my knowledge, this is the first report from Virginia. This pathogen attacks a number of plants in the genera of Centaurea, Coreopsis, Erigeron, Helianthus, and Verbena in addition to Rudbeckia spp. (2). Thus, it could significantly impact the ornamental plant nursery industry. References: (1) H. Dankers et al. Plant Health Progress. Online publication. doi:10.1094/PHP-2004-0119-01-HN, 2004. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989.

Phytophthora tropicalis Isolated from Diseased Leaves of Pieris japonica and Rhododendron catawbiense and Found in Irrigation Water and Soil in Virginia

An unidentified species of Phytophthora was isolated from irrigation water at a production nursery in Suffolk, VA in 2000 and 2001. Water samples were assayed using a filtration method (3). A similar species was recovered from soil samples collected in two mixed-hardwood forests in Fairfax County in 2002. Soil samples were air dried, remoistened, flooded, and then baited with rhododendron and camellia leaf pieces at room temperature (22 to 24°C) (2). A Phytophthora sp. was recovered from bait pieces cultured on PARPH-V8 selective medium (2). This same species also was isolated from symptomatic leaves of Pieris japonica cv. Temple Bells and Rhododendron catawbiense cv. Maximum Roseum at a garden center in Virginia Beach in 2004. On P. japonica, symptoms appeared as water-soaked, necrotic lesions and marginal necrosis on leaves and necrosis of shoot tips; on R. catawbiense, symptoms were wilting, dieback, and death of shoots. Representative isolates produced semipapillate to papillate sporangia with tapered bases that were caducous and had long pedicels (16 to 120 μm). Sporangia on four isolates were measured: mean lengths were 40.6 to 48.4 μm, mean widths were 26.9 to 31.4 μm, and length/width ratios consistently were 1.5. Sporangia occasionally were distorted and had dual apices, and they often contained a large globule after zoospore release. Chlamydospores ranged from 25 to 32 μm in diameter. All isolates were heterothallic; four isolates paired with known isolates of P. nicotianae were found to be mating type A1. Optimum temperature for mycelium growth on cornmeal agar was 25°C with slight growth at 35°C by some isolates and no growth at 4°C. These morphological characteristics were mostly consistent with those of P. tropicalis (1). P. tropicalis is reported to have sporangia that are papillate, have lengths of 40 to 55 μm, widths of 19 to 27 μm, and length/width ratios of 1.8 to 2.4 (1). The identity of these isolates as P. tropicalis was confirmed using single-strand conformational polymorphism analysis with comparison to a reference isolate (4). These isolates have been retained in permanent collections in the Hong and Jeffers labs. One isolate from each host plant and one isolate from irrigation water were tested for pathogenicity; agar blocks of mycelium (4 × 4 mm) were placed on wounded and nonwounded leaves of P. japonica cv. Mountain Fire and R. catawbiense cv. Olga plants and wrapped with Parafilm to prevent desiccation. Lesions formed on wounded and nonwounded leaves after 4 days at 20 to 30°C, and P. tropicalis was reisolated; no lesions formed on noninoculated control leaves. To our knowledge, this is the first report of P. tropicalis in the continental United States, in irrigation water systems, and as a cause of Phytophthora foliage blight on P. japonica and R. catawbiense (1). This study suggests that the host range of this pathogen is not limited to tropical plants. Although this pathogen did not cause significant economic loss in the garden center surveyed, it was isolated in irrigation water at the production nursery from late spring through fall. An investigation of its impact on nursery crops is warranted. References: (1) M. Aragaki and J. Y. Uchida. Mycologia 93:137, 2001. (2) A. J. Ferguson and S. N. Jeffers. Plant Dis. 83:1129, 1999. (3) C. X. Hong et al. Phytopathology 92:610, 2002. (4) P. Kong et al. Fungal Genet. Biol. 39:238, 2003.

Effects of Zoospore Concentration and Application Pressure on Foliage Blight of Catharanthus roseus Caused by Phytophthora nicotianae

This study investigated the effects of inoculum concentration, application pressure, use of carbon dioxide (CO₂), and agitation associated with passage through a spray nozzle on zoospore survival and on foliage blight caused by Phytophthora nicotianae. In a greenhouse experiment, plants of Catharanthus roseus were inoculated by spraying zoospore suspensions at pressures of 210, 420, and 630 kPa (30, 60, and 90 lbs/in² [psi]). A low-pressure 35-kPa (5-psi) control inoculation was provided with a hand-operated aspirator-type mister. There was a consistent reduction in level of disease with increased application pressure, regardless of the zoospore concentration. To determine the source of this disease reduction, laboratory assays were conducted. Zoospore suspensions were pressurized to 210, 420, and 630 kPa with CO₂ or air, then transferred from the pressure bottle into a flask by either spraying or pouring. From the flask, the suspensions were spread over plates of PARP-V8 agar and incubated for 72 h, at which time total colony numbers were recorded. CO₂ significantly reduced zoospore survival. Pressure strength and method of spore transfer out of pressure bottles also impacted survival to lesser extents. There were significant interactions between pressure source and means of spore suspension transfer, and between pressure strength and means of spore transfer. These results may lead to development of alternative methods of water decontamination to prevent inoculum from entering crop systems through irrigation water.

Shoot Blight of Forsythia × intermedia in Virginia Nurseries Caused by Phytophthora nicotianae

A severe blighting of shoots on Forsythia × intermedia cv. Lynwood Gold plants was observed at several commercial nurseries in Virginia from 2001 to 2004. Crop losses ranged from 10 to 35%. Symptoms first occurred at the tips of shoots, including those that were trimmed and not trimmed, and then progressed downward. Diseased shoots wilted quickly and usually turned black, and foliage on these shoots withered and became necrotic. With PARP-V8 selective medium (2), a species of Phytophthora was isolated consistently from symptomatic shoots (including tissues from shoot tips, leaves, and stems) as well as from apparently healthy roots. These isolates produced arachnoid mycelia and numerous noncaducous, papillate sporangia but did not produce sexual structures on isolation plates; these morphological characters are consistent with those of Phytophthora nicotianae. All isolates produced a single-strand conformation polymorphism pattern typical of P. nicotianae (3). To test pathogenicity, 1-year-old, healthy-appearing cv. Lynwood Gold forsythia plants (canopy size = 100 cm × 60 cm) in four 12-liter containers were sheared. Two plants were inoculated by spraying each plant with 200 ml of a zoospore suspension (1.6 × 10⁴ spores per ml, prepared from one isolate), and the other two plants were not treated and served as controls. Plants were covered with plastic bags overnight to encourage infection and then were grown in a field (temperature range = 20 to 33°C). Severe blight developed on trimmed shoots and new shoot tips of inoculated plants within 1 week after inoculation. The same pathogen was isolated from all blighted leaf and stem pieces assayed. Blight symptoms were not observed on control plants during a 1-month observation period. Phytophthora nicotianae has been reported to attack F. viridissima in Italy (1) causing root and collar rot but not shoot blight. To our knowledge, this is the first report of shoot blight on Forsythia spp. caused by P. nicotianae and the first report of P. nicotianae on Forsythia spp. in the United States. References: (1) S. O. Cacciola et al. Plant Dis. 78:525, 1994. (2) A. J. Ferguson and S. N. Jeffers. Plant Dis. 83:1129, 1999. (3) P. Kong et al. Fun. Gen. Biol. 39:238, 2003.

Crown Rot of Abies balsamea var. phanerolepis Caused by Phytophthora cactorum in Virginia

In early July 2004, a severe crown rot of Canaan fir (Abies balsamea var. phanerolepis Fern.) was reported to the Virginia Cooperative Extension, Frederick County Office, and subsequently to the Virginia Tech Disease Clinic in Virginia Beach. One thousand five-year-old Canaan fir transplants (approximately 11 mm in caliper and 31 cm high) had been purchased from a tree nursery in Oregon and planted in the field in Frederick County, VA, in April of 2004. The field site had not been cultivated for 4 years after an apple orchard had been removed in 2000. By mid-May, needle browning had become serious, affecting the lower crown first. By August, transplants had suffered 40% mortality. Basal stems of affected plants were obviously discolored. Root and basal stem samples from several infected plants were then cultured on PARP-V8 agar on three different dates. Phytophthora sp. isolates were recovered from all stem samples but none from the roots. These isolates produced a large number of papillate sporangia that were caducous with short pedicels. Abundant oogonia with paragynous antheridia formed oospores directly on isolation plates within 7 days. The isolates were keyed as P. cactorum (2). This identification was confirmed using a single-strand-conformation polymorphism analysis of ribosomal DNA internal transcribed spacer (ITS)-1 (4). It appears that the source of inoculum was P. cactorum associated with the previous apple crop, since Canaan fir from the same transplant lot planted in a nearby field without a history of apples remained healthy. P. cactorum has been reported to cause root rot of noble fir (A. procera Rhedo), Pacific silver fir (A. amabilis (Dougl.) Forbes), and Shasta red fir (A. magnifica var. shastensis Lemm.) in the Pacific Northwest (3). It has also caused crown rot of Fraser fir (A. fraseri (Pursh) Poir.), noble fir, white fir (A. concolor (Gord. & Glend.) Lindl.), and balsam fir (A. balsamea (L.) Mill.) in Michigan (1). To our knowledge, this is the first report of P. cactorum attacking Canaan fir. Canaan fir currently is a recommended Christmas tree species for areas where Fraser fir does not do well due to root rot caused by Phytophthora cinnamomi. This study suggests that such a recommendation must be used with caution. Growing Canaan fir trees in P. cactorum-infested soil could result in devastating crop losses as reported in this note. References: (1) G. C. Adams, Jr. and A. Bielenin. Plant Dis. 72:79, 1988. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (3) P. B. Hamm and E. M. Hansen. Eur. J. For. Pathol. 12:167, 1982. (4) P. Kong et al. Fungal Genet. Biol. 39:238, 2003.

First Report of Phytophthora cinnamomi on Ilex glabra in Virginia

During 2002, two nurseries in southeastern Virginia reported losses exceeding 75% of container-grown inkberry holly (Ilex glabra) cv. Shamrock. The development of necrotic leaf spots and blotches followed initial symptoms of leaf yellowing and wilting. Affected leaves rapidly turned brown and fell. Dark brown-to-black roots were washed and plated on agar media. Phytophthora cinnamomi Rands was consistently isolated and identified on the basis of its morphology (2) and single-stranded conformational polymorphism fingerprint (1). The organism had nonpapillate, internally proliferating, noncaducous, ovoid to ellipsoid sporangia that formed only in water. It did not grow at 35°C and had abundant botryose hyphal swellings, coralloid hyphae, and grape-like clusters of chlamydospores. The isolate, determined to be the A2 mating type, produced elongate cylindrical, amphigynous antheridia and oogonia with a tapered base. A pine bark potting mix amended with V8 juicetreated vermiculite colonized by the suspected pathogen was placed in 12-liter containers. Two inkberry holly cv. Shamrock liners were planted in each of three containers and two 1-yr-old plants were planted in each of three additional containers during April 2004. An identical set of six containers of noninoculated plants was also established. During June 2004, inoculated plants exhibited symptoms identical to those observed in nurseries, and P. cinnamomi was isolated. Noninoculated check plants did not develop symptoms. Japanese holly (I. crenata) was previously known as a host, but to our knowledge, this is the first report of inkberry holly (I. glabra) susceptibility. References: (1) P. Kong et al. Fungal Genet. Biol. 39:238, 2003. (2) D. J. Stamps et al. Mycol. Pap. No. 162. CAB International Mycological Institute, Wallingford, UK, 1990.

Rapid identification of Phytophthora ramorum using PCR-SSCP analysis of ribosomal DNA ITS-1

AIMS

The primary objectives of this study were to determine if a single-strand conformation polymorphism (SSCP) analysis can be used for rapid identification of Phytophthora ramorum, an important quarantine plant pathogen worldwide, and to further assess the potential of the SSCP technique as a taxonomic tool for the genus Phytophthora.

METHODS AND RESULTS

SSCP of ribosomal DNA internal transcribed spacer 1 was characterized for 12 isolates of P. ramorum, using a recently reported protocol. The SSCP patterns of this species then were compared with those of 18 closely related Phytophthora species. Phytophthora ramorum had a unique pattern and was easily distinguished from genetically, morphologically and ecologically close relatives.

CONCLUSION

An immediate benefit of this study is provision of a highly effective and efficient identification tool for P. ramorum in the quarantine process.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study also provides additional evidence demonstrating that the SSCP is an ideal DNA marker for species differentiation within the genus Phytophthora.

Efficacy of Chlorine on Multiple Species of Phytophthora in Recycled Nursery Irrigation Water

Recycled irrigation water is a primary source of inoculum for Phytophthora spp. and is capable of spreading propagules throughout nursery production. Chlorination commonly is used by the industry to disinfest recycled irrigation water; however, chlorine has not been fully researched as a disinfestant for this purpose. In this study, zoospores of seven species and eight isolates of Phytophthora were exposed for 2 min to free available chlorine at 0.25, 0.5, 1.0, 2.0, and 4.0 mg/liter. Zoospores, mycelial fragments, and culture plugs of P. nicotianae also were exposed to chlorine concentrations ranging from 0.25 to 8.0 mg/liter for periods ranging from 15 s to 8 min. In addition, chlorinated water was assayed monthly in 2000 and 2001 at two commercial nurseries, and quarterly in the first year at four other nurseries in Virginia, for chlorine and survival of pythiaceous species using a selective medium. No zoospores of any species tested survived endpoint free chlorine at 2 mg/liter, while limited mycelial fragments of P. nicotianae survived at 8 mg/liter, and mycelial plugs treated at the same level of chlorine were able to produce few sporangia. Phytophthora spp. were recovered only from nursery irrigation water with levels of free chlorine at 0.77 mg/liter or lower. The results of this study are essential for improving current chlorination protocols.

First Report on White Smut of Gaillardia × grandiflora Caused by Entyloma polysporum in Virginia

Disease samples of Gaillardia × grandiflora cvs. Goblin and Baby Cole were received at the Hampton Roads Agricultural Research and Extension Center in Virginia Beach in early April 2002. Samples were from a nursery in eastern Virginia, and most diseased plants had several to more than a dozen, round, flat, white to tan spots with indistinct margins up to 1 cm in diameter on their leaves. The spots later turned brown and necrotic, followed by necrosis of the entire leaf. Leaves of 'Baby Cole' were beginning to wilt and were more spotted than those of 'Goblin'. Fungal fruiting bodies were not observed on the surface of diseased leaves. However, microscopic examination of internal leaf tissues revealed masses of round, double-walled, pale green-to-yellow spores approximately 12 μm in diameter and typical of the ustilospores of Entyloma polysporum (2,3). Inoculum for pathogenicity tests was prepared by blending 10 diseased leaves in 200 ml of sterile distilled water (SDW) for 2 min in a blender at low speed. The spore suspension was adjusted to 5 × 10⁵ spores per ml with SDW. Healthy 'Goblin' gaillardia plants were obtained from a nursery where smut symptoms had never been seen. Four plants in one-gallon containers were inoculated by spraying them to runoff with the spore suspension. Four control plants were sprayed with SDW only. All plants were maintained in a greenhouse (15 to 35°C) and covered with a clean polyethylene plastic sheet overnight (14 h) to maintain high humidity and separated to avoid potential cross contamination. Inoculated and uninoculated plants were hand-watered separately, with application of water to the foliage to enhance spread of the disease. Typical white smut symptoms were observed on inoculated plants 2 weeks after inoculation, and numerous spores of E. polysporum were observed in the diseased tissues. No disease symptoms were seen on control plants. White smut has been reported on gaillardia in a few other states (1), but to our knowledge, this is the first report of the disease on gaillardia in Virginia. Growers at the affected nursery reported observing white smut symptoms on gaillardia in previous years, but in the spring of 2002, almost the entire gaillardia crop was destroyed. The disease has not been seen on gaillardia in any other nurseries, but it could have significant impact on production if it spreads. References: (1) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989. (2) W. Fischer. Manual of the North American Smut Fungi. Ronald Press, New York, 1953. (3) D. B. O. Savile. Can. J. Res. 25(C):109,1947.

Mycoflora of Stone Fruit Mummies in California Orchards

Stone fruit mummies infected by Monilinia fructicola were periodically collected in winter from trees and from the ground in eight orchards in 1995-96 and from five orchards in 1996-97. Mycoflora were determined by spreading mummy washings and plating inner tissues onto petri dishes containing acidified potato dextrose agar, then counting colonies of individual fungi after incubation at 23°C for 4 days. Twenty genera, representing 29 fungal species, were isolated from both mummy washings and inner tissues. Aspergillus japonicus, A. terreus, and species of Harknesia, Paecilomyces, and Trichoderma are the first recorded from species of Prunus in the United States, and Aureobasidium pullulans and Epicoccum purpurascens are the first reported for California. The principal mycoflora recovered from mummy washings were species of non-filamentous yeasts (32.1%), Penicillium (28.8%), Cladosporium (11.4%), and Mucor (10.8%). Major mycoflora of mummy inner tissues were species of Penicillium (23.7%), Mucor (19.6%), Cladosporium (17.3%), and Rhizopus (11.1%). The relative recoveries of individual fungi from mummy inner tissues differed with location, Prunus species, and sampling position (tree or ground), and changed as the season progressed. The relative recovery of M. fructicola from mummy inner tissues was negatively correlated with Botrytis (R = -0.53, P = 0.0052), Penicillium (R = -0.58, P = 0.0681), and Rhizopus (R = -0.50, P = 0.0696). These results could help obtain naturally occurring antagonists and maximize their use in biocontrol systems aimed at reducing primary inoculum for blossom blight of stone fruits in California orchards.

Prune, Plum, and Nectarine as Hosts of Trichothecium roseum in California Orchards

Trichothecium roseum (Pers.:Fr.) Link was frequently observed (up to 21%) on mummified peach (Prunus persica (L.) Batsch), nectarine (P. persica (L.) Batsch var. nectarina (Aiton) Maxim.), plum (P. salicina Lindl.), and prune (P. domestica L.) fruits in orchards during a 1995 to 1996 survey. Pink mold rot caused by T. roseum was also frequently observed (at about the 1 to 2% level) on a number of samples of prune fruit collected from commercial orchards in Glenn, Butte, Madera, Fresno, and Tulare counties in 1996, after storage at 4°C for 7 days and then 20°C for 4 days. Wounded and nonwounded prune (cv. French), plum (cv. Casselman), peach (cv. Fairtime), and nectarine (cv. Spring Bright) fruits were infected after inoculation with a drop (20 μl) of T. roseum suspension (5 × 10⁵ conidia/ml). Characteristic pink sporulation covered the surface of most fruit 7 days after inoculation. Conidia of T. roseum completely covered all wounded and nonwounded prune fruit, sparsely on the wounded plum fruit, and densely on both wounded and nonwounded peach and nectarine fruits (lesion diameter = 1 to 7 cm) 2 weeks after inoculation. T. roseum sporulated more rapidly and better on the fruits that were contaminated with either Monilinia fructicola (G. Wint.) Honey, or a Cladosporium sp. Peach has been listed as a host of T. roseum (California Plant Disease Host Index, Part 1: Fruits and Nuts, A M. French, ed., 1987), but this is the first report on the pathogenicity of this fungus on prune, plum, and nectarine from California.