Empirical and mathematical models on the relationship between patient age and nosocomial infection

This paper proposes two models, one a purely empirical one and the others a mathematical one, which depict the relationship between patient age and nosocomial infection rate. The empirical model is based on the two age-specific phenomena, the acquisition of resistance to infection with age mainly in the early years of life and the deterioration of existing resistance mechanisms with ageing predominantly in the later years of life. The net effect of these two factors is shown to approximate into a quadratic relationship betwen age and nosocomial infection rate, like the type demonstrated in earlier experimental studies. The second mathematical model is derived from studies on cancer research and here the relationship between age and nosocomial infection rate for patients in the age group 30–70 years is represented by a log linear model. The model was tested against experimental data derived from large surveys on nosocomial infection and the resulting correlation coefficient was 0.98. The model was an extremely good fit when tested against posto-operative wound infection rates as well as nasal carriage rate of antibiotic resistant Staph. aureus. Furthermore, when patients in the survey were subdivided into groups of male patients and female patients and into two groups based on the type of operative wound, the model was still found to be a very good fit to the experimental data. This confirmed the validity of the model even in the presence of other patient-related parameters. Finally, the model was tested against the results of a totally different experimental study conducted elsewhere and the resulting correlation coefficient was 0.999, which confirmed the validity of the model in a universal context.     

A comparison of complication rates in large and small inferior pedicle reduction mammaplasty

The main objective of this retrospective study was to determine whether the rates of complications are higher in large reductions (> or =1000 g per breast) as compared with smaller reductions (< or =999 g per breast) using the inferior pedicle technique. A retrospective chart review of 133 consecutive patients operated on between October of 2000 and March of 2002 was undertaken. Complication data were recorded and analyzed on a per-breast basis. Two hundred sixteen breasts had reductions of 999 g or less, whereas 50 breasts had reductions of 1000 g or more. The overall mean follow-up period was 152 days (range, 20 to 522 days). There were no statistically significant differences in the rates of nipple necrosis, hematoma formation, seroma, delayed healing, culture-positive wound infection, fat necrosis, cyst formation, nipple sensation, or hypertrophic scarring between the large and small reductions. However, the rate of wound dehiscence was significantly lower in the smaller reduction group. The rates of wound dehiscence and hypertrophic scarring were also significantly lower in patients who had received at least 5 days of postoperative antibiotics. A statistically significant difference was also reported for clinical wound infection (p < 0.0005). Body mass index had no statistically significant effect on the rate of nipple necrosis, hematoma formation, fat necrosis, cyst formation, nipple sensation, or hypertrophic scarring. However, body mass index had a statistically significant effect on delayed healing, wound dehiscence, and culture-positive wound infection. A higher mean body mass index predicted a delayed healing, wound dehiscence, and infection. The inferior pedicle technique is a safe method of breast reduction regardless of degree of parenchymal resection. However, the use of postoperative antibiotics for at least 5 days is recommended to reduce rates of wound dehiscence and improve postoperative scarring.     

A Study of Sepsis in Surgical Wounds

Published records of the frequency of wound sepsis are often unreliable sources of information on the general frequency of this complication because of unstandardized methods of reporting and because of the various views of different investigators as to what constitutes sepsis. A method of infection reporting, its study and analysis are outlined. A survey of postoperative infections by this method for the years 1959, 1960 and 1961 revealed infection rates of 2.02%, 1.20% and 1.14%, respectively. For the same period the percentages of wound infections caused by Staph. aureus were 83.06%, 69.8% and 51.8%, respectively. The most prevalent phage types were 55/53/54 and 52/80/81/82, although types 80/81/82 and 80 were also involved. Infections with Gram-negative organisms were encountered more often in 1961 than in 1959. The majority of these were of mixed type, and followed abdominal surgery.There is need for more comprehensive study and analysis of postoperative wound sepsis and its complications. It was apparent from this study that, statistically, a relatively low rate of postoperative infections may mask a high rate following a specific surgical procedure.     

Bilateral cleft lip reconstruction

Over a period of 8 years 140 bilateral cleft lips were operated using a muscle-repositioning banked fork-flap cheiloplasty. The use of buccal mucosal flaps in the intercartilaginous incision is helpful to decrease scarring and contracture by facilitating alar cartilage repositioning and wound closure without tension. Adding mucosa from the inferior turbinate makes complete wound closure relatively easy without tension. A lateral lip orbicularis muscle flap with white skin roll and vermilion is recommended for reconstruction of the Cupid's bow. Muscle continuity by freeing the muscle in one sheet and repositioning in front of the premaxilla with creation of a buccal alveolar sulcus is stressed to prevent the necessity of reentering the lip in a second procedure. The elongation of the columella is done at 1 to 6 years of age by advancing nasal floor tissue onto the columella and repositioning the alar cartilages superiorly and medially. When nasal floor tissue is inadequate, columellar lengthening is done by the use of a composite free ear graft.     

Effects of burn wound excision on bacterial colonization and invasion

Rates of survival after thermal injury have improved in the past two decades, and rates of wound infections and sepsis have decreased during the same period. Early excision has been advocated as one of the major factors, but its safety and efficacy and the exact timing of burn excision are still under debate. It was hypothesized that acute burn wound excision (in the first 24 hours after burning) would be superior to conservative treatment and delayed excision in preventing bacterial colonization and invasion. Twenty consecutive patients with thermal injuries were studied. Twelve patients underwent acute burn wound excision, and eight patients underwent conservative treatment and delayed excision. The second group of patients received topical treatments in another facility and underwent delayed excision after transfer to our service, on postburn day 6. Quantitative bacteriological assessments of the excised wound and biopsy samples of the wound bed, obtained before autografting and/or homografting, were performed. The effects of time on bacterial counts, differences between superficial and deep biopsy samples, and the effects of early versus late debridement were studied. Patients admitted early exhibited bacterial counts of less than 10 bacteria per gram of tissue. Patients in this group did not experience infection or graft loss. Patients admitted late exhibited counts of more than 10 bacteria (p = 0.001, compared with early admission). Three patients in the late excision group experienced infection and graft loss (p < 0.05, compared with the early excision group). Burn wound excision significantly decreased bacterial colonization for all patients (p < 0.001). Greater bacterial colonization and higher rates of infection were correlated with topical treatment and late excision (p < 0.001). It is concluded that burn wound excision significantly reduces bacterial colonization. Patients who undergo topical treatment and delayed burn wound excision exhibit greater bacterial colonization and increased rates of infection. Acute burn wound excision should be considered for all full-thickness burns.     

Resection of obstructing inferior turbinates following rhinoplasty

Total inferior turbinectomy was carried out in 38 patients who complained of nasal obstruction following rhinoplasty or rhinoseptoplasty and in whom hypertrophied inferior turbinates were found to be the cause of obstruction. Postoperatively, relief of nasal obstruction was reported by 84 percent of patients, while rhinoscopy showed wide, clean nasal airways in 92 percent. Nasal airflow measurements in 32 tested patients showed increased patency in all of them, including 3 who still complained of nasal obstruction postoperatively. The follow-up period ranged from 1 to 7 years (mean 2.8 years). Atrophic changes of the nasal mucosa or chronic purulent infection was not observed in any of the patients. Because the results of partial procedures on the inferior turbinates are often unsatisfactory, I suggest performing total inferior turbinectomy in patients with obstructing inferior turbinates following rhinoplasty.     

Determinants of poor outcome after laceration and surgical incision repair

The most important outcomes after repair of traumatic lacerations and surgical incisions are their long-term cosmetic appearance and development of infection. However, few studies have attempted to identify patient and wound characteristics associated with increased infection rates and suboptimal scar appearance. The authors determined patient and wound characteristics associated with wound infection or suboptimal appearance after laceration or incision repair. A secondary analysis of data collected from a multicenter randomized clinical trial comparing the outcome of lacerations and incisions closed with tissue adhesive or standard closure methods conducted at 10 clinical inpatient and outpatient sites was performed. The presence of infection and scar appearance were prospectively determined using validated outcomes. Univariate and multivariate analyses were performed to identify patient and wound characteristics associated with poor wound outcome (wound infection at 5 to 10 days or suboptimal appearance at 3 months). Eight hundred fourteen patients with 924 wounds (383 lacerations, 541 incisions) were enrolled. Mean age was 32 years and 47 percent were female. Characteristics associated with suboptimal cosmetic appearance on multivariate analysis were presence of associated tissue trauma [odds ratio (OR), 3.9; 95 percent confidence interval (CI), 1.4 to 10.7], use of electrocautery (OR, 3.4; 95 percent CI, 1.8 to 6.5), incomplete wound edge apposition (OR, 2.9; 95 percent CI, 1.7 to 5.0); extremity location (OR, 2.1; 95 percent CI, 1.2 to 3.7), and wound width (OR, 1.08; 95 percent CI, 1.01 to 1.14). Characteristics associated with wound infection on univariate analysis included associated tissue trauma (8.7 percent versus 1.2 percent, p = 0.04) and incomplete wound apposition (6.6 percent versus 0.5 percent). Suboptimal appearance was more common in infected wounds (relative risk, 3.2; 95 percent CI, 1.8 to 5.6). Suboptimal wound appearance is increased with extremity wounds, wide wounds, incompletely apposed wounds, associated tissue trauma, use of electrocautery, and infection. Type of closure device and use of deep sutures had no effect on infection rates or cosmetic appearance.     

A trial of the use of mupirocin in the nasal carriage of Staphylococcus aureus in medical personnel]

Many hospital-acquired purulent diseases and wound infections are due to multiresistant hospital strains of Staphylococcus aureus. The role of S. aureus nasal carriage in development of wound infections due to autoinfection is confirmed. Not only inpatients but also hospital staff can be highly colonized with coagulase positive staphylococci. The S. aureus persistence in hospital personnel results in distribution of the microorganisms in the environment. Therefore, detection of S. aureus carriers without signs of the infection among the hospital personnel and eradication of the pathogen make it possible to control outbreaks of S. aureus infection in hospitals. Clinical efficacy of nasal ointment of mupirocin in the treatment of S. aureus carriers among the intensive care personnel of the N. N.Blokhin Cancer Research Center was evaluated. S. aureus nasal carriage was diagnosed in 17 (26 per cent) out of 65 persons. All the isolates were susceptible to oxacillin. 5-7 days after discontinuation of the mupirocin nasal ointment use eradication of S. aureus was stated in 100 per cent of the cases. The effect was still observed in 94 per cent of the cases in 1 month, in 76 per cent of the cases in 5-6 months and in 60 per cent of the cases in 8-9 months. It is believed that mupirocin nasal ointment (Bactroban) is convenient to use, low toxic and highly active in the treatment of persons with S. aureus nasal carriage.     

Audit of major colorectal and biliary surgery to reduce rates of wound infection.

OBJECTIVE--To reduce the rates of wound infection for major colorectal and biliary surgery. DESIGN--Prospective audit of antibiotic prophylaxis by keeping copies of typed notes of operations and annotating them at discharge and at first follow up visit and annual review of prophylactic regimen according to yearly rate of wound infection and modification if necessary. SETTING--The work of one consultant surgeon working in a district general hospital. PATIENTS--All patients having major colorectal resection during 1976-89 (400) and cholecystectomy during 1981-9 (500). MAIN OUTCOME MEASURES--Wound infection, defined as any discharge from the wound as detected by observation during inpatient stay and by specific questioning at the first follow up visit six weeks later. RESULTS--Serial changes in prophylaxis for colorectal surgery resulted in a progressive reduction in the rate of wound infection from 43% in 1976, with no prophylaxis, to 1% during 1986-9 with single intravenous doses of metronidazole and cefuroxime intraoperatively and with lavage of the peritoneal cavity and wound with 0.1% tetracycline. During 1981-7, with no prophylaxis, the rate of infection in biliary surgery was 12% whereas in 1988-9, after the introduction of lavage with tetracycline alone, the rate was reduced to 2%. IMPLICATIONS AND ACTION--Simple prospective audit identified the need for changes in antibiotic prophylaxis; successive rounds of audit resulted in improved rates of wound infection, and lavage with 0.1% tetracycline seemed to be a major factor in achieving this.     

V-Y advancement flaps for closure of nasal defects

The nose is a difficult anatomic region in which to close defects resulting from resection of cutaneous malignancies. The V-Y flap is a technique for advancing adjacent tissue, thereby achieving wound closure while minimizing tension. A total of 120 V-Y flaps were used to close 114 nasal defects. The average defect size was 13.5 x 11 mm. Partial flap loss occurred in five patients, with total flap loss in one. One wound infection and two hematomas occurred.     

The role of nasal carriage in Staphylococcus aureus burn wound colonization

Thermal injury destroys the physical skin barrier that normally prevents invasion of microorganisms. This and concomitant depression of local and systemic host cellular and humoral immune responses are important factors that contribute to colonization and infection of the burn wound. One of the most common burn wound pathogens is Staphylococcus aureus. Staphylococcus aureus is both a human commensal and a frequent cause of infections leading to mild to life-threatening diseases. Despite a variety of infection control measures, for example patient cohorting and contact precaution at burn centres, S. aureus is still frequently encountered in burn wounds. Colonization with S. aureus has been associated with delayed wound healing, increased need for surgical interventions, and prolonged length of stay at burn centres. In this minireview, we focus on S. aureus nasal carriage in relation to S. aureus burn wound colonization and subsequent infection, and its impact on strategies for infection control.     

Frequency of nasal and wound isolates of Staphylococcus aureus associated with TSST-1 production in Jordanian population

A total of 110 Staphylococcus aureus isolates were obtained from nasal carriers and wound infections of Jordanian population. The isolates were identified by cultural and biochemical methods. The nasal carrier rate of S. aureus among individuals was 22.7%. In comparison with the nasal S. aureus isolates the wound isolates did not produce significantly more virulence factors except DNase. Toxic shock syndrome toxin-1 production was higher among the S. aureus nasal isolates (40%) as compared with the wound isolates (26%) detected by an ELISA method which proved to be uniformly more sensitive than the immunodiffusion optimal sensitivity plate (OSP) method.     

The dynamics of the wound microflora in the victims of the earthquake in Armenia]

The data on the composition of wound microflora, as well as changes in the contamination index over the course of treatment of patients with the syndrome of prolonged compression, who were brought to the institute after the earthquake in Armenia, are presented. The authors characterize the structure of the causative agents of wound infection in the patients treated at the traumatological department of the institute over several years. The epidemiological situation in the hospital in the period when the earthquake victims were treated there is analyzed.     

Prophylactic antibiotics in plastic and reconstructive surgery.

There is no consensus in the literature on the use of prophylactic antibiotics to prevent postoperative infection. This study was performed to investigate whether the use of prophylactic antibiotics has an effect on postoperative infection rates. A total of 1400 patients were classified into four groups based on their diagnosis. During the induction of anesthesia, half of each group received 2 g of a sulbactam-ampicillin combination and the other half received a placebo (saline solution) intravenously. Wound infection rates were observed in the postoperative period. Age, sex, and operative site of the patients with the same diagnosis were comparable in each group. The white blood cell count and the body temperature reading of each patient were recorded postoperatively. Wounds were observed daily in the postoperative period and graded according to a predetermined scale. Bacteriologic specimens were obtained from patients who had wound infections. According to our clinical experience, antibiotic prophylaxis is not necessary in plastic surgery. At the end of our 6-year study, a significant difference could not be found between the antibiotic prophylaxis and placebo groups.     

Follow-up study of type C influenza outbreak in a children's home

A follow-up study of type C influenza in a children's home was made where the first outbreak of type C influenza occurred in March, 1981. During the survey period of 2 years, 2 additional outbreaks occurred in April and October, 1982 and 4 cases of the secondary and 2 cases of the tertiary infections were serologically confirmed. All of the children exposed to the outbreaks, except 2 particular cases who were suffering from German measles, showed similar mild respiratory symptoms characterized by fever and long-lasting nasal discharge, irrespective of primary, secondary, and tertiary infections. No case of inapparent infection was observed. Incubation period was estimated to be not longer than 5 days and the period of virus shedding, to be longer than 22 days. Antibody response in the sera of patients to type C influenza virus was equally good after every infection, although it was not efficient to prevent the succeeding infection. Factors involved in the repeated infections of type C influenza were discussed.     

Closure of abdominal wounds by adhesive strips: a clinical trial.

In a randomized trial of wound closure in 512 abdominal wounds, wounds were closed with either reinforced Steristrip skin closures or interrupted silk sutures. Comparisons were made of wound pain and discomfort, wound infection, discharge, redness, width, and skin reaction. The causes of peeling of the tapes were assessed. The results showed that tapes were significantly more comfortable and that patients preferred them to sutures (P less than 0.01), but wide scars occurred more often. There was no difference in rates of wound infection and no case of allergy to the tapes was seen. Closure of abdominal wounds by these tapes is a satisfactory procedure that could be used more extensively.     

Repair of cleft lip with nonsurgical correction of nasal deformity in the early neonatal period

Auricular cartilage is soft and plastic at birth, so that congenital auricular deformities can easily be corrected nonsurgically in the early neonatal period. However, as the infant grows older, the flexibility of the auricle decreases. Alar cartilage exhibits the same elasticity as auricular cartilage in the early neonate. When a cleft lip is repaired, typically when the infant is about 3 months of age, it becomes difficult to correct the nasal deformity without surgical intervention. However, based on our experience, there is a fair possibility of correcting the cleft lip nasal deformity with a nonsurgical procedure in the early neonatal period. We performed cleft lip repair accompanied by nonsurgical correction of the nasal deformity in 44 neonates aged 2 to 7 days. A special retainer was placed in the affected nostril for 3 months. Following observation of 31 infants for 12 months or longer, their nasal shapes and symmetry were considered superior to those conventionally operated on at about 3 months of age. Except for one nasal infection, there were no complications.     

Morphological Differences Between Mandan And Historic Arikara Crania

Abstract

Arikara cranial measurements are compared with Mandan data to define the nature and magnitude of differences remaining at the beginning of the Historic period. A discriminant function approach is followed. Special attention is given to determining uniqueness of the two sets of crania as estimated by rates of group misclassification. Three validation procedures are applied in estimating these rates: resubstitution, jackknife, and holdout.

Several variables show significant heterogeneity between Arikara and Mandan including nasal height, maximum cranial breadth, and auricular height. Mandan crania tend to be narrower, have less nasal height, and are lower in auricular height. Functions developed for Leavenworth Arikara and Mandan crania have an accuracy of about 84 percent. Data for the Leavenworth Site are expanded with addition of a sample excavated by William H. Over 60 years ago.     

Transmission of urinary schistosomiasis in Sukumaland, Tanzania. 1. Snail infection rates and incidence of infection in school children

Seasonal density fluctuations of Bulinus nasutus populations with accompanying Schistosoma haematobium infection rates in relation to rainfall and habitat water volumes were studied at Ukiriguru, Mwanza, Tanzania. Alongside the snail investigations, 50 school children initially negative for urinary schistosomiasis were examined regularly to determine seasonal incidence rates for the infection. Of the 17,646 B. nasutus collected in 2 years, 156 (0.88%) were found shedding cercariae. Snail populations fluctuated seasonally as influenced by rainfall through its effects on habitat water volume. Monthly snail infection rates ranged from 0.09% to 3.19% and were highest in February and March, at the time of the short dry period. Monthly incidence of S. haematobium in school children ranged between 2.6% and 12.5%, being highest in April and May. There was a significant linear association between monthly snail infection rates and S. haematobium incidence rates in school children (r2s = 0.65 in 1982/83; r2s = 0.87 in 1983/84) suggesting that the maximum transmission period for urinary schistosomiasis in the area occurs during the short dry period, sometime in February/March so that most of the infections in the community would be detected in April/May.     

Vacuum-assisted closure in the treatment of sternal wound infection after cardiac surgery

Aim: Vacuum-assisted closure (VAC) was primarily designed for the treatment of pressure ulcers or chronic, debilitating wounds. Recently, VAC has become an encouraging treatment modality for sternal wound infection after cardiac surgery, providing superior results to conventional treatment strategies. Methods: From November 2004 to September 2006, 34 patients, undergoing VAC therapy for sternal wound infection following cardiac surgery, were prospectively evaluated. Ten patients (29 %) were treated for superficial sternal wound infection and 24 (71 %) for deep sternal wound infection. The median age was 69.9 years (range 48 to 82) and the median BMI was 33.4 kg/m(2) (range 28 to 41). Twenty patients (59 %) were women and 19 patients (59 %) were diabetics. Owing to sternal wound infection complications, 16 patients (47 %) were readmitted to the department. VAC was used following the previous failure of the conventional treatment strategy in 7 patients (21 %). Results: Thirty-three patients (97 %) were treated successfully. One patient (3 %) died of multiple organ failure. The overall length of hospitalization was 34.6 days (range 9 to 62). The median number of dressing changes was 4.6 (range 3 to 10). The median VAC treatment time until surgical closure was 9.2 days (range 6 to 21 days). VAC therapy was solely used as a bridge to definite wound closure. Three patients (9 %) with chronic fistula were re-admitted 1 to 6 months after VAC therapy. Conclusions: VAC therapy is a safe and reliable option in the treatment of sternal wound infection in cardiac surgery. VAC therapy should be considered an effective adjunct to conventional treatment modalities for the treatment of extensive and life-threatening wound infections following cardiac surgery, particularly in the presence of risk factors.