OBJECTIVETo investigate the effect of antibacterial peptide LL-37 on the integrity of Acinetobacter baumannii biofilm.

METHODSA model of Acinetobacter baumannii biofilm in vitro was constructed by plates and crystal violet staining method, and the minimal inhibitory concentration of LL-37 was determined by broth dilution. The biofilm morphology was observed by scanning electron microscopy and biofilm formation was analyzed by the crystal violet staining of the adherent biofilm in the presence of antibacterial peptide LL-37.

RESULTSIn the Acinetobacter baumannii biofilm model, the minimal inhibitory concentration of LL-37 was 64 µg/ml; LL-37 caused structural damage of the biofilm at a low concentration of 2.5 µg/ml. The biofilm was decreased gradually as the concentration of LL-37 increased.

CONCLUSIONLL-37 even at a concentration far below its minimal inhibitory concentration can cause structural damage of Acinetobacter baumannii biofilm in vitro.

Acinetobacter baumannii ; drug effects ; physiology ; Biofilms ; drug effects ; Cathelicidins ; pharmacology ; Microbial Sensitivity Tests

Infections caused by Acinetobacter baumannii (AB) have emerged as a knotty clinical problem in the burn wards due to its omni-resistance to antibiotics and high prevalence. Although our knowledge in regard to the pathogenesis and the resistance mechanisms of AB is increasing, the available treatment remains much limited. Measures to effectively control nosocomial infection are warranted. Meanwhile, development of novel therapeutic agents or combination of antibiotics should be considered.
Acinetobacter Infections ; epidemiology ; Acinetobacter baumannii ; drug effects ; Anti-Infective Agents ; pharmacology ; Burns ; microbiology ; Drug Resistance, Multiple, Bacterial ; Humans

Acinetobacter baumannii ; drug effects ; Anti-Bacterial Agents ; pharmacology ; Drug Resistance, Multiple, Bacterial ; Microbial Sensitivity Tests

Acinetobacter baumannii has emerged as one of the leading bacteria for nosocomial infections, especially in burn wards and ICUs. The bacteria can easily form biofilm and readily attach to abiotic and biotic surfaces, resulting in persistent biofilm-mediated infections. Being surrounded by self-produced extracellular polymeric substance (EPS), the microorganisms in biofilm can acquire protective property against detrimental environment and their tolerance toward antibiotics is increased. Poly-β-1-6-N-acetylglucosamine (PNAG), the common constituent of EPS in Acinetobacter baumannii, acts as the key virulence factor and plays a crucial role in biofilm formation process. This review describes the properties and functions of the PNAG and its influence on biofilm formation and drug resistance of Acinetobacter baumannii.
Acinetobacter Infections ; drug therapy ; Acinetobacter baumannii ; drug effects ; Anti-Bacterial Agents ; therapeutic use ; Biofilms ; drug effects ; growth & development ; Burns ; Cross Infection ; Drug Resistance, Multiple, Bacterial ; beta-Glucans ; metabolism

OBJECTIVETo study the in vitro antibacterial activity of meropenem combined with doxycycline, ciprofloxacin, sulbactam or cefoperazone/sulbactam against clinically isolated extensively drug-resistant Acinetobacter baumannii (XDRAB).

METHODSUsing a checker board synergy design, the minimal inhibitory concentration (MIC) of antibiotics against 50 isolates of XDRAB was determined by broth microdilution antifungal susceptibility test. The fractional inhibitory concentration (FIC) index was calculated to determine the combined effect of the antibiotics.

RESULTSMeropenem showed significantly reduced MIC50 and enhanced antimicrobial activities when combined with doxycycline, sulbactam or cefoperazone/sulbactam. The FIC results suggested that the main actions of doxycycline, sulbactam, and cefoperazone/sulbactam were synergistic (38%, 26%, and 10%, respectively) and addictive (62%, 74%, and 90%, respectively) without indifferent or antagonistic effects. The main actions of meropenem combined with ciprofloxacin were additive (56%) and indifference (44%) with synergistic and antagonistic effects.

CONCLUSIONMeropenem combined with doxycycline, sulbactam or cefoperazone/sulbactam shows excellent activity against clinical isolates of XDRAB.

Acinetobacter baumannii ; drug effects ; Anti-Bacterial Agents ; pharmacology ; Drug Combinations ; Drug Synergism ; Microbial Sensitivity Tests ; Thienamycins ; pharmacology

Acinetobacter baumannii ; drug effects ; Anti-Bacterial Agents ; pharmacology ; Carbapenems ; pharmacology ; Drug Resistance, Bacterial ; Microbial Sensitivity Tests ; Minocycline ; analogs & derivatives ; pharmacology

OBJECTIVETo investigate antibiotic resistance and carriage class 1 and 2 integrons in clinical isolates of Acinetobacter baumannii (A. baumannii) from Tehran, Iran.

METHODSAntimicrobial susceptibility testing was performed according to the Clinical and Laboratory Standards Institute. The presence of integrons was investigated by PCR using specific primers.

RESULTSAmong isolated A. baumannii strains, 82% were multidrug resistant, 27 samples (54%) were resistant to three or more than three antibiotics and 16 samples (32%) showed resistance to two antibiotics. Integrons were detected from 44 of 50 isolates (88%), with classes 1 and 2 being observed in 42% (21/50) and 82% (41/50) of isolates, respectively. Integron-positive A. baumannii isolates showed higher antibiotic resistance than integron-negative isolates and all showed a multidrug-resistant phenotype.

CONCLUSIONSOur findings show that classes 1 and 2 integrons, and especially classes 2 integrons are widely disseminated among A. baumannii strains isolated from Tehran and these structures are playing a major role in the acquisition of multidrug resistance in these strains. So monitoring of drug resistance with investigating carriage class 1 and 2 integrons is very important to plan specific infection control measures due to multidrug resistance A. baumannii in Iran hospitals.

Acinetobacter baumannii ; drug effects ; genetics ; Anti-Bacterial Agents ; pharmacology ; Drug Resistance, Multiple, Bacterial ; genetics ; Integrons ; genetics ; Iran ; Microbial Sensitivity Tests

OBJECTIVETo investigate the variance of antibiotic resistance of Acinetobacter Baumanii isolated from children in Wuhan between 2006 and 2008.

METHODSBacterial susceptibility testing was carried out by the Kirby-Bauer method in 679 strains of Acinetobacter Baumanii isolated in Wuhan Children's Hospital between 2006 and 2008. The results were assessed according to the guidelines of the Clinical and Laboratory Standards Institute (2008).

RESULTSThe nonsusceptible rates of Acinetobacter Baumanii to ceftazidime, cefepime and piperacillin/sulbactam increased significantly in 2007 compared with those in 2006 (P<0.05). By comparing the results of 2007, it was suggested that the nonsusceptible rates of Acinetobacter Baumanii to ceftazidime, cefepime, piperacillin/sulbactam, cefoperazone/sulbactam, imipenem and meropenem increased significantly in 2008 (P < 0.05).

CONCLUSIONSThe nonsusceptible rates of Acinetobacter Baumanii to beta-lactam antibiotics in children from Wuhan increased significantly year by year between 2006 and 2008.

Acinetobacter baumannii ; drug effects ; Anti-Bacterial Agents ; pharmacology ; Child ; Drug Resistance, Bacterial ; Humans ; Microbial Sensitivity Tests ; Time Factors

OBJECTIVETo monitor genotypes and drug-resistance trend of Acinetobacter baumannii (AB) isolated from burn wards.

METHODSTwenty-six strains of AB isolated from wound secretion, venous catheter, and blood were collected from burn patients hospitalized in our burn wards from November 2008 to February 2009, and June to September 2010. Homogeneous genotype analysis was performed with repetitive extragenic palindromic PCR, and drug-resistance rate to 13 antibiotics including amikacin, gentamicin, etc., which were commonly used in clinic, was tested by K-B paper disk diffusion. The data of drug-resistance rate were processed with chi-square test.

RESULTS(1) Sixteen AB strains were multi-drug resistant (MDR), 9 AB strains were pan-drug resistant (PDR). Among all strains, the resistance rate to gentamicin, piperacillin, piperacillin/tazobactam, cefuroxime, cefotaxime, ceftazidime, cefepime, ciprofloxacin, imipenem, and meropenem was respectively higher than 90.00%; the resistance rate against cefoperazone/sulbactam was the lowest (11/26, 42.31%). There were obvious difference among the drug-resistance rates of AB strains to 13 antibiotics (with rates from 42.31% to 100.00%, χ(2) = 97.371, P < 0.05). (2) There were 7 genotypes among 26 AB strains, respectively type A (17), type B (3), type C (2), type D (1), type E (1), type F (1), and type G (1). Out of the 17 AB strains in A genotype, 1 strain was from 2008, 1 strain was from 2009, 15 strains were from 2010, and among them 11 strains were collected from wound secretion and 6 strains were obtained from blood and venous catheter.

CONCLUSIONSAB strains in A genotype are dominant in our burn wards in recent years, which are MDR or PDR to commonly used antibiotics. Cefoperazone/sulbactam is the drug of choice for burn patients with AB infection.

Acinetobacter Infections ; epidemiology ; microbiology ; Acinetobacter baumannii ; drug effects ; genetics ; Burns ; microbiology ; Cross Infection ; epidemiology ; microbiology ; Drug Resistance, Multiple, Bacterial ; Genes, Bacterial ; Humans

Acinetobacter Infections ; etiology ; Acinetobacter baumannii ; drug effects ; isolation & purification ; Child, Preschool ; Drug Resistance, Bacterial ; Female ; Humans ; Infant ; Intensive Care Units, Pediatric ; Male ; Risk Factors