Streptococci 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. 

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. 

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). 

Clarithromycin is better absorbed and irritates the gastrointestinal tract less than erythromycin. It is presumed that its activity exceeds that of erythromycin by 2-4 times with respect to a number of streptococci and staphylococci, and to a few other microorganisms. It is used for treating bacterial bronchitis, pneumonia, skin and sexual infections. It is believed that clarithromycin is the most active macrolide for treating atypical mycobacteria. Synonyms of this drug are biaxin and others. 

This drug is effective for infections caused by streptococci, gonococci, pneumococci, staphylococci, and also colon bacillus. Sulfacytine is used for pneumonia, cerebral meningitis, staphylococcal and streptococcal sepsis, and other infectious diseases. A synonym of this drug is renoquid. 

Complicated intra-abdominal infections (used in combination with metronidazole) caused by E. coli, viridans group streptococci, P. aeruginosa, K. pneumoniae, Enterobacter spec es, or Bacteroides fragilis. 

Intra-abdominal infections Complicated appendicitis and peritonitis caused by viridans group streptococci, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bacterioides fragilis, Bacterioides thetaiotaomicron, and Peptostreptococcus sp. 

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. 

Erythromycin is effective in the treatment and prevention of S. pyogenes and other streptococcal infections, but not those caused by the more resistant fecal streptococci. Staphylococci are generally susceptible to erythromycin, so this antibiotic is a suitable alternative drug for the penicillin-hypersensitive individual. It is a second-line drug for the treatment of gonorrhea and syphilis. Although erythromycin is popular for the treatment of middle ear and sinus infections, including H. influenzae, possible erythromycin-resistant S. pneumoniae is a concern. 

Clindamycin is indicated for the treatment of skin and soft-tissue infections caused by streptococci and staphylococci. It is often active against community-acquired strains of methicillin-resistant S aureus, an increasingly common cause of skin and soft tissue infections. Clindamycin is also indicated for treatment of anaerobic infection caused by bacteroides and other anaerobes that often participate in mixed infections. Clindamycin, sometimes in combination with an aminoglycoside or cephalosporin, is used to treat penetrating wounds of the abdomen and the gut infections originating in the female genital tract, eg, septic abortion and pelvic abscesses and aspiration pneumonia. Clindamycin is now recommended rather than erythromycin for prophylaxis of endocarditis in patients with valvular heart disease who are undergoing certain dental procedures. Clindamycin plus primaquine is an effective alternative to trimethoprim-sulfamethoxazole for moderate to moderately severe Pneumocystis jiroveci pneumonia in AIDS patients. It is also used in combination with pyrimethamine for AIDS-related toxoplasmosis of the brain. 

Sulfonamides are infrequently used as single agents. Many strains of formerly susceptible species, including meningococci, pneumococci, streptococci, staphylococci, and gonococci, are now resistant. The fixed-drug combination of trimethoprim-sulfamethoxazole is the drug of choice for infections such as Pneumocystis jiroveci (formerly P carinii) pneumonia, toxoplasmosis, nocardiosis, and occasionally other bacterial infections. 

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