OVERVIEW
Secondary infection, also known as flora alternans, refers to the fact that in the process of using broad-spectrum antibiotics or combining antimicrobial drugs to treat infections, the original causative organisms are inhibited, but drug-resistant strains, such as Staphylococcus aureus, Candida albicans, etc., proliferate, resulting in aggravation of the condition or the emergence of new infections. Infections caused by its causative organisms include oral and digestive tract infections, lung infections, urinary tract infections, sepsis, etc. They are mostly seen in people who have applied broad-spectrum antimicrobial drugs for a long period of time, infants, the elderly, people with serious primary illnesses (e.g., malignant neoplasm, leukemia, diabetes mellitus, etc.), and people who have had major abdominal surgeries. The pathogenic bacteria of secondary infections are often resistant to a variety of antimicrobial drugs, coupled with a significant reduction in the body’s resistance due to the disease, often difficult to control and have a high morbidity and mortality rate.
Questions you may be concerned about
What is a secondary infection?
Dual infection, also called flora alternans, is a patient’s long-term use of broad-spectrum antibiotics, the body’s sensitive bacteria are inhibited, the insensitive bacteria in this case rapid reproduction and growth, resulting in the occurrence of dual infection.
When patients use broad-spectrum antibiotics or combine antimicrobial drugs due to the demand of the disease, the original sensitive bacteria are suppressed during the process of anti-infection, and the insensitive bacteria, such as Staphylococcus aureus, Candida albicans, etc., multiply, which aggravate the condition of the patients or lead to the emergence of new infections, such as digestive tract infections, lung infections, urinary tract infections, sepsis, which is the case of secondary infections.
This is a secondary infection. Secondary infections are mostly seen in long-term application of broad-spectrum antimicrobial drugs, infants, the elderly, patients with serious malignant tumors, leukemia, abdominal surgery, secondary infections of the pathogenic bacteria are often resistant to a variety of antimicrobial drugs, coupled with a decline in the body’s resistance, the condition will be more serious once the disease occurs.
When patients are treated with antimicrobial drugs and find that the primary symptoms and signs reappear or even intensify after a transient improvement, a secondary infection may have occurred, and blood and other body fluids should be re-collected for culture of germs, from which new causative organisms should be isolated and diagnosed as a secondary infection.
Once the diagnosis of secondary infection is made, it is important to go to the hospital promptly for treatment.
Causes
1. Long-term application of broad-spectrum antibacterial drugs
When long-term application of a variety of broad-spectrum antimicrobial drugs, the sensitive flora is inhibited and the uninhibited germs will multiply in large numbers.
2. Decrease of human resistance
Serious primary diseases, after major surgery, the application of adrenocorticotropic hormone and antimetabolic drugs can damage the body’s immune function, but also for the invasion of germs and secondary infections to create favorable conditions.
Symptoms
1. Oral infection
(1) Symptoms: tongue tingling, dry mouth, sore throat, difficulty in swallowing, decreased appetite, etc., which may be accompanied by stomatitis.
(2) Signs: Thrush is common, milky white plaque can spread to the oral mucosa, tongue, hard palate and pharynx, and in severe cases, it can spread to the trachea, esophagus and digestive tract. Tongue changes are more significant, mostly manifested as atrophic lingual inflammation, smooth tongue without moss, brick red color such as fresh beef; there are also hypertrophic lingual inflammation, tongue moss is very thick, tongue thorn hyperplasia.
2. Candida albicans enteritis and anal infection
Manifestation of watery stool or mucus stool, several times a day to more than ten times, without vomiting, abdominal pain is not obvious. Localized burning, pain, itching, etc., may be accompanied by anal fissure bleeding. Candida albicans infection can be complicated by bleeding or perforation of esophagus, duodenum or other intestinal segments.
3. Pseudomembranous enteritis
Clostridium difficile infection is common, manifested as a large number of watery stools, more than 10 times a day; stools often contain mucus, some have blood, a few can be discharged plaque-like pseudomembrane, accompanied by fever, abdominal pain, abdominal distension, nausea and vomiting. Severe patients can quickly appear dehydration, electrolyte disorders, circulatory failure, toxic megacolon, hypoproteinemia, and even ascites.
4. Alternating flora enteritis
Symptoms vary in severity, mostly manifested as watery diarrhea several times a day, occasionally dysentery-like symptoms.
5. Pneumonia
Fungal pneumonia symptoms are often not obvious, fever is not high or not fever, there may be cough, sputum, hemoptysis, etc., the lungs can be heard little rales; staphylococcus aureus pneumonia in children, the lesions can be involved in one side or both sides, often accompanied by obvious symptoms of intoxication and respiratory distress, the disease develops rapidly, rapid change, within a few hours can be a sudden deterioration in the signs and symptoms of the disease is not often parallel; gram-negative bacillus pneumonia is generally no characteristic Gram-negative bacillus pneumonia usually has no characteristic clinical manifestations.
6. Urinary tract infection
Most of them have fever, but the symptoms of urinary frequency and urgency are not obvious, and there may be pus urine.
7. Bloodstream infections
Clinical manifestations are not special, may be accompanied by migratory foci, brain, meninges, lungs, kidneys, liver, spleen, spine and other places can be involved. Fungal blood infections usually have a history of pulmonary, intestinal or urinary tract fungal infection.
Examination
1. Laboratory examination
(1) Blood count: elevated white blood cell count, elevated neutrophil ratio.
(2) Bacterial culture: new pathogenic bacteria are found.
(3) Urine routine: urinary tract infection may be manifested as pyuria.
(4) Stool routine: there may be an increase in the total number of white blood cells.
2. X-ray examination
Patients with pneumonia may have shadows in the lungs.
3. Fiber colonoscopy
Mostly in the lower colon, the mucosa is red and swollen, and there are plaques or fused pseudomembranes on the surface, suggesting pseudomembranous inflammation of the colon.
Diagnosis
In the process of applying antimicrobial drugs, if the patient’s primary symptoms and signs appear again or even intensify after a transient improvement, the possibility of secondary infection should be considered. In this case, the patient should be thoroughly examined, and the relevant specimens such as blood or other body fluids should be re-collected for bacterial culture, and the diagnosis of secondary infection can be established if new pathogenic bacteria are isolated from them.
Treatment
1. General treatment
Discontinue the use of antimicrobial drugs, correct the water and electrolyte disorders.
2. Drug treatment
(1) Fungal infections: use antifungal drugs such as mycobacteria, ketoconazole, amphotericin B, etc., pay attention to the interaction between drugs.
(2) Pseudomembranous enteritis: use vancomycin, desmethyl vancomycin, metronidazole, tinidazole treatment.
(3) Staphylococcus aureus enteritis: use benzoxacillin, cloxacillin, rifampicin and so on.
(4) Light bacterial alternating diarrhea: generally no special treatment, if necessary, can use drugs to inhibit intestinal peristalsis, such as compound phenethylpiperidine.
(5) Others: choose effective drugs according to the results of germ culture.
Prevention
Define the indications for the use of antimicrobial drugs, ask in detail about the history of the use of drugs and reactions, closely observe the changes in the condition, and adjust the treatment program in time. Once secondary infection occurs, broad-spectrum antimicrobials should be discontinued.