Many bacteria exist in the human being as normal flora, often in large numbers and in many areas (eg. As in the gastrointestinal tract). Only a few species of bacteria are pathogenic to humans.
Bacteria are microorganisms that circular double-stranded DNA, and (except for mycoplasma) possess cell walls. Most bacteria live extracellular. Some bacteria (. Eg Salmonella typhi, Neisseria gonorrhoeae, Legionella, Mycobacterium, Rickettsia, Chlamydia and Chlamydophila spp.) Live and multiply but preferably intracellularly. Some bacteria, such as Chlamydia, Chlamydophila sp. and rickettsia, are obligate intracellular pathogens (i. e. they are only within the host cells able to grow, reproduce, and to cause disease). Other (eg. As Salmonella typhi, Brucella sp, Francisella tularensis, N. gonorrhoeae, N. meningitidis, Legionella and Listeria spp., Mycobacterium tuberculosis) are facultative intracellular pathogens. Many bacteria exist in the human being as normal flora, often in large numbers and in many areas (eg. As in the gastrointestinal tract). Only a few species of bacteria are pathogenic to humans. The bacteria are classified by the following criteria (see Table: Classification of common pathogenic bacteria). Morphology bacteria can be Cylindrical (bacilli) Spherical (cocci) Spiral (spirochete) Few coccoid, many rod-shaped and most spirochetal species are mobile. The most common dye staining for the general identification of bacteria is the Gram stain. Gram-positive bacteria stain after Jodfixation, discoloration with alcohol and counter-staining with Safranin crystal violet (appears as a dark blue); Gram-negative bacteria that do not retain crystal violet color, appear red. Gram-negative bacteria have an additional outer membrane that contains lipopolysaccharide (endotoxin) and can increase the virulence of this bacteria. (For other virulence factors that enhance bacterial pathogenicity factors that facilitate microbial invasion.) The Ziehl-Neelsen and Kinyoun staining are acid-fast stains that are used primarily to identify mycobacteria, particularly M. tuberculosis. You can also Nocardia and Cryptosporidia ssp. identify. Carbol is applied, and then decolorized with hydrochloric acid and ethanol. The following is a counter-staining with methylene blue. Fluorochrome (z. B. auramine-rhodamine) also identify acid-fast organisms, but a special fluorescence microscope is required. Encapsulation Some bacteria are enclosed in capsules; for some encapsulated bacteria (eg. B. Streptococcus pneumoniae, Haemophilus influenzae) is helpful, the capsule in order to protect them from uptake by phagocytes. The encapsulation increases the bacterial virulence. Oxygen Demand Aerobic bacteria (obligate aerobic) need O2 to generate energy and to grow in culture. They produce energy through aerobic cellular respiration Anaerobic bacteria (obligate anaerobes overview of Anaerobic bacteria) do not need O2 and do not grow in culture when air is present. They produce energy by means of fermentation or anaerobee breathing. Anaerobic bacteria are common in the gastrointestinal tract, in the vagina in cervical areas and in wounds, if they are poor circulation. Facultative bacteria can grow with or without O2. They produce energy by fermentation or anaerobic respiration if O2 is absent and when O2 is available by aerobic cellular respiration. Microaerophilic bacteria prefer a reduced O2 tension (z. B. 2-10%). Chlamydia are obligate intracellular pathogens that acquire energy from the host cell and not make them yourself. Classification of common pathogenic bacteria type bacteria obligately aerobic Gram-negative cocci, Moraxella catarrhalis, Neisseria gonorrhoeae, N. meningitidis Gram-positive bacteria Corynebacterium jeikeium acid fast bacteria Mycobacterium avium complex, M. kansasii, M. leprae, M. tuberculosis, Nocardia sp Fermenters, non-enteric bacteria Acinetobacter calcoaceticus, Elizabethkingia meningoseptica (formerly Flavobacterium meningosepticum), Pseudomonas aeruginosa, P. alcaligenes, other Pseudomonas sp, Stenotrophomonas maltophilia sensitive gram-negative bacilli and coccoid rods Brucella, Bordetella, Francisella, and Legionella spp. Treponemataceae (spiral bacteria) Leptospira sp Obligate anaerobic Gram-negative rods Bacteroides fragilis, other Bacteroides sp, Fusobacterium sp, Prevotella sp Gram-negative cocci, Veillonella sp Gram-positive cocci Peptococcus niger, Peptostreptococcus sp non-spore forming gram-positive bacilli Actinomyces, Bifidobacterium, Eubacteri order and Propionibacterium spp. Endospore-forming gram-positive bacilli Clostridium botulinum, C. perfringens, C. tetani, other Clostridium sp facultative anaerobic gram-positive cocci, catalase-positive Staphylococcus aureus (koagulasepositiv), S. epidermidis (koagulasenegativ), other coagulase-negative staphylococci Gram-positive cocci, catalase negative Enterococcus faecalis, E. faecium, Streptococcus agalactiae (group B Streptococcus), S. bovis, S. pneumoniae, S. pyogenes (group A Streptococcus), Streptococcus viridans group (S. mutans, S. mitis, S. salivarius, S. sanguis), S. anginosus group (S. anginosus, S. mil leri, S. constellatus), Gemella morbillorum Gram positive rods of Bacillus anthracis, Erysipelothrix rhusiopathiae, Gardnerella Gram Negative vaginalis (gram variable) rods Enterobacteriaceae (Citrobacter sp aerogenes Enterobacter, Escherichia coli, Klebsiella sp, Morganella morganii, Proteus sp, Plesiomonas shigelloides, Providencia rettgeri, Salmonella typhi, other Salmonella sp, Serratia marcescens, Shigella sp, Yersinia enterocolitica, Y. pestis) fermenter, non-enteric bacteria Aeromonas hydrophila, Chromobacterium violaceum, Pasteurella multocida henselae susceptible Gram negative coccoid bacteria and chopsticks Actinobacillus actinomycetemcomitans, Bartonella bacilliformis, B., B. quintana, Eikenella corrodens, Haemophilus influenzae, other Haemophilus sp Mycoplasma Mycoplasma pneumoniae Treponemataceae (spiral bacteria) Borrelia burgdorferi, Treponema pallidum Microaerophilic Curved bacteria Campylobacter jejuni, Helicobacter pylori , Vibrio cholerae, V. vulnificus Obligate intracellular parasitic Chlamydiaceae Chlamydia trachomatis, Chlamydophila pneumoniae, C. psittaci Coxiellaceae Coxiella burnetii Rickettsia rickettsia prowazekii, R. rickettsii, R. typhi, R. tsutsugamushi, Ehrlichia chaffeensis, Anaplasma phagocytophila