Acinetobacter Infections ; microbiology ; Acinetobacter baumannii ; drug effects ; isolation & purification ; Anthracosis ; microbiology ; Anti-Bacterial Agents ; pharmacology ; Drug Resistance, Bacterial ; Fosfomycin ; pharmacology ; Humans ; Imipenem ; pharmacology ; Pneumonia, Bacterial ; microbiology

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

A nationwide antimicrobial resistance surveillance has been conducted since 1997 in Korea. In this study, susceptibility test data generated in 2004 by KONSAR group hospitals were analyzed and compared to those at a commercial laboratory. In hospitals, the rank orders of organisms in 2004 were identical to those in 2003. The most prevalent species was Staphylococcus aureus (20.2%) in hospitals, but Escherichia coli (29.7%) in the commercial laboratory. The proportions of Enterococcus faecium to all isolates of Enterococcus faecalis plus E. faecium were 47.2% in hospitals and 24.9% in the commercial laboratory. The mean resistance rates of significant antimicrobial-organism combinations in hospitals were: oxacillin-resistant S. aureus (68%), oxacillin-resistant (penicillin- nonsusceptible) Streptococcus pneumoniae (68%), vancomycin-resistant E. faecium (25%), cefotaxime-resistant E. coli (14%), ceftazidime- and cefoxitin-resistant Klebsiella pneumoniae (34% and 32%, respectively), and imipenem-resistant Acinetobacter spp. and Pseudomonas aeruginosa (17% and 24%, respectively). In conclusion, oxacillin-resistant staphylococci, expanded-spectrum cephalosporin-resistant K. pneumoniae, and imipenem-resistant Acinetobacter spp. and P. aeruginosa were prevalent in 2004. Increasing trends were observed for vancomycin-resistant E. faecium, cefoxitin- resistant E. coli and K. pneumoniae, and imipenem-resistant Acinetobacter spp. and P. aeruginosa. Certain antimicrobial- organism combinations were also prevalent among the commercial laboratory-tested strains.
Pseudomonas aeruginosa/drug effects/isolation & purification ; Microbial Sensitivity Tests ; Laboratories ; Korea ; Klebsiella pneumoniae/drug effects/isolation & purification ; Imipenem/*pharmacology ; Hospitals ; Gammaproteobacteria/*drug effects/isolation & purification ; Drug Resistance, Multiple, Bacterial ; Ceftazidime/*pharmacology ; Anti-Bacterial Agents/*pharmacology ; Acinetobacter/drug effects/isolation & purification

OBJECTIVETo investigate the distribution of burn pathogens and their antibiotic resistance in a burn unit, so as to provide reference for clinical practice.

METHODSThree hundred and forty-eight burn patients hospitalized in our department were enrolled in this study. The pathogens isolated from the wounds, blood, venous catheter, sputum, urine, purulent discharge of wounds in these patients, and their antibiotic resistance were surveyed by retrospective analysis from Jan, 2001 to Dec, 2006.

RESULTSTotal-ly 464 strains were isolated, among which Gram negative (G-) bacilli accounted for 52.6%, Gram positive microorganisms (G+) accounted for 40.5%, and fungi accounted for 6.9%. The main pathogens were Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter species and Escherichia coli, among which Staphylococcus aureus (MRSA) was predominant (93.5%). MRSA was 100% resistant to levofloxacin, penicillium, oxacillin, and it was also resistant to other antibiotics except Vancomycin. The resistance rate of Pseudomonas aeruginosa to Cefoperazone/Sulbactam, Imipenem and cefepime were 15.8%, 36.8%, 33.3%, respectively.

CONCLUSIONStaphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter species and Escherichia coli were predominant in the burn unit,among them Staphylococcus aureus and Acinetobacter were more resistant to antibiotics.

Acinetobacter baumannii ; drug effects ; isolation & purification ; Burn Units ; Burns ; microbiology ; Cross Infection ; microbiology ; Drug Resistance, Bacterial ; Escherichia coli ; drug effects ; isolation & purification ; Humans ; Pseudomonas aeruginosa ; drug effects ; isolation & purification ; Retrospective Studies ; Staphylococcus aureus ; drug effects ; isolation & purification

OBJECTIVETo analyze the detection, drug resistance, and status of infection of Acinetobacter baumannii (AB) in burn ICU during 3 years.

METHODSA total of 2 010 specimens of wound secretion, blood, venous catheter attachment, sputum, stool and urine were collected from 505 burn patients hospitalized in our burn ICU from January 2011 to December 2013, and bacterial culture was performed. Pathogens were identified by automatic microorganism identifying and drug sensitivity analyzer. Drug resistance of all the obtained AB to 16 antibiotics commonly used in clinic, including cefoperazone/sulbactam, polymyxin, etc., was tested with K-B paper disk diffusion method. Patients with AB infection were ascertained. The WHONET 5.6 software was used to analyze the distribution of pathogens during 3 years, the isolation of AB with different sources and the status of drug resistance of AB to 16 antibiotics each year, and the status of patients with AB infection, and their outcome.

RESULTSA total of 961 strains of pathogens were isolated, among which 185 (19.25%) strains were Gram positive cocci, 728 (75.75%) strains were Gram negative bacilli, and 48 (4.99%) strains were fungi. A total of 172 strains of AB were isolated, ranking the second place among all the detected pathogens, with 67 (38.95%) strains from wound secretion, 11 (6.40%) strains from blood, 23 (13.37%) strains from venous catheter attachment, and 71 (41.28%) strains from sputum, no AB strain was isolated from feces or urine. The AB strains were found sensitive to polymyxin and with relatively low drug resistance rate to minocycline, while the drug resistance rates were over 80.0% to the other 14 antibiotics commonly used in clinic in 2013. AB culture of wound secretion was positive in 27 patients. Among them, 7 patients suffered from wound infection, and the wound infection was caused by AB in 1 out of the 7 patients. AB culture of blood was positive in 7 patients. Among them, 3 patients suffered from bloodstream infection, and the infection was due to AB invasion in 1 out of the 3 patients. AB culture of venous catheter attachment was positive in 20 patients. Among them, 8 patients suffered from bloodstream infection, and the infection was due to AB invasion in 1 out of the 8 patients. AB culture of sputum was positive in 35 patients. Among them, 13 patients suffered from ventilatory associated pneumonia, and 2 out of the 13 patients were diagnosed as AB infection. A total of 69 patients were AB culture positive, among them 64 patients were cured, 2 patients were transferred to other hospitals, and 3 patients died, with the mortality rate of 4.35%.

CONCLUSIONSAB in our burn ICU has a high detection rate and extensive drug resistance in above-mentioned 3 years. However, AB was mainly colonized in patients with extensive burns with a low mortality rate.

Acinetobacter Infections ; drug therapy ; epidemiology ; microbiology ; Acinetobacter baumannii ; drug effects ; isolation & purification ; Anti-Bacterial Agents ; pharmacology ; Burns ; microbiology ; Cross Infection ; Drug Resistance ; Gram-Negative Bacteria ; isolation & purification ; Humans ; Intensive Care Units ; Microbial Sensitivity Tests

OBJECTIVETo analyze the distribution and drug resistance of bacteria in different wound infections and provide evidence for wound infection control in subtropical regions.

METHODSThis study involved 265 patients from 4 different departments of our hospital who experienced wound infections between July, 2007 and July, 2008. The bacterial strain distribution in the wounds and drug resistance of the bacteria were analyzed.

RESULTSAcinetobacter baumanii (39% of the total strain identified) was the most frequent bacterial strain causing infection of the burn wounds, followed by Proteus mirabilis (20%) and Pseudomonas aeruginosa (20%). E. coli infection was prevalent in the departments of general surgery (37%) and urinary surgery (64%), and Pseudomonas aeruginosa and Pseudomonas pneumonia infections were detected at the rate of 30% and 43% in the urinary surgery department, respectively. Different bacterial strains were found at similar rates around 10% in the wounds of patients undergoing traumatic surgery.

CONCLUSIONDespite that the commonly seen pathogenic bacteria in burn patients including Staphylococcus aureus have been effectively controlled by early application of antibiotics, the opportunistic pathogens such as Acinetobacter baumanii and Proteus mirabilis often survive these antibiotics, and some strains evolve to be drug-resistant and even multi-drug-resistant. E. coli infection is prevalent in general surgery and urinary surgery departments, where Staphylococcus aureus and Pseudomonas aeruginosa infections can also be found frequently. All kinds of bacteria infection are present in trauma surgery department, each found at the rate around 10%.

Acinetobacter baumannii ; drug effects ; isolation & purification ; Adolescent ; Adult ; Burns ; complications ; Child ; Child, Preschool ; Drug Resistance, Bacterial ; Escherichia coli ; drug effects ; isolation & purification ; Female ; Humans ; Male ; Middle Aged ; Pseudomonas aeruginosa ; drug effects ; isolation & purification ; Wound Infection ; etiology ; microbiology ; Young Adult

OBJECTIVETo observe the antimicrobial activity of topical agents commonly used for burns on Acinetobacter baumannii (AB) in both free and biofilm states, and their synergistic effect with ambroxol on AB within biofilm.

METHODSEleven AB strains were isolated from wound excretion, respiratory tract, and blood of patients hospitalized in our hospital from August 2005 to April 2007. (1) The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of mafenide acetate and chlorhexidine acetate to free AB (including drug-resistant, drug-sensitive, and standard strains) were determined by dilution method. (2) AB was cultured with LB or TSB medium for 12, 24, and 48 h to form biofilm, and it was treated with above-mentioned two topical agents in MBC (mafenide group and chlorhexidine group) for 30 min. Biofilm not treated by topical agent was used as control group. The biofilm thickness was determined with confocal laser scanning microscope. The proportion of living bacteria in biofilm was calculated. AB biofilm in each topical agent group was mixed and inoculated into LB culture dish to observe the growth of bacteria. (3) AB was cultured with LB medium for 48 h to form biofilm, which was respectively treated by above-mentioned two topical agents in MBC (mafenide group and chlorhexidine group) and combination of each topical agent with 3.75 mg/mL ambroxol solution (ambroxol + mafenide group and ambroxol + chlorhexidine group) for 30 min. Biofilm not treated by topical agents was used as control group. Growth of bacteria in biofilm was detected with MTT method (denoted as absorbance value). Data were processed with one-way analysis of variance and LSD-t test.

RESULTS(1) MIC of mafenide acetate and chlorhexidine acetate for free AB was respectively 25.00 mg/mL and 0.03 mg/mL. MBC of both agents for free AB was the same as their MIC. (2) Among three groups, the thickness of biofilm of sensitive AB was thicker than that of drug-resistant bacteria at most of the time points. Compared with those in control group, biofilm thickness and proportion of living bacteria in biofilm were slightly decreased in mafenide and chlorhexidine groups. The growth of bacteria was abundant in each group. (3) Absorbance value of drug-resistant bacteria in control, mafenide, and chlorhexidine groups was respectively 0.776 ± 0.071, 0.625 ± 0.063, and 0.420 ± 0.068. Absorbance value of drug-resistant bacteria in ambroxol + mafenide group (0.174 ± 0.089) was significantly lower than that of control group (t = 11.823, P = 0.000) and mafenide group (t = 9.248, P < 0.01). Absorbance value of ambroxol + chlorhexidine group (0.178 ± 0.044) was significantly lower than that of control group (t = 16.009, P = 0.000) and chlorhexidine group (t = 6.681, P < 0.01).

CONCLUSIONSDrug-resistant AB forms biofilm readily, which prevents topical agents from killing the bacteria inside. Combined use of ambroxol with topical agents gives synergistic effect on killing AB in biofilm in the wound.

Acinetobacter baumannii ; drug effects ; isolation & purification ; Anti-Bacterial Agents ; pharmacology ; Biofilms ; drug effects ; Burns ; microbiology ; Chlorhexidine ; pharmacology ; Drug Resistance, Bacterial ; Humans ; Mafenide ; pharmacology ; Microbial Sensitivity Tests

This study aimed to investigate whether CHROMagar Acinetobacter medium (CHROMagar, France) in combination with an antimicrobial supplement (modified CHROMagar Acinetobacter; CHROMagar, France) can be used for detecting and isolating multidrug-resistant Acinetobacter species (MRA) in nasal and rectal surveillance cultures. Nasal and rectal swab samples were collected from patients in an intensive care unit at a teaching hospital. The samples were used to inoculate modified CHROMagar Acinetobacter plates, which were examined after 24 and 48 hr of incubation at 37degrees C. Their susceptibility against the antimicrobial agents meropenem, imipenem, ciprofloxacin, and amikacin was analyzed using the Etest (bioMerieux, France). A total of 406 paired samples (406 nasal swabs and 406 rectal swabs) were obtained from 226 patients, and 120 samples (28 nasal and 28 rectal cultures, 47 nasal cultures only, and 17 rectal cultures only) yielded MRA. Seventy-five MRA isolates (18.5%) were recovered from the 406 nasal samples, and 45 MRA isolates (11.1%) were recovered from the 406 rectal samples. Of the 120 MRA isolates, 3 (2.5%) were detected only after 48 hr of incubation. The use of modified CHROMagar Acinetobacter together with nasal and rectal swabs and 1-day incubation is an effective surveillance tool for detecting MRA colonization.
Acinetobacter/drug effects/*isolation & purification ; Acinetobacter Infections/diagnosis/microbiology ; Anti-Bacterial Agents/pharmacology ; *Drug Resistance, Multiple, Bacterial/drug effects ; Humans ; Intensive Care Units ; Microbial Sensitivity Tests ; Nose/*microbiology ; Reagent Kits, Diagnostic ; Rectum/*microbiology

This study aimed to investigate whether CHROMagar Acinetobacter medium (CHROMagar, France) in combination with an antimicrobial supplement (modified CHROMagar Acinetobacter; CHROMagar, France) can be used for detecting and isolating multidrug-resistant Acinetobacter species (MRA) in nasal and rectal surveillance cultures. Nasal and rectal swab samples were collected from patients in an intensive care unit at a teaching hospital. The samples were used to inoculate modified CHROMagar Acinetobacter plates, which were examined after 24 and 48 hr of incubation at 37degrees C. Their susceptibility against the antimicrobial agents meropenem, imipenem, ciprofloxacin, and amikacin was analyzed using the Etest (bioMerieux, France). A total of 406 paired samples (406 nasal swabs and 406 rectal swabs) were obtained from 226 patients, and 120 samples (28 nasal and 28 rectal cultures, 47 nasal cultures only, and 17 rectal cultures only) yielded MRA. Seventy-five MRA isolates (18.5%) were recovered from the 406 nasal samples, and 45 MRA isolates (11.1%) were recovered from the 406 rectal samples. Of the 120 MRA isolates, 3 (2.5%) were detected only after 48 hr of incubation. The use of modified CHROMagar Acinetobacter together with nasal and rectal swabs and 1-day incubation is an effective surveillance tool for detecting MRA colonization.
Acinetobacter/drug effects/*isolation & purification ; Acinetobacter Infections/diagnosis/microbiology ; Anti-Bacterial Agents/pharmacology ; *Drug Resistance, Multiple, Bacterial/drug effects ; Humans ; Intensive Care Units ; Microbial Sensitivity Tests ; Nose/*microbiology ; Reagent Kits, Diagnostic ; Rectum/*microbiology

BACKGROUND: Despite increasing importance of Acinetobacter baumannii in nosocomial infections and rapid development of multi-antimicrobial resistance in this strain, the resistance mechanisms of beta-lactam antimicrobials in A. baumannii were not clearly defined. In order to observe the resistance mechanisms against beta-lactams and carbapenem, we characterized the production of beta-lactamases and outermembrane protein (OMP) profiles for the 44 clinical isolates of A. baumannii. METHODS: The MICs of antimicrobials were determined by agar dilution test. The secondary beta-lactamases were characterized by isoelectric focusing, polymerase chain reactions and nucleotide sequencing, and the production of chromosomal beta-lactamases was quantitated by spectrophotometric method. For two strains with an elevated MIC of carbapenem, outermembrane protein (OMP) profile was analyzed by ultracentrifugation of the sonicated bacteral cells and SDS-PAGE. RESULTS AND CONCLUSION: Twenty two or 4 of 44 strains produced TEM-1-like beta-lactamase or PER-1 extended-spectrum beta-lactamase, respectively. However, when we analyzed the MICs of several beta-lactams with the beta-lactamase production, the resistance level of beta-lactam was mainly determined by the production of chromosomal beta-lactamase, not by the secondary beta-lactamases in the clinical isolates of A. baumannii. In two strains with an elevated MIC of imipenem, a decrease or loss of about 35 kDa and 22 kDa proteins in OMP was observed, which suggested that the change of OMP played a role in carbapenem resistance.
Acinetobacter/*drug effects/isolation & purification/metabolism ; Acinetobacter Infections/drug therapy/microbiology ; Antibiotics, Lactam/*pharmacology ; Bacterial Outer Membrane Proteins/biosynthesis ; Carbapenems/pharmacology ; Cross Infection/drug therapy/microbiology ; Drug Resistance, Bacterial ; Human ; beta-Lactamases/biosynthesis