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Gram stain (Gram staining or Gram's method), is a method of staining used to classify bacterial species into two large groups: gram-positive bacteria and gram-negative bacteria. It may also be used to diagnose a fungal infection. [1] The name comes from the Danish bacteriologist Hans Christian Gram, who developed the technique in 1884. [2]
A Gram stain is performed to show Gram-positive cocci in chains. Then, the organism is cultured on blood agar . The rapid pyrrolidonyl arylamidase (PYR) test is commonly used, wherein a positive reaction confers a presumptive identification of group A beta-hemolytic streptococci if the appearance and clinical context is consistent.
IAP has been considered to be associated with the emergence of resistant bacterial strains and with an increase in the incidence of early-onset infections caused by other pathogens, mainly Gram-negative bacteria such as Escherichia coli. Nevertheless, most studies have not found an increased rate of non-GBS early-onset sepsis related to the ...
The term "atypical" does not relate to how commonly these organisms cause pneumonia, how well it responds to common antibiotics or how typical the symptoms are; it refers instead to the fact that these organisms have atypical or absent cell wall structures and do not take up Gram stain in the same manner as gram-negative and gram-positive ...
Both gram-positive and gram-negative bacteria commonly have a surface layer called an S-layer. In gram-positive bacteria, the S-layer is attached to the peptidoglycan layer. Gram-negative bacteria's S-layer is attached directly to the outer membrane. Specific to gram-positive bacteria is the presence of teichoic acids in the cell wall. Some of ...
If Gram-negative, oxidase-positive diplococci are visualized on direct Gram stain of urethral pus (male genital infection), no further testing is needed to establish the diagnosis of gonorrhea infection. [40] [41] However, direct Gram stain of cervical swabs is not useful because the N. gonorrhoeae organisms are less concentrated in these samples.
GBS infections in adults include urinary tract infection, skin and soft-tissue infection (skin and skin structure infection) bacteremia, osteomyelitis, meningitis and endocarditis. [6] GBS infection in adults can be serious and related with high mortality. In general penicillin is the antibiotic of choice for treatment of GBS infection.
Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. [1] Their defining characteristic is that their cell envelope consists of a thin peptidoglycan cell wall sandwiched between an inner ( cytoplasmic ) membrane and an outer ...