Identification of coagulase-negative staphylococci from farm animals

The species identity of 661 strains of coagulase-negative staphylococci isolated from the skin and nares of cattle, pigs, poultry, goats and sheep was determined. They belonged either to the novobiocin-sensitive species Staphylococcus hyicus, Staph. simulans, Staph. epidermidis, Staph. haemolyticus and Staph. warneri or to the novobiocin-resistant species Staph. sciuri, Staph. lentus, Staph. xylosus, Staph. cohnii. Staph. saprophyticus and Staph. gallinarum ; twenty-one strains remained unidentified. The staphylococcal flora of the farm animals studied differed markedly from that associated with man; several species which do not occur in man were isolated and novobiocin-resistant strains, which occur infrequently in man, were present in large numbers in animals. Two simplified schemes for the identification of staphylococci from farm animals and man are presented.     

Coagulase-Negative,Novobiocin-Resistant Staphylococci on the Skin of Animals and Man,on Meat and in Milk

The occurrence of coagulase-negative, novobiocin-resistant staphylococci, i.e. Staphylococcus cohnii, Staphylococcus saprophyticus, Staphylococcus sciuri and Staphylococcus xylosus, on the skin of animals and man has been studied. On cultures from cats, cows, dogs, guinea pigs, mice, rabbits and sheep studied, such organisms were predominant among the coagulase-negative staphylococci. From the skin of the hands of 21 of 38 persons whose professions brought them into contact with animals, e.g. inséminât ors, slaughterhouse workers and veterinarians, coagulase-negative, novobiocin-resistant staphylococci were isolated. This finding contrasted with that regarding 50 persons lacking such contacts, of whom only 1 harboured such bacteria. S. saprophyticus was isolated only from those slaughterers presenting with wounds on their hands. Coagulase-negative, novobiocin-resistant staphylococci were also isolated from every second specimen collected from the surface of meat at a slaughterhouse. No difference in the culture results could be demonstrated from specimens collected before and after cutting-up of the carcasses. Of 26 strains of coagulase-negative, DNase-negative staphylococci isolated from milk with pathological CMT, all but 5 were novobiocin-resistant. Fifteen were classified as S. xylosus, 4 as S. sciuri and 1 as S. cohnii. Of another 15 DNase-positive strains, 3 were resistant to novobiocin. Finally, clinical infections with coagulase-negative, novobiocin-resistant staphylococci in man, e.g. urinary tract infections caused by S. saprophyticus, are considered in relation to possible contagious reservoirs and modes of spread.     

Characteristics of staphylococci isolated from man, poultry and some other animals

Of 281 strains of staphylococci isolated from man and animals 36 (12–8%) were coagulase-positive and 245 (87–2%) were coagulase-negative. Staphylococcus aureus and Staph. intermedius were the commonest coagulase-positive staphylococci isolated from the hosts examined. Of the 20 strains that remained unclassifiable, 14 were isolated from sheep and goats.     

Characteristics of staphylococci isolated from man, poultry and some other animals

Of 281 strains of staphylococci isolated from man and animals 36 (12.8%) were coagulase-positive and 245 (87.2%) were coagulase-negative. Staphylococcus aureus and Staph. intermedius were the commonest coagulase-positive staphylococci isolated from the hosts examined. Of the 20 strains that remained unclassifiable, 14 were isolated from sheep and goats.     

A Comparison of Methods and the Validity of Deoxyribonuclease Tests for the Characterization of Staphylococci Isolated from Animals

Strains isolated from pigeons belonging to the coagulase-positive species Staphylococcus intermedius , coagulase-negative Staph. hyicus subsp. chromogenes strains from cattle and pigs, and Staph. aureus strains from poultry, gave weakly positive reactions in DNase plate culture tests and heat-resistant DNase tests. Staph. aureus and Staph. intermedius strains from other sources and coagulase-negative and coagulase-positive Staph. hyicus subsp. hyicus strains reacted strongly in these tests. A standardized plate culture test procedure is proposed and the use of DNase tests in the identification of staphylococci isolated from animals is discussed.     

Antimicrobial susceptibility of staphylococci isolated from otitis externa in dogs

Samples were obtained from 65 unmedicated adult dogs, processed for isolation of Staphylococcus species and tested for susceptibility to penicillin G, gentamicin, oxacillin, tetracycline, trimethoprim-sulphamethoxazole, streptomycin, ampicillin and rifampin. Forty-four isolates were obtained, which represents 67.7% of samples. Coagulase-negative species were most commonly found, and the most frequently isolated staphylococcus species were Staph. epidermidis and Staph. aureus. Other species, such as Staph. simulans, Staph. haemolyticus, Staph. saprophyticus and Staph. intermedius were also isolated. Resistance to antibiotics was frequently observed, with 90.9% of the isolates showing resistance to at least one drug. The most active antimicrobial agents against staphylococci isolated from otitis externa of dogs were rifampin and oxacillin. Multidrug resistance was a common finding, and one strain of Staph. haemolyticus species, was resistant to all tested antimicrobial agents. Resistance to three or more different drugs was a common finding, observed in 16 strains (36.4%) of both coagulase-positive and coagulase-negative staphylococci. This study highlights the emergence of cases of otitis externa determined by coagulase-negative staphylococcus strains and once more emphasizes the need for bacterial culture with species identification and susceptibility testing of swab specimens from the ear canal in order to choose appropriate antimicrobial agents.     

A simplified system for biotyping Staphylococcus aureus strains isolated from different animal species

D evriese , L.A. 1984. A simplified system for biotyping Staphylococcus aureus strains isolated from different animal species. Journal of Applied Bacteriology 56 , 215–220.
A biotyping system for Staphylococcus aureus strains is proposed which is a simplified version of biotyping procedures described in the literature. It differentiates Staph. aureus strains from man and animals into host-specific ecovars and biotypes which are not host-specific. With the help of tests for βhaemolysin, staphylokinase, coagulation of bovine plasma and the crystal-violet reaction, the origin of many but not all Staph. aureus strains can be determined: 604 of 809 strains from man. poultry, cattle, pigs, goats, rabbits and foods could be alloted to four ecovars which are typically associated with man, poultry, sheep and goats and cattle. The other strains belonged to five non-host specific biotypes.     

Expression of glycocalyx by coagulase-negative Staphylococcus species isolated from bovine milk

Two hundred and six strains of coagulase-negative Staphylococcus species were assessed for expression of glycocalyx on serum soft agar, india ink and adherence techniques. The organisms were maintained on trypticase soy agar plates at 4°C for 30 d (120 strains) or stored at -80°C in skim milk for 90 d (60 strains). Additionally, 26 milk samples from cows known to have excreted coagulase-negative staphylococci were used to inoculate serum soft agar directly. Nine of 26 direct culture samples and 43 of 180 strains maintained for an extended period had diffuse-type growth on serum soft agar. The proportion that exhibited an unstained halo by india ink was similar regardless of storage time. Slime production determined by in vitro adherence revealed a higher proportion of positive strains than had been predicted by serum soft agar or india ink techniques. More strains of Staphylococcus chromogenes, Staph. epidermidis, Staph. hominis, Staph. simulans and Staph. warneri expressed glycocalyx than other coagulase-negative Staphylococcus species. These results suggest that most coagulase-negative staphylococci produce slime rather than a capsule. However, evidence for classical encapsulation was demonstrated in several strains by india ink. The finding that Staphylococcus species other than Staph. aureus isolated from bovine milk are capable of glycocalyx production may be of importance in investigations on the relationship between staphylococci and host defence mechanisms.     

Expression of glycocalyx by coagulase-negative Staphylococcus species isolated from bovine milk

Two hundred and six strains of coagulase-negative Staphylococcus species were assessed for expression of glycocalyx on serum soft agar, india ink and adherence techniques. The organisms were maintained on trypticase soy agar plates at 4 degrees C for 30 d (120 strains) or stored at -80 degrees C in skim milk for 90 d (60 strains). Additionally, 26 milk samples from cows known to have excreted coagulase-negative staphylococci were used to inoculate serum soft agar directly. Nine of 26 direct culture samples and 43 of 180 strains maintained for an extended period had diffuse-type growth on serum soft agar. The proportion that exhibited an unstained halo by india ink was similar regardless of storage time. Slime production determined by in vitro adherence revealed a higher proportion of positive strains than had been predicted by serum soft agar or india ink techniques. More strains of Staphylococcus chromogenes, Staph. epidermidis, Staph. hominis, Staph. simulans and Staph. warneri expressed glycocalyx than other coagulase-negative Staphylococcus species. These results suggest that most coagulase-negative staphylococci produce slime rather than a capsule. However, evidence for classical encapsulation was demonstrated in several strains by india ink. The finding that Staphylococcus species other than Staph. aureus isolated from bovine milk are capable of glycocalyx production may be of importance in investigations on the relationship between staphylococci and host defence mechanisms.     

Application of current methods for isolation and identification of staphylococci in raw bovine milk

Samples of raw milk were examined for counts of somatic cells, total viable bacteria, staphylococci (Schleifer & Kramer's medium) and Staphylococcus aureus (Baird-Parker medium, Baird-Parker medium with pig plasma and Baird-Parker medium with additional antibiotics). For the isolation of staphylococci from raw milk, Schleifer & Kramer's medium was found to be very selective and in general performed satisfactorily. From the results obtained with the three remaining media the continued use of Baird-Parker medium for isolation of Staph. aureus from raw milk is recommended with the proviso that colonies selected for identification should include those that clear and do not clear the egg yolk and are not limited to colonies with diameters greater than 1 mm. Staphylococci isolated from raw milk were identified by key tests using a multipoint inoculation procedure. A selected number were also examined by the API STAPH system in conjunction with the API LAB computer programme for identification of staphylococci. Of the staphylococci examined, 90.0% were identified using the multipoint procedure. For strains identified as Staph. aureus, Staph. hyicus subsp. hyicus, Staph. epidermidis, Staph. simulans, Staph. xylosus or members of the Staph. hominis/Staph. warneri/Staph haemolyticus group, the API system provided confirmatory evidence. With strains identified by the multipoint procedure as Staph. hyicus subsp. chromogenes, Staph. sciuri subsp. sciuri and Staph. sciuri subsp. lentus the API system did not always provide concurring results. Several strains which could not be identified by the multipoint procedure could be identified by the API system. Staph. aureus, Staph. hyicus subsp. hyicus and Staph. hyicus subsp. chromogenes strains isolated from milk were examined for production of enterotoxin A-E. Only 3.9% of Staph. aureus strains examined produced detectable enterotoxin (type C). None of the Staph. hyicus subsp. hyicus or Staph. hyicus subsp. chromogenes strains produced any of the known enterotoxins.     

In-vitro bacteriocin-mediated antagonism by oral streptococci against human carrier strains of staphylococci

All strains of oral streptococci tested and specially those of Streptococcus mutans, Strep. sanguis and Strep. minor produced more than one distinct bacteriocin-like substance with variable inhibitory activity on 20 indicator staphylococci. Inhibitory activity was comparatively higher on nasal strains of Staph. aureus and Staph. epidermidis than on strains of both species isolated from the mouth. Nineteen of 20 staphylococcal indicators were inhibited by 1–12 of the 12 effector streptococci. Sensitivity of nasal staphylococci to bacteriocins (frequency of positive inhibitory tests and total inhibition zone diameters) was significantly higher ( P < 0·001, χ² test and P < 0·05, t test respectively) than that of oral ones. The sensitivity of nasal over oral Staph. aureus ( P < 0·001 and P < 0·01) and of oral Staph. epidermidis over oral Staph. aureus ( P < 0·01 and P < 0·05) was also significantly higher. The evaluation of variability of inhibitory patterns of bacteriocins produced by streptococci (p-typing), of sensitivity patterns of staphylococci to bacteriocins (s-typing) and of the significantly higher sensitivity of nasal over oral staphylococci to bacteriocins from the epidemiological and ecological veiwpoints are discussed.     

Safety-related properties of staphylococci isolated from food and food environments

Aims: To test some safety‐related properties within 321 staphylococci strains isolated from food and food environments. Methods and Results: The isolates were identified as Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus saprophyticus, Staphylococcus pasteuri, Staphylococcus sciuri, Staphylococcus warneri and Staphylococcus xylosus. Decarboxylase activity was quite common for the various Staphylococcus spp., and tyrosine was the most frequently decarboxylated amino acid. The frequency of antibiotic resistance was highest in Staph. pasteuri and Staph. xylosus. Several of the isolates were tolerant to QAC compounds, and in some cases, QAC tolerance was present in antibiotic‐resistant strains. Most of the strains displayed moderate to high adhesion rates to stainless steel and Teflon^®. The strains that readily formed biofilms belonged to the species Staph. aureus, Staph. epidermidis and Staph. pasteuri. Conclusions: An high incidence of some safety hazards was found within the staphylococcal strains of food origin tested in this study. In particular, amino acid decarboxylase activity and biofilm‐forming ability were common within strains, and antibiotic resistance and tolerance to QAC‐based compounds occurred frequently as well. These characteristics are an important safety concern for food industry. Significance and Impact of the Study: This work gives a first picture of safety hazards within staphylococcal species isolated from food environments. The presence of disinfectant‐resistant staphylococci is a concern because resistance can be genetically transferred between the various Staphylococcus species. This could lead an increase and spread of resistant enterotoxic staphylococci and/or pathogenic staphylococci.     

Isolation and characterization of staphylococci from goats milk produced in Northern Ireland

Goats milk was examined for total viable bacteria and staphylococci (Baird-Parker medium, Schleifer & Kramer's (SK) medium, SK medium with a reduced sodium azide content (SKR) and SK and SKR with 5% added sheep blood). Staphylococcus aureus, Staph. epidermidis and Staph. simulans were the predominant species isolated overall. SK medium proved inhibitory with respect to the isolation of Staph. caprae and Staph. chromogenes. This was reduced by plating on the modified SK media. Representative strains of each species isolated were examined for production of enterotoxins A-E. Enterotoxin C alone was produced by 35% of the Staph. aureus strains tested. None of the other staphylococcal species examined produced any of the known enterotoxins.     

In-vitro bacteriocin-mediated antagonism by oral streptococci against human carrier strains of staphylococci

All strains of oral streptococci tested and specially those of Streptococcus mutans, Strep. sanguis and Strep. mitior produced more than one distinct bacteriocin-like substance with variable inhibitory activity on 20 indicator staphylococci. Inhibitory activity was comparatively higher on nasal strains of Staph. aureus and Staph. epidermidis than on strains of both species isolated from the mouth. Nineteen of 20 staphylococcal indicators were inhibited by 1-12 of the 12 effector streptococci. Sensitivity of nasal staphylococci to bacteriocins (frequency of positive inhibitory tests and total inhibition zone diameters) was significantly higher (P less than 0.001, chi 2 test and P less than 0.05, t test respectively) than that of oral ones. The sensitivity of nasal over oral Staph. aureus (P less than 0.001 and P less than 0.01) and of oral Staph. epidermidis over oral Staph. aureus (P less than 0.01 and P less than 0.05) was also significantly higher. The evaluation of variability of inhibitory patterns of bacteriocins produced by streptococci (p-typing), of sensitivity patterns of staphylococci to bacteriocins (s-typing) and of the significantly higher sensitivity of nasal over oral staphylococci to bacteriocins from the epidemiological and ecological viewpoints are discussed.     

Enterotoxigenicity of Staphylococcus aureus strains isolated from poultry: raw poultry carcases as a potential food-poisoning hazard

Staphylococcus aureus strains were isolated from end-of-lay poultry carcases obtained from a plant at two different stages of processing before and after storage at different temperatures. These strains were supplemented with Staph. aureus strains isolated from poultry from a wide range of sources and biotyped, phage typed, and tested for production of enterotoxins A-E. The isolates were found to consist of poultry and human specific strains and each of these groups contained strains able to produce enterotoxin. Poultry strains produced only enterotoxin D whereas human strains produced enterotoxins A, C and D. The hen carcases used in storage experiments were found to be naturally contaminated with enterotoxin D producing staphylococci. No enterotoxin D could be detected on any of the carcases even after storage at temperatures which allowed multiplication of the organisms to occur (final Staph. aureus counts ranged from 10² to 10⁷/16 cm² of breast skin).     

Periodicity in the rise and fall of the numbers of the principal Staphylococcus aureus phage groups

The results of the phage typing of 5, 168 Staph. aureus strains isolated in a surgical hospital between 1959 and 1977 are analyzed for each year of this period. The wave of increase in the number of staphylococci belonging to phage group II which began, as discovered in this study, in 1965 and still showed no tendency towards decrease in 1977, as well as the periodicity of rises and falls in the number of staphylococci belonging to phage groups I and III are discussed and compared with the data contained in the literature. The authors come to the conclusion that Staph. aureus is subject to wave-like rises and falls in the number of strains belonging to the main phage groups of the species, and among them the strains belonging to phage groups I and III seem to be inversely related in respect of rises and falls in number, such changes occurring periodically at an interval of 10-12 years, while in the strains belonging to phage group II changes in number occur at a slower rate. The constant account of the percentage of phage groups I, II and III is recommended to ensure rational antibiotic therapy.     

Isolation and identification of staphylococci from milk powders produced in Northern Ireland

Milk powders (37 samples) from five different processing centres (A, B, C, D and E) were examined for total viable counts, total staphylococcal counts and staphylococcal enterotoxins. All powders from centres A, B and C contained low numbers of total viable bacteria and staphylococci but five from centres D and E had high total and staphylococcal counts. Nine different staphylococcal species were encountered in low count powders with a wide range of species occurring at each of the five centres. Three species (Staphylococcus capitis, Staph, saprophyticus and Staph. cohnii) were found whose natural hosts are humans. High count powders all contained added fat of various types and had a much more restricted staphylococcal microflora in which Staph. saprophyticus and Staph. cohnii predominated. None of 384 staphylococcal strains isolated were found to be Staph. aureus. In addition, no enterotoxins were detected.     

Isolation and identification of staphylococci from milk powders produced in Northern Ireland

Milk powders (37 samples) from five different processing centres (A, B, C, D and E) were examined for total viable counts, total staphylococcal counts and staphylococcal enterotoxins. All powders from centres A, B and C contained low numbers of total viable bacteria and staphylococci but five from centres D and E had high total and staphylococcal counts. Nine different staphylococcal species were encountered in low count powders with a wide range of species occurring at each of the five centres. Three species ( Staphylococcus capitis, Staph. saprophyticus and Staph. cohnii ) were found whose natural hosts are humans. High count powders all contained added fat of various types and had a much more restricted staphylococcal microflora in which Staph. saprophyticus and Staph. cohnii predominated. None of 384 staphylococcal strains isolated were found to be Staph. aureus. In addition, no enterotoxins were detected.     

Characteristics of some unclassifiable strains of staphylococci isolated from goats and sheep

A degoke , G.O. 1985. Characteristics of some unclassifiable strains of staphylococci isolated from goats and sheep. Journal of Applied Bacteriology 59 , 257–262.
Fourteen strains of catalase-positive, Gram-positive and coagulase-negative cocci that were sensitive to 20 μg/ml of furazolidone were isolated from goats and sheep. Two of the strains had glycerol with glucose teichoic acids whilst another possessed glycerol, glucose, glucosamine and acetylglucosamine teichoic acids. Six strains had peptidoglycan type L-Lys-Ala-Gly₄ peculiar to Staphylococcus sciuri and Staph. lentus but other phenotypic characters were different from those of Staph. sciuri and Staph. lentus . The guanine plus cytosine (G + C) content of the DNA determined for three of the strains examined ranged from 32.9–34.6 mol %. The coagulase-positive staphylococcal strain of caprine origin examined had glycerol and glucosarnine teichoic acids in addition to peptidogylcan type L-Lys-Gly_5–6. The characteristics of the strains of staphylococci described herein are different from those already described in the literature.     

Prevalence and antimicrobial susceptibility of staphylococci isolated from the skin surface of clinically normal cats

Samples were collected from 148 adult cats, processed for isolation of Staphylococcus species and tested for susceptibility to penicillin G, gentamicin, oxacillin, amoxycillin, ampicillin, cephalexin and rifampin. Methicillin resistance was also determined. Ninety-eight isolates were obtained (66% of samples). Coagulase-negative species were most common, and the most frequently isolated species (37 samples) was Staph. felis . Other coagulasenegative species, such as Staph. simulans , Staph. epidermidis and Staph. Saprophyticus were also isolated. Coagulase-positive species were obtained from 40 cats; the most frequent was Staph. intermedius (26 samples), followed by Staph. aureus (14 samples). Resistance to antibiotics was frequently observed, with 58·2% of the isolates showing resistance to at least one drug. Resistance to Penicillin G was observed in 49 of the 98 isolates (50%), 22 samples were resistant to oxacillin (22·4%) and 12 to rifampin (12·2%). Resistance to amoxycillin and ampicillin was very similar to that observed to Penicillin G. Gentamicin was the most active antimicrobial agent. Three MRSA (methicillin-resistant Staphylococcus aureus ) were isolated, which represents 21·4% of the isolates of that species. Nineteen MRS (methicillin resistant staphylococci) were also observed, distributed among Staph. intermedius (eight), Staph. simulans (six) and Staph. felis (five) isolates. The role of these micro-organisms on the skin of cats is discussed.