The nose: an underestimated source of Staphylococcus aureus causing wound infection

In cellulo synthesis of dendrimeric sensors for fluorescence-on imaging of bacterial phagocytosis

Methods for optical tracking of pathogen-host interactions are of biomedical significance. We herein have reported a high molecular weight pH sensor (Den-pH) that is assembled in bacteria and then stably trapped in bacteria irrespective of bacterial membrane potentials. Endowed with acidity-triggered red fluorescence, Den-pH allows signal-on tracking of S. aureus in phagocytosis by macrophages. Intra-bacterial formation of multifunctional optical probes, which offers the advantage of overcoming the liability of conventional potential-sensitive dyes to dissipate from stressed bacteria, offers a new tool to study stressed pathogens.

[Modern problems of modelling and treatment of soft tissues abscesses]

Increase of the frequency of soft tissues pyoinflammatory diseases and purulent-septic complications against the background the antibiotic-resistance of organism dictates the necessity of search of rational new surgical technologies and preparations with the intense bactericidal effect. Period of the connective tissue (cicatrix) formation on a place of wound defect of the operated purulent abscess of soft tissue (PAST) is defined by the speed of the granulations and epithelial tissue formation. Therefore, one of the task of experimental surgery is search of new methods of the effective postoperative influence on terms of the regeneration and complete obliteration of the PAST cavity. The perspective direction in treatment of surgical infection is application of metals nanoparticles. In treatment of pyoinflammatory processes it is applied the preparation Eplan and also zinc oxide nanoparticles which have bactericidal, antiinflammatory and regenerative effects. However, till now it was not carried out experimental works on modelling and surgical treatment of PAST with local application of the laser technologies in combinations with Eplan and metals nanoparticles.

Epidemiology and molecular characteristics of methicillin-resistantStaphylococcus aureus from skin and soft tissue infections in Shiraz, Iran

BACKGROUND/AIM

Panton-Valentine leukocidin (PVL)-positive methicillin-resistant Staphylococcus aureus (MRSA) infections are increasing in some regions of Iran. The aim of the current study was to assess the epidemiology and molecular characteristics of S. aureus isolated from patients with skin infections in Shiraz, Iran.

MATERIALS AND METHODS

Swab samples were obtained from patients admitted to the skin and burn units of hospitals. The medical records of each patient were collected via questionnaire. All staphylococcal isolates were collected and examined by conventional methods for detecting S. aureus strains. PCR was used to detect S. aureus harboring the mecA and pvl genes.

RESULTS

Out of 243 staphylococcal isolates, 55 (22.6%) S. aureus and 91 (37.4%) S. epidermidis were detected. Of the 45 patients, 21 (46.7%) were S. aureus carriers. The mecA gene was identified in 60% of S. aureus isolates, and the rest were sensitive to methicillin. Of the S. aureus isolates, 54.5% were positive for the pvl gene.

CONCLUSION

This study revealed a high prevalence of PVL-positive MRSA strains in the evaluated hospitals. Thus, early diagnosis of infections caused by this pathogen seems to be necessary by intake screening allowing for proper treatment, especially in high-risk patients and in order to prevent the spread of infection.

Isolation and Host Range of Bacteriophage with Lytic Activity against Methicillin-Resistant Staphylococcus aureus and Potential Use as a Fomite Decontaminant

Staphylococcus aureus (SA) is a commensal bacterium and opportunistic pathogen commonly associated with humans and is capable of causing serious disease and death including sepsis, pneumonia, and meningitis. Methicillin-resistant SA (MRSA) isolates are typically resistant to many available antibiotics with the common exception of vancomycin. The presence of vancomycin resistance in some SA isolates combined with the current heavy use of vancomycin to treat MRSA infections indicates that MRSA may achieve broad resistance to vancomycin in the near future. New MRSA treatments are clearly needed. Bacteriophages (phages) are viruses that infect bacteria, commonly resulting in death of the host bacterial cell. Phage therapy entails the use of phage to treat or prevent bacterial infections. In this study, 12 phages were isolated that can replicate in human SA and/or MRSA isolates as a potential way to control these infections. 5 phage were discovered through mitomycin C induction of prophage and 7 others as extracellular viruses. Primary SA strains were also isolated from environmental sources to be used as tools for phage discovery and isolation as well as to examine the target cell host range of the phage isolates by spot testing. Primary isolates were tested for susceptibility to oxacillin in order to determine which were MRSA. Experiments were performed to assess the host range and killing potential of newly discovered phage, and significant reductions in bacterial load were detected. We explored the utility of some phage to decontaminate fomites (glass and cloth) and found a significant reduction in colony forming units of MRSA following phage treatment, including tests of a phage cocktail against a cocktail of MRSA isolates. Our findings suggest that phage treatment can be used as an effective tool to decontaminate human MRSA from both hard surfaces and fabrics.

Body site Staphylococcus aureus colonization among maintenance hemodialysis patients

BACKGROUND

Patients on maintenance hemodialysis therapy are at high risk for health care-associated infections. Staphylococcus aureus is a common cause of health care-associated infections among maintenance hemodialysis patients. It is established that S. aureus colonization is associated with an increased risk for subsequent infection in this population. There is an increasing number of reports that extranasal S. aureus colonization is more common than previously believed and in certain body sites even more common than nasal colonization. There are few data describing extranasal colonization among maintenance hemodialysis patients.

METHODS

We surveyed 100 patients at 3 body sites (anterior nares, oropharynx, and inguinal region) for S. aureus colonization. Participants were also administered a standardized survey to assess risk factors for S. aureus colonization.

RESULTS

We found that 42% (95% CI 32-52) of patients were S. aureus colonized in >1 body site. Extranasal colonization was found among 32% (95% CI 23-41). There were trends suggestive of an association between S. aureus colonization and younger age (OR 0.97, 95% CI 0.94-1.001, p = 0.06) and not having been hospitalized in the previous 12 months (OR 0.44, 95% CI 0.19-1.06, p = 0.14).

CONCLUSION

Extranasal S. aureus colonization is common among maintenance hemodialysis patients with a prevalence of approximately one third. Future S. aureus decolonization efforts may need to consider not just nasal decolonization but also decolonization of the skin and oropharynx.

Poor outcomes after hepatectomy in patients with ascites infected by methicillin-resistant staphylococci

BACKGROUND

This study was designed to investigate the association between infectious ascites, clinical parameters and treatment outcomes after hepatectomy.

METHODS

Of 891 patients who underwent hepatectomy between 2006 and 2013, 74 who underwent paracentesis for bacterial cultivation of postoperative ascites after hepatectomy were analyzed.

RESULTS

Of the 74 patients, 42 had positive bacterial cultures (positive group) and 32 patients had negative cultures (negative group). Hospital mortality was significantly higher in the positive group than in the negative group [9/42 (21.4%) vs. 2/32 (6.3%); P = 0.035]. Hospital mortality associated with each bacterial strain was as follows: methicillin-resistant staphylococci (MRS) (5/13, 38.5%), staphylococci (2/11, 18.2%), enterococci (2/12, 16.7%), Enterobacter (0/3, 0%), Klebsiella (0/2, 0%), and others (0/1, 0%). Cox proportional multivariate analysis revealed that MRS infection in ascites was the only risk factor of hospital death (HR = 5.08, P = 0.041) and MRS wound infection was the only risk factor to predict MRS infection in ascites (HR = 5.67, P = 0.015).

CONCLUSION

Postoperative MRS infection in postoperative ascites after hepatectomy is a potentially fatal complication; therefore, the prevention of MRS wound infection is critical to decrease postoperative hospital mortality.

Postoperative differences between colonization and infection after pediatric cardiac surgery-a propensity matched analysis

Background

The objective of this study was to identify the postoperative risk factors associated with the conversion of colonization to postoperative infection in pediatric patients undergoing cardiac surgery.

Methods

Following approval from the Institutional Review Board, patient demographics, co-morbidities, surgery details, transfusion requirements, inotropic infusions, laboratory parameters and positive microbial results were recorded during the hospital stay, and the patients were divided into two groups: patients with clinical signs of infection and patients with only positive cultures but without infection during the postoperative period. Using propensity scores, 141 patients with infection were matched to 141 patients with positive microbial cultures but without signs of infection. Our database consisted of 1665 consecutive pediatric patients who underwent cardiac surgery between January 2004 and December 2008 at a single center. The association between the patient group with infection and the group with colonization was analyzed after propensity score matching of the perioperative variables.

Results

179 patients (9.3%) had infection, and 253 patients (15.2%) had colonization. The occurrence of Gram-positive species was significantly greater in the colonization group (p = 0.004). The C-reactive protein levels on the first and second postoperative days were significantly greater in the infection group (p = 0.02 and p = 0.05, respectively). The sum of all the positive cultures obtained during the postoperative period was greater in the infection group compared to the colonization group (p = 0.02). The length of the intensive care unit stay (p < 0.001) was significantly longer in the infection group compared to the control group.

Conclusions

Based on our results, we uncovered independent relationships between the conversion of colonization to infection regarding positive S. aureus and bloodstream results, as well as significant differences between the two groups regarding postoperative C-reactive protein levels and white blood cell counts.

Staphylococcus aureus colonization among household contacts of patients with skin infections: risk factors, strain discordance, and complex ecology

BACKGROUND

The USA300 methicillin resistant Staphylococcus aureus (MRSA) genetic background has rapidly emerged as the predominant cause of community-associated S. aureus infections in the U.S. However, epidemiologic characteristics of S. aureus household transmission are poorly understood.

METHODS

We performed a cross-sectional study of adults and children with S. aureus skin infections and their household contacts in Los Angeles and Chicago. Subjects were surveyed for S. aureus colonization of the nares, oropharynx, and inguinal region and risk factors for S. aureus disease. All isolates underwent genetic typing.

RESULTS

We enrolled 1162 persons (350 index patients and 812 household members). The most common infection isolate characteristic was ST8/SCCmec IV, PVL+ MRSA (USA300) (53%). S. aureus colonized 40% (137/350) of index patients and 50% (405/812) of household contacts. A nares-only survey would have missed 48% of S. aureus and 51% of MRSA colonized persons. Sixty-five percent of households had >1 S. aureus genetic background identified and 26% of MRSA isolates in household contacts were discordant with the index patients' infecting MRSA strain type. Factors independently associated (P < .05) with the index strain type colonizing household contacts were recent skin infection, recent cephalexin use, and USA300 genetic background.

CONCLUSIONS

In our study population, USA300 MRSA appeared more transmissible among household members compared with other S. aureus genetic backgrounds. Strain distribution was complex; >1 S. aureus genetic background was present in many households. S. aureus decolonization strategies may need to address extra-nasal colonization and the consequences of eradicating S. aureus genetic backgrounds infrequently associated with infection.

Staphylococcal colonization of caretakers of children who have community-acquired skin and soft tissue infections

PURPOSE

Colonization with Staphylococcus aureus is considered a risk factor for the rising incidence of pediatric community-acquired skin and soft tissue infections (CA-SSTIs), and intrafamily spread is thought to be the source of colonization.

METHODS

A prospective study was conducted to determine skin and nasal staphylococcal colonization rates among the caretakers of CA-SSTI patients and those of nonabscess controls. A questionnaire regarding risk factors was administered to all participants. Fisher's Exact test and the chi(2) test were used for statistical analysis.

RESULTS

Forty-six patients and their caretakers were enrolled in both the study and control groups. Of the caretakers in the study group, 19.6% (n = 9) had staphylococcal colonization of nares; and 2.2% (n = 1), skin. In the control group, 17.4% (n = 8) had nasal colonization; and none had skin colonization. Of the children in the study group, 58.7% (n = 27) had a family history of CA-SSTI compared with only 17.4% (n = 8) of controls (P = .0001). Of CA-SSTI patients, 45.7% (n = 21) had prior abscesses compared with 6.5% (n = 3) of controls (P = .0001). No other risk factor was identified.

CONCLUSION

There was no increase in nasal or skin staphylococcal colonization among caretakers of children with CA-SSTI. Family and personal histories of CA-SSTI were the only identified risk factors for CA-SSTI.

Comparative assessment of antimicrobial activities of antibiotic-treated penile prostheses

BACKGROUND

Although infections associated with penile implants are relatively infrequent, they result in serious medical consequences. Because treatment of these infections usually requires removal of the infected penile implant, prevention of infection is crucial. Since bacterial colonization of the implant is a prelude to clinical infection, antimicrobial modification of the devices may inhibit device colonization and subsequent infection.

OBJECTIVE

We compared the spectrum and durability, both in vitro and in vivo, of two antibiotic-treated penile prostheses: InhibiZone implants pre-impregnated with minocycline and rifampin (M/R) and Titan implants dipped in vancomycin.

DESIGN, SETTING, AND PARTICIPANTS

1×1-cm cylinder segments of (1) control untreated, (2) M/R-impregnated, and (3) vancomycin-dipped implants were studied. Baseline zones of inhibition (ZI) were determined against clinical isolates, including methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant S. epidermidis (MRSE), vancomycin-resistant Enterococcus (VRE), and Escherichia coli. In addition, ZI against methicillin-susceptible S. aureus were compared both in vitro after being washed in a flow chamber and after subcutaneous implantation in rabbits for 1, 2, 7, and 14 d.

MEASUREMENTS

ZI were measured as the diameter of the clear zone around each test device minus the external diameter of the device.

RESULTS AND LIMITATIONS

Implants pre-impregnated with M/R displayed a broader spectrum of antimicrobial activity than vancomycin-dipped implants against both gram-positive and -negative bacteria. The M/R-impregnated devices also yielded significantly larger zones of inhibition against S. aureus than vancomycin-dipped implants, both in vitro (p<0.003) and in vivo throughout the 14-d period of device implantation in rabbits (p≤0.03).

CONCLUSIONS

Penile prostheses impregnated with M/R have a broader spectrum in vitro and a more durable antimicrobial activity in vitro and in an animal model than implants dipped in vancomycin. Therefore, along with being a more practical model for incorporating antimicrobials onto the device, the use of implants pre-impregnated with M/R may help reduce the incidence of penile implant infection.

Revision washout decreases implant capsule tissue culture positivity: a multicenter study

PURPOSE

Positive cultures, visible biofilm and confocal micrography confirm bacterial presence on clinically uninfected inflatable penile prostheses at revision surgery. Salvage irrigation has been proved to rescue patients with clinically infected inflatable penile prostheses. Similar washout at revision for noninfectious reasons significantly lowers subsequent infection rates. We investigated a larger series of patients for positive culture rates and evaluated implant capsule tissue culture rates before and after revision washout.

MATERIALS AND METHODS

At 4 institutions a total of 148 patients with inflatable penile prostheses underwent revision surgery for noninfectious reasons between June 2001 and September 2005. Swab cultures of the fluid around the pump and visible biofilm were obtained. Also, in 65 patients a wedge of tissue from the capsule that forms around the pump was cultured. After implant removal revision washout of the implant spaces was performed and a second wedge of tissue was cultured.

RESULTS

Of the 148 patients 97 (66%) had positive bacterial swab cultures of the fluid around the pump or biofilm. A total of 124 isolates were cultured. Of the 65 implant capsule tissue cultures obtained before washout 28 (43%) were positive for bacteria, while 16 (25%) obtained after revision washout were positive.

CONCLUSIONS

Positive cultures and visible bacterial biofilm are present on clinically uninfected inflatable penile prostheses at revision surgery in most patients. Revision washout appears to decrease the bacterial load on implant capsule tissue at revision surgery of inflatable penile prostheses for noninfectious reasons.

Methicillin-resistant Staphylococcus aureus infection or colonization present at hospital admission: multivariable risk factor screening to increase efficiency of surveillance culturing

Identifying methicillin-resistant Staphylococcus aureus (MRSA) colonization or infection present at admission has become important in reducing subsequent nosocomial transmission, but the most efficient surveillance methods remain to be defined. We performed anterior nares surveillance cultures of all patients upon admission to and discharge from the general internal medicine floor in our community hospital over a 7-week period, and patients completed a questionnaire on MRSA risk factors. Of the 401 patients, 41 (10.2%) had MRSA upon admission. Of the 48 risk measures analyzed, 10 were significantly associated with admission MRSA, and 7 of these were independently associated in stepwise logistic regression analysis. Factor analysis identified eight latent variables that contained most of the predictive information in the 48 risk measures. Repeat logistic regression analysis including the latent variables revealed three independent risk measures for admission MRSA: a nursing home stay (relative risk [RR], 6.18; 95% confidence interval [95% CI], 3.56 to 10.72; P < 0.0001), prior MRSA infection (RR, 3.97; 95% CI, 1.94 to 8.12; P = 0.0002), and the third latent variable (factor 3; RR, 3.14; 95% CI, 1.56 to 6.31; P = 0.0013), representing the combined effects of homelessness, jail stay, promiscuity, intravenous drug use, and other drug use. Multivariable models had greater sensitivity at detecting admission MRSA than any single risk measure and allowed detection of 78% to 90% of admission MRSA from admission surveillance cultures on 46% to 58% of admissions. If confirmed in additional studies, multivariable questionnaire screening at admission might identify a subset of admissions for surveillance cultures that would more efficiently identify most admission MRSA.

Effects of controlled perioperative antimicrobial prophylaxis on infectious outcomes in pediatric cardiac surgery

OBJECTIVES

To examine the efficacy of a protocol for the prophylactic use of antimicrobials in pediatric cardiac surgery.

DESIGN

Nonrandomized comparison of two groups of patients studied sequentially.

SETTING

Pediatric intensive care unit of university hospital.

PATIENTS

Infants and children <18 yrs of age who had undergone cardiac surgery.

INTERVENTIONS

Limitation of prophylactic antimicrobials to <48 hrs after operation and, in patients at high risk of methicillin-resistant Staphylococcus aureus, strong recommendation to use glycopeptides.

MEASUREMENTS AND MAIN RESULTS

No intervention was applied in 189 patients (control group) during the first 21 months, whereas the intervention was applied in 185 patients (intervention group) during the next 18 months. In the intervention group, prophylaxis was recommended to be discontinued <48 hrs postoperatively. As a result, antimicrobials were administered for a median of 4 days (range 2-14) in the intervention group, significantly shorter than 7 days (3-35) in controls. This was associated with a trend toward a lower frequency of postoperative infections, including at the surgical site, and with significantly lower costs of antimicrobial therapy and a significantly lower rate of newly acquired nasal colonization with antibiotic-resistant pathogens in the intervention group (8%) than in controls (17%).Since, in the intervention group, glycopeptides were strongly recommended for patients at high risk of methicillin-resistant S. aureus, the frequency of surgical-site infections (0% vs. 18%) and the frequency of all infections (11% vs. 39%) were significantly lower in the intervention group than in the control group.

CONCLUSIONS

Limiting the duration of prophylactic antimicrobials was cost-effective and reduced the risk of acquiring resistant pathogens without increasing the frequency of postoperative infections. The use of glycopeptides in properly selected patients at high risk of methicillin-resistant S. aureus infection can lower the risk of postoperative infections.

ESBL-producing Enterobacteriaceae: controlling the spread of infection

Extended spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae were first reported in Europe in the 1980s and have since become a worldwide problem. This has resulted in increased morbidity, mortality and cost in treating the infections they cause (Paterson et al, 2001; Bisson et al, 2002). In the UK the prevalence of ESBL rose from 5.4% in 1997 to 22.7% in 1999 (Goossens, 2000). ESBL are not the only beta-lactamases to present resistance to 1st, 2nd and 3rd generation cephalosporins but are the most important. New strains produce a particular type of ESBL, the CTX-M type, which is able to break down a wider range of antibiotics. These strains were unrecorded in the UK prior to 2000. They have spread rapidly since 2003, causing infections such as urinary tract infections (UTIs) in hospital patients as well as those treated in the community (Livermore associated infection (HAI). Their antimicrobial resistance is commonly caused by the production of beta-lactamases, therefore this article discusses methods used to limit the emergence of ESBL-producing strains and to prevent the spread of those already present.

A case-control study of mastitis: nasal carriage of Staphylococcus aureus

BACKGROUND

Mastitis is a common problem for breastfeeding women. Researchers have called for an investigation into the possible role of maternal nasal carriage of S. aureus in the causation of mastitis in breastfeeding women.

METHODS

The aim of the study was to investigate the role of maternal S. aureus nasal carriage in mastitis. Other factors such as infant nasal S. aureus carriage, nipple damage, maternal fatigue and oversupply of milk were also investigated. A case-control design was used. Women with mastitis (cases, n = 100) were recruited from two maternity hospitals in Melbourne, Australia (emergency departments, breastfeeding clinics and postnatal wards). Breastfeeding women without mastitis (controls, n = 99) were recruited from maternal and child health (community) centres and the rooms of a private obstetrician. Women completed a questionnaire and nasal specimens were collected from mother and baby and placed in charcoal transport medium. Women also collected a small sample of milk in a sterile jar.

RESULTS

There was no difference between nasal carriage of S. aureus in breastfeeding women with mastitis (42/98, 43%) and control women (45/98, 46%). However, significantly more infants of mothers with mastitis were nasal carriers of S. aureus (72/88, 82%) than controls (52/93, 56%). The association was strong (adjusted OR 3.23, 95%CI 1.30, 8.27) after adjustment for the following confounding factors: income, private health insurance, difficulty with breastfeeding, nipple damage and tight bra. There was also a strong association between nipple damage and mastitis (adjusted OR 9.34, 95%CI 2.99, 29.20).

CONCLUSION

We found no association between maternal nasal carriage of S. aureus and mastitis, but nasal carriage in the infant was associated with breast infections. As in other studies of mastitis, we found a strong association between nipple damage and mastitis. Prevention of nipple damage is likely to reduce the incidence of infectious mastitis. Mothers need good advice about optimal attachment of the baby to the breast and access to skilled help in the early postpartum days and weeks.

Biofilm formation on clinically noninfected penile prostheses

PURPOSE

Biofilms are matrix enclosed bacterial populations that adhere to each other and/or to surfaces of implanted medical devices. Biofilm formation has consistently been demonstrated in association with infected penile prosthetic material. Clinically noninfected patients undergoing revision for mechanical malfunction have a surprisingly high rate of positive intraoperative cultures. After revision replacement prostheses have a higher rate of postoperative infection than first time implants. We characterized biofilm formation on penile prostheses in clinically noninfected patients undergoing revision surgery.

MATERIALS AND METHODS

Ten patients undergoing revision or removal of inflatable penile prosthetic devices due to mechanical malfunction were included. Specimens from the corporeal cylinders, scrotal pump and reservoir were analyzed. Bacterial biofilm coverage was detected and characterized using confocal scanning laser microscopy.

RESULTS

Bacterial biofilm formation associated with multiple microorganisms was demonstrated on 8 of 10 prostheses. Biofilms consisted of gram-positive rods, cocci and fungal elements.

CONCLUSIONS

The degree of biofilm formation on these prosthetic devices suggests that most patients have bacterial coverage on the implant. Host mechanisms to control infection may lead to a homeostatic balance that enables biofilms to exist on the surface of the prosthesis without generating clinical infection. A critical threshold of biofilm extent may exist beyond which clinical infection may occur. These results justify further evaluation of biofilms and penile prosthesis infections. Furthermore, the findings help to explain why strategies such as mini salvage procedures to eliminate subclinical biofilms may decrease the postoperative infection risk in patients undergoing repair or replacement of penile prostheses.

Risk factors for isolation of low-level mupirocin-resistant versus -susceptible methicillin-resistant Staphylococcus aureus from patients in intensive care units

OBJECTIVES

The aim of this study was to determine the risk factors for the recovery of low-level mupirocin-resistant (mup(r)) or -susceptible (mup(s)) MRSA from patients in intensive care units (ICUs).

METHODS

A case-case-control study was conducted from November 2003 to April 2004. Two case groups consisted of patients with low-level mup(r) MRSA and mup(s) MRSA. A control group was frequency matched.

RESULTS

Mup(r) MRSA and mup(s) MRSA were isolated from 20 to 51 patients, respectively, during a six-month period. Risk factors identified for mup(r) MRSA were as follows: exposure to piperacillin-tazobactam (odds ratio [OR] 13.8; 95% confidence intervals [CI], 1.8-105.0), third-generation cephalosporins (OR, 5.0; 95% CI, 1.6-15.5) and quinolones (OR, 3.4; 95% CI, 1.1-10.7). Risk factors identified for mup(s) MRSA were as follows: length of ICU stay (OR, 1.1; 95% CI, 1.0-1.1), surgery (OR, 3.7; 95% CI, 1.5-9.0), exposure to third-generation cephalosporins (OR, 8.4; 95% CI, 3.3-21.7) and quinolones (OR, 7.7; 95% CI, 2.8-21.3).

CONCLUSIONS

Our results suggest that nosocomial isolation of low-level mup(r) MRSA may be affected by piperacillin-tazobactam.

Perioperative intranasal mupirocin for the prevention of surgical-site infections: systematic review of the literature and meta-analysis

OBJECTIVE

To review the evidence evaluating perioperative intranasal mupirocin for the prevention of surgical-site infections according to type of surgical procedure.

DESIGN

Systematic review and meta-analysis of published clinical trials.

SETTING

Studies included were either randomized clinical trial or prospective trials at a single institution that measured outcomes both before and after an institution-wide intervention (before-after trial). In all studies, intervention and control groups differed only by the use of perioperative intranasal mupirocin in the intervention group.

PATIENTS

Patients undergoing general or nongeneral surgery (eg, cardiothoracic surgery, orthopedic surgery, and neurosurgery).

MAIN OUTCOME MEASURE

Risk of surgical-site infection following perioperative intranasal mupirocin versus usual care.

RESULTS

Three randomized and four before-after trials met the inclusion criteria. No reduction in surgical-site infection rate was seen in randomized general surgery trials (summary estimates: 8.4% in the mupirocin group and 8.1% in the control group; relative risk [RR], 1.04; 95% confidence interval [CI95], 0.81 to 1.33). In nongeneral surgery, the use of mupirocin was associated with a reduction in surgical-site infection in randomized trials (summary estimates: 6.0% in the mupirocin group and 7.6% in the control group; RR, 0.80; CI95, 0.58 to 1.10) and in before-after trials (summary estimates: 1.7% in the mupirocin group and 4.1% in the control group; RR, 0.40; CI95, 0.29 to 0.56).

CONCLUSIONS

Perioperative intranasal mupirocin appears to decrease the incidence of surgical-site infection when used as prophylaxis in nongeneral surgery. Given its low risk and low cost, use of perioperative intranasal mupirocin should be considered in these settings.

Analysis of genetic diversity among Staphylococcus aureus isolates from patients with deep-seated and superficial staphylococcal infections using pulsed-field gel electrophoresis

Molecular typing was performed to reveal the genetic diversity among Staphylococcus aureus strains causing deep-seated versus superficial staphylococcal infections. Pulsed-field gel electrophoresis with cluster analysis, plasmid and antimicrobial susceptibility profiling of 50 S. aureus strains collected from these 2 groups of patients were undertaken. A total of 19 (designated A through S) distinct genotypes were identified by PFGE of Sma I-digested genomic DNA. The most prevalent PFGE type was L, which accounted for 30% of isolates and was detected among superficial isolates only. The second most prevalent PFGE type, type A (18%), was predominant among deep-seated isolates. Remaining PFGE types varied in distribution between the 2 groups. Plasmid profile analysis revealed that deep isolates harbour plasmids more frequently (comprising 64% of isolates) than superficial isolates (4%) and showed 10 and 2 distinct patterns, respectively, with pattern 1 being the dominant among deep isolates. Antimicrobial susceptibility data suggested an increased prevalence of antibiotic resistance among deep isolates with the majority (40%) exhibiting identical antibiograms compared to superficial isolates. No resistance was detected against clindamycin and vancomycin. The results of our study indicate a previously unrecognized dichotomy of S. aureus strains, causing deep-seated and superficial infections.

Increasing rates of nasal carriage of methicillin-resistant Staphylococcus aureus in healthy children

BACKGROUND

Prior studies, including one from our institution performed in 2001, suggest that nasal colonization with methicillin-resistant Staphylococcus aureus (MRSA) occurs infrequently in the healthy pediatric population (0.2-2.2%). However, infections caused by community-associated MRSA have increased remarkably in recent years. As a result, we restudied the prevalence of MRSA nasal colonization in healthy children, comparing results from 2001 and 2004.

PATIENTS AND METHODS

Nasal swabs were collected from 500 children presenting for health maintenance visits. Samples were cultured quantitatively, and MRSA isolates were confirmed by growth on selective media, coagulase testing and the presence of the mecA resistance gene. MRSA isolates were further analyzed for antibiotic susceptibilities, genetic relatedness by pulsed field gel electrophoresis and polymerase chain reaction for the detection of the gene encoding Panton-Valentine leukocidin.

RESULTS

There were 182 children (36.4%) colonized with S. aureus, and 46 (9.2%) colonized with MRSA. This is significantly higher than the MRSA colonization rate in 2001 (0.8%; P < 0.001). There were no significant associations between potential risk factors and MRSA colonization except for having a family member work in a hospital (odds ratio, 2.0; 95% confidence interval, 1.03-4.1). Pulsed field gel electrophoresis revealed heterogeneity of circulating strains, and the Panton-Valentine leukocidin gene locus was detected in 10 of 46 MRSA isolates (22%).

CONCLUSION

Nasal MRSA colonization in healthy children in Nashville has increased significantly in the past 3 years. As colonization typically precedes infection, this increase may be a major factor in the emergence of community-associated MRSA as a pathogen of healthy children.

Controlling the risk of MRSA infection: screening and isolating patients

Methicillin-resistant Staphylococcus aureus (MRSA) continues to be a major cause for concern to health boards and trusts through the UK and the rest of the world. A review of literature sourced via Cinahl, Medline and Pubmed examines the discussions for and against screening patients for MRSA and isolating MRSA-positive patients as a means of managing MRSA within the hospital setting. The research evidence available on the ability of MRSA strains to spread within the healthcare setting and how this influences the opposing arguments is explored. Other factors considered when examining the arguments for and against screening and isolation are: the implications both in cost and resources; the effect of MRSA infection on patient morbidity and mortality; and the need for individual risk assessment of MRSA colonized or infected patients to prevent the transmission of MRSA isolates. The arguments raised lead to the conclusion that screening and isolation should be universal to decelerate the rate of transmission of MRSA.

Penile prosthesis cultures during revision surgery: a multicenter study

PURPOSE

Initial implantation of inflatable penile prosthesis has a 3% risk of infection. Reoperation of penile implants has a higher rate of infection, estimated between 10% and 18%. To explain the higher risk in revision surgery in this prospective study we cultured clinically uninfected prostheses requiring revision. Prosthesis pain was also investigated as a predictor of positive culture.

MATERIALS AND METHODS

At 3 institutions cultures were prospectively obtained from 77 clinically uninfected penile prostheses at revision surgery. Immediately upon surgical exposure of the pump cultures were obtained. If a bacterial biofilm was noted on any component it was additionally cultured. All culture isolates positive for a staphylococcus species were tested for sensitivity to rifampin and tetracycline (minocycline). An implant is now available that is coated with these antibiotics. Patient history of chronic prosthesis pain was ascertained.

RESULTS

Culture positive bacteria were found in 54 of 77 (70%) patients with clinically uninfected penile prostheses. In some patients more than 1 organism grew and, occasionally, the pump culture was negative but the biofilm was positive. Of 54 patients 49 had positive (90%) culture for staphylococcus genus with 10 different species. All staphylococcal species were sensitive to rifampin and/or tetracycline. We did not find a significant association between prosthesis related pain and culture laboratory results.

CONCLUSIONS

The majority of clinically uninfected penile prostheses have organisms growing in the implant spaces at reoperation. Most of these organisms are staphylococcal species that are sensitive to rifampin/minocycline.

Skin and soft-tissue infections: impact of resistant gram-positive bacteria

Surgical site infections remain significant causes of postoperative morbidity and mortality despite an improved understanding of risk factors and an increasing armamentarium of antimicrobial agents. The overall rates of surgical site infections have been slowly decreasing, but the proportion of infections with gram-positive bacteria continues to increase, and drug-resistant species continue to become more prevalent. Although new antibiotic classes have efficacy against such organisms, these agents are only short-term solutions to the problem of multiple-drug resistance. Surgeons must focus on prevention of infections by appropriately using antibiotics, emphasizing principles of infection control, and understanding nontraditional measures that may decrease infection risk.

Infection control measures for adult cardiac surgery in the UK--a survey of current practice

The aim of the study was to define current UK practice for antimicrobial prophylaxis and preoperative screening for bloodborne viruses and methicillin-resistant Staphylococcus aureus (MRSA) before routine cardiac surgery. An e-mail survey was sent to the Association of Cardiothoracic Anaesthetists (ACTA) Linkmen in all 36 UK adult cardiac surgical units, during May 2001. Questions were asked regarding MRSA, hepatitis B, C and human immunodeficiency virus (HIV) screening. Regarding antimicrobial prophylaxis questions were asked regarding agent(s), dose, frequency and duration of use for coronary artery and value surgery. Responses were received from 29 units (response rate 81%). There was a wide variety of practices for all units surveyed. For MRSA screening, 19 units (65%) screened all patients before surgery, but two (7%) screened none, with the remaining eight units (28%) screening selected high-risk groups. Regarding screening for bloodborne viruses: eight units (28%) tested all patients routinely for hepatitis B, 11 units (39%) selectively tested only high-risk patients and transplant recipients. No units tested for hepatitis C and HIV infection routinely. All units used prophylactic antibiotics routinely, but the type and number of agents, along with dose and duration of therapy all varied widely. For coronary artery bypass graft (CABG) surgery, a single agent was used by 16 units (55%), two agents by 12 units (41%) and three agents by one unit (4%). There is a wide variation in infection control practice in adult cardiac units throughout the UK. Rationalization of preoperative screening and use of prophylactic antibiotics, by adopting nationally agreed practice guidelines, could significantly reduce costs and potentially reduce the incidence of resistant organisms.

Guidelines for the Prevention of Intravascular Catheter–Related Infections

These guidelines have been developed for practitioners who insert catheters and for persons responsible for surveillance and control of infections in hospital, outpatient, and home health-care settings. This report was prepared by a working group comprising members from professional organizations representing the disciplines of critical care medicine, infectious diseases, health-care infection control, surgery, anesthesiology, interventional radiology, pulmonary medicine, pediatric medicine, and nursing. The working group was led by the Society of Critical Care Medicine (SCCM), in collaboration with the Infectious Disease Society of America (IDSA), Society for Healthcare Epidemiology of America (SHEA), Surgical Infection Society (SIS), American College of Chest Physicians (ACCP), American Thoracic Society (ATS), American Society of Critical Care Anesthesiologists (ASCCA), Association for Professionals in Infection Control and Epidemiology (APIC), Infusion Nurses Society (INS), Oncology Nursing Society (ONS), Society of Cardiovascular and Interventional Radiology (SCVIR), American Academy of Pediatrics (AAP), and the Healthcare Infection Control Practices Advisory Committee (HICPAC) of the Centers for Disease Control and Prevention (CDC) and is intended to replace the Guideline for Prevention of Intravascular Device–Related Infections published in 1996. These guidelines are intended to provide evidence-based recommendations for preventing catheter-related infections. Major areas of emphasis include 1) educating and training health-care providers who insert and maintain catheters; 2) using maximal sterile barrier precautions during central venous catheter insertion; 3) using a 2% chlorhexidine preparation for skin antisepsis; 4) avoiding routine replacement of central venous catheters as a strategy to prevent infection; and 5) using antiseptic/antibiotic impregnated short-term central venous catheters if the rate of infection is high despite adherence to other strategies (i.e., education and training, maximal sterile barrier precautions, and 2% chlorhexidine for skin antisepsis). These guidelines also identify performance indicators that can be used locally by health-care institutions or organizations to monitor their success in implementing these evidence-based recommendations.

Guidelines for the prevention of intravascular catheter-related infections. The Hospital Infection Control Practices Advisory Committee, Center for Disease Control and Prevention, U.S

These guidelines have been developed for practitioners who insert catheters and for persons responsible for surveillance and control of infections in hospital, outpatient, and home health-care settings. This report was prepared by a working group comprising members from professional organizations representing the disciplines of critical care medicine, infectious diseases, health-care infection control, surgery, anesthesiology, interventional radiology, pulmonary medicine, pediatric medicine, and nursing. The working group was led by the Society of Critical Care Medicine (SCCM), in collaboration with the Infectious Disease Society of America (IDSA), Society for Healthcare Epidemiology of America (SHEA), Surgical Infection Society (SIS), American College of Chest Physicians (ACCP), American Thoracic Society (ATS), American Society of Critical Care Anesthesiologists (ASCCA), Association for Professionals in Infection Control and Epidemiology (APIC), Infusion Nurses Society (INS), Oncology Nursing Society (ONS), Society of Cardiovascular and Interventional Radiology (SCVIR), American Academy of Pediatrics (AAP), and the Healthcare Infection Control Practices Advisory Committee (HICPAC) of the Centers for Disease Control and Prevention (CDC) and is intended to replace the Guideline for Prevention of Intravascular Device-Related Infections published in 1996. These guidelines are intended to provide evidence-based recommendations for preventing catheter-related infections. Major areas of emphasis include 1) educating and training health-care providers who insert and maintain catheters; 2) using maximal sterile barrier precautions during central venous catheter insertion; 3) using a 2% chlorhexidine preparation for skin antisepsis; 4) avoiding routine replacement of central venous catheters as a strategy to prevent infection; and 5) using antiseptic/antibiotic impregnated short-term central venous catheters if the rate of infection is high despite adherence to other strategies (ie, education and training, maximal sterile barrier precautions, and 2% chlorhexidine for skin antisepsis). These guidelines also identify performance indicators that can be used locally by health-care institutions or organizations to monitor their success in implementing these evidence-based recommendations.

Prevalence of methicillin-resistant Staphylococcus aureus nasal carriage in the community pediatric population

BACKGROUND

Reports from various geographic regions indicate that the prevalence of community-acquired methicillin-resistant (MRSA) infection is increasing. The primary reservoir is the anterior nares; nasal carriage is a risk factor for infection in a variety of populations. Little is known about MRSA nasal carriage rates among children in Nashville, TN and the associated likelihood of community MRSA transmission.

METHODS

Nasal swabs were collected from 500 children at well-child visits at either a university hospital pediatric clinic or a private pediatric office. Cultures were plated onto selective staphylococcal media, with or without oxacillin. isolates were confirmed by coagulase tube testing. Antibiotic susceptibilities were determined for suspected methicillin-resistant isolates by standard broth microdilution methods (National Committee for Clinical Laboratory Standards). Pulsed field gel electrophoresis was used to evaluate epidemiologic relatedness. PCR testing was done to assess for the gene. A parent questionnaire was administered regarding MRSA risk factors.

RESULTS

Four patients had oxacillin-resistant isolates (MIC >or= 4 microg/ml), and two had borderline resistant isolates (MICs = 1 and 2 microg/ml). One of the borderline-resistant isolates and one of the MRSA isolates had pulsed field gel electrophoresis typing results indicating close relatedness. The gene was present in all resistant isolates and one of the borderline-resistant isolates. Only having a household member employed in a hospital was associated with a greater risk of MRSA nasal carriage (odds ratio, 9.6; P= 0.008).

CONCLUSIONS

MRSA nasal colonization is present within Nashville's healthy pediatric population. Children with household contacts employed in a hospital are significantly more likely to be colonized.

Applying the science to the prevention of catheter-related infections

BACKGROUND

Catheter-related bloodstream infection (CR-BSI) remains a leading cause of nososcomial infection, despite the fact that many CR-BSIs are preventable. Simple principles of infection control and the use of novel devices to reduce these infections are not uniformly implemented.

OBJECTIVE

To review and summarize the evidence that promotes strategies to prevent CR-BSIs.

DATA SOURCES

The Medline database and bibliographies of review articles and book chapters were searched for relevant articles.

STUDIES INCLUDED

In vitro and in vivo laboratory-based studies, controlled clinical trials, prospective interventional trials, and epidemiologic investigations.

OUTCOME MEASURES

Reduction in CR-BSI, catheter colonization, tunnel infection, or local site infection.

SYNTHESIS

The recommended prevention strategies with strong supportive evidence include educating and training of health care providers who insert and maintain catheters; using full barrier precautions during central venous catheter insertion; using a 2% chlorhexidine preparation for skin antisepsis; eliminating the practice of scheduled replacement of central venous catheters for prevention of infection; and using antiseptic/antibiotic impregnated short-term central venous catheters.

CONCLUSION

Simple interventions can reduce the risk for serious catheter-related infection. Health care provider awareness and adherence to these prevention strategies is critical to reducing the risk for CR-BSI, improving patient safety, and promoting quality health care.

Enterocolitis caused by methicillin-resistant Staphylococcus aureus: molecular characterization of respiratory and digestive tract isolates

We investigated the mechanism of outbreak of enterocolitis caused by methicillin-resistant Staphylococcus aureus (MRSA). Five epidemiological markers [coagulase type, enterotoxin type, toxic shock syndrome toxin-1 (TSST-1) production, beta-lactamase production and pulsed-field gel electrophoresis (PFGE)] of 45 strains of MRSA isolated simultaneously from the respiratory tract (nasal cavity and/or pharynx and/or sputum) and stool (plus one sample of gastric juice) in 13 patients (8 males and 5 females, mean age, 77.1 years) were compared retrospectively. Forty-four of the 45 isolates of MRSA were positive for enterotoxin C and TSST-1 production, and the remaining isolate was positive for enterotoxin A and negative for TSST-1 production. All isolates were coagulase type II, and 27 showed beta-lactamase production. The patterns of coagulase type, enterotoxin type, TSST-1 and beta-lactamase production of MRSA isolated from the respiratory tract were similar to those of MRSA isolated from the intestine in 12 of 13 patients. Molecular typing by PFGE demonstrated that the pattern of respiratory tract isolates was identical to those of stool isolates in 9 (69.2%), similar in 3 (23.1 %), and different in 1 (7.7%). The data suggested that enterocolitis might be caused by the MRSA colonized in the respiratory tract and incorporated into the digestive tracts. Therefore, we propose that early eradication of MRSA in the respiratory tract is important for protection of patients against the development of enterocolitis, particularly in susceptible patients, e.g., immunocompromised or pre-operated patients with digestive diseases, especially malignant disease.

Searching the health care literature efficiently: from clinical decision-making to continuing education

Searching the health care literature is an activity in which infection control professionals must routinely engage to seek evidence-based answers to specific practice questions and to stay abreast of developments in the field. Without the appropriate tools, the tremendous volume of clinical literature makes both of these daunting tasks. In this article, we illustrate techniques for searching MEDLINE efficiently, both as a means of answering particular clinical questions and for generating periodic updates on topics of general interest. With use of a specific example relevant to infection control, we demonstrate the identification of appropriate Medical Subject Headings terms that capture a given question or topic and the development of effective searches with use of these terms. We also touch on the advantages of targeting systematic reviews and meta-analyses in searching for evidence and staying abreast of the literature in general.

[Nasal carriers of methicillin-resistant Staphylococcus aureus among cuban children attending day-care centers]

BACKGROUND

Recent but scarce reports of methicillin-resistant Staphylococcus aureus strains (MRSA) among children without risk factors associated with its acquisition prompted us to investigate its presence in the community.

PATIENTS AND METHODS

During the September and October months in 1997, nasal and pharyngeal swabs were obtained from 358 children aged less than five years who attended three day-care centers in the Marianao Area, La Habana City, Cuba. The isolated S. aureus strains were characterized for antimicrobial sensitivity using the Kirby-Bauer method. Methicillin resistance was confirmed by te Oxacillin Salt-Agar Screening-Plate method recommended by the National Committee for Clinical Laboratory Standards.

RESULTS

18.7% of children were carriers of S. aureus in the upper respiratory tract; 2.2% of children carried MRSA strains. The highest resistance levels corresponded to erythromycin (50.74%) and tetracycline (29.9%). All tested strains were sensitive to ciprofloxacin.

CONCLUSIONS

Our results provide evidence on the recovery of MRSA strains among healthy children attending day-care centers and are suggestive of a rapid colonization and spread of these microorganisms in the community.

Intranasal mupirocin reduces sternal wound infection after open heart surgery in diabetics and nondiabetics

BACKGROUND

This study was designed to determine whether decreasing nasal bacterial colonization by applying Mupirocin (MPN) intranasally decreases sternal wound infections.

METHODS

We prospectively followed 992 consecutive open heart surgery (OHS) patients who did not receive MPN prophylaxis (group I) from January 1, 1995 to October 31, 1996. Group II consisted of 854 consecutive patients followed prospectively from December 1, 1997 to March 31, 1999 treated with intranasal MPN given on the evening before, the morning of OHS, and twice daily for 5 days postoperatively.

RESULTS

There was a significant difference in the rate of overall sternal wound infections between the untreated (group I) and the treated group (group II): 2.7% (27 of 992) versus 0.9% (8 of 854) (p = 0.005). The difference was also significant in the diabetic subgroup: 5.1% (14 of 277) (group I) versus 1.9% (5 of 266) (group II) (p = 0.04) and the nondiabetic group: 1.8% (13 of 715) (group I) versus 0.5% (3 of 588) (group II) (p = 0.03). The cost of MPN treatment was $12.47 per patient compared with $81,018 +/- $41,567 for a deep wound infection with no antibiotic-related complications recorded.

CONCLUSIONS

Prophylactic intranasal MPN is safe, inexpensive, and very effective in reducing the overall sternal wound infections by 66.6%.

Emergence and spread of low-level mupirocin resistance in methicillin-resistant Staphylococcus aureus isolated from a community hospital in Japan

The objective of this study was to investigate the state of mupirocin resistance in methicillin-resistant Staphylococcus aureus (MRSA) in a community hospital in Japan. Ninety strains of MRSA were isolated from the respiratory tract of 56 patients (group I, Jun 1990-Aug 1996) before introduction of mupirocin in Japan, which were compared with 168 strains from 48 patients (group II, Sept 1996-Jan 1998) and 146 strains from 85 patients (group III, Feb 1999-Dec 1999) isolated after introduction of mupirocin. Comparisons were made by determining the minimum inhibitory concentrations (MIC) against nine antibiotics. Fifty-five MRSA isolates from 27 patients [13 (27.1%) of 48 in group II and 14 (16.5%) of 85 in group III] after introduction of mupirocin showed low-level resistance to mupirocin (MIC, 6.25 to 50 microg/ml) but the remaining isolates were sensitive to mupirocin (MIC < or =3.13 microg/ml). Most patients colonized with low-level mupirocin-resistant MRSA were elderly (> or =65 years of age), on total parenteral nutrition or nasal feeding and had other underlying diseases. The proportion of patients colonized with low-level mupirocin-resistant MRSA following repeated use of mupirocin was higher in patients of group II than those of group III. Molecular typing by pulsed-field gel electrophoresis (PFGE) demonstrated that the pattern of 13 MRSA isolates from 13 patients of group II consisted of three patterns (A, B, C) with predominance of pattern A, while the pattern of 13 MRSA isolates from 13 patients of group III consisted of three patterns (A, C, D) with predominance of patterns A and D. Our results indicated that resistance of MRSA to mupirocin remains at a low level at present in Japan. However, we should be aware of the possible emergence of MRSA highly resistant to mupirocin in the future.