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PubMed2005

Acinetobacter immune responses in multiple sclerosis: etiopathogenetic role and its possible use as a diagnostic marker.

Multiple sclerosis (MS) is the most common cause of neurologic disability among young people. The etiology of MS is controversial, but immune responses are considered to somehow be involved. The diagnosis of MS depends on a combination of various clinical and laboratory features, but apart from some myelin-neuronal autoantibody profiles or oligoclonal bands in the cerebrospinal fluid no other serologic diagnostic test or marker has yet been discovered. However, the presence of antibodies to Acinetobacter species in MS patients opens the possibility of developing a composite laboratory diagnostic marker, the myelin-Acinetobacter-neurofilament index. Whether Acinetobacter is the triggering agent of MS remains to be determined, but the measurement of anti-Acinetobacter antibodies could be used as a marker of disease activity. To evaluate this, prospective randomized controlled studies should be performed with MS patients, especially in the early stages of the disease.

Acinetobacter↗
PubMed1982

Nosocomial bacteremia due to Acinetobacter calcoaceticus.

In 1980, 13 patients with positive blood cultures for Acinetobacter calcoaceticus were detected in an 800 bed university medical center. Twelve of the 13 isolates were identified as Acinetobacter calcoaceticus var. anitratus and one as var. lwoffi. In the same period there were 361 positive specimens of A. calcoaceticus. Eight of the patients were classified as having significant bacteremia (Group A) with a serious infection in which Acinetobacter was considered a significant pathogen. Five additional patients, however, (Group B) had fever and only one set of positive blood cultures. The significance of these positive isolates was unclear to the attending clinicians. All but one Group A patient appeared to have acquired their infection during hospitalization. In this group, one patient had an underlying pneumonia as the source of bacteremia. In the remaining patients bacteremia was related to some form of invasive catheterization. Seven patients responded rapidly to appropriate antimicrobial therapy and one patient with terminal cancer died as a result of infection. This report reviews the clinical spectrum of Acinetobacter bacteremia, which can range from mild, possibly self-limiting bacteremia to serious, life-threatening septicaemia, especially in compromised hospitalized patients.

Acinetobacter↗
PubMedDate not supplied

Acinetobacter septicemia: a threat to neonates? Special aspects in a neonatal intensive care unit.

Acinetobacter is one of the organisms responsible for nosocomial infections in intensive care, neurosurgery, burn and hemodialysis units. There are only a few reports on Acinetobacter infections in neonatal intensive care units. Over a 31 month period, nine cases of Acinetobacter sepsis occurred in our unit, with four deaths. There was a cluster of four cases within 3 days. In this study the English literature on this pathogen is reviewed and it is suggested that Acinetobacter should be added to the list of organisms causing severe nosocomial infection in neonatal intensive care units.

Acinetobacter↗
PubMed1998

Resistance mechanism of Acinetobacter spp. strains resistant to DW-116, a new quinolone.

DW-116 is a new fluoroquinolone antimicrobial agent with a broad spectrum. In order to elucidate the resistance mechanism to DW-116 in Acinetobacter spp. bacteria, total chromosomal DNA was isolated from 10 strains of Acinetobacter spp. resistant to DW-116. Quinolone resistance determinant region (QRDR) of DNA gyrase gene was amplified by PCR. The 345 bp nucleotide fragment yielded was inserted into pKF 3 which was used as the vector. Comparisons of the DNA sequences of 8 strains with that of the wild type strain revealed a Ser-83 to Leu mutation in mutants and all ten strains contained one silent mutation(T-->G) in QRDR. From Acinetobacter MB4-8 strain, DNA gyrase was isolated and purified, through no-vobiocin-sepharose, heparin-sepharose affinity column chromatography. The enzyme was composed of two subunits and the molecular mass of subunits A and B were 75.6 and 51.9 kDa, respectively. The supercoiling activity of the reconstituted DNA gyrase composed of subunit A from Acinetobacter MB4-8 and subunit B from E. coli was not inhibited by 128 micrograms/ml of ciprofloxacin. It might be said that one of the resistance mechanisms to DW-116 in A-cinetobacter MB4-8 was subunit A alteration of DNA gyrase.

Acinetobacter↗
PubMed1993

Nosocomial colonization and infection with multiresistant Acinetobacter baumannii: outbreak delineation using DNA macrorestriction analysis and PCR-fingerprinting.

The prevalence of nosocomial acinetobacter colonization and infection in a university hospital was reviewed and multiresistant Acinetobacter baumannii infections in an intensive care unit (ICU) were investigated using epidemiological typing and a case-control study. Acinetobacter colonization at various body sites was found in 3.2 to 10.8 per 1000 patients. Acinetobacter infection accounted for 0.3% of endemic nosocomial infections in critically ill patients and for 1% of nosocomial bacteraemia hospitalwide. Over a three-week period, four ventilated patients developed colonization, followed by pneumonia in two patients, with A. baumannii resistant to multiple antimicrobials. Cultures of samples from respiratory equipment and ICU surfaces (n = 27) as well as from hands of personnel (n = 14) failed to yield A. baumannii, except for one sample of respiratory tubing. Antibiogram, biotype, chromosomal DNA macrorestriction profiles and polymerase chain reaction (PCR) mediated fingerprints of A. baumannii isolates (n = 31) indicated that this outbreak was caused by two strains, one of which later spread to another hospital where it caused a second outbreak. Both strains were clearly discriminated from control strains from cases of sporadic infection. Risk factors for cross-colonization that were identified by a case-control comparison were neurosurgery, mechanical ventilation and treatment with broad-spectrum antibiotics. Transmission was controlled by implementing contact isolation precautions and routine sterilization of ventilator tubing. Wider use of sensitive genotypic methods like DNA macrorestriction analysis and PCR-mediated fingerprinting for typing nosocomial pathogens should improve the detection of micro-epidemics amenable to early control.

Acinetobacter↗
PubMed2006

Multiplex PCR for genes encoding prevalent OXA carbapenemases in Acinetobacter spp.

Carbapenem resistance in Acinetobacter baumannii is a growing public health concern and is most often mediated by OXA carbapenemases. We describe a novel multiplex polymerase chain reaction (PCR) assay able to detect and distinguish alleles encoding three subgroups of acquired OXA carbapenemases (OXA-23-like, OXA-24-like and OXA-58-like) that are scattered in Acinetobacter spp., and a fourth subgroup, OXA-51-like, which appears to be intrinsic to Acinetobacter baumannii. Isolates belonging to two prevalent UK A. baumannii 'OXA' clones (OXA-23 clones 1 and 2) had alleles encoding both an intrinsic OXA-51-like and an acquired OXA-23 enzyme, whereas isolates of the 'SE clone' had only an intrinsic bla(OXA-51-like) allele. Genes encoding OXA-58 were detected (with bla(OXA-51-like)) in a cluster of related isolates from a single hospital. This simple assay will assist in monitoring the mechanisms responsible for carbapenem resistance in Acinetobacter spp.

Acinetobacter↗
PubMed1997

Impact of Acinetobacter spp. in intensive care units in Great Britain and Ireland.

Acinetobacter spp. are of increasing importance as hospital pathogens in intensive care units (ICUs) but it is unclear what clinical impact these bacteria have in Great Britain and Ireland. A survey was carried out by questionnaire on the impact of Acinetobacter in ICUs and the laboratory methods used to identify and type isolates. There were 70 respondents, of whom 25 reported that Acinetobacter had not been recovered from ICU patients within the previous 12 months. The remaining 45 respondents reported that the respiratory tract was the most common site from which these bacteria were isolated, but they were currently endemic in one ICU only. There were considerable differences in methods used to identify Gram-negative bacilli recovered from ICU patients, which may partly explain differences in the reported prevalence of isolates between centres, and 12 laboratories attempted to type isolates by a range of techniques. The availability and use of agreed antibiotic policies specific for ICUs may be particularly important in prevention and control where infection with Acinetobacter is prevalent.

Acinetobacter↗
PubMed2002

[Incidence of colonization and infection by Acinetobacter baumannii in an endemic seting (ICU). Analysis of risk factors by means of a surveillance study].

BACKGROUND: Our ICU has witnessed a gradual increase in infections due to Acinetobacter baumannii complex that has reached a level of stable endemia since 1995. This situation, aggravated by a high degree of resistance, has led to the present prospective study, designed to establish the incidence of Acinetobacter colonization and to investigate the role of risk factors and their relation to environmental colonization. METHODS: Serial sampling of all patients from the time of ICU admission to discharge. Sample collection from the environment and from hospital personnel. Monitorization of pre-established risk factors and detection of episodes of infection. RESULTS: One-third of patients were colonized during their stay, with the trachea (43%), rectum (31%), and skin (35%) being the most frequent sites. In 92% of cases, colonization was established within the first 9 days after admission. Significant risk factors included mechanical ventilation (p < 0.01) and previous use of antibiotics (p < 0.007). Acinetobacter was recovered from thermometers (35%), respirator switches (43%), and damp surfaces (54%). Infection developed in 8% of patients; all had been previously colonized. CONCLUSIONS: In an endemic setting, Acinetobacter colonization can occur in a third of ICU patients. This event is relatively early and often precedes infection. Duration of mechanical ventilation and previous use of antibiotics are the main risk factors. Environmental elements are frequent bacterial reservoirs, but the main reservoir is the colonized patient.

Acinetobacter↗
PubMed2001

Investigation of synergism of meropenem and ciprofloxacin against Pseudomonas aeruginosa and Acinetobacter strains isolated from intensive care unit infections.

The aim of this study was to determine synergistic effects of meropenem and ciprofloxacin against Pseudomonas aeruginosa and Acinetobacter strains isolated from intensive care unit (ICU) infections. A total of 18 P. aeruginosa and 17 Acinetobacter strains were tested. MICs were determined using the broth microdilution method. The synergy of meropenem and ciprofloxacin was investigated in glass tubes using time-kill methodology. The synergistic effect of meropenem and ciprofloxacin in combination was found to be 22% at 0.5 x the MIC and 61% at 1 x the MIC in P. aeruginosa strains. Two strains (11%) showed synergy at both 0.5 and 1 x the MIC. Of the 18 P. aeruginosa strains, 1 strain (6%) did not show a synergistic effect at either 0.5 or 1 x the MIC. In Acinetobacter strains, the synergistic effect of meropenem and ciprofloxacin in combination was found to be 29% at 0.5 x the MIC and 18% at 1 x the MIC. One strain (6%) showed synergy at both 0.5 and 1 x the MIC. Of the 17 Acinetobacter strains, 8 strains (47%) did not show a synergistic effect at either 0.5 or 1 x the MIC. According to the results of this study, the combination of meropenem and ciprofloxacin is more effective than either antibiotic alone in ICU infections due to P. aeruginosa strains.

Acinetobacter↗
PubMed1999

Acinetobacter bacteremia in Hong Kong: prospective study and review.

The epidemiological characteristics of 18 patients with acinetobacter bacteremia were analyzed. Patients (mean age, 55.5 years) developed bacteremia after an average of 14.1 days of hospitalization. Fifteen of 16 patients survived bacteremia caused by Acinetobacter baumannii. Cultures of blood from the remaining two patients yielded Acinetobacter lwoffii. Most patients (78%) resided in the general ward, while four patients (22%) were under intensive care. Genotyping by arbitrarily primed polymerase chain reaction analysis and the temporal sequence of isolation were more useful than phenotyping by antimicrobial susceptibility in the determination of the source of bacteremia, and the intravascular catheter was the leading infection source (39% of cases). The possibility of an association of glucose with the pathogenesis of acinetobacter infection was raised.

Acinetobacter↗
PubMed1993

Nosocomial acinetobacter meningitis secondary to invasive procedures: report of 25 cases and review.

The medical records of 25 patients with nosocomial meningitis due to Acinetobacter baumannii were retrospectively reviewed. Most cases occurred in the neurosurgical intensive care unit over a 5-year period, with an increased rate during summer. The majority of infections were associated with indwelling ventriculostomy tubes or CSF fistulae in patients receiving antimicrobial therapy. Repeated environmental cultures failed to reveal a source of the microorganism, and control measures had no apparent effect on the outbreak. However, no further cases appeared following a sharply reduced total intake of antibiotics in the neurosurgical department. Forty-one cases of acinetobacter meningitis, secondary to invasive procedures, were found in the English-language literature and were compared with the cases presented. To our knowledge, our series is the largest of acinetobacter meningitis reported hitherto. Although not one of the most common pathogens in hospitals, Acinetobacter constitutes an increasing threat for patients, especially those receiving antimicrobial therapy in intensive care units who are being maintained by various life-support systems.

Acinetobacter↗
PubMed1995

[Bacteremia with Acinetobacter species--clinicopathological characteristics of 27 cases].

Acinetobacter spp. are non-fermented gram-negative rods that are widespread in the environment and colonize in the human skin. They are known to be a nosocomial pathogen causing, pneumonia, meningitis and bacteremia. Recently, they have been found increasingly in catheter-related infections (CRI). Thirty-seven cases of bacteremia were developed in our hospital during the past five years. Of these 27 cases were chosen out of the medical records for discussion in this paper. Twenty-three cases are blood positive for Acinetobacter anitratus and 4 cases for A. lwoffii. Most cases have an underlying disease like hematological malignancy, solid tumor and infantile congenital abnormality. There were also some clinical signs; high fever, hypotension, tachycardia, tachypnea, peripheral cyanosis. A central venus catheter was inserted in 22 cases, and in 13 of these, the catheter was removed after the bacteremic episode. Nine cases became afebrile after the removal of the catheter and A. anitratus was isolated from the catheter tip in four cases. Heparin was administered through the catheter in 7 cases. Formerly Acinetobacter spp. were not recognized as a major pathogen, but recently found increasingly in CRI. We also found 9 cases which were definitely diagnosed or suspected as CRI, and were successfully treated by removal of the central venus catheter. Association between administration of heparin and bacteremia of Acinetobacter spp. was reported, we actually detected such association in 7 cases, but the potential role of heparin has not been clarified yet. Compared with A. lwoffii, A. anitratus were resistant to many drugs, but had good susceptibility to imipenem, minocycline, aminoglycoside, and fluoroquinolone.(ABSTRACT TRUNCATED AT 250 WORDS)

Acinetobacter↗
PubMed1999

Identification of Acinetobacter baumannii strains with monoclonal antibodies against the O antigens of their lipopolysaccharides.

Despite the emergence of Acinetobacter baumannii strains as nosocomial pathogens, simple methods for their phenotypic identification are still unavailable. Murine monoclonal antibodies specific for the O-polysaccharide moiety of the lipopolysaccharide (LPS) of two A. baumannii strains were obtained after immunization with heat-killed bacteria. The monoclonal antibodies were characterized by enzyme immunoassay and by Western and dot blot analyses and were investigated for their potential use for the identification of A. baumannii strains. The antibodies reacted with 46 of the 80 A. baumannii clinical isolates that were investigated, and reactivity was observed with 11 of 14 strains which were isolated during outbreaks in different northwestern European cities; no reactivity was observed with Acinetobacter strains of other genomic species, including the closely related genomic species 1 (Acinetobacter calcoaceticus), 3, and 13 sensu Tjernberg and Ursing, or with other gram-negative bacterial strains. The results show that O-antigen-specific monoclonal antibodies such as the ones described are convenient reagents which can be used to identify Acinetobacter strains in clinical and research laboratories.

Acinetobacter↗
PubMed1995

Identification of Acinetobacter genomic species by amplified ribosomal DNA restriction analysis.

A total of 53 field and reference strains, including the type strains of the seven named species (nomenspecies) and belonging to the 18 described genomic species (DNA groups) of the genus Acinetobacter, were studied by amplified ribosomal DNA restriction analysis (ARDRA). Restriction analysis with the enzymes AluI, CfoI, MboI, RsaI, and MspI of the enzymatically amplified 16S rRNA genes allowed us to identify all species except the genomic species 4 (Acinetobacter haemolyticus) and 7 (A. johnsonii), 5 (A. junii) and 17, and 10 and 11, which clustered pairwise in three respective groups. Further analysis with the enzyme HaeIII, HinfI, NciI, ScrFI, or TaqI did not allow us to differentiate the species within these three clusters. However, use of a few additional simple phenotypic tests (hemolysis, growth at 37 degrees C, production of acid from glucose, and gelatin hydrolysis) can be used to differentiate between the species within these clusters. ARDRA proved to be a rapid and reliable method for the identification of most of the Acinetobacter genomic species, including the closely related DNA groups 1 (A. calcoaceticus), 2 (A. baumannii), 3, and 13. The results of this study suggest that ARDRA can be used for the identification of Acinetobacter species and as such may help to elucidate the ecology and clinical significance of the different species of this genus. Since ARDRA uses universal 16S rRNA gene primers, it is expected to be applicable to the identification of most bacterial species. Furthermore, ARDRA is less prone to contamination problems than PCR for detection, since the use of cultured organisms results in a large initial quantity of target DNA.

Acinetobacter↗
PubMed1995

Clinical and epidemiological investigations of Acinetobacter genomospecies 3 in a neonatal intensive care unit.

A prospective study of Acinetobacter isolates from a neonatal intensive care unit was performed for 24 months. Fifty-six isolates were obtained from 21 patients, and another eight were obtained from environmental specimens. Infection due to Acinetobacter organisms was established for 16 patients, 6 with septicemia, 9 with pneumonia, and 1 with a wound infection. Further investigations were performed with 38 representative isolates. Twenty-nine isolates were identified as unnamed DNA-DNA hybridization group (genomospecies) 3, three were identified as genomospecies 2 (Acinetobacter baumannii), one was identified as genomospecies 5 (Acinetobacter junii), three were identified as genomospecies 14, and two were unclassified. Eight distinguishable protein profiles, coded I through VIII, were found by cell envelope protein electrophoresis. Profile V, a common profile, was observed for 17 isolates that had been recovered from 11 patients and 1 dust specimen. These isolates, all of which belonged to genomospecies 3, had similar antibiograms and biotypes. This study has revealed that genomospecies 3 can be associated with infection and be spread in hospitals.

Acinetobacter↗
PubMed2000

Molecular surveillance of European quinolone-resistant clinical isolates of Pseudomonas aeruginosa and Acinetobacter spp. using automated ribotyping.

Nosocomial isolates of Pseudomonas aeruginosa and Acinetobacter spp. exhibit high rates of resistance to antibiotics and are often multidrug resistant. In a previous study (D. Milatovic, A. Fluit, S. Brisse, J. Verhoef, and F. J. Schmitz, Antimicrob. Agents Chemother. 44:1102-1107, 2000), isolates of these species that were resistant to sitafloxacin, a new advanced-generation fluoroquinolone with a high potency and a broad spectrum of antimicrobial activity, were found in high proportion in 23 European hospitals. Here, we investigate the clonal diversity of the 155 P. aeruginosa and 145 Acinetobacter spp. sitafloxacin-resistant isolates from that study by automated ribotyping. Numerous ribogroups (sets of isolates with indistinguishable ribotypes) were found among isolates of P. aeruginosa (n = 34) and Acinetobacter spp. (n = 16), but the majority of the isolates belonged to a limited number of major ribogroups. Sitafloxacin-resistant isolates (MICs > 2 mg/liter, used as a provisional breakpoint) showed increased concomitant resistance to piperacillin, piperacillin-tazobactam, ceftriaxone, ceftazidime, amikacin, gentamicin, and imipenem. The major ribogroups were repeatedly found in isolates from several European hospitals; these isolates showed higher levels of resistance to gentamicin and imipenem, and some of them appeared to correspond to previously described multidrug-resistant international clones of P. aeruginosa (serotype O:12) and Acinetobacter baumannii (clones I and II). Automated ribotyping, when used in combination with more discriminatory typing methods, may be a convenient library typing system for monitoring future epidemiological dynamics of geographically widespread multidrug-resistant bacterial clones.

4-Quinolones↗
PubMed2001

Epidemiology and infection control implications of Acinetobacter spp. in Hong Kong.

In a previous study, we showed that Acinetobacter genomic DNA group 3 was the most common species among blood culture isolates and was commonly found on superficial carriage sites of the healthy and the sick, which are different findings from those reported in Europe and North America. We used amplified ribosomal DNA restriction analysis and pulsed-field gel electrophoresis to study further the molecular epidemiology of acinetobacters in our region. Over a study period of 6 weeks with 136 consecutive routine clinical isolates (1.33% of all specimens), genomic DNA groups 2 (Acinetobacter baumannii), 3, and 13TU were obtained from 59 of 69 positive patients. There is a significant difference in the specimen sources of the three genomic DNA groups, with group 13TU being significantly associated with the respiratory tract (chi-square exact test, P = 0.0064). Settle plates showed a significantly heavier environmental load from the intensive care unit (ICU) than from the four surgical wards examined (22 of 70 versus 76 of 120 plates with <5 colonies; chi-square test, P < 0. 0001). Genomic group 3 accounted for 6 of 12 clusters of possibly related strains among patients, between patients and the ICU environment, and in the ICU environment. Genomic groups 2 and 3 accounted for 21% of the 132 genomically identified isolates recovered from 21 of 41 local vegetables, 53 of 74 fish and meat samples, and 22 of 60 soil samples. Group 13TU was present only in patients' immediate surroundings. The role played by the environment and by human carriage should be evaluated in order to devise a cost-effective infection control program pertinent to our situation of acinetobacter endemicity.

Acinetobacter↗
PubMed1993

Endemic acinetobacter in intensive care units: epidemiology and clinical impact.

AIMS: To assess whether Acinetobacter isolates obtained over 20 months in a tertiary care hospital were epidemiologically related; to establish the clinical importance of the organisms; and to identify the isolates according to the recent taxonomy. METHODS: Fifty eight Acinetobacter isolates from 49 patients collected during 1984 and 1985 were investigated. Most isolates were from respiratory tract specimens from intensive care patients. The organisms were typed by cell envelope protein electrophoresis and by a quantitative carbon source growth assay; patients' charts were reviewed to differentiate between colonisation and infection; representative isolates were identified to species level by DNA-DNA hybridisation. RESULTS: Twelve protein profiles were distinguished in the isolates. Forty two isolates were of the same protein profile (profile I); other profiles were observed in a few or single isolates. Cluster analysis of carbon source growth divided profile I isolates into two groups--one of isolates from 1984 and one from 1985. They were identified as A baumannii and associated with infections in eight patients. Four other infections were caused by acinetobacters with other protein profiles (three of A baumannii; one of the unnamed DNA group 3). CONCLUSIONS: Apart from sporadic strains, two strains of the same protein profile, but distinguishable by carbon source growth, were successively endemic. Cluster analysis was a valuable tool in the interpretation of typing and epidemiological data. The 12 (28%) infections of Acinetobacter in 43 patients in intensive care suggest that the presence of these organisms in wards of severely ill patients should be a cause of concern.

Acinetobacter↗