Streptococci pathogenicity

Haemolysins are produced by most of the pathogenic staphylococci and streptococci. They have a lytie effeet on red blood eells, releasing iron-containing nutrients. 

The treatment of bacterial infections of the central nervous system highlights a number of important therapeutic considerations. Bacterial meningitis is caused by a variety of bacteria although their incidence varies with age. In the neonate, E. coli and group B streptococci account for the majority of infections, while in the preschool child H. influenzae is the commonest pathogen. Neisseria meningitidis has a... 

Bacterial resistance to antibiotics has been recognized since the first drugs were introduced for clinical use. The sulphonamides were introduced in 1935 and approximately 10 years later 20% of clinical isolates of Neisseria gonorrhoeae had become resistant. Similar increases in sulphonamide resistance were found in streptococci, coliforms and other bacteria. Penicillin was first used in 1941, when less than 1 % of Staphylococcus aureus strains were resistant to its action. By 1947,3 8% of hospital strains had acquired resistance and currently over 90% of Staph, aureus isolates are resistant to penicillin. Increasing resistance to antibiotics is a consequence of selective pressure, but the actual incidence of resistance varies between different bacterial species. For example, ampicillin resistance inEscherichia coli, presumably under similar selective pressure as Staph, aureus with penicillin, has remained at a level of 30-40% for mai years with a slow rate of increase. Streptococcus pyogenes, another major pathogen, has remained susceptible to penicillin since its introduction, with no reports of resistance in the scientific literature. Equally, it is well recognized that certain bacteria are unaffected by specific antibiotics. In other words, these bacteria have always been antibiotic-resistant. 

Leucocidins kill leucocytes and are produced by many strains of streptococci, most strains of Staphylococcus aureus and likewise most strains of pathogenic Gram-negative bacteria, isolated from sites of infection. 

Mutans streptococci are the major pathogenic organisms of dental caries in humans. The pathogenicity is closely related to production of extracellular, water-insoluble glucans from sucrose by glucosyltransferase and acid release from various fermentable sugars. Poly(catechin) obtained by HRP catalyst in a phosphate buffer (pH 6) markedly inhibited glucosyltransferase from Streptococcus sorbrinus 6715, whereas the inhibitory effect of catechin for this enzyme was very low. 

The most common pathogens in bacterial keratitis are Pseudomonas (including Pseudomonas aeruginosa) and other gram-negative rods, staphylococci, and streptococci. If the keratitis is related to the use of contacts, Pseudomonas is the most common cause followed by Serratia marcescens. For hospitalized infants and adults on respirators, Pseudomonas is the most common.19... 

If conventional treatment fails, unresolved diaper rash can also lead to secondary bacterial infections. Staphylococcus aureus and streptococci are the most likely pathogens responsible for these infections and require treatment with systemic antibiotics.3 37 While topical protectants may be used as an adjunct in treatment, suspected bacterial infections should always be referred to a physician for accurate diagnosis and the selection of an appropriate antibacterial regimen.34 Figure 62-7 shows a useful algorithm for the effective treatment of diaper dermatitis. 

Recognizing the presumed site of infection and most common pathogens associated with the infectious source should guide antimicrobial choice, dose, and route of administration. For example, community-acquired pneumonia is caused most commonly by S. pneumoniae, E. coli is the primary cause of uncomplicated UTIs, and staphylococci and streptococci are implicated most frequently in skin and skin-structure infections (e.g., cellulitis). 

The pathogenesis of diabetic foot infection stems from three key factors neuropathy, angiopathy, and immunopathy. Aerobic gram-positive cocci, such as S. aureus and P-hemolytic streptococci, are the predominant pathogens in acutely infected diabetic foot ulcers. However, chronically infected wounds are subject to polymicrobial infection and require treatment with broad-spectrum antibiotics. 

Enteric gram-negative bacilli, anaerobes, group B streptococci, and enterococci are all possible pathogens that may... 

Given the diversity of disease-causing organisms, the interactions between farm-specific environmental factors and the types of mastitis causing pathogens found, the potential efficacy of antibiotic treatments can only be assessed accurately in the context of the specific on-farm conditions. Furthermore, many recent investigations concluded that, except for some specific infections caused by streptococci, a prophylactic and or longer-term use of antibiotics for chronic and sub-clinical mastitis should not recommended in the future (Deluyker et al., 2005). 

It is now recognized that opiates reduce resistance to a variety of infectious agents in both humans and animals. These effects are summarized in Table 30.3 and Table 30.4 and discussed below. For example, pulmonary infections caused by mycobacteria, staphylococci, streptococci, Hemophilus and other common organisms are frequent among opium abusers.23 24 Other infectious diseases caused by microbial pathogens in... 

Likewise, for zinc, bacteria have developed active uptake systems (Hantke, 2001). In many bacteria the high-affinity Zn2+ uptake system uses an ABC transporter of the cluster 9 family, which mostly transports zinc and manganese and is found in nearly all bacterial species. First identified in cyanobacteria and pathogenic streptococci, but also found in E. coli, the system is encoded by three genes ZnuABC and consists of an outer membrane permease ZnuB, a periplasmic-binding protein ZnuA and a cytoplasmic ATPase ZnuC. Low-affinity transporters of the ZIP family, described later in this chapter, such as ZupT, have also been shown to be involved in bacterial zinc uptake. 

Since direct studies and calculations of the survival rate of the specific pathogenic agents and viruses is complex and excessively laborious, we evaluated the possibility of risks to hygiene by means of indices of fecal contamination (streptococci and coliforms). 

Coffin, D. L.. and E. J. Blommer. Alteration of the pathogenic role of streptococci group C in mice conferred by previous exposure to ozone, pp. 54-61. In I. H. Silver. Ed. Aerobiology. Proceedings of the Third International Symposium held at the University of Sussex, England. 1%9. New York Academic Press, 1970. 

It is 2-A times less active than erythromycin with respect to a number of streptococci and staphylococci, and to a number of other organisms however, it is more active than other macrolides with respect to certain anaerobic organisms. Like other macrolides, it is active with respect to pathogens of the respiratory tract and pathogens transmitted sexually. It is used for treating bacterial bronchitis, pneumonia, skin, and sexual infections. Synonyms of this drug are zithromax and others. 

This drag has antibacterial activity with respect to streptococci, pneumococci, staphylococci, meningococci, gonococci, colon bacillus, pathogenic dysentery, and others. It is not very toxic. It is generally used for acute, uncomplicated infections of the urinary tract that... 

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