Staphylococcal infections

Bacterial genus of the Micrococcaceae family: Gram-positive, aerobic, immobile, spherical cocci that form irregular, clustered clusters.
The most common staphylococci are Staphylococcus aureus, S. epidermidis and S. saprophyticus.

In principle and from a clinical point of view, staphylococci are divided into:

• Coagulase-positive staphylococci (main representative: Staphylococcus aureus)
• Coagulase-negative staphylococci (main representatives: Staphylococcus epidermidis, S. sparophyticus and about 50 other species)

Widespread colonization of the skin and the anterior pharynx (up to 25 % of the population; even more frequent among hospital staff!) and the genital mucous membranes (vagina: up to 10 % of all premenopausal women).

A basic distinction must be made between diseases caused by the invasive presence of staphylococci and those induced by staphylococcal toxins.

Localized infections of the skin, skin appendages, urethra.

• Folliculitis
• boils
• carbuncle
• impetigo
• Abscess of sweat glands
• Hidradenitis suppurativa
• Mastitis puerperalis
• Wound infections
• "Plastic infections" (catheters, foreign bodies such as joint replacement materials)
• Urinary tract infections (honeymoon cystitis caused by S. saphrophyticus; this can adhere to the uroepithelium and is capable of producing a large amount of urease).

Superimposed colonization in various diseases (e.g. atopic eczema). High (> 80 %) colonization density in the nasal mucosa and on weeping areas); formation of IgG and IgE class antibodies against exfoliative toxins of Staphylococcus aureus.

Furthermore:

• Bacteremia and sepsis as consequences of a local infection
• Endocarditis (second most common germ in bacterial endocarditis)
• Pneumonia (see pneumonia below)
• osteomyelitis
• ostitis
• Staphylococcal enteritis

• Staphylococcal enterocolitis (is triggered by the toxins of large quantities of toxin-producing (enterotoxins A-E) staphylococci or by an excessive multiplication of staphylococci in the intestine - around 30% of all people are carriers!)

Transitional forms between invasive and staphylococcal toxin-mediated diseases:

• Staphylococcal Scalded Skin Syndrome (SSSS): Infection with S. aureus, usually phage type 71, whose exotoxin (exfoliatin) triggers the typical exfoliative skin changes.
• Staphylococcal scarlet fever: In older children, the exfoliative skin changes of "staphylogenic Lyell" remain in the exanthema stage. This may be due to partial immunity caused by protective anti-epidermolysin antibodies.
• Shock syndrome, toxic: A clinical picture triggered by the exotoxin TSST-1 produced by certain S. aureus strains with scarlet fever-like skin symptoms, shock symptoms and multiple organ symptoms. Occurs mainly in young women who use tampons.
• Recalcitrant erythematous desquamating disorder (RED) recurrent toxin-induced perianal erythema caused by toxin-producing staphylococci (erythema triggered by staphylococcal or streptococcal superantigens)
• Recurrent tox in-inducedperineal erythema (toxin-induced perineal dermatitis)
• Food poisoning: Diseases caused by the formation of heat-labile enterotoxins (enterotxoin B, which acts like a superantigen ) with a short incubation period (4-6 hours) with fever, nausea, vomiting and diarrhea. Mostly self-limited.

Penicillinase-resistant penicillins, e.g. flucloxacillin (e.g. Stahylex); beta-lactamase inhibitors(ampicillin / sulbactam); carbapenems(imipenem); cephalosporins(cefadroxil; cefotaxime; ceftriaxone). Reserve antibiotics include linezolid, tigecycline, quinupristin / dalfopristin.

Poor efficacy: penicillin G, aminopenicillins, tetracyclines, increasingly also erythromycin and clindamycin.

Detection: The pathogen must be detected by culture from suitable test material (blood, wound swab, stool, food residues). Spa typing is suitable for epidemiological studies (especially for MRSA infections). This involves sequencing the gene for protein A.

Note! Increasing problem: MRSA!

• Staphylococcus aureus is held responsible for an exacerbation of atopic eczema, among other things. According to a Brazilian study, narrow-band UVB therapy should significantly reduce colonization with S. anreus on the skin.
• Retapamulin (Altargo) is a topically applied antibiotic that is effective against MRSA.

1. Jokinen E et al (2018) Spa type distribution in MRSA and MSSA bacteremias and association of spa clonal complexes with the clinical characteristics of bacteremia. Eur J Clin Microbiol Infect Dis 37: 937-943.
2. Rittenhouse S et al (2006) Selection of retapamulin, a novel pleuromutilin for topical use. Antimicrob Agents Chemother 50:3882-3885
3. Silva SH et al (2006) Influence of narrow-band UVB phototherapy on cutaneous microbiota of children with atopic dermatitis. J Eur Acad Dermatol Venereol 20: 1114-1120