Operating room ventilation and the risk of revision due to infection after total hip arthroplasty: assessment of validated data in the Norwegian Arthroplasty Register.

BACKGROUND: The air in the operating room is considered a risk factor for surgical site infection (SSI) due to airborne bacteria shed from the surgical staff or from patients themselves. AIM: To assess the influence of validated operating room (OR) ventilation data on the risk of revision surgery due to deep infection after primary total hip arthroplasty (THA) reported to the Norwegian Arthroplasty Register (NAR). METHODS: Forty orthopaedic units reporting THAs to the NAR during the period 2005-2015 were included. The true type of OR ventilation in all hospitals at the time of primary THA was confirmed in a previous study. Unidirectional airflow (UDF) systems were subdivided into: small, low-volume, unidirectional vertical flow (lvUDVF) systems; large, high-volume, unidirectional vertical flow (hvUDVF) systems; and unidirectional horizontal flow (UDHF) systems. These three ventilation groups were compared with conventional, turbulent, mixing ventilation (CV). The association between the end-point, time to revision due to infection, and OR ventilation was estimated by calculating relative risks (RRs) in a multivariate Cox regression model, with adjustments for several patient- and surgery-related covariates. FINDINGS: A total of 51,292 primary THAs were eligible for assessment. Of these, 575 had been revised due to infection. A similar risk of revision due to infection after THA performed was found in ORs with lvUDVF and UDHF compared to CV. THAs performed in ORs with hvUDVF had lower risk of revision due to infection compared to CV (RR = 0.8; 95% CI: 0.6-0.9; P = 0.01). CONCLUSION: THAs performed in ORs with hvUDVF systems had lower risk of revision due to infection compared to THAs performed in ORs with CV systems. The perception that all UDF systems are similar and possibly harmful seems erroneous.

Secular trends in nosocomial bloodstream infections: antibiotic-resistant bacteria increase the total burden of infection.

BACKGROUND: It is unknown whether rising incidence rates of nosocomial bloodstream infections (BSIs) caused by antibiotic-resistant bacteria (ARB) replace antibiotic-susceptible bacteria (ASB), leaving the total BSI rate unaffected. METHODS: We investigated temporal trends in annual incidence densities (events per 100 000 patient-days) of nosocomial BSIs caused by methicillin-resistant Staphylococcus aureus (MRSA), ARB other than MRSA, and ASB in 7 ARB-endemic and 7 ARB-nonendemic hospitals between 1998 and 2007. RESULTS: 33 130 nosocomial BSIs (14% caused by ARB) yielded 36 679 microorganisms. From 1998 to 2007, the MRSA incidence density increased from 0.2 to 0.7 (annual increase, 22%) in ARB-nonendemic hospitals, and from 3.1 to 11.7 (annual increase, 10%) in ARB-endemic hospitals (P = .2), increasing the incidence density difference between ARB-endemic and ARB-nonendemic hospitals from 2.9 to 11.0. The non-MRSA ARB incidence density increased from 2.8 to 4.1 (annual increase, 5%) in ARB-nonendemic hospitals, and from 1.5 to 17.4 (annual increase, 22%) in ARB-endemic hospitals (P < .001), changing the incidence density difference from -1.3 to 13.3. Trends in ASB incidence densities were similar in both groups (P = .7). With annual increases of 3.8% and 5.4% of all nosocomial BSIs in ARB-nonendemic and ARB-endemic hospitals, respectively (P < .001), the overall incidence density difference of 3.8 increased to 24.4. CONCLUSIONS: Increased nosocomial BSI rates due to ARB occur in addition to infections caused by ASB, increasing the total burden of disease. Hospitals with high ARB infection rates in 2005 had an excess burden of BSI of 20.6 per 100 000 patient-days in a 10-year period, mainly caused by infections with ARB.

Development of a method to measure bacterial transfer from hands.

A method was developed to investigate the transfer of bacteria from the hands of healthcare workers (HCWs). The method involved standardised hand contact between the HCW and a recipient wearing sterile gloves, followed by sampling of the bare hands of the HCW and the gloved hands of the recipient by the glove juice method. The duration of contact, degree of friction and dryness of the hands could be varied. We investigated the applicability of the method for measuring transfer from hands artificially contaminated with Escherichia coli as well as from naturally contaminated hands following a 30s contact time with moderate friction and dry hands. Only a small proportion of bacteria on donor hands was recovered from the recipient: 0.15% for E. coli and 0.07% for natural hand flora. A smaller proportion of E. coli was recovered from bare skin compared with gloves, suggesting reduced survival of bacteria as a result of contact with natural skin. We suggest that these data are clinically relevant, and may indicate low transfer of bacteria during short contact with dry hands. This method is suitable to investigate the effect of potential risk factors for ineffective hand hygiene and the effect of hand hygiene procedures on contact transmission in clinical studies with large numbers of HCWs.

Surgical-site infections at Kilimanjaro Christian Medical Center.

A five-month prospective survey of surgical-site infections (SSI) was conducted in the department of general surgery at Kilimanjaro Christian Medical Center, Tanzania. SSI were classified according to Centers for Disease Control and Prevention (CDC) criteria and identified by bedside surveillance and post-discharge follow-up. This study showed that 77 (19.4%) of the patients developed SSI. Twenty-eight (36.4%) of these infections were apparent only after discharge from hospital. Eighty-seven percent of those who developed SSI had received antibiotic prophylaxis. Significant risk factors for developing SSI during hospital stay were: operations classified as contaminated or dirty, operations lasting for more than 50 min and the length of preoperative stay. The only significant risk factor for those who developed SSI after discharge was having undergone a clean-contaminated operation. Staphylococcus aureus was the most frequently isolated micro-organism followed by Escherichia coli and Klebsiella spp., most of which were multi-resistant. An exception was S. aureus where 54.5% of the isolates were fully susceptible. The incidence of SSI and the prevalence of antibiotic resistance in this teaching and tertiary care hospital are high. The risk factors were similar to those reported from countries with more resources. The findings suggest that infection prevention measures, particularly antibiotic prophylaxis, should be re-evaluated.

Biological monitoring of sterilizers and sterilization failures in Norwegian dental offices in 1985 and 1996.

It is essential that dental office sterilizers be regularly challenged with biological indicators (BIs) in order to prove that the test spores are being killed during sterilization. The aims of the study were to biologically monitor Norwegian dental office sterilizers and to identify factors contributing to sterilization failure. In 1985, participants received a packet containing: (i) 4 BI units; (ii) a set of instructions; (iii) a questionnaire concerning operation (including biological monitoring) of the office sterilizer(s), and (iv) a return-address envelope. In 1996, offices were sent (i) a survey which included demographic questions and inquiries concerning instrument sterilization processes; (ii) 2 sets of 3 BI units with instructions for their use on 2 different days; (iii) 1 control BI unit that was not to be processed, and (iv) a return-address envelope. Both private and public offices participated. Response rate to the 1996 study was 60%, which was 9.1% of all dental offices in Norway. Testing results indicated a 6.3% overall sterilization failure rate. Three out of 163 steam autoclaves (SAs) (1.8% of total) and 14 out of 109 dry heat (DH) ovens (12.8% of total) failed. DH ovens were over 7 times more likely to fail BI testing than were SAs (chi2, P < 0.01). Demographic or hygiene procedural factors could not be correlated to sterilization performance (chi2, P > 0.05). The failure rate for SAs (n = 216) in 1985 was almost 5 times greater than in 1996 (8.8% vs 1.8%). Improvement in sterilizer performance during the decade may be related to issuance in 1986 of Norway's 1st infection control guidelines for dentistry and greater awareness of infection control practices and/or to increases over the previous 10 years in the number of postgraduate courses offered in infection control. The current Norwegian guidelines on infection control practices in public health services, including dentistry, recommend regular biological monitoring of sterilizers without specifying how often. There is a lack of information among Norwegian dentists as to how frequently dental office sterilizers should be regularly monitored by BI.

Surveillance of the overall consumption of antibacterial drugs in humans, domestic animals and farmed fish in Norway in 1992 and 1996.

The annual overall consumption of antibacterial drugs in Norway, categorized into human use, use in domestic animals and in farmed fish, was estimated from wholesaler and feed-mill sales statistics. Comprehensive data on drug consumption in human medicine in Norway are published on a regular basis on behalf of the drug authorities. These data, including use of antibacterial drugs, are expressed as the number of defined daily doses (DDD)/1000 inhabitants/year. DDD cannot be employed to compare antibiotic consumption in human and veterinary medicine as it is possible to calculate such data for only a few veterinary drugs. The only parameter for which data are generally available, so far, is the amount used in kilograms of active substance, which is the unit of measurement chosen in this study. It was found that annual overall sales of antibacterial drugs in Norway, including antibacterial and ionophore feed additives, decreased from 77 tonnes in 1992 to 49 tonnes in 1996, a 37% reduction. The use in 1996 in human medicine, animals and farmed fish was 35 tonnes, 13 tonnes and 1 tonne, respectively. While the annual amounts used in human medicine remained unchanged from 1992 to 1996, therapeutic use in fish farming declined by 96%. In domestic animals, therapeutic use and use as feed additives declined by 17% and 5%, respectively. During the study period, the size of the human and domestic animal populations at risk remained almost constant, while the biomass (weight) of farmed fish at risk increased by > 100%. This implies that both the absolute and relative consumption of antibacterial drugs in Norway decreased substantially during the study period. The use of antibacterial drugs, both in humans and in domestic animals, has changed in favour of penicillins, this being in accordance with general recommendations. The reduction in the use of antibacterial drugs in farmed fish has been almost solely due to the introduction of oil-adjuvanted vaccines against furuncolosis. It is concluded that the decline in the amount of antibacterial drugs used in domestic animals, and the changes with regard to choice of drugs, could be mainly attributed to changes in prescribing behaviour following advice and recommendations. Moreover, the overall use of antibacterial drugs in Norway is very low compared with that in most other countries and has been significantly reduced during the 1990s.

Azithromycin versus placebo in acute infectious rhinitis with clinical symptoms but without radiological signs of maxillary sinusitis.

In this double-blind, parallel-group, multicenter study, 169 patients with symptoms of maxillary sinusitis but without radiographically confirmed empyema (pus) were randomly assigned to receive either 500 mg azithromycin once daily for 3 days (87 patients) or placebo daily for 3 days (82 patients). Nasal secretion, maxillary tenderness and pain, nasal obstruction, general malaise, and hyposmia were assessed at the start of the study and on days 4, 11, and 25 of treatment. After 11 days 58% of the patients in the azithromycin group were cured versus 31% in the placebo group; after 25 days the cure rate was 79% versus 67%, respectively. When both cure and improvement were considered, the corresponding figures after day 25 were 90% and 88%, respectively. Adverse events, predominantly gastrointestinal, occurred in 24 (27%) of the azithromycin-treated patients and in 15 (18%) of those treated with placebo, but the difference was not statistically significant. There was a difference in efficacy in favor of azithromycin in the treatment of rhinitis with symptoms of maxillary sinusitis but without radiological signs of empyema (pus). Antibiotics should only be used to alleviate symptoms in patients with moderate to severe symptoms, as the results after 25 days for both improvement and cure are equal. In the treatment of acute rhinitis with symptoms and signs of maxillary sinusitis but without empyema, treatment with azithromycin seems to result in a better cure rate after 10-12 days when compared with placebo.

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.

Preoperative bacterial colonization and its influence on postoperative wound infections in plastic surgery.

During two separate periods a total of 654 patients were included in a clinical study relating preoperative bacterial colonization to occurrence of postoperative wound infection in plastic surgery. During the second period one half of the patients were randomized to receive prophylactic azithromycin. Bacteriological samples were collected from the nasal vestibulum during both periods, and additionally from the surgical field during the second period. All patients had preoperative chlorhexidine bathing. The bacteriological findings were categorized as either normal flora or potentially pathogenic bacteria, and as either having no growth. Surgical wounds were divided into four contamination classes. Postoperative follow-up was 30 days, and assessment of wound infection was based on a graded scale. We did not find any statistically significant relation between preoperative bacterial colonization and postoperative wound infection, regardless of place of sample collection, method of bacterial classification, class of contamination or use of prophylactic azithromycin.

Efficacy and safety of azithromycin versus phenoxymethylpenicillin in the treatment of acute maxillary sinusitis.

In the treatment of acute maxillary sinusitis, azithromycin offers an advantage over phenoxymethylpenicillin in that a complete course of treatment requires drug administration once daily for only three days. In this double-blind, parallel-group, multicenter study, 438 patients with radiographically verified maxillary sinusitis were randomly assigned to receive either 500 mg azithromycin once daily for three days (221 patients) or 1.3 g phenoxymethylpenicillin three times daily for ten days (217 patients). Nasal secretion, maxillary tenderness and pain, nasal obstruction, general malaise, and hyposmia, were assessed at the start of the study and on days 4, 11, and 25 of treatment. After 11 days 58% of the patients in the azithromycin group were cured versus 51% in the penicillin group; after 25 days the cure rate was 79% versus 76%, respectively. When both cure and improvement were considered, the corresponding figures after 11 days were 97% (azithromycin) and 95% (penicillin); after 25 days they were 92% and 88%, respectively. Adverse events, predominantly gastrointestinal, occurred in 73 (33%) of the azithromycin-treated patients and in 87 (40.1%) of those treated with penicillin. No difference in efficacy was found between the two drugs in the treatment of acute maxillary sinusitis, and the adverse effects were comparable. The short duration of treatment with azithromycin offers a significant advantage over treatment with phenoxymethylpenicillin.

Generation of hydroxyl radicals by polymorphonuclear neutrophils during exposure to direct current and iron.

Human polymorphonuclear neutrophils were exposed to direct output current of 3 or 5 mA at either 300 or 500 V for 1 h in the presence and absence of iron. The current density was 25 or 40 nA/cm2. The formation of free oxygen radicals was measured as breakdown products from deoxyribose and methional. The cells were shown to generate oxygen radicals on electrical stimulation. A physiological concentration of iron enhanced radical formation, but OH. was also formed in the absence of added iron. The most pronounced stimulation was seen at output current 5 mA and 500 V.

A prospective, double-blind, placebo-controlled trial of a single dose of azithromycin on postoperative wound infections in plastic surgery.

Over a 9-month period from September of 1991 to May of 1992, 339 patients were included in a randomized, double-blind, placebo-controlled study using azithromycin as the prophylactic agent to determine whether it effects a clinically meaningful reduction in postoperative surgical infections in plastic surgery. Azithromycin was given as prophylaxis in 171 patients and placebo in 168 patients. The study medication was a single oral dose taken at 8 P.M. the day before surgery. The patients were followed up for a minimum of 4 weeks after surgery. The patients who received wound infection prophylaxis had 5.1 percent infections compared with 20.5 percent in the placebo group (p = 0.00009). Eighty percent of all wound infections were first seen after discharge, explaining why plastic surgeons might overlook their infectious complications. There was a significant reduction in postoperative complications (p = 0.04) and in the additional use of antibiotics postoperatively (p = 0.007) in the prophylaxis group. Subgroup analysis showed a significant reduction in surgical infections in breast surgery (p < 0.05) and reconstructive surgery with flaps (p < 0.05). No effect of the prophylactic regime was demonstrated in patients undergoing secondary surgery for cleft lip and palate disease.

Inhibition of growth of Proteus mirabilis and Escherichia coli in urine in response to fasting and vegetarian diet.

It has recently been shown that serum antibody levels against Proteus mirabilis decreased in patients with rheumatoid arthritis who improved clinically during treatment with 7-10 days of fasting followed by a one-year vegetarian diet. As P. mirabilis is commonly implicated in urinary tract infections, this study was carried out to examine whether fasting and vegetarian diet may influence the growth of P. mirabilis and Escherichia coli in urine. Urine samples were collected from 22 patients who were referred to a health farm for various reasons. The dietary regimen recommended by the health farm consisted of fasting for 7 to 10 days followed by a vegan diet. The growth of both bacteria in urine samples collected after 8 days was significantly slower than in samples collected at baseline. In urine samples collected after 18 days growth was also reduced, although not significantly for E. coli. Our results show that dietary manipulation may reduce the ability of urine to support the growth of P. mirabilis and E. coli.

A prospective, randomized surveillance study of postoperative wound infections after plastic surgery: a study of incidence and surveillance methods.

In a postoperative wound infection study in plastic surgery, 315 patients were randomized to either outpatient wound control after 30 days (group I) or self-control by questionnaire (group II). We present a new definition of wound infection based on physiologic wound healing. The surveillance of postoperative wound infection showed follow-up rates of 95 and 68 percent and infection rates of 16.3 and 17.1 percent for groups I and II, respectively. Of the 43 patients (16.7 percent) with postoperative wound infections, 31 (72 percent) were diagnosed after leaving the hospital, and only 12 (28 percent) were diagnosed during hospital stay. The monthly wound infection rate declined from 23.5 percent when the registration started to 12.2 percent at the end of the surveillance. The wound infection rate nearly tripled when duration of surgery was more than 120 minutes compared with less than 60 minutes. Postoperative wound infection was significantly related to preoperative contamination class, with an increase from 10.2 percent wound infections in class "clean" to 37.5 percent in class "dirty." We conclude that postoperative wound infection also crops up in the plastic surgical department, and this situation has not, to date, been documented sufficiently. A simple questionnaire gives a useful survey of postoperative wound infections. An active follow-up for at least 30 days is essential to register the rate of surgical infections.

Granulocyte colony-stimulating factor improves myelopoiesis and host defense in fulminant intra-abdominal sepsis in rats.

The therapeutic efficacy of granulocyte colony-stimulating factor (G-CSF) was studied in a model of fulminant sepsis in rats. Polymicrobial peritonitis was induced by a 4 mm cecal perforation and 10 micrograms/kg recombinant human G-CSF was given intravenously every 12 h, with the first dose at sepsis induction or 4 h post-induction. Rats were sacrificed at various intervals throughout sepsis to measure levels of neutrophil progenitors in the bone marrow and neutrophils and bacteria in blood and peritoneal fluid. Sepsis gave a sustained neutropenia and bacteremia, but did not affect numbers of blast- or GM-colonies, and only a delayed and moderate proliferation of G-clones was seen. Treatment with G-CSF at sepsis induction improved myelopoiesis by doubling the numbers of GM- and G-progenitors at 12 and 24 h post-induction. Concentrations of neutrophils increased twofold in blood and 5-fold in peritoneal fluid, while bacteria counts in the same compartments declined logarithmically. Mortality was 92% in untreated sepsis and declined to 46% when G-CSF therapy was started at sepsis induction, and to 42% following 4 h delayed therapy.

[Infection control in Norwegian somatic hospitals 1990]. / Infeksjonskontroll ved norske somatiske sykehus 1990.

The authors present results from a survey of infection control in Norwegian somatic hospitals, carried out during summer/autumn 1990. In 15 of 74 hospitals (20%) one of the hospital doctors was appointed as responsible for infection control. 35 hospitals (48%) had an infection control nurse. Only nine hospitals (12%) reported routine prospective surveillance of hospital infections. The survey revealed a clear under-utilization of commonly accepted methods to survey and prevent hospital infections. Many of the respondents stated the need for national guidelines for infection control. The health authorities should take the initiative to remedy this situation. A new law concerning secondary health care will be passed in the near future, requiring hospitals to establish effective quality assurance systems. Infection control is a very concrete example of quality assurance, and should be given priority when setting up quality assurance systems for hospitals.

Intestinal microbial conversion of cholesterol to coprostanol in man. Influence of antibiotics.

The intestinal microbial conversion of cholesterol to coprostanol has been measured in groups of healthy subjects before, during and after they received the antibiotics ampicillin, bacitracin, clindamycin, co-trimoxazole, doxycycline, erythromycin, metronidazole, nalidixic acid, ofloxacin or vancomycin orally for 6 days. Before they received antibiotics, the subjects demonstrated two distinct patterns of cholesterol conversion. One pattern was characterised by extensive conversion of cholesterol, the other by little or no conversion. Intake of bacitracin, clindamycin, erythromycin, metronidazole and vancomycin significantly reduced the conversion to coprostanol. In the groups receiving ampicillin or doxycycline, marked reductions were found in most of the subjects. No alterations were found in the groups receiving co-trimoxazole, nalidixic acid or ofloxacin. In 6 subjects no conversion of cholesterol to coprostanol was found up to 5 weeks after the end of the antibiotic intake. We conclude that orally given antibiotics may cause alterations in the intestinal conversion of cholesterol, reflecting changes in the anaerobic, Gram-positive component of the gut flora.

Antimicrobial actions of calcium binding leucocyte L1 protein, calprotectin.

The calcium binding L1 protein was found to inhibit growth of blood culture isolates of Candida spp and cerebrospinal fluid isolates of Cryptococcus neoformans. Minimum inhibitory concentrations (MIC) were 4-128 mg/l, and concentrations 2-4 times the MIC were fungicidal. Blood culture isolates of Escherichia coli, Klebsiella spp, Staphylococcus aureus, and Staphylococcus epidermidis had MIC values of 64-256 mg/l. Antibacterial activity was strongly influenced by the nature of the culture medium. In view of the biological activity of L1, the name calprotectin is proposed to describe this antimicrobial protein with calcium binding properties.

In vitro activity of 9 antimicrobial agents against 177 strains of Haemophilus influenzae isolated from hospitalized patients.

In vitro activity of 4 commonly used and 5 new antibiotics was examined against 177 strains of Haemophilus influenzae. All strains were collected from various sites in patients with clinical infections. The study confirms that several newer antibiotics are useful alternatives to older drugs, as measured by in vitro activity. Ciprofloxacin and ofloxacin were the most active agents, (MIC90 0.012 micrograms/ml and 0.05 micrograms/ml respectively), followed by aztreonam (MIC90 0.1 micrograms/ml) and cefuroxime (MIC90 0.8 micrograms/ml). A new macrolide, azithromycin (CP 62,993), was more active than erythromycin, MIC90 1.6 micrograms/ml vs 6.4 micrograms/ml. Beta-lactamase production was detected in 4.5% (8/177) of the strains. In vitro activity was the same against strains collected in 1985 and 1988. No increase in beta-lactamase production was recorded.