Development of erythromycin-resistance in Staphylococcus aureus as a consequence of high erythromycin consumption

In a mixed ward for skin and venereology patients the erythromycin consumption was 6-8 fold higher than in other wards at the same hospital. Erythromycin-resistance occurred in 15.5% of the infecting Staphylococcus aureus strains isolated from this ward, compared with 3.5% in other wards of the hospital and 2.3% in Denmark as a whole. The resistant strains belonged to different phage-type patterns, but 18 out of 19 strains contained a 1.5 MDa plasmid and had an erythromycin-inducible resistance mechanism. Erythromycin resistance was frequent (approximately 10%) among Danish S. aureus strains in the years 1963 to 1969, mainly due to the spread of multiply-resistant strains of the 83A complex. During the last ten years, however, only 1-2% of the strains have been resistant, but a slow increase in resistance has taken place during the last three years among strains of all phage patterns including strains of group II, the 94, 96 complex and type 95.     

Spread of Staphylococcus aureus strains of phage-type 95 in Denmark 1968-1989.

The spread of Staphylococcus aureus strains of phage-type 95 was traced retrospectively in Denmark by the review of more than 15,000 S. aureus bacteraemia isolates (1957-88) and from data collected by phage-typing of c. 260,000 isolates from all body sites (1977-89). The first two type 95 strains had been isolated from blood in 1968, and after an interval of 3 years there was a steady increase of bacteraemia strains all over Denmark. From 1977 to 1989 the incidence of type 95 strains among isolates from all body sites increased from 3.8 to 18.8%. Different patterns of increase were recorded in 13 major hospitals and in various clinical departments of two hospitals and these were further analysed. Conjunctival swabs gave the highest percentage of type 95 strains and those from abscesses gave the lowest percentage. Of the type 95 bacteraemia strains 90.4% were resistant to penicillin, but neither methicillin nor gentamicin resistance was recorded.     

The decline of methicillin resistance among Danish Staphylococcus aureus strains

OBJECTIVE: To describe the occurrence and decline of methicillin-resistant Staphylococcus aureus in Denmark from 1966 to 1986, and to illustrate why it has been possible to retain a frequency of only 0.2% MRSA since 1984. DESIGN: A study of antibiotic susceptibility and phage-type of 522,978 S aureus strains isolated from hospitalized patients in Denmark during the years 1960 to 1988 combined with clinical information on patients with methicillin-resistant strains during the years 1986 through 1988. SETTING: All strains and information were collected at the centralized, national laboratory for S aureus phage-typing. PATIENTS: Hospitalized patients with S aureus isolates, and especially patients with methicillin-resistant strains. INTERVENTION: Antibiotic treatment. RESULTS: The frequency of MRSA rose to 15% in the years 1967 through 1971 but decreased to 0.2% in 1984, and has remained so ever since. The increase was due mainly to the spread of a single or a few clones of the phage-type complex 83A. Occurrence of strains of these phage-types declined from 18% in 1969 to 0.6% in 1989. In 1986 through 1988, at least 48% of the MRSA strains were imported by patients from abroad. Cross-infection occurred only in two cases. High awareness and special precautions were taken when MRSA was detected. CONCLUSIONS: MRSA of a single or a few clones spread in Danish hospitals in the years 1967 through 1971. Since 1984, only 0.2% of the Danish S aureus population has been MRSA, and imported MRSA strains have been prevented from spreading.     

Prevalence of and risk factors for colonization with methicillin-resistant Staphylococcus aureus in an outpatient clinic population.

OBJECTIVES: To determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) colonization in an outpatient population and to identify risk factors for MRSA colonization. DESIGN: Surveillance cultures were performed during outpatient visits to identify S. aureus colonization. A case-control study was performed to identify risk factors for MRSA colonization. SETTING: Primary care internal medicine clinic. PATIENTS: Adults presenting for non-acute primary care (N = 494). RESULTS: S. aureus was isolated from 122 (24.7%) of the patients for whom cultures were performed. Methicillin-susceptible S. aureus was isolated from 107 (21.7%) of the patients, whereas MRSA was isolated from 15 (3.0%) of the patients. All MRSA isolates were resistant to multiple non-beta-lactam antimicrobial agents. In multivariate analyses, MRSA colonization was independently associated with admission to a nursing home (adjusted odds ratio [OR], 103; 95% confidence interval [CI95], 7 to 999) or hospital in the previous year, although the association with hospital admission was observed only among those without chronic illness (adjusted OR, 7.1; CI95, 1.3 to 38.1). In addition, MRSA colonization was associated with the presence of at least one underlying chronic illness, although this association was observed only among those who had not been hospitalized in the previous year (adjusted OR, 5.1; CI95, 1.2 to 21.9). CONCLUSIONS: We found a low prevalence of MRSA colonization in an adult outpatient population. MRSA carriers most likely acquired the organism through contact with healthcare facilities rather than in the community. These data show that care must be taken when attributing MRSA colonization to the community if detected in outpatients or during the first 24 to 48 hours of hospitalization.     

Carriage of Staphylococcus aureus among 104 healthy persons during a 19-month period.

The present study was undertaken to investigate the frequency of the nasal carrier rate of Staphylococcus aureus. The investigation was performed on 104 healthy persons. The total number of swabs performed was 1498 and this resulted in isolation of 522 S. aureus strains. All strains have been identified, tested for antibiotic susceptibility, and phage-typed. The carrier-index (number of positive swabs/number of total swabs for each individual person) was compared with different sampling and culturing methods, phage type, age, and resistance to antibiotics. There was statistical difference in carrier rate according to sex (P < 0.05). Among the 104 persons 15 (14.4%) were persistent carriers, 17 (16.3%) intermittent carriers, 55 (52.9%) occasional carriers and 17 (16.3%) non-carriers. Among intermittent and occasional carriers the phage-type distribution was different from the S. aureus strains isolated from Danish hospitalized patients in 1992, while the persistent carriers had similar phage-type distribution.     

The epidemiology of glycopeptide-resistant enterococci on a haematology unit--analysis by pulsed-field gel electrophoresis

As part of an interventional study to determine glycopeptide-resistant enterococci (GRE) acquisition on a three-ward haematology unit, rectal swabs were taken weekly from 293 patients recruited to the study between June 1995 and December 1996. The GRE isolates obtained from the first positive rectal swab from 120 colonized patients, the isolates from 7 patients with clinical infection and 43 isolates obtained from the ward environment were compared by pulsed-field gel electrophoresis (PFGE). Sixty-three of 120 patients were colonized by one of strains A-H, while 49 were colonized by unique strains. The first 18 weeks were associated with the highest prevalence of GRE by rectal swab, with a single strain A responsible for 52% of acquisitions on ward 2, 22% on ward 3 and 36% on ward 4. Other smaller ward associated clusters were evident. Environmental sampling of ward 2 during this time showed that all but 2 of 30 isolates were indistinguishable from strain A. As the GRE prevalence fell, rectal swab and environmental isolates became more heterogeneous, and strain A disappeared after week 55. GRE prevalence rose again in the final 15 weeks of the study, and a new predominant strain B emerged on ward 2 responsible for 50% of new acquisitions. In the seven patients with clinical infection with GRE, the clinical isolates were compared with the contemporaneous rectal swab isolate, and were found to be the same in only two cases. An analysis of five long-term carriers colonized for a median of 19 weeks (range 11-34) showed colonization with at least two and in one case six distinct strains, raising the question of how many strains may be colonizing a patient at any one time, and suggesting that multiple colonies should be analysed. These data suggest that cross-infection was an important factor in the spread of GRE when the colonization rate was high.     

Hospital-acquired infection with methicillin-resistant and methicillin-sensitive staphylococci

In-patients at a London hospital over one year from whom the south-east England strain of 'epidemic' methicillin-resistant Staphylococcus aureus (MRSA) was isolated were compared with in-patients with strains of methicillin-sensitive Staphylococcus aureus (MSSA). MRSA were virtually entirely hospital-acquired; isolates before 10 days were uncommon and related to recent previous admission. Thereafter first isolates occurred at a fairly constant daily rate of about 1.9 per 1,000 in-patients. Acquisition of MSSA after more than 4 days in hospital occurred at a similar constant rate. Such strains were less likely to be penicillin-sensitive than strains isolated in the first 4 days after admission (11 vs. 22%) and were considered to be hospital-acquired. The single MRSA strain caused 40 infections in a year, about half of all hospital-acquired staphylococcal infections. Patients prescribed anti-staphylococcal antibiotics and patients with indwelling cannulae both had about a ninefold increased risk of acquiring MRSA. There was no reciprocal increase in MSSA infections after control measures had substantially reduced the number of MRSA infections.     

Prevalence of and risk factors for colonization with methicillin-resistant Staphylococcus aureus at the time of hospital admission.

OBJECTIVES: To determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) colonization among patients presenting for hospital admission and to identify risk factors for MRSA colonization. DESIGN: Surveillance cultures were performed at the time of hospital admission to identify patients colonized with S. aureus. A case-control study was performed to identify risk factors for MRSA colonization. SETTING: A tertiary-care academic medical center. PATIENTS: Adults presenting for hospital admission (N = 974). RESULTS: S. aureus was isolated from 205 (21%) of the patients for whom cultures were performed. Methicillin-sensitive S. aureus was isolated from 179 (18.4%) of the patients, and MRSA was isolated from 26 (2.7%) of the patients. All 26 MRSA-colonized patients had been admitted to a healthcare facility in the preceding year, had at least one chronic illness, or both. In multivariate analyses comparing MRSA-colonized patients with control-patients, admission to a nursing home (odds ratio [OR], 16.5; 95% confidence interval [CI95], 1.4 to 192.1; P = .025) or a hospitalization of 5 days or longer during the preceding year (OR, 3.91; CI95, 1.1 to 13.9; P = .035) were independent predictors of MRSA colonization. CONCLUSIONS: Patients colonized with MRSA admitted to this hospital likely acquired the organism during previous encounters with healthcare facilities. There was no evidence that MRSA colonization occurs commonly among low-risk individuals in this community. These data suggest that evaluation of recent healthcare exposures is essential if true community acquisition of MRSA is to be confirmed.     

Enterotoxins and toxic-shock syndrome toxin-1 in non-enteric staphylococcal disease.

Over the 7 years 1985-91, 997 strains of Staphylococcus aureus from 962 patients with diseases other than food poisoning have been tested for the production of enterotoxins and toxic shock syndrome toxin-1 (TSST-1) and phage typed. In all, 128 cases could be classified as confirmed or probable toxic shock syndrome (TSS) but a further 199 cases were classified as possible or unconfirmed TSS. In 219 cases, an alternative diagnosis could be supported and 45 cases were classified as sudden infant death syndrome. In 371 cases, insufficient information for classification was available. Strains of phage group I producing TSST-1 were associated with menstrual TSS. Many menstrual TSS cases were aged less than 20 and were using non-introducer tampons. When all strains were reviewed, strong associations were observed between TSST-1 production and phage group I strains, enterotoxin B production and group V strains, enterotoxin C and phage-type 95 strains and between enterotoxin A without TSST-1 and phage group III strains.     

重症监护病房医务人员鼻前庭细菌定植情况及耐药性调查

目的了解重症监护病房（ICU）医务人员鼻前庭病原菌定植情况,为加强ICU医院感染的预防与控制提供依据。方法2015年5月主动筛查某院ICU非感染状态下的医务人员鼻前庭细菌定植情况,并进行细菌培养、菌株分离及菌种鉴定。分析调查结果并与同期患者检出细菌的耐药情况进行比较。结果共调查医务人员96名,从鼻前庭标本中分离病原菌43株,分别来自不同的医务人员,病原菌分离率及携带率均为44.79%。分离的主要病原菌为金黄色葡萄球菌（15株,占34.88%）,其次为产气肠杆菌（9株,占20.93%）、肺炎克雷伯菌（7株,占16.28%）等。医生、经常吸烟及从不锻炼的医务人员鼻前庭病原菌的检出率较高,差异具有统计学意义（均P＜0.05）。43株病原菌中检出1株耐亚胺培南的肺炎克雷伯菌。医务人员检出的7株肺炎克雷伯菌对氨苄西林/舒巴坦、头孢唑林、呋喃妥因的耐药率均＞50.00%,对头孢噻肟与亚胺培南的耐药率分别为28.57%、14.29%;同期患者检出的11株肺炎克雷伯菌对呋喃妥因的耐药率为100.00%,对其他常用抗菌药物均敏感。医务人员检出的4株大肠埃希菌对氨苄西林的耐药率为75.00%,对庆大霉素、妥布霉素、左氧氟沙星、环丙沙星及复方磺胺甲口恶唑的耐药率均为50.00%,而同期患者检出的6株大肠埃希菌对大部分常用抗菌药物均耐药。结论长期工作在ICU的医务人员鼻前庭病原菌定植率高,定期主动对医务人员鼻前庭病原菌定植情况进行筛查及监测,对预防医院感染,防止医务人员与患者之间的交叉传播具有重要意义。     

2015—2018年住院患者治疗性抗菌药物使用前分离菌株及药敏情况

目的 了解住院患者首次治疗性使用抗菌药物前分离菌株及药敏结果,为医院抗菌药物合理使用提供可靠的微生物依据。方法 基于某院抗菌药物临床决策支持系统后台相关节点数据及医院检验信息系统收集的住院患者分离菌株及药敏结果,收集2015—2018年患者入院后首次治疗性使用抗菌药物前临床分离菌株和住院期间送检标本所有临床分离菌株,比较抗菌药物使用前后菌株分布及其耐药情况。结果 2015—2018年住院患者所有送检标本共检出非重复菌株69 037株（包括细菌及真菌）,其中革兰阳性菌17 900株（占25.93%）,革兰阴性菌44 055株（占63.81%）,真菌7 082株（占10.26%）。住院患者入院后首次治疗性使用抗菌药物前采集标本中检出非重复菌株15 017株,其中革兰阳性菌4 661株（占31.04%）,革兰阴性菌9 451株（占62.93%）,真菌905株（占6.03%）。治疗用药前标本分离菌居前5位的依次是大肠埃希菌、肺炎克雷伯菌、金黄色葡萄球菌、铜绿假单胞菌和凝固酶阴性葡萄球菌,所有送检标本分离菌居前5位的分别为肺炎克雷伯菌、鲍曼不动杆菌、铜绿假单胞菌、假丝酵母菌属、大肠埃希菌,苛养菌如链球菌属、流感嗜血杆菌、卡他莫拉菌在所有送检标本中占比,较用药前低。临床常见分离菌包括金黄色葡萄球菌、大肠埃希菌、肺炎克雷伯菌、铜绿假单胞菌、鲍曼不动杆菌,抗菌治疗后送检标本分离菌株中耐药率更高。结论 研究首次报道大样本治疗性抗菌药物使用前临床送检标本分离的菌株及药敏情况,临床常见分离菌包括金黄色葡萄球菌、大肠埃希菌、肺炎克雷伯菌、铜绿假单胞菌、鲍曼不动杆菌,在抗菌治疗后标本中显示更高的耐药性。     

Staphylococcal zoonosis on dairy farms in Assam and Meghalaya

OBJECTIVE: To assess if Staphylococcus aureus is transmitted between man and animals & vice-versa. METHODS: Staphylococcus aureus belonging to biotype C (bovine origin) were isolated from nares and hands of workers on six dairy farms of Assam and Meghalaya. The cows on the farms had a high rate of prevalence of mastitis caused by the same biotype of S. aureus. Three strains of S. aureus biotype A (human origin) were isolated from mastitis milk samples from cows on one of these farms, in which one of the workers was having cuteneous lesions (crusty abscess) and one strain of S. aureus biotype A was isolated from a swab sample collected from an abscess on the skin of the worker. RESULTS: It has been revealed that all the members of the workers family were suffering from a similar type of cuteneous infection, indicating that it was a case of impetigo. The antibiotic susceptibility pattern of all the three biotype A strains from bovine origin was identical to that of the biotype A strains isolated from the worker. The percentage of resistance to 12 commonly used therapeutic antimicrobial agents was higher among the biotype C strains from human origin than the biotype C strains from bovine origin. Several strains from cattle and human origins showed identical antimicrobial susceptibility patterns against the tested agents.     

Emergence of multidrug-resistant Salmonella enterica serotype Typhimurium phage-type DT104 among salmonellae causing enteritis in Israel

The relative frequency of salmonella strains isolated from hospitalized and non-hospitalized patients in Southern Israel changed during the period, 1994-6. Salmonella enterica serotype Typhimurium definitive phage-type 104 (DT104) appeared in Israel in 1994 and became the most prevalent strain in 1996. An outbreak of enteritis due to Salmonella enterica serotype Agona occurred in Israel, in October 1994 and lasted for 4 months. The relative frequency of Salmonella enterica serotype Enteritidis remained almost constant during these years, with seasonal fluctuations only. The importance of the increase in the prevalence of Typhimurium DT104 has been the epidemic spread of a multiresistant strain of R-type ACT (A, ampicillin; C, chloramphenicol; T, tetracycline) belonging to this phage-type. Since 1995 the frequency of Typhimurium DT104 isolates that possess, in addition to the above R-type, a chromosomally encoded resistance to the quinolone drug, nalidixic acid, increased tenfold. In 1996, 27% of the Typhimurium DT104 isolates were of R-type ACTN. S. Enteritidis exhibited over 95% susceptibility to at least eight of the most commonly used antibiotic drugs, and none of the isolates was resistant to quinolone or fluoroquinoline.     

Rates of carriage of methicillin-resistant and methicillin-susceptible Staphylococcus aureus in an outpatient population.

OBJECTIVES: To assess the prevalence of and the clinical features associated with asymptomatic Staphylococcus aureus colonization in a healthy outpatient population, and to compare the characteristics of colonizing methicillin-resistant S. aureus (MRSA) strains with those of strains causing infection in our community and hospital. SETTING: Outpatient military clinics. METHODS: Specimens were obtained from the nares, pharynx, and axillae of 404 outpatients, and a questionnaire was administered to obtain demographic and risk factor information. MRSA strains were typed by pulsed-field gel electrophoresis (PFGE) and evaluated for antibiotic susceptibility. Antibiograms of study MRSA strains were compared with those of MRSA strains causing clinical illness during the same time period. RESULTS: Methicillin-susceptible S. aureus (MSSA) colonization was present in 153 (38%) of the 404 asymptomatic outpatients, and MRSA colonization was present in 8 (2%). Detection of colonization was highest from the nares. No clinical risk factor was significantly associated with MRSA colonization; however, a tendency was noted for MRSA to be more common in men and in those who were older or who had been recently hospitalized. All colonizing MRSA strains had unique patterns on PFGE. In contrast to strains responsible for hospital infections, most colonizing isolates of MRSA were susceptible to oral antibiotics. CONCLUSIONS: MRSA and MSSA colonization is common in our outpatient population. Colonization is best detected by nares cultures and most carriers of MRSA are without apparent predisposing risk factors for acquisition. Colonizing isolates of MRSA are heterogeneous and, unlike nosocomial isolates, often retain susceptibility to other non-beta-lactam antibiotics.     

Interaction between methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA)

In this paper we describe the in vitro interaction between three strains of methicillin-sensitive Staphylococcus aureus (MSSA) [NCTC 11561 and two strains derived from patients (PMSSA)] and endemic methicillin-resistant Staphylococcus aureus (EMRSA) 1, 3, 15 and 16. Mixed bacterial cultures of MSSA and EMRSA were incubated and subcultured after one, two and seven days. A proportion of MRSA in 50 randomly selected colonies was assessed. All strains of EMRSA (EMRSA 1, 3, 15 and 16) outgrew and virtually eradicated MSSA (NCTC 11561) after 24 h. The interaction between strains of PMSSA and the various strains of EMRSA was variable. PMSSA strain 1 was almost completely outgrown by EMRSA 1 and EMRSA 3 after seven days. Similarly there was a substantial increase of EMRSA 1 and 3 when tested against PMSSA strain 2. EMRSA 15 increased modestly against both strains, but EMRSA 16 failed to increase in proportion against either of the strains. We conclude that there is a complex interaction between various strains of EMRSA and MSSA. This interaction may have an important bearing on colonization of patients with MRSA.     

Double-blind comparative study on the care of the neonatal umbilical cord using 80% ethanol with or without chlorhexidine

We conducted a double-blind comparative study on the effectiveness of 80% ethanol (EtOH), with or without chlorhexidine (CHD), in the prevention of neonatal umbilical colonization by Staphylococcus aureus, the most frequently isolated pathogen on the neonatal umbilicus in the early period. A total of 100 neonates born at the National Tokyo Medical Centre from March to May 2000 and nursed at a maternity ward were enrolled. Forty-eight were randomly allocated to the group for whom umbilical cord disinfection was performed using 80% EtOH containing 0.5% CHD (CHD group) and 52 to disinfection with 80% EtOH alone (EtOH group). The mothers of the neonates and the nursing staff were unaware as to which disinfectant was being used. Disinfection of the umbilicus and the surrounding area was done immediately after birth and twice daily thereafter, after bathing and in the evening, throughout the hospitalization period. Specimens for bacterial culture were taken from the umbilical cord and surrounding skin on day 4 or 5 after birth. As a disinfectant susceptibility test, we checked the minimum killing concentration (MKC) of CHD and EtOH. There was no statistically significant difference between the two groups with respect to sex, gestation period, birthweight, APGAR score or delivery method. In the CHD group, S. aureus was isolated from 25% of the patients, while it was isolated from 57.7% in the EtOH group (P<0.001). In the CHD group, 50% of the S. aureus strains were MRSA, compared with 73.3% in the EtOH group (non-significant). All the S. aureus strains were killed by the combination of both CHD and EtOH at the concentrations used. In terms of the MKC90, there was no significant difference between the CHD group and the EtOH group. For the daily care of the neonatal umbilicus, disinfection using 80% EtOH containing CHD was found to be more effective than that using 80% EtOH alone in preventing colonization by S. aureus.     

Occurrence of quinolone resistance in Staphylococcus aureus from nosocomial infection.

Among 63 Staphylococcus aureus isolates (one isolate per one patient) counted from infections (from August to November 1991) in hospital T., eight exhibited resistance to fluoroquinolones. Seven of these quinolone-resistant isolates were multiply- and methicillin-resistant S. aureus (QR-MRSA). The results of phage-, plasmid- and genotyping (pulsed field electrophoresis) revealed that six different strain-clones of these MRSA were spread in the hospital. In vitro spontaneous mutants resistant to fluoroquinolones are 10-100-fold more frequent in MRSA than in other S. aureus when selected on isosensitest-agar containing 1 microgram/ml of ciprofloxacin. However, the same mutant frequencies were found in strain 8325-4 with and without the mecA-determinant. The resistance phenotype was stable over 30 generations of subculture in nutrient broth as well in natural quinolone resistant MRSA as in mutants of other types of S. aureus selected in vitro. The phenotypic association of quinolone resistance and MRSA is rather likely due to a higher frequency of spontaneous resistant mutants which are present in natural populations of MRSA. Data of chemotherapy prior to the isolation of S. aureus show that three of seven patients from whom QR-MRSA were isolated were treated with a quinolone. In eight cases of infections with non-MRSA and quinolone treatment the isolated S. aureus strains were in vitro sensitive to quinolones.     

辽宁省部分地区2006年虫媒病毒分离鉴定

目的 调查辽宁省虫媒病毒的种类及分布.方法 2006年8月在辽宁省沈阳市、营口市、盘锦市、锦州市和丹东市采集蚊虫标本,利用组织细胞培养分离病毒,对病毒分离物进行血清学和分子生物学鉴定.结果 5个市共采集蚊虫标本5410只,分离到8株阳性分离物,经鉴定其中3株(LN0684、LN0688、LN0689)为版纳病毒,1株(LN0636)为甲病毒属盖塔病毒,另外4株尚在鉴定.新分离的版纳病毒与我国此前的分离株处于同一个进化簇,核苷酸同源性91.2%～94.7%.新分离的盖塔病毒与韩国分离株(swine)在一个进化枝上,核苷酸同源性为99.2%,与俄罗斯分离株、中国大陆分离株及台湾分离株的核苷酸同源性在95%～99%之间.结论 2006年在辽宁省分离到3株版纳病毒、1株盖塔病毒和4株未知虫媒病毒.版纳病毒、盖塔病毒为辽宁省首次分离;盖塔病毒核苷酸同源性和韩国分离株最近.     

Crystal violet reactions of Staphylococcus aureus strains colonizing infants in the first six weeks.

Nasal colonization with Staphylococcus aureus occurred in 18% of babies leaving a maternity unit and had risen to 40% by 6 weeks after birth. S. aureus was first acquired by 34.5% of babies after discharge. Female infants were more likely to be colonized than males. Colonization was not significantly different between babies receiving standard postnatal care and those nursed on the Special Care Baby Unit. Crystal violet (CV) tests showed that purple-reacting isolates accounted for approximately 60% of strains, whether first detected at hospital discharge or subsequently acquired. Purple-reacting strains, once acquired, were significantly better able to persist than non purple-reacting strains and formed a cumulatively higher proportion of the strains isolated at 6 weeks after birth than at hospital discharge. CV purple-reactions were significantly associated with lysis by phages of groups III and I and non-purple-reactions were significantly associated with lysis by phages of group II and/or 94/96. Maternity units remain a significant route whereby strains of S. aureus with some characteristics associated with a hospital origin gain access to the community.     

Evidence of enterotoxins and toxic shock syndrome toxin (TSST-1) in strains of Staphylococcus aureus isolated from various biological materials

Among 413 strains of S. aureus isolated from patients with chronic staphylococcal infections, from haemocultures in bacteriaemia and septic conditions, from gynaecological materials and nasal plugs of healthy carriers the authors detected the production of one or several types of enterotoxins in 124 strains (30.0%), production of TSST-1 in 19 strains (4.6%) and the concurrent production of enterotoxins and TSST-1 in 38 strains (9.2%). The highest ratio of toxigenic strains of S. aureus was found in departments (51.4%) and from hospitalized patients in blood cultures in bacteriaemias and septic conditions (41.2%). In a group of 184 strains from patients with chronic staphylococcal infection toxin production was proved in 49 strains (26.6%). Of 74 strains of S. aureus isolated from healthy carriers there were 16 toxigenic strains (21.6%). The most frequent type of enterotoxins were enterotoxins type A (26.7%) and C (24.4%). 21 strains (24.4%) produced more than one type of enterotoxins.