Chapter 131. Diphtheria and Other Infections Caused by Corynebacteria and Related Species (Part 7)

Other Nondiphtherial CorynebacteriaC. xerosis is a human commensal found in the conjunctiva, nasopharynx, and skin. This nontoxigenic organism is occasionally identified as a source of invasive infection in immunocompromised or postoperative patients and prosthetic joint recipients. C. striatum is found in the anterior nares and on the skin, face, and upper torso of normal individuals. Also nontoxigenic, this organism has been associated with invasive opportunistic infections in severely ill orimmunocompromised patients. C. amycolatum is a new species isolated from human skin and is identified on the basis of a unique 16S ribosomal RNA sequence associated with opportunistic infection. C....
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Chapter 131. Diphtheria and Other Infections Caused by Corynebacteria and Related Species (Part 7) Chapter 131. Diphtheria and Other Infections Caused by Corynebacteria and Related Species (Part 7) Other Nondiphtherial Corynebacteria C. xerosis is a human commensal found in the conjunctiva, nasopharynx,and skin. This nontoxigenic organism is occasionally identified as a source ofinvasive infection in immunocompromised or postoperative patients and prostheticjoint recipients. C. striatum is found in the anterior nares and on the skin, face, andupper torso of normal individuals. Also nontoxigenic, this organism has beenassociated with invasive opportunistic infections in severely ill orimmunocompromised patients. C. amycolatum is a new species isolated fromhuman skin and is identified on the basis of a unique 16S ribosomal RNAsequence associated with opportunistic infection. C. glucuronolyticum is a newnonlipophilic species that causes male genitourinary tract infections such asprostatitis and urethritis. These infections may be successfully treated with a widevariety of antibacterial agents, including β-lactams, rifampin, aminoglycosides, orvancomycin; however, the organism appears to be resistant to fluoroquinolones,macrolides, and tetracyclines. C. imitans has been identified in Eastern Europe asa nontoxigenic cause of pharyngitis. C. auris has been isolated from children withotitis media and is susceptible to fluoroquinolones, rifampin, tetracycline, andvancomycin but resistant to penicillin G and variably susceptible to macrolides. C.pseudodiphtheriticum (C. hofmannii) is a nontoxigenic component of the normalhuman flora. Human infections—particularly endocarditis of either prosthetic ornative valves and invasive pneumonia—have been identified only rarely. AlthoughC. pseudodiphtheriticum may be isolated from the nasopharynx of patients withsuspected diphtheria, it is part of the normal flora and does not produce diphtheriatoxin. C. propinquum, a close relative of C. pseudodiphtheriticum, is part of CDCGroup ANF-3 and is isolated from human respiratory tract specimens and blood.C. afermentans subspecies lipophilum belongs to CDC Group ANF-1 and has beenisolated from human blood and abscess infections. C. accolens has been isolatedfrom wound drainage, throat swabs, and sputum and is typically identified as asatellite of staphylococcal organisms; it has been associated with endocarditis. C.bovis is a veterinary commensal that has not been clearly identified as a cause ofhuman disease. C. aquaticum is a water-associated organism that is occasionallyisolated from patients using medical devices (e.g., for chronic ambulatoryperitoneal dialysis or venous access). Rhodococcus Rhodococcus species are phylogenetically related to the corynebacteria.These gram-positive coccobacilli have been associated with tuberculosis-likeinfections in humans with granulomatous pathology. Although R. equi is bestknown, other species have been identified, including R. (also Gordonia)bronchialis, R. (also Tsukamurella) aurantiacus, R. luteus, R. erythropolis, R.rhodochrous, and R. rubropertinctus. R. equi has been recognized as a cause ofpneumonia in horses since the 1920s; it causes related infections in cattle, sheep,and swine. R. equi is found in soil as an environmental microbe. The organismsvary in length; appear as spherical to long, curved, clubbed rods; and producelarge, irregular mucoid colonies. R. equi does not ferment carbohydrates or liquefygelatin and is often acid fast. An intracellular pathogen of macrophages, R. equican cause granulomatous necrosis and caseation. The organism has been identifiedmost commonly in pulmonary infections, but infections of brain, bone, and skinhave also been reported. Most commonly, R. equi disease manifests as nodularcavitary pneumonia of the upper lobe—a picture similar to that seen intuberculosis or nocardiosis. Most patients are immunocompromised, often withHIV infection. Subcutaneous nodular lesions have also been identified. Theinvolvement of R. equi should be considered in any patient presenting with atuberculosis-like syndrome. Infection due to R. equi has been treated successfullywith antibiotics that penetrate intracellularly, including macrolides, clindamycin,rifampin, and trimethoprim-sulfamethoxazole. β-Lactam antibiotics have not beenuseful. The organism is routinely susceptible to vancomycin, which is consideredthe drug of choice. Actinomyces pyogenes A cause of seasonal leg ulcers in humans in rural Thailand, A. pyogenes is awell-known pathogen of cattle, sheep, goats, and pigs. A few human cases ofsepsis, endocarditis, septic arthritis, pneumonia, meningitis, and empyema havebeen repo ...