Skin bacterial infections are often observed in eczema patients, but the risk factors are not fully understood. The current study evaluated the prevalence of clinically suspected bacterial infection and its associated risk factors. Moreover, we investigated the practice of skin infection diagnosis in China. A hospital-based, multicenter, cross-sectional epidemiologic survey of bacterial infection was performed in a total of 6208 outpatients diagnosed with dermatitis and eczema from 39 tertiary hospitals of 15 provinces and municipalities in China. All patients completed a specific questionnaire regarding their demographic characteristics, disease duration, distribution of lesions, severity of itching, and medical history. Univariate analysis and multivariate analysis were used to evaluate risk factors associated with bacterial infection in patients with different types of eczema. The prevalence of clinically suspected bacterial infection was 47.0% in patients with eczema. Compared to atopic dermatitis, widespread eczema (OR=1.50, P<0.001) and other eczema (OR=1.42, P<0.001) were more likely to suffer bacterial infection. The itching grade was positively associated with the infection (OR=2.11, 7.04, and 12.3 in patients with mild, moderate, and severe itching, respectively; P<0.001). Lesion distribution in the cubital fossa, popliteal fossa, ear, shoulder and back, axillary, foot, and pudendum was positively associated with bacterial infection (all OR>1.0, P<0.05). In contrast, the face and abdomen were reversely associated with bacterial infection (OR<1.0, P<0.005). History of asthma, allergic rhinitis, allergic conjunctivitis, atopic dermatitis, infantile eczema, and flexion dermatitis was positively associated with bacterial infection (all OR>1.0, P<0.005), while the history of dry skin was reversely associated with bacterial infection (OR=0.76, 95% CI: 0.64-0.90; P=0.002). Patients with eczema were easily infected with bacteria. Widespread eczema and other eczema were more likely to have bacterial infection than atopic dermatitis. The high rate of infection may attribute to the lack of corresponding bacterial detection, suggesting the need of guideline development in China to prevent overuse of topical antibiotics.