Tags: Soft tissue infections

Actinomyces

Essentials of Diagnosis “Sulfur granules” in specimens and sinus tract drainage: hard, irregularly shaped, yellow particles measuring from 1 to 5 mm in size Gram-positive branching filaments arranged in ray-like projections under the microscope Colonies with characteristic “molar tooth” appearance Production of extensive fibrosis with “woody” induration No specific antibody or antigen detection tests General Considerations A. Epidemiology. The Actinomyces species are facultative anaerobes that commonly inhabit the oral cavity, the gastrointestinal tract, and the female genital tract, where they exist as commensals. Diversity within this genus is broad, which has led to taxonomic revision and reclassification of some species as members of the Arcanobacterium genus, eg, Actinomyces pyogenes. Disease occurs …

Continue Reading...

Other Mycobacteria

Essentials of Diagnosis Demonstration of the acid-fast bacillus. Infections more common in immunocompromised hosts. Infections mainly pulmonary or soft tissue. General Considerations The increasingly relative importance of the atypical mycobacteria, many of which are ubiquitous in the environment, was recognized with the decline in tuberculous disease. Generally, atypical mycobacteria are unusual causes of disease in patients who are immunocompetent but can in immunocompromised hosts such as AIDS and cancer patients. Most infections caused by atypical mycobacteria are skin and soft tissue abscesses, sometimes following pulmonary infection or implantation of prosthetic devices. There have been a few reports of epidemics of iatrogenic infection with atypical mycobacteria, associated with injection of contaminated materials. …

Continue Reading...

Important Anaerobes

Essentials of Diagnosis • Foul odor of draining purulence. • Presence of gas in tissues. • No organism growth on aerobic culture media. • Infection localized in the proximity of mucosal surface. • Presence of septic thrombophlebitis. • Tissue necrosis and abscess formation. • Association with malignancies (especially intestinal). • Mixed organism morphologies on Gram stain. General Considerations A. Epidemiology and Ecology. Anaerobic bacteria are the predominant component of the normal microbial flora of the human body. The following sites harbor the vast majority of them: • Skin: Mostly gram-positive bacilli such as Propionibacterium acnes • Gastrointestinal tract: In the oral cavity Prevotella spp., Porphyromonas spp., Peptostreptococcus spp., microaerophillic streptococci, and …

Continue Reading...

Toxin-Mediated Infections

1. TETANUS Tetanus is a disease of global incidence produced by the toxin of Clostridium tetani. The risk of acquiring it increases in people > 60 years of age and in neonates, especially in Third World countries where poor sanitary conditions predispose to umbilical stump contamination. Immunization campaigns have played a crucial role in bringing about the observed decreasing incidence in the United States. The pathogenesis of tetanus involves the absorption of preformed toxin, or, less commonly, invasion of toxin-producing organisms from contaminated wounds; it may complicate surgical wounds colonized with C tetani. Incubation periods vary depending on the portal of entry. The toxin tetanospasmin blocks the transmission of inhibitory neurons, …

Continue Reading...

Vibrio & Campylobacter

VIBRIO INFECTIONS VIBRIO CHOLERAE INFECTIONS Essentials of Diagnosis • History of exposure, particularly travel to endemic or epidemic locales. • Acute onset of voluminous, watery diarrhea, with low-grade fever and mild abdominal pain, which are disproportionate to the amount of diarrhea. • During outbreaks, the presence of straight-to-curved gram-negative bacilli, with a single polar flagellum, in the stool of infected patients. • In wet preparations, these organisms demonstrate a characteristic darting or “shooting star” motility. The identification may be confirmed by motility inhibition with specific antisera. • Cultures of V cholerae from stool with differential media, such as thiosulfate-citrate-bile salts-sucrose (TCBS) medium. • Bacterial growth in nutrient broth, without 1% NaCl …

Continue Reading...

Pseudomonas Aeruginosa

Essentials of Diagnosis • Nosocomial acquisition. • Predisposing factors include immunosuppression (neutropenia, cystic fibrosis [CF], AIDS, corticosteroid use, diabetes mellitus); presence of a foreign body, prosthesis, or instrumentation; prolonged hospitalization and antibiotic use; intravenous drug use. • Most common infections include pneumonia, bacteremia, urinary tract infection, otitis media, skin and skin structure infections, including ecthyma gangrenosa. • Gram stain shows gram-negative bacilli; recovery of microorganism from culture of blood or other tissue. General Considerations A. Epidemiology. The genus Pseudomonas consists of a number of human pathogens, the most important of which is Pseudomonas aeruginosa. P aeruginosa is an opportunistic pathogen found widely in soil, water, and organic material, reflecting its limited …

Continue Reading...

Infection in Patients With Aids

Paeruginosa infections may occur in patients with AIDS. Risk factors for infection include a CD4 count of < 100 cells/mL3, neutropenia or functional neutrophil defects, intravascular catheterization, hospitalization, and prior use of antibiotics including ciprofloxacin or trimethoprim-sulfamethoxazole. Many cases are community acquired. Bacteremia is common, and the lung or an intravenous catheter is the most frequent portal of entry. An impaired ability to mount immunotype-specific antibodies to Pseudomonas lipopolysaccharide antigen has been noted in HIV-positive individuals with bacteremia. Relapse is frequent, and mortality is high, 40%. Pneumonia is usually associated with cavitation and a high relapse rate. Bacterial sinusitis is an important and frequently undetected illness in HIV-positive individuals, and P …

Continue Reading...

Skin & Soft Tissue Infections

Infections caused by P aeruginosa involving the skin may be primary or secondary. Secondary infections have been described above and include ecthyma gangrenosum, subcutaneous nodules, vesicles, bullae, cellulitis, deep abscesses, and necrotizing fasciitis. Primary skin lesions are noted as complications of neutropenia, burns, decubitus ulcers, prematurity, exposure to a moist environment, and hydrotherapy. Burn wound sepsis is a serious complication that may be caused by P aeruginosa. Colonization of the burn may lead to invasive disease. The signs are black, brown, or violet discoloration of the burn eschar; destruction of granulation tissue leading to rapid eschar separation and subcutaneous hemorrhage; erythematous nodules; edema or hemorrhage of adjacent uninfected tissue; black neoeschar …

Continue Reading...

Enteritis Caused by Escherichia coli & Shigella & Salmonella Species

Essentials of Diagnosis • Enteritis: diarrhea, which may be watery, bloody, or dysenteric; abdominal pain; and fever and/or; • Systemic disease: highly variable presentations that may include enteric fever, hemolytic uremic syndrome, or bacteremia with infectious foci in distant sites. • History of exposure, possibly in known endemic areas or associated with an outbreak, through the ingestion of unclean water, unpasteurized juice or milk, undercooked meats, or other possibly contaminated food. • Microbiologic isolation and identification of enteric pathogens or molecular detection. General Considerations The Enterobacteriaceae are a diverse family of bacteria that, in nature, exist in soil, on plant material, and in the intestines of humans and other animals. Another …

Continue Reading...

Streptococcus Dysgalactiae Subspp. Equisilimis & Streptococcus Zooepidemicus:Clinical Syndromes

1. PHARYNGITIS The symptoms of pharyngitis caused by these organisms mimic those of S pyogenes pharyngitis (Box 50-1; see also site). Poststreptococcal glomerulonephritis has been described following S dysgalactiae subspp. equisimilis and S zooepidemicus pharyngitis. Notably, however, no antistreptolysin O antibody response will be detected as these organisms do not produce streptolysin O. S dysgalactiae subspp. equisimilis pharyngitis has been associated with sterile reactive arthritis. Acute rheumatic fever, however, has not been described in association with S dysgalactiae subspp. equisimilis and S zooepidemicus pharyngitis. 2. SKIN & SOFT TISSUE INFECTIONS Cellulitis, wound infections, pyoderma, erysipelas, impetigo, and cutaneous ulcers can be caused by these organisms (see site). Breaches in skin integrity …

Continue Reading...
CLOSE
CLOSE