Identification of staphylococci from bovine udders: evaluation of the API 20GP system

The API 20GP system (Analytab Products, Plainview, NY) correctly identified 56.1% of staphylococci isolated from the bovine mammary gland. The system identified 90.2% of Staphylococcus aureus strains, but failed to recognize strains of Staphylcoccus hyicus and others. Poor performance was attributed to the limited number of veterinary strains contained in the profile index data base. The API 20GP was determined to be an unacceptable method for identification of staphylococci isolated from the bovine mammary gland.     

Prevalence of Enterotoxigenic Staphylococci in Nose,Throat and Skin Lesions in Meat-Workers

The frequency of enterotoxigenic coagulase-positive and coagulase-negative staphylococci in nose and throat and in hand lesions was investigated in 86 meat cutters and dressers. Enterotoxin-producing staphylococci were demonstrated in nasal swabs from 22% of clinically well workers and from 42% of a group with mild coryza. The corresponding rates in throat swabs were 6 and 12%. Four of 16 superficial lesions of the hand harbored enterotoxigenic staphylococci. The implications for contamination of food and outbreaks of staphylococcal food poisoning are discussed.     

Typing of Nontypable Staphylococci by Lysogeny

Strains of coagulase-positive staphylococci which were nontypable with the routine typing set of phages could be typed by lysogeny with phage-propagating strains as indicators and with ultraviolet induction. About 10% of the strains could be typed without induction. About 36% of them could be typed by this method when ultraviolet irradiation was used as an inducing agent. The phage groups from which the majority of the nontypable staphylococci originated were easily identified by this method of typing.     

Staphylococci Isolated from Carriage Sites and Infected Sites of Dogs as a Reservoir of Multidrug Resistance and Methicillin Resistance

The aim of this study was to compare the spread of multidrug-resistant (MDR) and methicillin-resistant (MR) staphylococci in healthy dogs and in dogs with evident symptoms of infection. The samples from 172 healthy and 197 infected dogs were examined. The staphylococci were identified with conventional methods and by means of the polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) method (MboI). Susceptibility to 15 antibiotics from 10 different antimicrobial classes was tested. Resistance to methicillin was confirmed by the presence of Staphylococcus aureus mecA and S. sciuri mecA genes. Multidrug resistance was defined as resistance to three or more antimicrobial classes. The oral mucosa to be the most frequent site of staphylococcal colonization (55.8 %), followed by nasal cavity (44.2 %), and anus (32.6 %). The prevalence of MDR staphylococci in infected dogs was significantly higher than in the healthy animals (74/137 vs. 34/95, P = 0.006). The MR strains of S. pseudintermedius (2.9 %) originated solely from infected dogs. In contrast, the MR coagulase-negative strains (7.4 %) were isolated solely from healthy dogs. S. aureus strains originated from nasal swabs, MRSA strains were not isolated. MDR staphylococci and MR S. pseudintermedius are more common among infected dogs, but coagulase-negative staphylococci (mostly S. sciuri) seem to be a reservoir of methicillin resistance in healthy dogs.     

Susceptibility to selected coagulase-negative chemotherapeutic agents of methicillin resistant staphylococci isolated from clinical materials in 1997-1998

The study was aimed at assessment of the sensitivity of methicillin-resistant coagulase-negative staphylococci isolated from clinical material in 1997/1998 to selected chemotherapeutic agents. The investigated material comprised 96 methicillin-resistant coagulase-negative staphylococci from hospital and ambulatory infections isolated during the period from April 1997 to May 1998. Species affiliation was determined by classical identification methods and commercial diagnostic tests for identification of staphylococci. Methicillin resistance was determined by agar disk-diffusion method and screening. Sensitivity to chemotherapeutics was determined by agar disk-diffusion method and agar dilution methods. All the investigated strains were sensitive to nitrofurantoin, furazolidone and vancomycin. To teicoplanin--the second glycopeptide antibiotic--84% strains were sensitive, whereas the percentages of resistant and moderately sensitive strains amounted to 5.2% and 10.4%, respectively. 85% and 82% of coagulase-negative staphylococcal strains were sensitive to fusidic acid and mupirocin. Considerable differences were noted with respect to sensitivity to aminoglycoside group antibiotics. About 35% of strains were sensitive to gentamicin, and 90% sensitive to netilmicin. Ca. 40% of coagulase-negative staphylococci were resistant both to cotrimoxazole and trimethoprim, which, in view of 98% resistance to the second component of cotrimoxazole, may be associated with the activity of only one of the components of the drug--trimethoprim.     

Staphylococci in Competition: IV. Effect of Starch and Kind and Concentration of Sugar on Staphylococcal Growth in Mixed Populations

Foods containing large amounts of carbohydrate have frequently been involved in staphylococcal food poisoning. Custard has been considered to be a highly favorable culture medium for staphylococci; however, it may be a selective medium rather than an ideal one. The influence of dextrose, lactose, and sucrose in varying amounts from 0.25 to 18%, and of starch, on the growth of staphylococci in mixed populations with saprophytes was determined. The inhibitory effect of the sugars was much greater on the saprophyte population than on the staphylococci. Of the three sugars, sucrose was most inhibitory to the saprophytes. It greatly decreased their lag periods as the concentration of sugar increased. Dextrose was the least inhibitory; in fact, 0.5% dextrose gave considerable stimulus to saprophyte growth. This sharply repressed staphylococcal growth. Lactose occupied an intermediate position. Rapid onset of the death phase of the staphylococci was observed in all increased sugar concentrations and seemed to be a pH effect rather than a result of competition. Sucrose exerted an inhibitory effect on the growth of saprophytes at and above room temperature. In the presence of 2.5% corn starch, staphylococcal growth in mixed cultures was slightly inhibited, while the death phase was sharply accelerated. Thus, carbohydrates exert their influence on staphylococcal growth in mixed cultures through their effect on the saprophytes by decreasing or increasing competition.     

A comparative evaluation of phenotypic and molecular methods in the identification of members of the Staphylococcus sciuri group

Members of the Staphylococcus sciuri group (S. sciuri, S. lentus, and S. vitulinus) are coagulase-negative, novobiocin-resistant staphylococci that could be distinguished from other staphylococci on the basis of positive oxidase activity. In the present study, a scheme based on conventional methods and utilization of various carbohydrates was evaluated for the identification of oxidase-positive staphylococci, and validated using two molecular techniques. Of the 173 oxidase-positive staphylococcal tested strains, 161 were identified as S. sciuri, 9 as S. lentus, 2 as S. vitulinus, and one as S. fleurettii by our scheme. The level of agreement with tRNA intergenic length polymorphism analysis (tDNA-PCR) was high (97.5-100% correlation). The accuracy and ease of use of this protocol suggest that it may be useful and valuable in microbiological laboratories for the identification of members of this group.     

A comparative study of the cutaneous microflora of normal feet with low and high levels of odour

A comparison of the cutaneous microflora found on normal feet with varying levels of odour has been made. High population densities of staphylococci and aerobic coryneform bacteria predispose to foot odour. There was no association between odour and the carriage on feet of any particular micro-organism, including brevi-bacteria. All organisms isolated were screened for exoenzyme activity. Only staphylococci produced lipase (78% of the staphylococci), whereas 97% of micrococci, 68% of aerobic coryneform bacteria, 25% of staphylococci and 94% of propionibacteria produced proteinase. The ability to degrade callous was exhibited by 47% of micrococci, 24% of aerobic coryneforms and 17% of the staphylococci. Feet with high odour had significantly higher population densities of micro-organisms with the ability to produce these exoenzymes than feet with low odour. No association was observed between foot odour and the carriage of micro-organisms capable of producing methanethiol. A hypothesis for the role of micro-organisms in the production of foot odour is proposed.     

Detection of the capsule of staphylococci isolated in urological diseases]

In studying the cultures isolated from urological patients the seed material was found to yield a high proportion (40%) of coagulase-negative, white staphylococci. Capsule-forming organisms constituted 58.8% of the isolated Staphylococcus aureus. As the presence of capsules is indicative of pathogenicity of staphylococci, in urological diseases the presence of capsulary strains in urine should be taken into consideration.     

Investigation of aminoglycoside modifying enzyme genes in methicillin-resistant staphylococci

Methicillin-resistant staphylococci may also be resistant to some other antibiotics as well as beta-lactams. In this study, co-existence of resistance to methicillin and aminoglycosides was genetically investigated in staphylococci. A total of 50 staphylococci from in-patients, 17 Staphylococcus aureus and 33 coagulase negative staphylococci (CNS) that contained mecA (gene encoding PBP 2a, an altered penicillin-binding protein) determined by polymerase chain reaction (PCR) were included in the study. Aminoglycoside modifying enzyme (AME) genes were investigated using multiplex-PCR. Aminocyclitol-6'-acetyltransferase-aminocyclitol-2'-phosphotransferase [aac(6')/aph(2')] gene (encoding bifunctional acetyltransferases/phosphotransferases) was determined in 66% of the isolates, aminocyclitol-4'-adenylytransferase (ant(4')-Ia) gene (encoding phosphotransferases) in 24%, and aminocyclitol-3'-phosphotransferase (aph(3')-IIIa) gene (encoding nucleotidyltransferases) in 8%. Two isolates contained all these three genes. Thirty-six (72%) isolates had at least one of these genes. Three CNS and one S. aureus isolates sensitive to oxacillin had the mecA gene. In conclusion, a high rate of aminoglycoside resistance was determined in methicillin-resistant staphylococci. The aac(6')/aph(2') was the most frequently detected.     

Production and novel quantification of haemolysins produced by coagulase-negative staphylococci isolated from subclinical mastitis in sheep

Coagulase-negative staphylococci producing cell-damaging toxins were isolated from the milk of sheep with subclinical mastitis. The haemolytic activity of Coagulase-negative staphylococcal strains was assessed on solid and liquid culture media. More than 61% and 76% of the tested strains on solid media produced evidence of alpha- and delta- haemolysins and more than 78% produced synergistic haemolysis. However almost all isolates producing haemolysin in liquid culture media produced only very few units of haemolysin compared to the positive control of five Coagulase-positive strains of staphylococci. It was concluded that solid media are better for classifying Coagulase-negative staphylococci as producers or not of haemolysins, and liquid media for measuring the size of this activity within the first few hours of intramammary infection.     

医院工作人员鼻腔葡萄球菌带菌状况年度推移的调查报告

本文报道1989年从202名医院工作人员鼻腔分离葡萄球菌的带菌状况和药敏性检测结果。并将此结果同作者等于1985年对200名同类人员检测的结果相比较,作了年度推移的调查分析发现1989年度的总带菌率(76.6％)比1985年度(84.5％)略有下降,但其中的金黄色葡萄球菌带菌率却从1985年的7.5％上升为10.4％。从1989年和1985两个年度的调查中,均发现临床科室人员金葡菌带菌率高于其它辅助科室人员,说明医务人员带菌率与接触病人成正相关关系。分离菌株对12种抗菌药物的耐药性检测结果显示,1989年分离菌株对其中9种的敏感性下降,并且从耐药谱显示出对5种抗菌药物耐药的多重耐药菌株明显增多。另从金葡菌的耐药情况,也看出1989年的耐药率高于1985年菌株。还在1989年分离的金葡菌中出现25％的耐甲氧西林菌株。     

Antibiotic resistance of staphylococci isolated from outpatients

The aim of the study was to determine susceptibility of 587 strains of S. aureus and 85 strains of coagulase-negative staphylococci isolated from outpatients in Poznań to co-trimoxazole, amoxycillin/clavulanic acid, erythromycin, gentamycin, doxycycline, ampicillin, oxacillin, cephradine, clindamycin and neomycin. Also methicillin-resistant strains were determined as well as strains ability to produce beta-lactamases. Susceptibility testing and examination of methicillin-resistant strains were performed by the disc diffusion techniques according to recommendation of NCCLS. Methicillin-resistant strains were additionally examined to their sensitivity to vankomycin and teicoplanin. beta-lactamase production was detected using nitrocefin impregnated discs and iodometric method. Amoxacillin/clavulanic acid, gentamycin, co-trimoxazole, cephradin, oxacillin and clindamycin occurred to be very active against both, S. aureus and coagulase-negative staphylococci. 84.7% to 100% of examined strains were sensitive to these drugs. Doxycyclin, erythromycin and ampicillin were less effective. Nine strains (1.5%) of 587 strains of S. aureus as well as 7 strains (8.7%) of coagulase-negative staphylococci were methicillin-resistant. All of methicillin-resistant strains were sensitive to vancomycin and teicoplanin. More than 75% of S. aureus and close to 50% of coagulase-negative staphylococci were able to produce beta-lactamases.     

TELLURITE-EGG AGAR, A SELECTIVE AND DIFFERENTIAL MEDIUM FOR THE ISOLATION OF COAGULASE POSITIVE STAPHYLOCOCCI

SUMMARY: The preparation and use of tellurite-egg agar (TEA), a medium for the isolation of coagulase positive staphylococci, are described. The medium, based on that of Ludlam (1949), was non-inhibitory to coagulase positive staphylococci and colonies on it of these organisms could easily be distinguished from contaminating types. Comparisons were made between the medium and three other media in common use for the isolation of coagulase positive staphylococci.     

Circulation of methicillin-resistant staphylococci in hospitals with different profiles

Analysis of prevalence of methicillin-resistant staphylococci in hospitals with different specializations was performed. 2584 strains were isolated. Methicillin-resistant (MR) strains were present in different profile hospitals and their total prevalence between isolated strains was 12.3% while significantly varied in different hospitals (from 8% to 37%). Along with MRSA (methicillin-resistant Staphylococcus aureus), MRSE (methicillin-resistant Staphylococcus epidermidis) and MRSS (methicillin-resistant Staphylococcus saprophyticus) were presented in all studied hospitals. The prevalence of MR strains was highest among strains isolated from flame burn wounds (37%), while in samples from newborns in maternity hospital resistant strains represented 12% of isolates, and in general clinical hospital--not more than 9% of isolates. Relationship between rates of isolation of methicillin-resistant staphylococci and specialization of hospital unit was noted. For example, prevalence of MR staphylococci in isolates from newborns in ICU (47.5%) differed from the same one in maternity hospital (11.6%).     

Biofilm production, a marker of pathogenic potential of colonizing and commensal staphylococci

Biofilm is one of the known virulence factors of staphylococci, a human and animal pathogen and commensal. Some of the strains become invasive under favorable conditions while others do not cause disease. Early detection and management of potentially pathogenic staphylococci is the essential step to prevent device-associated infections. There is also a need to evaluate one simple method for the detection of potential pathogens. Hence this study was planned to study the difference in potential of commensal, colonizing and invasive strains of staphylococci to produce biofilm. We used one qualitative (Congo red agar) and one quantitative (microtiter plate) method for detection of biofilm production and evaluated the sensitivity and specificity of Congo red agar method by using microtiter plate method as a gold standard. We consecutively enrolled staphylococcal strains isolated from peripheral intravenous device (IVD), venous blood, site of IVD insertion and nasal mucosa of patients admitted to pediatric ward with peripheral intravenous devices in place for more than 48 h. Total 100 invasive, 50 colonizing and 50 commensal isolates were studied. Of 100 invasive isolates 74% (74/100) were biofilm positive while only 68% (34/50) colonizing and 32% (16/50) commensal isolates were biofilm positive. The difference in biofilm production by commensal, colonizing and invasive strains was statistically significant (p<0.0001). Sensitivity and specificity of Congo red agar test for detection of biofilm producers were 90.63% and 90.79% for Staphylococcus aureus and 75.86% and 96.88% respectively for coagulase negative staphylococci. CRA is a method that could be used to determine whether an isolate has the potential for biofilm production or not.     

Use of Shake Cultures in a Semisolid Thioglycolate Medium for Differentiating Staphylococci from Micrococci

The standard diagnostic test for differentiating staphylococci from micrococci is based on the ability of the former to produce acid anaerobically in a glucose-containing growth medium. This test has been modified to provide greater convenience, easier interpretation of results, and better correlation with deoxyribonucleic acid (DNA) base composition. In the modified test, shake cultures in Brewer's fluid thioglycolate medium with 0.3% agar added are observed for growth in the anaerobic zone of the tubes. This test was applied to 125 strains of staphylococci and micrococci, and all except two strains gave results that were consistent with other criteria. Of particular interest were eight strains of Micrococcus saprophyticus and three strains of M. lactis that have a DNA composition of 30 to 37% guanine plus cytosine (GC). All 11 of these cultures produced anaerobic growth and thus would be classified as staphylococci. Strains of M. lactis that have a high GC content in their DNA grew only aerobically. Some cultures of staphylococci produced characteristic band patterns of anaerobic growth and other cultures produced only a few anaerobic colonies from an inoculum of 10(6) to 10(7) cells. These observations suggest some interesting genetic and metabolic capabilities in such cultures.     

Biological characteristics of Staphylococci circulating in hospitals in Nizhniĭ Novgorod

The study of 513 clinical isolates of staphylococci revealed that 8.4% of them were methicillin-resistant, their proportion in the isolates obtained from hospital patients being significantly higher than in the isolates obtained from patients in outpatient clinics (11.8% compared with 1.48%). Most of these isolates were coagulase-hegative staphylococci. The isolates obtained from urine, blood, discharge of the middle ear were in all cases represented by coagulase-negative staphylococci. Methicillin-resistant variants of S. aureus occurred mainly in discharge of surgical wounds and in sputum.     

THE ISOLATION OF COAGULASE POSITIVE STAPHYLOCOCCI FROM ROUTINE COMPOSITE MILK SAMPLES

SUMMARY: Composite morning milk samples were taken once weekly for 9 weeks from 24 dairy farms. In all 208 samples were tested, and coagulase positive staphylococci ( aureus, albus and citreus ) were isolated from 127 (61%). The week by week recovery of these staphylococci from individual farm samples varied between 11% and 88% Penicillin resistant coagulase positive strains were recovered from 20 samples (10%).     

Occurrence of Staphylococcus aureus enterotoxigenic strains isolated from pregnant women with pathology

137 S. aureus strains, isolated from the larynx of pregnant women in cases of pathology, were studied for the formation of staphylococcal enterotoxins of types A and B (SEA and SEB) by the indirect hemagglutination test. The study revealed that SEA was produced by 35.0% and SEB, by 56.6% of the strains under study. The proportion of SEA and SEB producers among staphylococci isolated from mothers and children was, respectively, 18.4% and 20.0%, 89.41% and 67.5%. The number of enterotoxigenic staphylococci in the upper respiratory tract of newborn infants and mothers practically coincided with that in mothers. The occurrence of SEA- and SEB-producing enterotoxigenic strains in the medical personnel was 25.5% and 62.7% respectively.