Articles on Medical Diseases and Conditions

Entries for the ‘Bacterial Infectious Diseases (Including Chlamydia, Mycoplasma, and Legionella Infections)’ Category

Antibiotic Removal

One of the major frustrations in microbiology is the interference to bacterial growth caused by previous administration of antibiotics. Culture growth inhibition may occur even if the organism is not sensitive to the antibiotic. Several antibiotic removal devices are now available, based on membrane filtration or resin adsorption. These are useful for liquid specimens such […]

Serum Bacteriostatic or Bacteriocidal Concentration (Schlichter Test)

In patients with bacterial endocarditis whose symptoms persist despite treatment, it is important to know whether antibiotic therapy really is effective in vivo. Also, some antibiotics, such as gentamicin, have a therapeutic range close to the toxic range. Blood levels of some antibiotics can be measured using various methods. This will provide some assurance that […]

Antibiotic Sensitivity Procedures

Disk diffusion method Antibiotic sensitivity testing is usually done using either the tube dilution or the agar diffusion (sometimes called “disk sensitivity”) technique. Of these, agar diffusion is by far the more common, and the Kirby-Bauer modification of this technique is the standard procedure. The Kirby-Bauer method involves (1) isolating a bacterial colony from its […]

Nosocomial Infections

A nosocomial infection is one that is acquired in a hospital. This subject is extremely important but cannot be covered in detail in a book that concentrates on laboratory tests. The most common cause of nosocomial infection is the indwelling urinary catheter. Some other important factors are surgery, long-term indwelling vascular catheters or equipment, conditions […]

Intraabdominal Abscess

Intraabdominal abscess is a recurrent problem that deserves attention. Some use the term “subphrenic” synonymously with intraabdominal, although most use the term subphrenic to refer only to abscess just below the diaphragm. The most common etiologies are postoperative complications of biliary tract or peptic ulcer surgery, penetrating abdominal trauma, and perforated appendix. Some 80%-90% of […]


The word pneumonia means inflammation of the lung. Although this could result from noninfectious sources (e.g., a chemical inflammation secondary to aspiration), the great majority of cases are due to bacterial or nonbacterial infectious agents. Almost any bacterium, many species of fungi, and many viruses could be associated with pneumonia under some circumstances. Except for […]

Infectious Diarrhea due to Bacterial Agents

Diarrhea caused by Clostridium difficile related to antibiotic therapy was discussed previously. Many cases of diarrhea produced by bacterial infection are also part of the spectrum of “food poisoning.” Clostridium botulinum generates a preformed neurotoxin and in adults is associated with improperly canned food. Usually there is no diarrhea. The organism was discussed earlier with […]

Infective Endocarditis

Endocarditis is infection of one or more heart valves, although infection of mural thrombi is usually included. The disease used to be separated into two types, acute and subacute. The acute type was most often caused by S. aureus, usually affected a normal heart valve, and had a relatively short severe course. Other bacteria less […]

Septicemia and Bacteremia

The concept of septicemia should probably be separated from that of bacteremia, although in many studies the two are not clearly separated. In bacteremia, a few bacteria from a focal area of infection escape from time to time into the peripheral blood. However, the main focus remains localized, and symptoms are primarily those that are […]

General Concepts in Bacterial Infection

The main systemic signs and symptoms of severe bacterial infection are fever and weakness. The most characteristic laboratory finding is leukocytosis, with an increase in number and immaturity of the neutrophils. However, in proven infection sometimes leukocytosis may be minimal or even absent, and occasionally fever may be minimal or may not be present (page […]