Streptococci, haemolytic

CqHqNj02S2. Whitc powder, m.p. 200-203 C. Sulphathiazole has the typical actions of sulphonamides, being effective against y -haemolytic Streptococci, Pneumococci, Gonococci and Staphylococci. 

Staphylococcus aureus is less sensitive to erythron rdn than are pneumococci or haemolytic streptococci, and there may be a rapid development of resistance, especially of staphylococci, in vitro. However, in vivo with successM short courses of treatment, resistance is not usually a serious clinical problem. On the other hand, resistance is likely to develop when the antibiotic is used for long periods. 

Sulphonamides were introduced by Domagk in 1935. It had been shown that a red azo dye, prontosil (Fig. 5.16B), had a curative effect on mice infected with /3-haemolytic streptococci it was subsequently found that in vivo, prontosil was converted into sulphanilamide. Chemical modifications of the nucleus of sulphanilamide (see Fig. 5.16A) e compounds with higher antibacterial activity, although this was often accompanied by greater toxicity. In general, it may be stated that the sulphonamides... 

Bacteria which are almost always sensitive to the sulphonamides include Strep, pneumoniae, /3-haemolytic streptococci, Escherichia coli and Proteus mirabilis those almost always resistant include Enterococcus faecalis, Ps. aeruginosa, indole-positive Proteus and Klebsiella whereas bacteria showing a marked variation in response include Staph, aureus, gonococci, El. influenzae and hospital strains of E. coli and Pr. mirabilis. 

Hyaluronidase and streptokinase are produced by the haemolytic streptococci and enable the organism to spread rapidly through the tissue. Hyaluronidase dissolves hyaluronic acid (intercellular cement), whereas streptokinase (Chapter 25) dissolves blood clots. 

Figure 1.1. Opposite) Sulpha drugs and their mode of action. The first sulpha drug to be used medically was the red dye prontosil rubrum (a). In the early 1930s, experiments illustrated that the administration of this dye to mice infected with haemolytic streptococci prevented the death of the mice. This drug, while effective in vivo, was devoid of in vitro antibacterial activity. It was first used clinically in 1935 under the name Streptozon. It was subsequently shown that prontosil rubrum was enzymatically reduced by the liver, forming sulphanilamide, the actual active antimicrobial agent (b). Sulphanilamide induces its effect by acting as an anti-metabolite with respect to /iflra-aminobenzoic acid (PABA) (c). PABA is an essential component of tetrahydrofolic acid (THF) (d). THF serves as an essential co-factor for several cellular enzymes. Sulphanilamide (at sufficiently high concentrations) inhibits manufacture of THF by competing with PABA. This effectively inhibits essential THF-dependent enzyme reactions within the cell. Unlike humans, who can derive folates from their diets, most bacteria must synthesize it de novo, as they cannot absorb it intact from their surroundings...

The majority of sepsis cases, especially the more severe forms, have bacterial etiologies. Common bacterial species include Staphylococcus aureus. Streptococcus pneumoniae, Escherichia coli. Salmonella typhi (and other enterobacterial species). Pseudomonas species and haemolytic streptococci in children Haemophilus influenzae and Neisseria meningitidis are important whereas nosocomial episodes of sepsis are frequently caused by Staphylococcus epidermidis. Streptococcus faecalis (syn. enterococci), yeasts and anaerobes. 

Rheumatic fever is now less common in developed countries, but in Hannah s youth it was an important cause of heart disease. The illness is due to infection with beta-haemolytic ( -haemolytic) streptococci, which cause a sore throat. In some young people, the bacterium induces antibody-mediated autoimmune responses, which initiate inflammatory changes in joints and heart valves, particularly in the mitral valve. Inflammation thickens and may partly fuse the cusps ofthe mitral valve, making it narrow and unable to close properly in ventricular systole. Eventually, cardiac output decreases and the ventricle begins to fail from overwork. Since blood is not pumped effectively from the left ventricle, pulmonary congestion develops. 

Streptokinase is a protein derived from p-haemolytic streptococci it forms a complex with plasminogen (bound loosely to fibrin) where it converts plasminogen to plasmin. Too rapid administration causes abrupt fall in blood pressure. The is 20 min. 

Staphylococcus aureus is less sensitive to erythromycin than are pneumococci or haemolytic streptococci, and there may be a rapid development... 

J Brown, LW Wannamaker, P Ferrieri. Enumeration of beta-haemolytic streptococci on normal skin by direct agar contact. J Med Microbiol 8(4) 503-511, 1975. 

Studies have shown that the pathogens responsible for diabetic foot infections are Staphylococcus aureus and beta haemolytic streptococci which respond to narrow spectmm antibiotics such as Flucloxacillin and cefalexin. However, progression in severity of infection will result in the emergence of bacteria such as Enterobacterium, Pseudomonas and obligate anaerobes, requiring a broader therapeutic target range. 

Another report about the treatment of pneumococcal meningitis with intramuscular or intravenous penicillin and intravenous tetracyclines (chlo-rtetracycline, oxytetracycUne, tetracycline) confirmed that the mortality was much lower in those given only penicillin, rather than the combination of penicillin and a tetracycline. fri the treatment of scarlet fever (Group A beta-haemolytic streptococci), no difference was seen in the initial response to treatment with penicillin (oral procaine benzylpenicillin) and chlortetracycUne or the penicillin alone, but spontaneous re-in-feetion occurred more frequently in those who had received both antibacterials. ... 

E-tests can be used to determine MIC for fastidious organisms such as Streptococcus pneumoniae, P-haemolytic streptococci, Neisseria gonorrhoeae, Haemophilus sp. and anaerobes. It can also be used for non-fermenting Gram-negative bacilli, e.g.. Pseudomonas sp. and Burkholderia pseudomallei. 

Figure 5.6 Structure of the Disaccharide Repeat Unit of Hyaluronic Acid the Capsular Polysaccharide of Group A Haemolytic Streptococci...

Some features of the primary structure and the complete amino-acid sequence of the lysozyme from a Chalaropsis species have been reported. The effects of body fluids and macromolecules on the lysis of group A Streptococci by Streptomyces albus lysozyme have been studied. The purification and characterization of S. albus lysozyme ( cnrfo-A-acetylmuramidase ), which degrades the cells of group A and other j8-haemolytic Streptococci, have been reported. ... 

P-haemolytic streptococci Rainbow trout Immersion/injection 70% Sakai eta/. (1987 1989)... 

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