This group of diseases are infectious or infectious diseases caused by bacteria.There are two main classifications of bacteria. One is phenotypic classification, which is based onBacteriaFormbiochemical reaction And serum reaction.The other is to classify by nucleic acid research, that is, by analyzing the base composition of bacterial DNA, the size of the genome and the homology of DNA.The latter classification is very scientific, which makes some bacteria belong to or change their names.
There are various microorganisms on the body surface of normal people and in the cavity connected with the outside world, such as oral cavity, nasopharynx, intestinal tract, reproductive tract, etc. They are beneficial to the human body under the condition of normal immune function, and are called normal flora.Among them, Staphylococcus aureus, Epistaphylococcus aureus, Corynebacterium JKPropionibacterium acnesEtc.Those living in the mouth and pharynx are:Staphylococcus, alpha and beta hemolytic streptococcus, non hemolytic streptococcus, pneumococcusNeisseria, MoracataHaemophilusAnaerobic coccusLactobacillus、Diphtheria like bacilli, Eubacterium, Clostridium, BacteroidesCandida albicansEtc.People living in the intestinal tract (from the end of the jejunum to the colon) have E. coliEnterobacter aerogenes, ProteusPseudomonas aeruginosa, StaphylococcusEnterococcus, Clostridium perfringens, digestive coccus, digestive streptococcus, Bacteroides (mainly Bacteroides fragilis)BifidobacteriumEubacterium, Clostridium, Candida albicans, etc.The bacteria living in the vagina are: Lactobacillus, Diphtheria like bacteria, Bacteroides, Enterococcus, Escherichia coli, Neisseria, Anaerococcus, etc.
When the body's resistance is reduced, or the defense immune function is reduced due to various reasons (such as old age, diabetes, cirrhosis, tumor, blood disease, chemotherapy, radiotherapyImmunosuppressant, hormone and antibacterial drug application), the original normal resident bacteria or bacteria with low pathogenicity may invade other parts of the human body and cause infection, which is calledOpportunistic pathogen(Conditional pathogen)。These conditional pathogenic bacteria can be normal human flora, or people who usually do not cause disease in the environment, such as Escherichia coliPneumonia, Pseudomonas aeruginosaEnterobacteriaceae, Serratia, Salmonella, Staphylococcus aureus, Epistaphylococcus, Enterococcus, Aerobacter, Listeria, Nocardia, etc;It can also be candida, aspergillus, cryptococcus neoformans, mucor and other fungi.In addition, it can also be caused by some viruses or protozoa.[2]
clinical manifestation
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Clinically, a bacterium can infect different parts and cause different diseases. For example, Staphylococcus aureus can cause skin and soft tissue infections, as well as pneumonia, osteomyelitis, meningitis, sepsis or endocarditis;Enterotoxigenic Staphylococcus aureus can causefood poisoning；A staphylococcus aureus producing a special exotoxin (TSST-1) can causeToxic shock syndrome。In addition, different bacteria can cause similar clinical manifestations, such as E. coli, pneumonia bacillus, influenza bacillus, etc., which can cause pneumonia, meningitis, septicemia, etc;Staphylococcus aureus, alpha hemolytic and non hemolytic streptococci, enterococci, alkali producing bacteria, pseudomonas aeruginosa, etc. can all causeInfective endocarditis。
（3） Principle and method of serum bactericidal titre test and tube dilution methodDrug susceptibility testSame as.The test was conducted with the patient's serum after the treatment of antibiotics and the patient's own pathogenic bacteria. The maximum dilution of the patient's serum that can inhibit the growth of bacteria is the serum bactericidal titer.It is generally believed that the serum bactericidal titer above 1 ∶ 8 indicates that the treatment is effective, and below 1 ∶ 4, the treatment may fail.This test is of great reference significance for the prognosis of patients with severe infection (such as infective endocarditis) or those with granulocytopenia and sepsis.However, the pathogen must be obtained for this test.
（4） Bacteria βLactamaseActivity determination Many pathogenic bacteria can produce β - lactamase, which hydrolyzes penicillin andcephalosporinβ lactam ring in the structure, such as Staphylococcus aureus, Neisseria gonorrhoeae, and Influenza bacilli, etcampicillinResistance.Therefore, when the clinical laboratory conducts drug sensitivity tests on the above bacteria, it is of great reference significance for clinical drug selection to detect the production of bacterial β - lactamase.The determination methods include iodine method, microbial method, acidity (pH) method, etc;withCefnitrothiophene(nitrocefin or cefinase paper) method is the most sensitive and reliable, and the results can be known in a few minutes.
(V)Blood concentration monitoringOr therapeutic drug monitoring (TDM), the strength of drug action is directly proportional to the drug concentration in tissues and body fluids, and the latter is in parallel with the blood drug concentration, so the determination of blood drug concentration can be used as an indirect indicator of the drug concentration at the infection site.Therapeutic drug monitoring refers to the use of advanced and sensitive testing technology to determine the concentration of drugs in body fluids, especially in blood, to study the relationship between the concentration of drugs in blood and efficacy, toxicity, determine the optimal dose and interval between drug administration, improve drug efficacy and reduce adverse reactions.In the application of antibacterial drugs, blood drug concentration monitoring is mainly applicable to drugs with low therapeutic index and high toxicity, such asAminoglycosidesAntibioticsvancomycin, or there is or may be drug accumulation in the body when the newborn or infant uses chloramphenicol, or when the patient with renal function damage uses the antibacterial drugs excreted by the kidney.Sometimes high dose penicillin treatment must also be monitored to prevent the occurrence of“Penicilline encephalopathy "。
The methods for determining the blood concentration include microbiological methodradioimmunoassayEnzyme immunoassay, fluorescence immunoassay, gas chromatography and high performance liquid chromatography.The latter ones have the advantages of fast speed, high specificity and high sensitivity, but they also have certain disadvantages and limitations, requiring special equipment and instruments.
Treatment instructions
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Among the clinical isolates of Staphylococcus aureus and Staphylococcus epidermidis, more than 90% were resistant to penicillin G.Staphylococcus aureusCefothiopheneThe drug resistance rate was 20%~40%.The data of our hospital shows that staphylococcus aureus has a significant effect on erythromycin, tetracycline, chloramphenicolLincomycin、KanamycinandgentamicinThe resistance rate of Staphylococcus aureus to rifampicin and compound SMZ is about 70% or more, and about 30% of Staphylococcus aureus is resistant to rifampicin and compound SMZ.Staphylococcus aureusMethicillinThe incidence of drug-resistant strains in Shanghai was 5% and 24% before 1980 and 1986, respectively, but it could reach as high as 50-60% in some hospitals after the 1990s.Enterococcus showed high sensitivity to penicillin G, ampicillin and rifampicin, but most of them were resistant to other antibiotics.Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus were extremely sensitive to vancomycin, and there were few drug-resistant strains.
In intestinal bacteriaShigellaThe resistance to antibiotics is the most significant. In urban hospitals, Shigella is mostly resistant to sulfonamides, streptomycin, tetracycline and chloramphenicol, while it is resistant to ampicillin and chloramphenicolCarboxybenzyl penicillinThe drug resistance rate of SMZ was about 40%~80%, and it was sensitive to compound SMZ.The drug resistance of Sonnei is more serious than that of Fustella, but the drug resistance rate to gentamicin and kanamycin is generally less than 10%.Pipemidic acidnorfloxacinetc.QuinolonesAre very sensitive.
these yearsTyphoid bacillusThe resistance rate to chloramphenicol, ampicillin and SMZ-TMP was less than 10%.However, typhoid outbreaks caused by drug-resistant strains occurred in Jiangsu, Zhejiang, Jiangxi, Liaoning, Hubei, Guizhou and other provinces in the late 1980s, and more than 80% of the bacteria were resistant to the above antibiotics.In other Salmonella genera, typhimurium is often resistant to many antibiotics such as chloramphenicol, tetracycline, streptomycin, SMZ-TMP, ampicillin, etc., which can cause sporadic or epidemic infection in some provinces and cities;But fosfomycin, some broad-spectrum semi synthetic penicillinsCephalosporinsAnd new quinolones, among whichOfloxacin, Enoxacin and other drugs have achieved satisfactory results.
Enterobacteriaceae bacteria and Pseudomonas aeruginosa have different degrees of resistance to commonly used antibiotics. The resistance to ampicillin and carboxybenzycillin accounts for 65% - 100% and 15% - 60% respectivelyPiperacillinAbout 30% of the patients were drug resistant.New cephalosporins (second and third generation), especially the second generation cephalosporinsCefuroximeCefuroxime, cefotaxime, ceftriaxoneCeftazidime(ceftazidime) and cefoperazone have strong antibacterial activity against Enterobacteriaceae bacteria;The latter two also have strong effects on Pseudomonas aeruginosa, especially ceftazidimePseudomonasAcinetobacter spp. and glucose nonfermenting gram-negative bacilli also have good effects.The resistance rate of Gram negative bacilli to gentamicin is about 20%~40% (Pseudomonas aeruginosa 40%~50% or more);Bacterial effects on gentamicinTobramycin, sisomicin, and dibekacinAmikacinThe drug resistance rate of amikacin is mostly between 10% and 20%.
Pathogen treatment
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Drugs for bacterial diseases include antibiotics andChemosynthetic drugs, which mainly acts onGram positive bacteriaPenicillin G, procaine penicillin and penicillin V, macrolides (erythromycinMedimycin、Acetylspiramycin, columnar leucomycin, clarithromycin, azithromycin, etc., and the latter two also have good effects on legionella, mycobacterium, mycoplasma, chlamydia, and other pathogenic microorganisms), lincomycin (and clindamycin), vancomycin, and compound sulfa drugsTrimethoprimMixture SMZ-TMPSulfadiazineAnd trimethoprim mixture SD-TMP).Antibiotics acting on drug-resistant Staphylococcus aureus include: ① acting onPenicillinaseStaphylococcus aureus, such asOxacillin、Cloxacillin, Cefothiophene, Cefazolin, LincomycinClindamycin, aminoglycosides, fluoroquinolones, rifampicin, fosfomycin, etc.; ②Action on methicillin resistantstaphylococcusVancomycin, rifampicinCompound sulfamethoxazole, netilmicin, etc.
Antibacterial drugs mainly acting on gram-negative bacilli include aminoglycosides (kanamycin, gentamicin, amikacin, etc.), semi synthetic penicillin (ampicillinAmoxicillin, carbenicillin, piperacillin, etc.), second generation cephalosporins such as cefuroxime, third generation cephalosporins (cefotaximecefatriaxone, ceftazidime, cefoperazone, etc.) and fluoroquinolones (ciprofloxacin, ofloxacin, etc.).Acting on Pseudomonas aeruginosa and othersPseudomonasAminoglycosides, semi synthetic penicillin (carbenicillin, piperacillin, aloxicillin, etc.), ceftazidime, cefoperazone, aztreonamImipenem(imipenem, the mixture of imipenem and cilastatin, called tienam), fluoroquinolones, etc.
The drugs acting on anaerobic bacteria include metronidazole, clindamycin, penicillin G (ineffective against bacteroides), chloramphenicol, piperacillin, tienam, etc.
lucky charmCultivated bacterial diseases, such as bacterial haemorrhage, rotten cheeks, enteritis, red skin disease, vertical scale disease, printing disease, white skin disease, etc.All pathogens have one thing in common: they are conditional pathogens.
pathogeny
Only when the breeding density is too high and the management is improper, which causes the water body to deteriorate, the fish body to be injured, and the immunity to decline, the pathogenic bacteria will multiply in large numbers and invade the fish body to cause disease.Therefore, when preventing bacterial diseases, disinfectants should be used to disinfect the water body, and then beneficialMicrobial preparationMaintain a good water quality environment.At the same time, a series of comprehensive methods such as the use of biological enzymes, polysaccharide active additives to improve the self immunity of fish body, etc.
Prevention and control methods
The first aspect is the regulation and control of the water environment. Through beneficial microorganisms to inhibit the growth of harmful bacteria, some conditionally treated bacteria can be effectively controlledlucky charmBreeding provides a good environment for growth and development.
The second aspect is to improve the physical fitness of koi by feeding nutritional health care agents, so that they can have a strong resistance to environmental degradation[1]。The third aspect is to disinfect and sterilize the water body to reduce harmful bacteria and toxic substances in the water.
One last point: when the condition worsens and people do not eat, injection is also a good way to control bacteria.
