Synergistic combination of colistin with imipenem, amikacineor ciprofloxacin against Acinetobacter baumannii andPseudomonas aeruginosa carbapenem-resistant isolated inAnnaba hospital Algeria

Objective:The aim of this study is to detect in vitro the synergetic activity of colistin in combination with imipenem,amikacin or ciprofloxacin,at sub-inhibitory concentrations,against carbapenems-resistant(CR)Acinetobacter baumannii and Pseudomonas aeruginosa strains isolated from various wards in Annaba teaching hospital in eastern Algeria.Materials and Methods:The minimal inhibitory concentrations(MIC)were determined by broth macrodilution(BMD).Carbapenemase encoding genes were screened using polymerase chain reaction(PCR).The activity of colistin in combination with second antibiotic was evaluated by the Checkerboard Technique.Results:39 CR P.aeruginosa and 21 CR A.baumanni strains where collected.The MIC values ranging from(0.25 to 4μg/ml)to colistin,≥16μg/ml for imipenem,≥4μg/ml to amikacin and≥8μg/ml ciprofloxacin.The PCR reveals the presence of the genes blaOXA23(n=12),blaOXA24(n=6),blaNDM1(n=3)in A.baumannii and blaVIM2(n=12)in P.aeruginosa.The combination of colistin with imipenem showed synergistic effect on 57.14%and 46.15%of A.baumannii and P.aeruginosa isolates,respectively.For colistin and amikacin,the synergistic effect is detected in 28.6%of A.baumannii and 30.8%of P.aeruginosa.While colistin and ciprofloxacin showed synergy on 14.29%and 15.38%of A.baumannii and P.aeruginosa isolates,respectively.Conclusion:CR A.baumannii and P.aeruginosa remain the most prevalent infection agents in patients from high-risk wards at Annaba Hospital.Colistin associated with imipenem or with amikacin at sub-inhibitory concentrations gives very encouraging results allowing better management of infections caused by this type of bacteria.

The Increased Frequency of Carbapenem Resistant Non Fermenting Gram Negative Pathogens as Causes of Health Care Associated Infections in Adult Cancer Patients

Background and Aim: Multi drug resistant Non fermenting gram negative bacilli (NFGNB) have emerged as a major cause of health-care associated infections especially in immunocompromised hosts. The aim of the study was to investigate the prevalence of NFGNB as a cause of health-care associated infections (HAI) in cancer patients and determine their resistance pattern. Patients and Methods: During the study period, 158 NFGNB isolates were collected. Microscan Walk Away 9 was used for identification and testing for the metallo-β-lactamases (MBLs) was done by Imipenem-EDTA combined disk synergy test (CDST-IPM). Results: NFGNB represented 29.0% of infections caused by gram negative organisms. Carbapenem resistance, the multi-drug resistant (MDR) phenotype, and MBL production were documented in 70%, 63%, and 59% of NFGNB isolates, respectively. MDR-NFGNB rates were significantly higher among hospitalized patients, medical department and those with longer duration of hospital stay (p = 0.034, 0.026, 0.019;respectively) than non MDR-NFGNB. Conclusion: A high level of carbapenem and multi-drug resistance were detected among the non-fermenter pathogens isolated from hospitalized cases and were more frequently encountered in high risk adult cancer patients requiring longer duration of hospitalization. The MDR-NFGNB are constituting important causes of health-care associated infections in cancer patients.