Sexually Transmitted Diseases - I. I. Mavrov 2005

Other bacterial infections of the urogenital tract
Urogenital infections caused by Enterobacteriaceae

Infections caused by Gram-negative bacilli belonging to the Enterobacteriaceae family. Urogenital infections are triggered by Representatives of the genera Escherichia, Klebsiella, Enterobacter, Serratia, Hafnia, Salmonella, Edwardsiella, Citrobacter, Providencia, and Proteus. Enterobacteria can be isolated from the Vagina in cases of vaginitis, cervicitis, or other inflammatory conditions. They are very frequently detected in association with anaerobic microorganisms and trichomonads. The presence of enterobacteria in the vagina is characteristic of women who fail to maintain proper personal hygiene.

Escherichia coli is a member of the normal intestinal flora and a saprophyte of the Large Intestine. Conditionally pathogenic and pathogenic serotypes of the colon bacillus cause various pathogenetic and Clinical forms of infectious processes. Their pathogenic features correlate to some extent with the presence of a specific antigen, meaning they belong to a particular serogroup. Urinary Tract infections are commonly associated with serogroups O2, O6, O9, among others, whereas cholecystitis is linked to O1, O8, O11, and others.

Coli infections of the urinary tract are more frequently observed in girls and women, particularly in the presence of vulvitis and vulvovaginitis.

The source of infection is patients with coli infections or healthy carriers of pathogenic E. coli serotypes. Transmission occurs primarily via the fecal-oral route, and occasionally sexually. A hematogenous route of pathogen dissemination into the Kidneys and urinary tract from an extrarenal focus of infection is also possible.

In adults, coli infections most commonly manifest as inflammatory changes in Organs adjacent to the intestine—such as the Urethra, Urinary Bladder, vagina, and Uterus (urethritis, cystitis, pyelitis, Pyelonephritis, colpitis, endometritis)—or connected to it, such as the Gallbladder and biliary tract (cholecystitis, cholangitis). In children, coli infections may localize in the Lungs. Generalization of the infection and The Development of Sepsis are also possible.

It is not uncommon for Escherichia coli, in association with staphylococci or certain Gram-negative Bacteria (such as Proteus or Pseudomonas), to cause nosocomial infections, particularly in gynecological clinics and newborn wards.

A definitive Diagnosis of an E. coli-induced infection can only be established through Bacteriological examination, which includes isolating a pure culture of E. coli, identifying it based on morphological and biochemical characteristics, and determining its serogroup.

Coli infections are treated using Antibiotics (such as polymyxin, ampicillin, and Tetracyclines).

Klebsiella pneumoniae, previously known as pathogens of the Respiratory system, are nowadays frequently the cause of congenital infections accompanied by respiratory and urinary tract involvement. When grown on nutrient media, these bacteria form characteristic mucous colonies; microscopic examination reveals wide polysaccharide capsules surrounding non-motile Cells.

Enterobacter aerogenes is detected in urinary tract infections and sepsis. These bacteria are often motile, form slightly mucous colonies, and some strains produce a capsule.

Serratia marcescens consists of small bacilli capable of producing an intense red pigment in cultures (a variable trait).

Representatives of the genus Serratia typically ferment lactose very slowly, and some strains ferment urea weakly. Unpigmented variants of these bacteria can cause toxic sepsis.

Hafnia alvei is occasionally isolated, aside from gastroenterocolitis, in cases of urethritis or vaginitis as well.

Bacteria belonging to the genera Edwardsiella and Citrobacter share similar biochemical properties; their pathogenicity remained questionable until recently. Specific serotypes are found in sporadic or outbreak-associated foodborne toxic infections, urinary tract infections, and other conditions.

Representatives of the genus Salmonella cause gastroenteritis, sepsis, endometritis, and urinary tract infections.

Providencia species are biochemically similar to Proteus; they deaminate Amino Acids (such as Lysine) and do not hydrolyze urea. They are detected in urinary tract infections, sepsis, and other pathologies.

Routes of Transmission. Most bacteria of this family constitute a significant portion of the normal aerobic intestinal flora and typically do not cause disease; on the contrary, they contribute to the normal functioning of the gut. These microorganisms become pathogenic only when they invade body Tissues, particularly the urinary tract, lungs, Peritoneum, or Meninges, where they are capable of initiating an inflammatory process. They may enter the bloodstream via venous or urethral catheters, gain access to the urogenital tract during instrumental examinations (nosocomial transmission), or cause urinary tract infections following the administration of contaminated medicinal products, especially intravenously. Sexual transmission is also possible.

Epidemiology and General Pathology. Escherichia coli and certain other Enterobacteriaceae colonize an infant's intestine within just a few days after birth, forming the core of the body's normal aerobic microflora from that point onward. When inflammation develops—regardless of the clinical picture, Etiology, or Pathogenesis—A large number of diverse microorganisms often invade the urinary tract simultaneously. Within a short period, one of them begins to dominate, suppressing the growth of the others.

The dominant species accounts for approximately 80% of all bacteriuria cases. When the body's immune mechanisms fail to mount a response against a particular microorganism, the latter rapidly establishes itself within the Urinary System. For instance, individuals with Blood group III (B) do not produce Antibodies against E. coli serotype O86 due to antigen identity. Clinical observations indicate that such individuals are more susceptible to coli infections than people with other Blood Groups.

Urinary tract infections can occur following urinary bladder catheterization, potentially leading to bacteremia and urosepsis. Bacteremia is frequently diagnosed in the prostatic bed following prostatectomy (adenomectomy) As a result of cystitis, bladder atony, or occasionally due to calculus formation, urethral stricture, recurrence of a past pyelonephritis, or asymptomatic bacteriuria. The infection may be introduced by an indwelling catheter during surgery, often immediately following the Procedure, and frequently persists for months. In benign prostatic hyperplasia, Gram-negative bacteria are typically not isolated from the prostate tissue itself; however, infectious complications within the urinary system are precisely caused by these microorganisms.

In some cases, patients with bacteriuria exhibit elevated blood pressure. The reverse phenomenon is also observed: Hypertension can foster the development of bacteriuria, which may subsequently progress to pyelonephritis and complicate the course of hypertension. Therefore, the onset of either condition warrants consideration of the potential Development of the other.

Bacteria of the family Enterobacteriaceae frequently cause secondary infections, including Pneumonia, endocarditis, and bacteremia, particularly in intravenous drug users and hospitalized patients.

Clinical Manifestations. The manifestations of infections caused by Enterobacteriaceae depend on the localization of the pathological process. Because they cannot be differentiated from other bacterial infections based on symptoms and signs alone, it is crucial to identify the CAUSATIVE AGENT OF the urogenital infection, determine its species and type characteristics, quantify its concentration per 1 mL of fresh urine, and assess its antimicrobial susceptibility. Systematic Study of the species, type, and other traits of microorganisms causing urogenital infections is essential for elucidating the pathogenesis of urinary tract infections and determining appropriate therapeutic approaches.

Diagnosis. Depending on the site of the pathological process, diagnostic specimens may include genital secretions, urine, blood, CEREBROSPINAL FLUID, and others. Stained smears reveal short Gram-negative bacilli that may form chains; they closely resemble one another, and only the presence of wide capsules holds diagnostic value for the genus Klebsiella. The specimen is simultaneously inoculated onto blood Agar and media containing specific Dyes and CARBOHYDRATES, which allows for the rapid differentiation of lactose-fermenting and non-fermenting colonies. Bacteria isolated on these media are subsequently identified using biochemical and serological tests. Rapid preliminary identification is also possible based on the microorganisms' ability to ferment lactose.

Treatment and Prophylaxis. Ampicillin, tetracyclines, Aminoglycosides, polymyxins, and sulfonamides exhibit marked antimicrobial activity against Enterobacteriaceae. However, susceptibility to these agents varies among individual strains, necessitating laboratory determination. Multiple drug resistance is frequently encountered.

Therapeutic efficacy can be improved by the simultaneous use of aminoglycosides with furagin or ampicillin, or trimethoprim with sulfamethoxazole and polymyxin. Other combinations of antibacterial agents are also advisable, along with drugs that potentiate antibiotic action, boost the patient's immune defenses, facilitate the delivery of antibacterials to lesion sites, and ensure their therapeutic concentration in tissues and blood serum.

Prevention and effective management of these infections largely depend on diligent hand hygiene, strict adherence to asepsis and antisepsis protocols (instrument sterilization, equipment disinfection), caution in administering intravenous medications, and personal urogenital hygiene. It is crucial to remember that many gram-negative bacteria are opportunistic pathogens capable of causing disease in immunocompromised or debilitated hosts. In healthcare settings, these bacteria are frequently transmitted by medical personnel or via contaminated instruments and parenteral drugs.

Urinary tract infections are frequently caused by bacteria of the genus Proteus (family Enterobacteriaceae). These are motile, gram-negative, aerobic bacilli that do not ferment lactose and produce urease, which rapidly hydrolyzes urea to release ammonia. They exhibit a tendency to "swarm," spreading rapidly across The surface of solid growth media. Swarming can be inhibited by adding phenylethyl alcohol or 0.1% chloral hydrate to the agar medium. Proteus species grow poorly in acidic environments.

Modes of transmission. Like other members of Enterobacteriaceae, Proteus species cause disease in humans only when they breach their normal anatomical niche (the gastrointestinal tract). Nosocomial transmission, sexual spread, and poor personal hygiene are also common routes of infection.

Epidemiology and general pathology. Proteus species are frequently isolated in chronic urinary tract infections, as well as in cases of bacteremia, pneumonia, and localized lesions in debilitated or intravenously treated patients. Proteus mirabilis is the most prevalent species and the only indole-negative microorganism within the genus, followed by Proteus morganii and Proteus rettgeri. Proteus vulgaris is isolated less frequently.

As noted above, Proteus species produce urease, an enzyme that breaks down urea into ammonia, thereby promoting The formation of phosphate calculi. Ammonia is nephrotoxic, causing renal tissue necrosis and microabscesses. It also inactivates Complement Proteins present in urine, enabling bacteria to proliferate unhindered within renal tissue and significantly enhancing their invasiveness. Infections caused by urease-producing Proteus strains result in more severe intoxication and destruction of renal tissue.

Clinical manifestations. Bacteria of the genus Proteus are frequently implicated in complicated calculous pyelonephritis, congenital urinary tract anomalies, and post-surgical infections. In such cases, various Enterobacteriaceae are often isolated initially, followed later by The Emergence of Proteus species, which drive the chronic, complicated course of the urinary tract infection.

Treatment and prevention. Diseases caused by Proteus species must be treated with antibiotics to which the specific isolates are susceptible. It should be noted that antibiotic susceptibility varies considerably among different Proteus strains. Gentamicin and amikacin are among the most active agents. The growth of P. mirabilis is frequently inhibited by penicillin and ampicillin. The administration of Cephalosporins (such as cefotaxime or claforan) is also indicated.

The prevention of Proteus infections, as with other infectious diseases, requires a comprehensive set of measures aimed at identifying the source of infection, interrupting transmission routes, and reducing host susceptibility. The spread of infection must be curbed through strict aseptic and antiseptic practices. This applies equally to nosocomial infections caused by Proteus species.