Anaerobes have been found in<unk> s throughout the human body. The frequency of the host or patient's recovery depends on the employment of proper methods of collection of specimen, their transportation to the microbiology laboratory and cultivation. The recovery of organisms depends on the site of<unk>  and is related to the adjacent mucous membranes microbial flora. Central nervous system Anaerobes are able to cause all types of intracranial<unk> s. These often cause subdural empyema, and brain abscess, and rarely cause epidural abscess and meningitis. The origin of brain abscess is generally an adjacent chronic ear, mastoid, or sinus<unk>  oropharynx, teeth or lungs. Mastoid and ear or<unk> s generally progress to the temporal lobe or cerebellum, while facial sinusitis commonly causes frontal lobe abscess. Hematogenous spread of the<unk>  into the CNS often occurs after oropharyngeal, dental, or pulmonary<unk> . Infrequently bacteremia originating of another location or endocarditis can also cause intracranial<unk> . Meningitis due to<unk>  bacteria is infrequent and may follow respiratory tract<unk>  or complicate a cerebrospinal fluid shunt. Neurological shunt<unk> s are often caused by skin bacteria such as Cutibacterium acnes, or in instances of ventriculoperitoneal shunts that perforate the gut, by anaerobes of enteric origin (i.e. Bacteroides fragilis).Clostridium perfringens can cause of brain abscesses and meningitis following intracranial surgery or head trauma. The anaerobes often isolated from brain abscesses complicating respiratory and dental<unk> s are<unk>  Gram-negative bacilli (AGNB, including Prevotella, Porphyromonas, Bacteroides), Fusobacterium and Peptostreptococcus spp. Microaerophilic and other streptococci are also often isolated. Actinomyces are rarely isolated. At the stage of encephalitis, antimicrobial therapy and utilization of measures to lower the increase in the intracranial pressure can prevent the formation of an intracranial abscess However, after an abscess has emerged, surgical removal or drainage may be necessary, along with an extended course of antimicrobial therapy (4–8 weeks). Some advocate complete drainage of intracranial abscess, while others use repeated aspirations of the abscess., Repeated aspirations of an abscess are preferable in those with multiple abscesses or when the abscess is located in a predominate brain site. Administration of antimicrobials in a high-dose for an extended period of time can offer an alternative treatment strategy in this type of patients and may substitute for surgical evacuation of an abscess. Because of the poor penetration of many antimicrobial agents through the blood–brain barrier, there are few agents available for the treatment of intracranial<unk> s. The antimicrobials with good intracranial penetration are metronidazole, chloramphenicol, penicillins, and meropenem. Optimally, the selection of antimicrobial is done according to the recovered isolates and their antimicrobial susceptibilities. A substantial improvement in patients' survival rate has occurred after the introduction of computed tomography (CT) and other scans and utilization of metronidazole therapy. Upper respiratory tract and head and neck<unk> s Anaerobes can be isolated from most types of upper respiratory tract and head and neck<unk> , and are especially common in chronic ones. These include tonsillar, peritonsillar and retropharyngeal abscesses, chronic otitis media, sinusitis and mastoiditis, eye ocular)<unk> s, all deep neck space<unk> s, parotitis, sialadenitis, thyroiditis, odontogenic<unk> s, and postsurgical and nonsurgical head and neck wounds and abscesses., The predominant organisms are of oropharyngeal flora origin and include AGNB, Fusobacterium and Peptostreptococcus spp. Anaerobes involve almost all dental<unk> s. These include dental abscesses, endodontal pulpitis and periodontal (gingivitis and periodontitis)<unk> s, and perimandibular space<unk> . Pulpitis can lead to abscess formation and eventually spread to the mandible and other neck spaces. In addition to strict<unk>  bacteria, microaerophilic streptococci and Streptococcus salivarius can also be present. Fusobacterium spp. and<unk>  spirochetes are often the cause of acute necrotizing ulcerative gingivitis (or Vincent's angina) which is a distinct form of ulcerative gingivitis. Deep neck<unk> s that develop as a consequence of oral, dental and pharyngeal<unk> s are generally polymicrobial in nature. These include extension of retropharyngeal cellulitis or abscess, mediastinitis following esophagus perforation, and dental or periodontal abscess. Lung<unk> s In adults the most common source of aspiration pneumonia is aspiration of oropharyngeal secretions or gastric contents. In children the most common cause is aspiration of infected amniotic fluid, or vaginal secretions. Severe periodontal or gingival diseases are important risk factors for establishment of an<unk>  pleuropulmonary<unk> . Progression of the<unk>  from pneumonitis into necrotizing pneumonia and pulmonary abscess can occur, with or without the development of empyema., The<unk>  is often polymicrobial in nature and isolates of community-acquired<unk>  (in 60–80% of cases) are aerobic and<unk>  belonging to the individual's oropharyngeal flora. The<unk>  bacteria commonly recovered are Prevotella, Porphyromonas, Fusobacterium and Peptostreptococcus spp., and the aerobic bacteria are beta-hemolytic and microaerophilic streptococci.<unk>  bacteria can also be isolated in about 35% of individuals who suffer from nosocomial-acquired aspiration pneumonia and pneumonia associated with tracheostomy with and without mechanical ventilation, where they are often isolated along with Enterobacteriaceae, Pseudomonas spp. and Staphylococcus aureus. It is important that specimens are obtained in a method that avoids their contamination by the oral micro flora. Abdominal<unk> s Secondary peritonitis and intra-abdominal abscesses including splenic and hepatic abscesses generally occur because of the entry of enteric micro-organisms into the peritoneal cavity through a defect in the wall of the intestine or other viscus as a result of obstruction, infarction or direct trauma. Perforated appendicitis, diverticulitis, inflammatory bowel disease with perforation and gastrointestinal surgery are often associated with polymicrobial<unk> s caused by aerobic and<unk>  bacteria, where the number of isolates can average 12 (two-thirds are generally anaerobes). The most common aerobic and facultative bacteria are Escherichia coli, Streptococcus spp. (including Enterococcus spp.), and the most frequently isolated<unk>  bacteria are the B. fragilis group, Peptostreptococcus spp., and Clostridium spp. Abdominal<unk> s are characteristically biphasic: an initial stages of generalized peritonitis associated with Escherichia coli sepsis, and a later stages, in which intra abdominal abscesses harboring<unk>  bacteria ( including B. fragilis group ) emerge. The clinical manifestations of secondary peritonitis are a reflection of the underlying disease process. Fever, diffuse abdominal pain, nausea and vomiting are common. Physical examination generally show signs of peritoneal inflammation, isuch as rebound tenderness, abdominal wall rigidity and decrease in bowel sounds. These early findings may be followed by signs and symptoms of shock. Biliary tract<unk>  is usually caused by E. coli, Klebsiella and Enterococcus spp. Anaerobes (mostly B. fragilis group, and rarely C. perfringens) can be recovered in complicated<unk> s associated with carcinoma, recurrent<unk> , obstruction, bile tract surgery or manipulation. Laboratory studies show elevated blood leukocyte count and predominance of polymorphonuclear forms. Radiographs studies may show free air in the peritoneal cavity, evidence of ileus or obstruction and obliteration of the psoas shadow. Diagnostic ultrasound, gallium and CT scanning may detect appendiceal or other intra-abdominal abscesses. Polymicrobial postoperative wound<unk> s can occur. Treatment of mixed aerobic and<unk>  abdominal<unk> s requires the utilization of antimicrobials effective against both components of the<unk>  as well as surgical correction and drainage of pus. Single and easily accessible abscesses can be drained percutaneously. Female genital<unk> s Female genital tract<unk> s caused by<unk>  bacteria are polymicrobial and include: soft-tissue perineal, vulvar and Bartholin gland abscesses; bacterial vaginosis; endometritis; pyometra; salpingitis; adnexal abscess; tubo-ovarian abscesses; intrauterine contraceptive device-associated<unk> ; pelvic inflammatory disease, which may include pelvic cellulitis and abscess; amnionitis; septic pelvic thrombophlebitis; septic abortion; and postsurgical obstetric and gynecologic<unk> s., Getting adequate microbiological cultures is essential. It is important to avoid contaminating the culture with the normal genital flora. Methods that can ensure adequate cultures are laparoscopy, culdocentesis, or obtaining quantitative endometrial cultures employing a telescoping catheter. The anaerobes often recovered include Prevotella bivia, Prevotella disiens, and Peptostreptococcus, Porphyromonas and Clostridium spp. Bacteroides fragilis group is rarely recovered in these<unk> s compared to intra-abdominal<unk> . Actinomyces spp. and Eubacterium nodatum are often recovered in<unk> s associated with intrauterine devices. Mobiluncus spp. can be associated with bacterial vaginosis. The aerobic bacteria also found mixed with these<unk>  bacteria include Enterobacteriaceae, Streptococcus spp. (including groups A and B), Neisseria gonorrhoeae, Chlamydia spp. and Mycoplasma hominis. Free gas in the tissues, abscess formation and foul-smelling discharge is commonly associated with the presence of<unk>  bacteria. Treatment of these<unk> s includes the use of antimicrobials active against all of the potential aerobic and<unk>  bacterial pathogens. Antimicrobials against sexually transmissible pathogens should also be administered. Skin and soft-tissue<unk> s The<unk> s that frequently involve<unk>  bacteria include superficial<unk> s, including infected paronychia, infected human or animal bites, cutaneous ulcers, cellulitis, pyoderma, and hidradenitis suppurativa. Secondary infected sites include secondary infected diaper rash, gastrostomy or tracheostomy site wounds, scabies or kerion<unk> s, eczema, psoriasis, poison ivy, atopic dermatitis, eczema herpeticum, infected subcutaneous sebaceous or inclusion cysts, and postsurgical wound<unk> . Skin involvement in subcutaneous tissue<unk> s includes: cutaneous and subcutaneous abscesses, breast abscess, decubitus ulcers, infected pilonidal cyst or sinus, Meleney's ulcer infected diabetic (vascular or trophic) ulcers, bite wound,<unk>  cellulitis and gas gangrene, bacterial synergistic gangrene, and burn wound<unk> . Deeper<unk>  soft-tissue<unk> s are necrotizing fasciitis, necrotizing synergistic cellulitis, gas gangrene and crepitus cellulitis. These can involve the fascia
Anaerobic infection
Fungal infection
Odontogenic infection
Protozoan infection
Antibiotic synergy
Electrolyte exclusion effect
Opportunistic infection
Viral disease