The relationship between nasal and conjunctival cultures of antimicrobial-resistant isolates of methicillin-resistant Staphylococcus aureus

PurposeNasal screening is performed to avoid the complications of postoperative surgical site infections (SSI), especially those due to antimicrobial-resistant species such as methicillin-resistant Staphylococcus aureus (MRSA). This study examined the relationship between bacterial isolates from the conjunctiva and the nasal cavity.MethodsAll patients were diagnosed with ocular surface infections, and the organisms in the conjunctiva and the nasal cavity were isolated. We investigated the relationship of the following antimicrobial-resistant bacteria between the conjunctiva and the nose: MRSA, methicillin-resistant CNS (MRCNS), levofloxacin-resistant (LVFX-R) Corynebacterium spp. Data were analyzed using Fisher’s exact test, and the odds ratio was examined.ResultsThis study included 188 eyes of 188 subjects (87 males and 101 females; mean age 58.5 years, range 11–97 years). MRSA (4 eyes), MRCNS (29 eyes), and LVFX-R Corynebacterium spp. (41 eyes) were identified from the conjunctiva, and MRSA (6 eyes), MRCNS (38 eyes), and LVFX-R Corynebacterium spp. (41 eyes) were identified from the nasal cavity. There was a significant relationship detected between the conjunctiva and the nose for MRSA, MRCNS, and LVFX-R Corynebacterium spp. MRSA displayed high sensitivity (0.750, 95% confidence interval [CI]; 0.301 to 0.987) and specificity (0.984, 95% CI; 0.953 to 0.996) in nasal cavity cultures, and the odds ratio was 181.00 times (95% CI; 18.41 to 2320).ConclusionThis study showed a significant relationship between conjunctival and nasal cultures of MRSA, MRCNS, and LVFX-R Corynebacterium spp., suggesting that nasal cavity culture is a potentially useful screening method for detecting resistant bacteria, especially MRSA, in the conjunctiva.     

Association between commensal bacteria and opportunistic pathogens in the dental plaque of elderly individuals

Opportunistic infections in the oral cavity of the elderly may increase the incidence of systemic disease. The objective of this study was to investigate the differences in the oral bacterial flora between dependent elderly (inpatients) and independent elderly (community-dwelling residents). After multiple variables were taken into account, inpatients had significantly lower detection rates than community-dwelling residents for alpha-streptococci (p < 0.001) and Neisseria (p 0.004), and higher detection rates for Pseudomonas aeruginosa (p 0.024), methicillin-resistant Staphylococcus aureus (MRSA) (p 0.011) and Actinomyces spp. (p 0.005). Among inpatients, the requirement for a high degree of care was related negatively to detection of alpha-streptococci, but was related significantly to detection of P. aeruginosa (p 0.018) or MRSA (p 0.004). Tube-fed inpatients had a significantly lower detection rate for alpha-streptococci (p 0.041) and a higher detection rate for P. aeruginosa (p 0.004) than those who did not require tube feeding. Inpatients with a history of antibiotic use had a significantly lower detection rate for alpha-streptococci (p 0.049) and a higher detection rate for MRSA (p 0.007) than those without a history of antibiotic use. The detection rates for P. aeruginosa or MRSA in inpatients without alpha-streptococci were higher than in inpatients with alpha-streptococci after controlling for age and gender (P. aeruginosa, p 0.006; MRSA, p 0.001). Overall, detection of alpha-streptococci had an inverse correlation with the detection of P. aeruginosa and MRSA in the oral cavity and is likely to be an indicator of pathogenic bacterial infection.     

Semmelweis’ present day follow-up: Updating bacterial sampling and enrichment in clinical hygiene

Potentially dangerous antibiotic resistant contaminants have permanently penetrated at least well-off western populations. The danger is so evident that some hospitals have started to refuse accepting patients who carry such bacteria. Sampling and enrichment measures in hygiene monitoring must be updated as they are corner stones in handling the problems and safeguarding the health care units. Their patients, when exposed to microorganisms are strenuous to treat. Sometimes even this fails, if the infections are spreading in weakened patients. The present review summarizes currently used technologies and the abilities of bacteria to avoid detection. Improved protocols on environmental monitoring in healthcare units are required. They should be comparable with contamination control in industries. Actually these measures in health care should be even stricter because human lives are directly endangered as the resistance of especially elderly patients is low.     

Effectiveness of a hospital-wide selective screening programme for methicillin-resistant Staphylococcus aureus (MRSA) carriers at hospital admission to prevent hospital-acquired MRSA infections

Screening of potential MRSA-positive patients at hospital admission is recommended in German and international guidelines. This policy has been shown to be effective in reducing the frequency of nosocomial MRSA transmissions in the event of an outbreak, but the influence of screening on reducing hospital-acquired MRSA infections in a hospital setting where MRSA is endemic is not yet well-documented. This study describes the effect of hospital-wide screening of defined risk groups in a 700-bed acute care hospital during a period of 19 months. In a cohort study with a 19-month control period, the frequencies of hospital-acquired MRSA infections were compared with and without screening. In the control period, there were 119 MRSA-positive patients, of whom 48 had a hospital-acquired MRSA infection. On the basis of this frequency, a predicted total of 73.2 hospital-acquired MRSA infections was calculated for the screening period, but only 52% of the expected number (38 hospital-acquired MRSA infections) were observed, i.e., 48% of the predicted number of hospital-acquired MRSA infections were prevented by the screening programme. The screening programme was performed with minimal effort and can therefore be recommended as an effective measure to help prevent hospital-acquired MRSA infections.     

Control of endemic methicillin-resistant Staphylococcus aureus—recent advances and future challenges

Although the exact burden of disease caused by methicillin-resistant Staphylococcus aureus (MRSA) remains largely unknown, most experts agree that MRSA infections are an important clinical and public health problem. Thousands of reports have been published during the last four decades concerning epidemiological and microbiological aspects of MRSA, but uncertainty remains about the best approach to prevent and control this worldwide plague, especially endemic MRSA. Epidemiological methods, e.g., risk scores for targeted screening upon admission, rapid molecular tests and pre-emptive isolation of high-risk patients, new decontamination regimens and restriction of certain antibiotic classes, are all promising approaches that may decrease MRSA cross-transmission; however, further evidence is needed before these strategies can be implemented on a wide scale. Control of community MRSA is an additional challenge for the future, requiring improved surveillance and contact tracing, as well as education and treatment of both infected cases and colonised contacts. This review summarises recent advances and studies that address these issues. Overall, it seems that there is no level of MRSA prevalence for which active control measures are no longer warranted.     

Distribution of the exfoliative toxin D gene in clinical Staphylococcus aureus isolates in France

Exfoliative toxin D (ETD) was identified recently as a new exfoliative toxin serotype. Like other exfoliative toxins, ETD induces intra-epidermal cleavage through the granular layer of the epidermis of neonatal mice. The distribution of ETD production was investigated in Staphylococcus aureus isolates from infected and colonised patients in France. The etd gene was found in 55 (10.5%) of 522 isolates tested. Isolates responsible for bullous impetigo and generalised staphylococcal scalded skin syndrome did not harbour etd, but etd was significantly more frequent in isolates causing cutaneous abscesses and furuncles. Most etd- and Panton-Valentine leukocidin-positive strains belonged to the clone of community-acquired methicillin-resistant S. aureus spreading currently throughout France.     

Preoperative methicillin‐resistant Staphylococcus aureus (MRSA) screening: An effective method to control MRSA infections on elective orthopaedics wards

Background: Methicillin‐resistant Staphylococcus aureus (MRSA) infections continue to increase in UK hospitals despite the introduction of various control measures. These infections have serious clinical and economic implications, particularly in relation to elective orthopaedic surgery. Methods: A prospective study was performed from August 2003 to July 2004 to assess the effect of preadmission screening and ‘ring fencing’ of beds on the incidence of infection in an elective orthopaedics unit. Results: The preoperative incidence of MRSA colonization was 2.25% and 53% of these patients had at least one risk factor. There were no postoperative MRSA infections in the ring‐fenced orthopaedic unit. Conclusions: Preoperative screening and ring fencing reduced the MRSA incidence to zero in the operated patients. Mechanisms need to be developed where screening and isolation of MRSA cases can be performed in most, if not all, hospital admissions.     

医院内感染病原菌及其对抗生素的耐药状况

调查1988年3月～5月我院591例住院病例,发生96例次院内感染,总发病率16.2％。院内感染病原菌中,革蓝氏阴性杆菌占72.9％,革蓝氏阳性球菌占12.9％,念珠菌属占14.1％。院内感染病原菌的耐药性明显高于院外菌株。绿脓杆菌对庆大霉素和羧苄青霉素的耐药率分别为63.6％和54.5％。其它革蓝氏阴性杆菌院内株对常用抗生素如氨苄青霉素、羧苄青霉素、庆大霉素和妥布拉霉素的耐药率分别为82.5％、 67.5％、47.5％和45％。革蓝氏阳性球菌院内株的耐药性也很严重,表葡菌对多种半合成青霉素类、红霉素、复方新诺明甚至万古霉素的耐药率达60％以上。同时分离出耐甲氧西林金葡菌。     

替代万古霉素对MRSA感染的治疗选药

近十年来,许多国家耐甲氧西林/笨唑西林金黄色葡萄球菌(MRSA)增多,由于MRSA的多重耐药性,目前万古霉素仍为治疗MRSA全身性或深部感染的最佳选择。妥布霉素对MRSA的作用很小,因为MRSA的mecDNA中含有编码妥布霉素和卡那霉素的耐药基因(aadD),而且此基因可传播MRSA的耐药性。近年来,法国的一些医院分离出对庆大霉素敏感但对妥布霉素耐药的MRSA菌株,而希腊的一所医院则分离出对所有的氨基糖苷类抗生素均敏感的MRSA。本文报导希腊某些医院发生的MRSA临床感染,这些MRSA菌株对所有抗葡萄球菌的非β-内酰胺类抗生素均敏感。