The aim of the study is to evaluate the role of addition of Acetyl cysteine in the management of VAP induced by carbapenem resistant klebsiella. The primary outcome indicator is the change in modified clinical pulmonary infection score. The secondary outcome indicator is duration of mechanical ventilation.

Ventilator-associated pneumonia remains the most common intensive care unit infection of patients on mechanical ventilation, and is associated with substantial morbidity/mortality, a longer hospital stays, and increased healthcare costs.

Multi drug resistance bacterial infection in Ventilator-associated pneumonia patients presents a global challenge due to its increasing morbidity and mortality. Multi drug resistance is defined as acquired nonsusceptibility to at least one agent in ≥ three antimicrobial categories according to the European Center for Disease Prevention and Control, The most common (80%) Ventilator-associated pneumonia pathogens were Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae.

Klebsiella pneumoniae is a common pathogen for community-and hospital-acquired infections, such as pneumonia, urinary tract infection, and bacteremia.

Infections due to Multi drug resistance Klebsiella species Were found to be associated with high mortality and hospital outbreaks. Carbapenem-resistant Klebsiella pneumoniae is among the bacteria that the World Health Organization gives critical priority to and poses the greatest threat to human health. According to China Antimicrobial Surveillance Network, carbapenem resistance in Klebsiella pneumoniae increased rapidly from 3% in 2005 to more than 25% in 2019. In case of new drugs unavailable or not active invitro, guidelines recommend combination of drugs active invitro (o polymyxins, aminoglycosides, tigecycline or Fosfomycin) with no recommendation for or against specific combinations.

In case of severe infections caused by Carbapenem-resistant Klebsiella carrying metallo-blactamases, guidelines recommend aztreonam and ceftazidimeavibactam combination therapy. Several studies demonstrated that acetyl Cysteine when added to antibacterial agent invitro, potentiates the antibacterial compound activities. The role of acetyl cystiene antioxidant and anti-inflammatory activities is being widely investigated in viral infections.

Since the mechanisms of acetyl cystiene effects in viral infections include its antioxidant and anti-inflammatory activities, they may also be beneficial in bacterial Multi drug resistance bacterial infections, The hypothesis of this study is that addition of acetyl cysteine to antibiotics in vivo could have a synergistic effect in Multi drug resistance bacterial infections and could help in decreasing high doses of antibiotics required, improving outcome and decrease hospital stay.

Inclusion Criteria:

• Patients who are mechanically ventilated
• Age from 21 to 65
• Both sexes.

Exclusion Criteria:

• Patient guardians who refuse the consent • Hypersensitivity to acetyl Cysteine.
• Extrapulmonary infection.
• Cardiac patient with chronic heart failure
• Patient with lung diseases (tumors, tuberculosis, ,Chronic Obstructive Pulmonary Disease, Bronchiectasis and lung fibrosis)
• Severe immunosuppression (total leucocyte < 1000 mm3 or neutrophil < 500 cell/mm3.
• Patients on steroid or immunosuppressive drugs.

6 months