Streptococci Streptococcus pneumoniae

As the name implies, these organisms grow in pairs, otherwise they are similar to streptococci and are now referred to as streptococci. Streptococcus pneumoniae is the causal agent of acute lobar pneumonia and also of meningitis, peritonitis and conjunctivitis. This organism can also initiate an invasive infection. 

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. 

The streptococci are the other group of gram-positive cocci that cause ocular infections morphologically, they are arranged in chains. This group includes Streptococcus pneumoniae (morphologically seen as diplococci), which causes corneal ulcers and pediatric conjunctivitis. 

Some streptococci have developed a different mechanism of acquired resistance to penicillin drugs. These bacteria have altered transpeptidases (also known as penicillin-binding proteins) that no longer bind penicillin, and thus peptidoglycan synthesis is not disrupted. This mechanism of resistance is found in Streptococcus pneumoniae. Estimates of penicillin-resistant S. pneumoniae in the United States range from 25% to 66%, including strains recovered from ocular and periocular infections. Many isolates of penicillin-resistant S.pneumoniae also are resistant to the cephalosporins, macrolides, and the older fluoroquinolones. Use of alternative antibiotics such as vancomycin is necessary for infections caused by penicillin-resistant isolates. 

Streptococcus pneumoniae was isolated in 30% of 40 HIV-infected and 50% of 162 HIV-negative children living in a Romanian orphanage (57). Multidrug-resistant streptococci were highly prevalent, and 21% of the isolates were resistant to chloramphenicol. 

An area of increasing concern and clinical importance is the increasing macrohde resistance that has been reported over the last several years with some of the common pathogens, particularly Streptococcus pneumoniae, group A streptococci, and Haemophilus influenzae, and may result in failure of therapy of pneumonia, phar5mgitis, and skin infections (54). High rates of resistance of several groups of streptococci to macrohdes have been reported from all parts of the world (55-64). 

Maaolides are appropriate antibiotics for the management of respiratory tract infections because they are active against Streptococcus pneumoniae. Streptococcus pyogenes (group A streptococci), and atypical organisms such as Legionella pneumophila. Mycoplasma pneumoniae, and Chlamydia pneumoniae. The newer generation macrolides such as clar-... 

Since 1987, gram-positive organisms are the predominant pathogens in sepsis and septic shock, accounting for approximately 50% of all cases. The causes are Staphylococcus aureus, Streptococcus pneumoniae, coagulase-negative staphylococci, and enterococci. Streptococcus pyogenes and viridans streptococci are less commonly involved. ... 

In E. coli, UFAs are generated through the activity of FabA, which anaerobically introduces the double bond into a 10-carbon intermediate formed in the fatty acid biosynthetic pathway (Bloch, 1963, for a recent review see Mansilla et al., 2004). However, other bacteria lacking fab A synthesize UFAs under anoxic conditions. For example, Streptococcus pneumoniae compensates FabA absence with an enzyme called FabM, that is capable of isomerising the trans unsaturated bond of the key 10-carbon intermediate to its cA-isomer (Marrakchi et al., 2002). Nevertheless, FabM seems to be specific for streptococci indicating that there are new anaerobic pathways of UFAs synthesis to be discovered. 

Gram-positive staphylococci [5. aureus (ATCC 6538 and 29213), S. epi-dermidis (ATCC 12228), Staphylococcus hominis. Staphylococcus haemolyticus, and Staphylococcus saprophyticus]. Micrococcus luteus (ATCC 7468), and streptococci [Streptococcuspyogenes. Enterococcus faecalis (ATCC 29212), Enterococcus faecium, and Streptococcus pneumoniae]. 

Pneumococci Streptococcus pneumoniae) are soluble in bile and incubation at 37 °C for 15 minutes causes clearing of suspensions. The bile activates an autocatalytic enzyme and the test distinguishes various types of streptococci. 

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. 

Werno AM, Christner M, Anderson TP, Murdoch DR. Differentiation oi Streptococcus pneumoniae from nonpneumoeoeeal Streptococci of the Streptococcus mitis Group by matrix-assisted laser desorption ionization-time of flight mass speetrometry. J Clin Mierobiol. 2012 50(9) 2863-7. 

Gluck, U. and Gebbers, J.O. 2003. Ingested probiotics reduce nasal colonization with pathogenic bacteria (Staphylococcus aureus. Streptococcus pneumoniae, and beta-hemolytic streptococci). Am J Clin Nutr 77(2), 517-520. 

In addition to S. pneumoniae, the viridans group of streptococci is also developing resistance to penicillin through the same mechanism, altered penicillin-binding proteins. In contrast, resistance has not developed in Streptococcus pyogenes, and both penicillins G and V are antibiotics of choice for systemic infections caused by this organism. 

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