Purpose This study was design to investigate of Purpose This study was design to investigate of P. aeruginosa, an example of Gram-negative bacteria, in seven primary and secondary schools of Baghdad city, and the effects of Ethanol and Dettol of P. aeruginosa biofilm. Design/methodology/approach Seventy swabs were collected from seven primary and secondary schools of Baghdad city, Iraq, during November -December 2022. Swabs were collected from classes desk, doors handles, students hands and water taps. Standard microbiological testing methods were used on the samples for isolation and identification. The ability of bacteria to form biofilm and the effects of Ethanol and Dettol on “preformed” biofilms was examined by microtiter plate with the use of an ELISA reader. Findings In 70 swabs from seven primary and secondary schools, growth was observed in 33 swabs as P. aeruginosa. Primary schools were higher contaminated than secondary and water taps and door handles represented the main source of this contamination. The ability of bacteria to produce biofilm was observed in 19 (57.6%) isolates and 14 (42.4%) nonbiofilm producers. As well as, Ethanol (70%) treatment of preformed biofilms led to enhance biofilm formation and revealed significantly greater staining after 4 and 24h than Dettol (3%) compared to an untreated control (tryptic soy broth (TSB) incubation). Originality/value Studies on P. aeruginosa in Iraqi schools are quite rare. This work is considered distinctive because it drew attention to the presence of pathogenic bacteria within primary and secondary schools, which are not considered their natural environment., an example of Gram-negative bacteria, in seven primary and secondary schools of Baghdad city, and the effects of Ethanol and Dettol of P. aeruginosa biofilm. Design/methodology/approach Seventy swabs were collected from seven primary and secondary schools of Baghdad city, Iraq, during November -December 2022. Swabs were collected from classes desk, doors handles, students hands and water taps. Standard microbiological testing methods were used on the samples for isolation and identification. The ability of bacteria to form biofilm and the effects of Ethanol and Dettol on “preformed” biofilms was examined by microtiter plate with the use of an ELISA reader. Findings In 70 swabs from seven primary and secondary schools, growth was observed in 33 swabs as P. aeruginosa. Primary schools were higher contaminated than secondary and water taps and door handles represented the main source of this contamination. The ability of bacteria to produce biofilm was observed in 19 (57.6%) isolates and 14 (42.4%) nonbiofilm producers. As well as, Ethanol (70%) treatment of preformed biofilms led to enhance biofilm formation and revealed significantly greater staining after 4 and 24h than Dettol (3%) compared to an untreated control (tryptic soy broth (TSB) incubation). Originality/value Studies on P. aeruginosa in Iraqi schools are quite rare. This work is considered distinctive because it drew attention to the presence of pathogenic bacteria within primary and secondary schools, which are not considered their natural environment.