Impact of infection control interventions on rates of Staphylococcus aureus bacteraemia in National Health Service acute hospitals, East Midlands, UK, using interrupted time-series analysis.

BACKGROUND: Reducing healthcare-associated infection (HCAI) is a UK national priority. Multiple national and regional interventions aimed at reduction have been implemented in National Health Service acute hospitals, but assessment of their effectiveness is methodologically challenging. AIM: To assess the effectiveness of national and regional interventions undertaken between 2004 and 2008 on rates of meticillin-resistant Staphylococcus aureus (MRSA) and meticillin-sensitive Staphylococcus aureus (MSSA) bacteraemia within acute hospitals in the East Midlands, using interrupted time-series analysis. METHODS: We used segmented regression to compare rates of MRSA and MSSA bacteraemia in the pre-intervention, implementation, and post-intervention phases for combined intervention packages in eight acute hospitals. FINDINGS: Most of the change in MSSA and MRSA rates occurred during the implementation phase. During this phase, there were significant downward trends in MRSA rates for seven of eight acute hospital groups; in four, this was a steeper quarter-on-quarter decline compared with the pre-intervention phase, and, in one, an upward trend in the pre-intervention phase was reversed. Regarding MSSA, there was a significant positive effect in four hospital groups: one upward trend during the pre-intervention phase was reversed, two upward trends plateaued, and in one hospital group an indeterminate trend decreased significantly. However, there were significant increasing trends in quarterly MSSA rates in four hospital groups during the implementation or post-intervention periods. CONCLUSION: The impact of interventions varied by hospital group but the overall results suggest that national and regional campaigns had a beneficial impact on MRSA and MSSA bacteraemia within the East Midlands.

Enzyme amplified immunoassay: a novel technique applied to direct detection of Chlamydia trachomatis in clinical specimens.

Endocervical swabs from 212 women and urethral swabs from 100 men were tested by the routine methods for McCoy cell culture and simultaneously by a novel enzyme amplified immunoassay test to detect chlamydia antigen. Overall correlation of the amplified test with culture was 96.5%. The test proved to be a suitable screening procedure for genital chlamydial infection, particularly for large numbers of specimens or in cases in which culture was not available.

New and old agents in diarrhea: a prospective study of an indigenous adult African population.

We conducted a prospective study 77 indigenous African adults with acute diarrhea seeking care at the major hospital in Nairobi, Kenya, to determine the major pathogens responsible for this syndrome in adults. Fecal and blood specimens were collected and examined for enteric bacterial pathogens, viruses, and parasites. In 13 (26%) inpatients and 11 (49%) outpatients Shigella was found, and heat-labile and heat-stable forms of enterotoxigenic Escherichia coli were found in 9 (18%) inpatients and 1 (4%) outpatient. Human revirus-like agent titers rose significantly in another 3 (6%). Amebic dysentery was not seen although hemagglutination-inhibition tests for invasive Entamoeba histolytica were positive in 4 inpatients. An etiologic agent was found in 65% of patients.

Use of a non-radioactive hybridisation assay for direct detection of gram-negative bacteria carrying TEM beta-lactamase genes in infected urine.

DNA in infected urines from 81 patients with urinary tract infection was hybridised directly with a non-radioactive DNA probe specific for bacterial genes coding for TEM-type beta-lactamase. The results were assessed by means of a computerised image analysis system and compared with those obtained following isolation of the infecting organism, conventional sensitivity testing and isoelectric focusing (IEF) procedures for the detection of TEM-type beta-lactamase. Of the 27 ampicillin-resistant gram-negative organisms isolated in pure culture from the urines, 14 were shown by both hybridisation and IEF to carry a gene for TEM beta-lactamase production. Only four discordant results were obtained: three "false positive" direct hybridisation results, one due to urine pigmentation, and one, possibly, to a TEM beta-lactamase gene which was not being expressed, and one "false negative" result due to insufficient cell numbers in the urine. The system is capable of screening large numbers of samples and is applicable to any gene for which a suitable DNA probe is available.

A bacteriological survey of amputation wound sepsis.

A retrospective survey of 100 lower limb amputations performed for ischaemia were analysed to assess the influence of preoperative bacterial isolates and the use of prophylactic antibiotics on wound sepsis. Forty-eight per cent had previously undergone a vascular procedure to attempt limb salvage and 17% were diabetics. Benzylpenicillin was given preoperatively and continued for 5 days; diabetics received metronidazole in addition. A total of 51 isolates were obtained from 30 patients preoperatively; Staphylococcus aureus and Enterobacteriaceae each accounted for over 25%. Postoperatively, 74 isolates (20 multiple) were obtained with an overall sepsis rate of 40%. Those patients with a positive preoperative culture were significantly more likely to develop wound sepsis. There was no significant difference in wound sepsis rates for diabetics. In view of the range of organisms causing postoperative infection, we recommend prophylaxis with a broad spectrum antibiotic for amputations.

Randomised study of prophylactic parenteral sulbactam/ampicillin and cephazolin in biliary surgery: significant benefit in jaundiced patients.

Two hundred consecutive patients undergoing biliary-tract surgery were entered into a randomized trial of prophylactic single dose cephazolin or sulbactam/ampicillin. There was no overall difference in the infection rates between the two antibiotic groups, but in the group of patients with jaundice there was an excess of wound infections in the cephazolin group compared to the sulbactam/ampicillin group (35% vs. 14%). We conclude that sulbactam/ampicillin is a satisfactory prophylactic agent for use in biliary-tract surgical sepsis, and that it may be superior to cephazolin in jaundiced patients.

Bacteriology and ultrastructure of the bladder in patients with urinary tract infections.

Tissue obtained by biopsy of the bladder from 33 patients with various urinary tract symptoms was studied by conventional bacteriological techniques and by scanning electron microscopy (SEM). All the patients had recurrent urinary tract symptoms which had not completely responded to antibiotic therapy. Eleven of the patients had greater than or equal to 10(8) colony-forming units (CFU) of bacteria/1 urine; six had between 10(6) and 10(7) CFU/1, and 16 were abacteruric. Bacteria were isolated, however, from the tissue obtained by biopsy from eight of the 16 patients with sterile urine and bacteria were seen on the uro-epithelium in 14 of these patients. By comparison, in all samples of tissue obtained from the 11 patients with greater than or equal to 10(8) CFU/1 of urine bacteria were seen on the uro-epithelium and from nine of these, bacteria were subsequently grown. Fastidious organisms were not isolated from any of the patients. The uro-epithelium of all those studied was also shown to be grossly disrupted with increased disturbance and loss of the epithelial cells when compared with tissue obtained from uninfected patients. The degree of uro-epithelial disturbance was greatest in patients with histories of urinary tract infections lasting more than 4 months. The findings suggest that bacteriological examination of the urine does not always reflect bacterial infection on the bladder surface nor disruption of the uro-epithelium. The changes on the bladder surface may explain the patients' symptoms. In view of the results, a scheme is proposed that explains the development of symptoms in patients with urinary tract and bladder infections.

The penetration of antibiotics into the normal intervertebral disc.

The role of antibiotics in the treatment of disc-space infection is controversial. This study assessed the tissue penetration of flucloxacillin and cephradine into the normal intervertebral disc after intravenous administration of a bolus dose of antibiotic. Twenty-five discs were removed from 12 adolescent patients having anterior spinal surgery to correct scoliosis; antibiotic had been administered between 30 minutes and four hours before operation. Despite high blood levels, no antibiotic could be detected by bioassay or by high-pressure liquid chromatography (h.p.l.c.) in any of the specimens from the nucleus pulposus or the annulus fibrosus.

Perioperative prophylaxis with sulbactam and ampicillin compared with metronidazole and cefotaxime in the prevention of wound infection in children undergoing appendectomy.

Sulbactam is a beta-lactamase inhibitor, which when administered with ampicillin, increases the latter agents antibacterial activity against beta-lactamase producing organisms. One hundred children between the ages of 5 and 14 undergoing emergency appendectomy were entered into a prospective randomized trial comparing sulbactam and ampicillin (SA) with metronidazole and cefotaxime (MC) as prophylaxis against postoperative wound infection. Patients in whom the appendix was perforated or gangrenous received a 72-hour course of antibiotics, others received a single dose only. The overall wound infection rate was 8% (14% in patients with perforation or gangrene and 4% in those without). There was no difference in infection rate between the two antibiotic groups; there were three wound infections and one subphrenic abscess in patients receiving SA and four wound infections in patients receiving MC. SA, therefore, appears to be a suitable antibiotic combination for use as prophylaxis in appendicitis in children.

Tissue and serum concentrations of amoxycillin and clavulanic acid in patients having reconstructive vascular surgery.

Fifteen patients received amoxycillin/clavulanic acid combination intravenously at anaesthetic induction as part of a three-dose schedule of antibiotic prophylaxis for vascular surgery. After 30 min, the mean serum concentration of amoxycillin was 39.9 mg/l and clavulanic acid was 9.3 mg/l. Mean amoxycillin tissue concentrations in fat, 5.1 mg/l; vein, 7.5 mg/l; and artery, 4.8 mg/l, were lower than serum values. Mean clavulanic acid concentrations were: fat, 0.7 mg/l; vein, 1.2 mg/l; and artery, 1.6 mg/l. At the end of surgery, the serum amoxycillin level was always greater than 6 mg/l and clavulanic acid greater than 2 mg/l, which were both still within the therapeutic range. Concentrations in fat had declined by the end of the surgery ranging from 0.76 to 5.2 mg/l for amoxycillin and from 0.03 to 0.6 mg/l for clavulanic acid, there being almost none detected in four cases. Serum and tissue concentrations of both compounds 30 min after injection were sufficient to inhibit the growth of 97% of pathogenic organisms recovered from the skin of 135 vascular surgical patients. In a few cases tissue levels of the compounds were below inhibitory concentrations for coliforms and anaerobes at the time of skin closure, although they were still effective against most Gram-positive organisms. Amoxycillin/clavulanic acid combination is suitable antibiotic prophylaxis for vascular surgery.

Risk factors in vascular surgical sepsis.

The risk factors for sepsis after vascular surgery were studied in 100 consecutive patients with lower limb arterial ischaemia. Patients were randomised either to a short or long course of antibiotic prophylaxis with amoxycillin/clavulanic acid combination (Augmentin). Pathogenic organisms were isolated from the skin preoperatively in 39 (36%) cases, significantly more frequently in patients with ischaemic rest pain and skin necrosis (66%) than rest pain alone (21%) (P = 0.0004) or claudication/aneurysm (11%) (P = 0.0001). All but three organisms isolated (5%) were sensitive to amoxycillin/clavulanic acid. A wound infection occurred after 21 (19%) reconstructions, significantly more frequently both in patients suffering rest pain with skin necrosis (P = 0.001) and rest pain without skin necrosis (P = 0.04) compared with claudication/aneurysm. Sixteen of the 21 patients with a wound infection had at least one organism isolated from their skin preoperatively (P = 0.0001). Twelve patients (57%) had a similar organism isolated from the skin preoperatively and from the postoperative wound infection. Reducing the course of antibiotic prophylaxis from 5 days to 3 doses did not significantly increase the infection rate. The only other significant risk factor for sepsis was increasing age of the patient. Although prophylaxis is undisputed in patients having synthetic grafts, antibiotics may not be as important in the prevention of wound sepsis as had been thought. The role of antiseptic agents requires further evaluation.

Changing carriage rate of Neisseria meningitidis among university students during the first week of term: cross sectional study.

OBJECTIVE: To determine the rates of, and risk factors for, meningococcal carriage and acquisition among university students. DESIGN: Repeated cross sectional study. PARTICIPANTS: 2,507 students in their first year at university. MAIN OUTCOME MEASURES: Prevalence of carriage of meningococci and risk factors for carriage and acquisition of meningococci. RESULTS: Carriage rates for meningoccoci increased rapidly in the first week of term from 6.9% on day 1, to 11.2% on day 2, to 19.0% on day 3, and to 23.1% on day 4. The average carriage rate during the first week of term in October among students living in catered halls was 13.9%. By November this had risen to 31.0% and in December it had reached 34. 2%. Independent associations for acquisition of meningococci in the autumn term were frequency of visits to a hall bar (5-7 visits: odds ratio 2.7, 95% confidence interval 1.5 to 4.8), active smoking (1.6, 1.0 to 2.6), being male (1.6, 1.2 to 2.2), visits to night clubs (1. 3, 1.0 to 1.6), and intimate kissing (1.4, 1.0 to 1.8). Lower rates of acquisition were found in female only halls (0.5, 0.3 to 0.9). The most commonly acquired meningococcal strain was C2a P1.5 (P1.2), which has been implicated in clusters of invasive meningococcal disease at other UK universities. CONCLUSIONS: Carriage rates of meningococci among university students increase rapidly in the first week of term, with further increases during the term. The rapid rate of acquisition may explain the increased risk of invasive meningococcal disease and the timing of cases and outbreaks in university students.