Bjørg Marit Andersen

Multiply Beta-lactam Resistant Enterobacter cloacae Infections Linked to the Environmental Flora in a Unit for Cardiothoracic and Vascular Surgery

During the period March 1987-May 1988, postoperative infection or colonization with Enterobacter cloacae occurred in 9/379 (2.4%) patients who underwent cardiovascular surgery. Five of the patients were infected with multiply beta-lactam resistant E. cloacae, of whom 4 had been infected with an identical, resistant strain during intervals of months. This strain was also found in the environmental flora of the cardiovascular operating suite and in a sink reservoir in the surgery department. All 4 patients with the identical resistant strain had serious complications during the postoperative period with symptoms of septicaemia in 3, multiorgan failure and shock in 2, and mediastinitis in 3. The single resistant strain of a different serotype was also associated with severe postoperative complications. The 4 sensitive strains were all different serotypes. None caused septicaemia, one was associated with mediastinitis, another with an uncomplicated sternum infection, and 2 were from sputum. In the 3 latter patients with sensitive strains and few postoperative complications, cephalosporins had not been used during the pre- or postoperative period.

Low Faecal Carrier Rate of Vancomycin Resistant Enterococci in Norwegian Hospital Patients

The faecal carrier rate of vancomycin resistant enterococci (VRE) was surveyed among 616 patients in selected departments of 7 Norwegian hospitals. One Enterococcus gallinarum isolate harbouring a vanB2 element was recovered from a child with malignant disease treated with vancomycin and ceftazidime. No vancomycin resistant Enterococcus faecalis or Enterococcus faecium were detected and no VRE isolates of the VanA type were identified. The low level of VRE carriage corresponds to the limited use of glycopeptide antibiotics for human therapeutic purposes in Norway. It indicates a low risk of acquiring VRE infections in Norwegian hospitals.

Hospital-acquired infections before and after healthcare reorganization in a tertiary university hospital in Norway

BACKGROUND To evaluate hospital-acquired infections (HAIs) in somatic (all admissions other than psychiatric) and psychiatric patients admitted to a tertiary university hospital in Oslo, before and after reorganization of the Norwegian healthcare system in 2002. METHODS Point prevalence studies were conducted four times per annum and over the period from 1995 to 2007. RESULTS A total of 57,360 patients were studied over the whole time period: 80.5% in somatic wards and 19.5% in psychiatric wards. The HAI rate was 6.9%, of which 8.1% were somatic and 1.9% psychiatric. 13.4% of operated patients had HAI, including 6.2% due to surgical wound infections. In somatic wards, 0.6-1% were re-admitted with HAI, 15.2-23% had infections and 18-23% used antibiotics. There was a reduction in HAI until 2002. From 2003 on, HAI increased (P = 0.010) in somatic wards (P = 0.002), in non-operated patients (P = 0.024) and in extra costs. In 2002, the Norwegian healthcare system was reorganized. This reorganization led to a 30% increase in somatic patients treated from 2003 to 2007 (P = 0.054), 27% increase in the total workload per work position (P = 0.024) and 23.5% decrease in internal service work. CONCLUSION A declining trend of HAI was observed from 1995 to 2002 at the tertiary university hospital in Norway. In 2002, the Norwegian healthcare system was reorganized. From 2003 to 2007, HAI increased significantly as did the number of somatic patients and workload at our hospital.

Ciprofloxacin versus a Tobramycin/Cefuroxime Combination in the Treatment of Serious Systemic Infections: A Prospective, Randomized and Controlled Study of Efficacy and Safety

Sequential intravenous and oral ciprofloxacin (CF) was compared with a combination of tobramycin and cefuroxime (T/C) in the treatment of serious systemic infections. Altogether 310 patients were randomized, 160 receiving CF and 150 T/C, the 2 groups being reasonably well balanced. 29 patients without infection were excluded from the analysis. Complete clinical resolution was obtained in 75% (107/143) patients receiving CF and in 78% (107/138) receiving T/C; the difference was not statistically significant. The rate of bacterial eradication in septicaemia was 72% (95% confidence interval (95% c.i.): 58-86%) for patients treated with CF and 87% (95% c.i.: 77-96%) when T/C was given, while the eradication rates in urinary tract infection were 72% (95% c.i.: 54-90%) and 45% (95% c.i.: 23-67%) for CF and T/C, respectively. Significant differences in bacteriological response for other diagnoses were not detected. Also for lower respiratory tract infections (LTRI) the clinical and bacteriological responses were quite similar, although relatively more failures occurred in CF treated patients with LRTI caused by pneumococci. The frequencies of adverse reactions were comparable, but the reactions were less serious following CF treatment. Our results indicate that CF may be used for empirical treatment of serious infections. However, if pneumococcal etiology is likely, alternative antibiotics should be used, and if necessary, coverage against anaerobic bacteria should be added.

Endotoxin liberation from neisseria meningitidis correlates to their ability to induce procoagulant and fibrinolytic factors in human monocytes

Endotoxin released from different strains of Neisseria meningitidis were studied for their ability to induce procoagulant (tissue factor, TF), fibrinolytic (plasminogen activator, PA) and antifibrinolytic (plasminogen activator inhibitor 2, PAI-2) factors in human monocytes. Two meningococcal strains that liberate endotoxin (E+; 270+ and 840+) and 2 non-liberating (E-; 270- and 840-) strains were used. The endotoxin activity in culture filtrates of these strains was monitored with the Limulus amoebocyte lysate (LAL) test. There was a marked difference between E+ and E- strains in their ability to liberate endotoxin. Suspensions of whole bacteria of all 4 strains induced a significant (14-19-fold) increase in monocyte TF expression when present in concentrations > 10(5) CFU/ml. At lower concentrations (10(4) CFU/ml), E+ strains were clearly more potent stimulators of TF synthesis than E- strains. Culture filtrates of E+ strains were up to 10(4)-fold more potent in inducing TF synthesis than filtrates from E- strains. This marked difference in inducing potency between E+ and E- strains was also observed when monocyte PAI-2 synthesis was examined. The PA expression, on the other hand, was suppressed when monocytes were incubated in the presence of culture filtrates, especially filtrates from the E+ strains. The increased procoagulant and antifibrinolytic activity, together with reduced profibrinolytic activity of monocytes, was closely correlated to the amount of endotoxin measured in the culture filtrates. These changes may contribute substantially to the coagulopathic state seen during systemic meningococcal disease.

Endotoxin liberation associated with growth, encapsulation and virulence of Neisseria meningitidis.

Endotoxin liberation, encapsulation and growth was studied in 123 isolates of Neisseria meningitidis. Free endotoxin appeared in culture filtrates during exponential growth. Meningococci with free endotoxin titre greater than or equal to 10(2) (E+) showed a higher mean number of viable bacterial counts (CFU/ml) during growth than isolates with titre less than 10(2) (E-), p less than 0.001. Differences in endotoxin liberation was, however, far more pronounced than what was indicated by growth differences alone. E+ property and increased growth rate was significantly more often found among encapsulated than non-encapsulated meningococci. Within the serogroup B isolates, there tended to be a higher mean number of CFU/ml during growth in E+ than E- meningococci, particularly among carrier isolates studied separately (p = 0.009). Case isolates of B meningococci, which had generally a higher amount of capsular material and a higher proportion of E+ strains, had also higher mean CFU/ml than B carrier isolates. This indicates that the endotoxin liberation and growth may be correlated to presence and amount of capsular polysaccharide. Endotoxin liberation, presence of capsular polysaccharide and growth ability are 3 factors which are likely to coincide in meningococci. This combination of properties may be of importance for the development of meningococcal disease.

Endotoxin liberation studied by biological and chemical methods

Release of endotoxin (or lipopolysaccharides, LPS) from four meningococcal strains was studied with a chemical and a biological technique. Two strains were endotoxin‐liberating (E+; 270E+ and 840E+) and two had no or low endotoxin release E‐; 270E‐ and 840E‐). LPS was quantitated by gas chromatography (GC) of LPS‐specific hydroxy fatty acids, in parallel with assay of endotoxin by Limulus Amebocyte Lysate (LAL), in cell suspensions of equal O.D. and in filtered samples. The GC and LAL methods showed a reasonably good agreement in the determination of LPS in filtrates, which had distinctly higher levels (approx. 10–100 times) for the E+ strains than the E‐ strains, in accordance with earlier LAL studies. This difference was not due to overproduction of LPS in the E+ strains, since all four strains had the same level of LPS (by GC) in cell suspensions of equal O.D. Here the agreement between the GC and LAL methods was substantially less, with lower values by LAL for the two E‐ strains. The chemical composition of purified LPS was determined by methanolysis and GC for the four strains and for two additional strains 247 and 714 with a high degree of genetic similarity with strains 270E‐ and 840E‐, respectively. Amounts of unphosphorylated L‐glycero‐D‐manno heptose and 2‐keto‐3‐deoxyoctonic acid were the same in all 6 LPS. Otherwise distinct differences were found between LPS of the 6 strains. LPS of the two E+ strains formed one group with about 2.4 mol of galactose (gal), 1.4 mol of glucose (glc) and 2.8 mol of glucosamine (glcN) in the carbohydrate chain. Another group, LPS of all the E‐ strains except 270E‐, had 1.1 mol of gal, 2.8 mol of glc and 1.3 mol of glcN in the LPS chain. LPS 270E‐ also had 1.3 mol of glcN but deviated strongly form all other LPS by a complete lack of gal and glc. On the basis of genetic evidence strain 270E‐ is regarded as a “rough” LPS mutant of strain 247. The atypical chemistry of LPS 270E‐ may explain an observed hydrophobicity of this LPS, and it may be related to the previously described sulfonamide sensitivity. Whether the chemical difference observed for LPS of the E+ and E‐ strains is a mere coincidence remains to be elucidated by detailed studies of more strains of known tendency of endotoxin liberation.

Endotoxin Release from Invasive Meningococci Related to Sulfonamide Resistance, Serogroup and Serotype

The relationship between endotoxin liberation, sulfonamide resistance, serogroups and serotypes was studied in 28 Neisseria meningitidis strains isolated from patients with meningococcal disease. Sulfonamide resistance was present in 15/28 strains. 22 strains belonged to serogroup B, and 5 to group C; 1 strain was non-groupable. Free endotoxin activity in growing cultures of meningococci with endotoxin titre of greater than or equal to 10(2) was found in 27/28 strains. A high endotoxin activity was present in both sulfonamide-sensitive and -resistant invasive meningococci. A high endotoxin release with titre greater than or equal to 10(3) seemed to be more associated with serogroup C than B, and more to the serotypes 2 and 15/16 than to the non-typable strains.

Multilocus genotypes of two strains of Neisseria meningitidis and their presumed variants obtained upon subcultivation

Loss of sulfonamide resistance and endotoxin liberation have been described in two strains of Neisseria meningitidis serogroup B, upon subcultivation every 1 to 2 months over an 18‐month period. Subsequently, the two laboratory variants, designated 270E‐ and 840E‐, were also found to differ from the parent strains, 270E+ and 840E+, in serotype, outer membrane protein pattern, and virulence in mice. We report here the multilocus genotypes determined by enzyme electrophoresis, of the four isolates 270E+, 270E‐, 840E+, and 840E‐, and demonstrate that 270E‐ and 840E‐ strains could not have originated from subcultivation of 270E+ and 840E+, respectively, but that a mix‐up of strains has occurred.

Biochemical profiles and serotypes of nosocomial Enterobacter cloacae strains in Northern Norway: biochemical identification problems with commercial test systems.

During a period of 2 years, 118 strains ofEnterobacter cloacae were collected consecutively in connection with nosocomial infections in Northern Norway; identified by conventional methods and by the API 20E system. The API 20E profile 3305573 predominated and was present in 73 of 118 strains. Among 96 serotyped strains, 73 were serotypable, 20 nontypable and two polyagglutinable. Predominating serotypes were 3 (29 strains), 8 (21 strains) and 23 (nine strains). When the API 20E profiles of the 118 strains were read in the new ATB (automated computer-assisted) 20E data base system, 97 of 118 (82.2%) strains were identified asE. cloacae. The 118 strains were tested in the new ATB Rapid ID 32E and ATB ID 32E (ATB system, bioMérieux, France) systems. Only 69 of 118 (58.5%) strains were identified asE. cloacae in both systems. The ATB Rapid ID 32E identified 97 of 118 strains (82.2%), and the ATB ID 32E only 80 of 118 strains (67.8%). Among 73 serotypable strains, the ATB Rapid ID 32E identified 79.5% asE. cloacae, while the ATB ID 32E identified only 64.4%. Among 40 serotypable strains with API 20E profile 3305573, all 40 were identified asE. cloacae by the ATB Rapid ID 32E, while only 27 (67.5%) by the ATB ID 32E system. Further improvements may increase the value of biochemical identification ofE. cloacae in diagnostic work. Während 2 Jahren wurden 118 konsekutive Stämme vonEnterobacter cloacae, die in Nordnorwegen im Zusammenhang mit nosokomialen Infektionen isoliert wurden, gesammelt. Die Identifizierung erfolgte mit konventionellen Methoden und mit dem API 20E-System. Am häufigsten fand sich das API 20E-Profil 3305573, das bei 73 der 118 Stämme nachzuweisen war. Die Serotypisierung war bei 73/96 Stämmen möglich, 20 Stämme konnten nicht serotypisiert werden und bei zwei Stämmen trat Mehrfachagglutination ein. Die häufigsten Serotypen waren 3 (29 Stämme), 8 (21 Stämme) und 23 (neun Stämme). Bei Auswertung der API 20E-Profile der 118 Stämme mit der neuen ATB (automatischen, komputerassistierten)-Methode für das 20E system wurden 97/118 (82,2%) der Stämme alsE. cloacae identifiziert. Die 118 Stämme wurden einer Testung mit der neuen ATB ID 32E-Schnellmethode und dem ATB 32E (ATB System bioMérieux, Frankreich) unterzogen. Nur 69/118 (58,5%) der Stämme wurden mit beiden Methoden alsE. cloacae identifiziert. Die ATB ID 32E Schnellmethode identifizierte 97/118 Stämmen (82,2%) und die ATB IS 32E-Methode nur 80/118 (67,8%) der Stämme. Bei 73 serotypisierbaren Stämmen gelang die Identifizierung alsE. cloacae mit der ATB ID 32E-Schnellmethode in 79,5% der Fälle und mit ATB ID 32E in nur 64,4% der Fälle. 40 serotypisierbare Stämme, die das API 20E 3305573-Profil aufwiesen, wurden mit dem ATB ID 32E-System in allen Fällen alsE. cloacae identifiziert, mit dem ATB ID 32E-System hingegen nur 27 (67,5%). Weitere Verbesserungen dürften dazu beitragen, daß der Wert der biochemischen Identifizierung vonE. cloacae in der Diagnostik erhöht wird.SummaryDuring a period of 2 years, 118 strains ofEnterobacter cloacae were collected consecutively in connection with nosocomial infections in Northern Norway; identified by conventional methods and by the API 20E system. The API 20E profile 3305573 predominated and was present in 73 of 118 strains. Among 96 serotyped strains, 73 were serotypable, 20 nontypable and two polyagglutinable. Predominating serotypes were 3 (29 strains), 8 (21 strains) and 23 (nine strains). When the API 20E profiles of the 118 strains were read in the new ATB (automated computer-assisted) 20E data base system, 97 of 118 (82.2%) strains were identified asE. cloacae. The 118 strains were tested in the new ATB Rapid ID 32E and ATB ID 32E (ATB system, bioMérieux, France) systems. Only 69 of 118 (58.5%) strains were identified asE. cloacae in both systems. The ATB Rapid ID 32E identified 97 of 118 strains (82.2%), and the ATB ID 32E only 80 of 118 strains (67.8%). Among 73 serotypable strains, the ATB Rapid ID 32E identified 79.5% asE. cloacae, while the ATB ID 32E identified only 64.4%. Among 40 serotypable strains with API 20E profile 3305573, all 40 were identified asE. cloacae by the ATB Rapid ID 32E, while only 27 (67.5%) by the ATB ID 32E system. Further improvements may increase the value of biochemical identification ofE. cloacae in diagnostic work.ZusammenfassungWährend 2 Jahren wurden 118 konsekutive Stämme vonEnterobacter cloacae, die in Nordnorwegen im Zusammenhang mit nosokomialen Infektionen isoliert wurden, gesammelt. Die Identifizierung erfolgte mit konventionellen Methoden und mit dem API 20E-System. Am häufigsten fand sich das API 20E-Profil 3305573, das bei 73 der 118 Stämme nachzuweisen war. Die Serotypisierung war bei 73/96 Stämmen möglich, 20 Stämme konnten nicht serotypisiert werden und bei zwei Stämmen trat Mehrfachagglutination ein. Die häufigsten Serotypen waren 3 (29 Stämme), 8 (21 Stämme) und 23 (neun Stämme). Bei Auswertung der API 20E-Profile der 118 Stämme mit der neuen ATB (automatischen, komputerassistierten)-Methode für das 20E system wurden 97/118 (82,2%) der Stämme alsE. cloacae identifiziert. Die 118 Stämme wurden einer Testung mit der neuen ATB ID 32E-Schnellmethode und dem ATB 32E (ATB System bioMérieux, Frankreich) unterzogen. Nur 69/118 (58,5%) der Stämme wurden mit beiden Methoden alsE. cloacae identifiziert. Die ATB ID 32E Schnellmethode identifizierte 97/118 Stämmen (82,2%) und die ATB IS 32E-Methode nur 80/118 (67,8%) der Stämme. Bei 73 serotypisierbaren Stämmen gelang die Identifizierung alsE. cloacae mit der ATB ID 32E-Schnellmethode in 79,5% der Fälle und mit ATB ID 32E in nur 64,4% der Fälle. 40 serotypisierbare Stämme, die das API 20E 3305573-Profil aufwiesen, wurden mit dem ATB ID 32E-System in allen Fällen alsE. cloacae identifiziert, mit dem ATB ID 32E-System hingegen nur 27 (67,5%). Weitere Verbesserungen dürften dazu beitragen, daß der Wert der biochemischen Identifizierung vonE. cloacae in der Diagnostik erhöht wird.