![]() Pharyngitis wound infections septicemiaīacteremia, endocarditis in injection drug users and immunocompromised patients lower respiratoryīacteremia and other infections in immunocompromised hostsĬatalase negative coccobacilli β-hemolytic Nontoxigenic strains-bacteremia, endocarditis Grayish white colonies multidrug resistant + +Ĭlub-shaped rods that form metachromatic granules black colonies on tellurite media Anaerobic bacteria are discussed in Chapter 21. The medically important genera of aerobic gram-positive bacilli are listed in Table 12-1. The genera include Listeria and Erysipelothrix these bacteria are more closely related to the anaerobic Lactobacillus species, which sometimes grow well in air, to the spore-forming Bacillus and Clostridium species-and to the gram-positive cocci of the Staphylococcus and Streptococcus genera-than they are to the coryneform bacteria. Other non–spore-forming gram-positive bacilli have more regular shapes and a lower guanosine plus cytosine content. Actinomyces and Propionibacterium are classified as anaerobes, but some isolates grow well aerobically (aerotolerant) and must be differentiated from the aerobic coryneform bacteria. These bacteria have a high guanosine plus cytosine content and include the genera Corynebacterium, Arcanobacterium, Mycobacterium, and others ( Table 12-1). + +Ĭorynebacterium species and related bacteria tend to be clubbed or irregularly shaped although not all isolates have the irregular shapes, the terms “coryneforms” or “diphtheroid bacteria” are convenient ones for denoting this broad group. Nocardia and Rhodococcus species are found in the soil and are significant pathogens among immunocompromised patients. ![]() Listeria monocytogenes and Erysipelothrix rhusiopathiae are primarily found in animals and occasionally cause severe disease in humans. However, among the aerobic gram-positive bacilli are significant pathogens such as Corynebacterium diphtheriae, an organism that produces a powerful exotoxin that causes diphtheria in humans, and Mycobacterium tuberculosis (see Chapter 23), the causative agent of tuberculosis. Specific genera of both groups, namely, Corynebacterium species and Propionibacterium species, are members of the normal microbiota of skin and mucous membranes of humans and, as such, are frequently contaminants of clinical specimens submitted for diagnostic evaluation. The anaerobic, non–spore-forming gram-positive bacilli such as Propionibacterium species and Actinomyces species are discussed in Chapter 21 on anaerobic infections. This chapter focuses on the aerobic members of this group. The non–spore-forming gram-positive bacilli are a diverse group of aerobic and anaerobic bacteria. ![]()
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