The effect of preoperative oral antibiotic use on the risk of periprosthetic joint infection after primary knee or hip replacement: a retrospective study with a 1-year follow-up.

OBJECTIVES: Antibiotics are used for various reasons before elective joint replacement surgery. The aim of this study was to investigate patients' use of oral antibiotics before joint replacement surgery and how this affects the risk for periprosthetic joint infection (PJI). METHODS: Patients having a primary hip or knee replacement in a tertiary care hospital between September 2002 and December 2013 were identified (n = 23 171). Information on oral antibiotic courses purchased 90 days preoperatively and patients' chronic diseases was gathered. Patients with a PJI in a 1-year follow-up period were identified. The association between antibiotic use and PJI was examined using a multivariable logistic regression model and propensity score matching. RESULTS: One hundred and fifty-eight (0.68%) cases of PJI were identified. In total, 4106 (18%) joint replacement operations were preceded by at least one course of antibiotics. The incidence of PJI for patients with preoperative use of oral antibiotics was 0.29% (12/4106), whereas for patients without antibiotic use it was 0.77% (146/19 065). A preoperative antibiotic course was associated with a reduced risk for subsequent PJI in the multivariable model (OR 0.40, 95% CI 0.22-0.73). Similar results were found in the propensity score matched material (OR 0.34, 95% CI 0.18-0.65). CONCLUSIONS: The use of oral antibiotics before elective joint replacement surgery is common and has a potential effect on the subsequent risk for PJI. Nevertheless, indiscriminate use of antibiotics before elective joint replacement surgery cannot be recommended, even though treatment of active infections remains an important way to prevent surgical site infections.

The impact of preoperative bacteriuria on the risk of periprosthetic joint infection after primary knee or hip replacement: a retrospective study with a 1-year follow up.

OBJECTIVES: Patients who undergo elective joint replacement are traditionally screened and treated for preoperative bacteriuria to prevent periprosthetic joint infection (PJI). More recently, this practice has been questioned. The purpose of this study was to determine whether preoperative bacteriuria is associated with an increased risk of PJI. METHODS: Patients who had undergone a primary hip or knee replacement in a tertiary care hospital between September 2002 and December 2013 were identified from the hospital database (23 171 joint replacements, 10 200 hips, and 12 971 knees). The results of urine cultures taken within 90 days before the operation were obtained. Patients with subsequent PJI or superficial wound infection in a 1-year follow-up period were identified based on prospective infection surveillance. The association between bacteriuria and PJI was examined using a multivariable logistic regression model that included information on the operated joint, age, gender and the patients' chronic diseases. RESULTS: The incidence of PJI was 0.68% (n = 158). Preoperative bacteriuria was not associated with an increased risk of PJI either in the univariate (0.51% versus 0.71%, OR 0.72, 95% CI 0.34-1.54) or in the multivariable (OR 0.82, 95% CI 0.38-1.77) analysis. There were no cases where PJI was caused by a pathogen identified in the preoperative urine culture. Results were similar for superficial infections. CONCLUSIONS: There was no association between preoperative bacteriuria and postoperative surgical site infection. Based on these results, it seems that the preoperative screening and treatment of asymptomatic bacteriuria is not required.

Evidence of streptococcal origin of acute non-necrotising cellulitis: a serological study.

Bacteriological diagnosis is rarely achieved in acute cellulitis. Beta-haemolytic streptococci and Staphylococcus aureus are considered the main pathogens. The role of the latter is, however, unclear in cases of non-suppurative cellulitis. We conducted a serological study to investigate the bacterial aetiology of acute non-necrotising cellulitis. Anti-streptolysin O (ASO), anti-deoxyribonuclease B (ADN) and anti-staphylolysin (ASTA) titres were measured from acute and convalescent phase sera of 77 patients hospitalised because of acute bacterial non-necrotising cellulitis and from the serum samples of 89 control subjects matched for age and sex. Antibiotic treatment decisions were also reviewed. Streptococcal serology was positive in 53 (69%) of the 77 cases. Furthermore, ten cases without serological evidence of streptococcal infection were successfully treated with penicillin. Positive ASO and ADN titres were detected in ten (11%) and three (3%) of the 89 controls, respectively, and ASTA was elevated in three patients and 11 controls. Our findings suggest that acute non-necrotising cellulitis without pus formation is mostly of streptococcal origin and that penicillin can be used as the first-line therapy for most patients.

Obesity and nosocomial infections.

BACKGROUND: The prevention of healthcare-associated infections (HCAIs) is a major goal in modern healthcare. Intrinsic, patient-related factors may contribute to the risk of HCAIs. AIM: To review the association between obesity and the risk and outcome of HCAIs. METHODS: A PubMed search of relevant studies on obesity and nosocomial infections and obesity and dosing of antimicrobials. Search terms were: 'obesity', 'infection', 'nosocomial infection', 'surgical site infection', 'critical care unit', 'bacteremia', 'urinary tract infection', 'health care associated infection'. FINDINGS: Obesity has been shown to be associated with an increased risk of HCAIs in several studies. The association is most clear in cardiac, vascular, orthopaedic and gastrointestinal surgery. Body mass index (BMI) data are frequently recorded in patients undergoing surgical and invasive procedures. The recording of BMI data is not systematic in the literature and in many studies median BMI of the control group or reference group (normal weight) also indicates overweight or obesity. Thus, clear BMI cut-offs for increased infection risk cannot be determined. Obesity is frequently associated with underdosing of antimicrobials in both prophylaxis and treatment of HCAIs. Studies indicate that obesity affects the pharmacokinetics of antimicrobial drugs. However, there are no dosing recommendations for antimicrobial use in obesity. CONCLUSIONS: Obesity increases the risk of nosocomial infections and is frequently associated with underdosing of antimicrobials in both prophylaxis and treatment of HCAIs. A challenge in future hospital hygiene prevention lies in our capacity to combat obesity epidemics.

Recurrent cellulitis with benzathine penicillin prophylaxis is associated with diabetes and psoriasis.

Risk factors for recurrent cellulitis were assessed in a case-control study including 398 patients receiving prophylactic treatment with benzathine penicillin and 8,005 controls derived from a national population-based health survey. In the multivariate analysis, psoriasis [odds ratio (OR) 3.69], other chronic dermatoses (OR 4.14), diabetes (OR 1.65), increasing body mass index (OR 1.17), increasing age (OR 1.06) and history of previous tonsillectomy (OR 6.82) were independently associated with recurrent cellulitis. Forty percent of the patients reported a cellulitis recurrence, despite ongoing benzathine penicillin prophylaxis. The role of previous tonsillectomy in recurrent cellulitis needs further evaluation.

Factors predisposing to acute and recurrent bacterial non-necrotizing cellulitis in hospitalized patients: a prospective case-control study.

Acute non-necrotizing cellulitis is a skin infection with a tendency to recur. Both general and local risk factors for erysipelas or cellulitis have been recognized in previous studies using hospitalized controls. The aim of this study was to identify risk factors for cellulitis using controls recruited from the general population. We also compared patients with a history of previous cellulitis with those suffering a single episode, with regard to the risk factors: length of stay in hospital, duration of fever, and inflammatory response as measured by C-reactive protein (CRP) level and leukocyte count. Ninety hospitalized cellulitis patients and 90 population controls matched for age and sex were interviewed and clinically examined during the period April 2004 to March 2005. In multivariate analysis, chronic oedema of the extremity, disruption of the cutaneous barrier and obesity were independently associated with acute cellulitis. Forty-four (49%) patients had a positive history (PH) of at least one cellulitis episode before entering the study. Obesity and previous ipsilateral surgical procedure were statistically significantly more common in PH patients, whereas a recent (<1 month) traumatic wound was more common in patients with a negative history (NH) of cellulitis. PH patients had longer duration of fever and hospital stay, and their CRP and leukocyte values more often peaked at a high level than those of NH patients. Oedema, broken skin and obesity are risk factors for acute cellulitis. The inflammatory response as indicated by CRP level and leukocyte count is statistically significantly more severe in PH than NH patients.

Effect of interleukin-10 on NF-kB and AP-1 activities in interleukin-2 dependent CD8 T lymphoblasts.

Interleukin-10 is a multifunctional cytokine, which regulates the function of various cell types of the immune system. In CD8 T cells it is known to accelerate the interleukin-2 dependent proliferation and to induce the differentiation of these cells to active cytolytic cells. Now we have studied interleukin-10 induced intracellular signaling mechanisms in human interleukin-2 dependent CD8 T lymphoblasts. The data obtained demonstrate that interleukin-10 alone can activate the AP-1 transcription factor and potentiate the interleukin-2 induced NF-kappa B activity. Moreover, interleukin-10 induced a rapid tyrosine phosphorylation of several proteins. The pattern of proteins phosphorylated was very similar to that induced by interleukin-2. Together, these findings suggest that tyrosine kinase dependent activation of NF-kappa B and AP-1 transcription factors are involved in the signaling mechanism of interleukin-10. This activation pathway resembles that of interleukin-2 in the same cell type.

Comparison of three serological methods for diagnosing Mycoplasma pneumoniae infection.

AIMS: To compare the novel Serofast latex agglutination test (International Mycoplasma, Toulon-Cedex, France) with the complement fixation test and enzyme immunoassay (EIA) for diagnosing acute Mycoplasma pneumoniae infection. METHODS: Paired sera from 60 patients with respiratory infection who had tested positive for M pneumoniae by complement fixation test were analysed with Serofast and indirect EIA for specific IgG and IgM antibodies. RESULTS: Serofast was less sensitive than the two other tests. Only 30 (50%) out of 60 paired sera which showed a diagnostic seroconversion or had high positive, unchanged antibody titres by complement fixation test or EIA, or both, tested positive with Serofast. Positive test results with Serofast were associated with the presence of a complement fixation test titre of > or = 512 and high positive IgM antibody titres measurable by EIA; virtually all patients with a complement fixation test titre of < 256 or those responding primarily in the IgG class tested negative with Serofast. Based on analysis of sera taken at the acute phase of infection, 10 (17%) of the 60 patients tested positive by complement fixation test, 10 (17%) by EIA, and only four (7%) by Serofast. CONCLUSIONS: Serofast was less sensitive than complement fixation test and EIA and it cannot be recommended as a replacement for either test in routine diagnostic use. It might prove useful in laboratories where non-specific tests, such as the determination of cold agglutinins, are still used for the diagnosis of M pneumoniae infection. Testing paired sera is, however, a prerequisite for obtaining acceptable sensitivity by Serofast as well as other serological methods currently available.