Effects of lactic acid bacteria and coagulase-negative staphylococci on dry-fermented sausage quality and safety: Systematic review and meta-analysis

The meta-analysis aim was to confirm and quantifying the influence of starter cultures on microbiological and physical-chemical parameters of dry-fermented sausages at the end fermentation stage. The literature search yielded 1194 citations, and 77 studies with 178 experiments were eligible and included in the meta-analysis, a random-effects model was used to estimate the pooled weighted mean difference (MD) with 95% confidence interval (CI).The use of starter culture in dry-fermented sausages significantly reduced pH (MD: -0.364; CI: -0.414; -0.319), moisture (MD: -1.443; CI: -1.931; -0.955), aw (MD: -0.011; CI: -0.017; -0.006), Enterobacteriaceae count (MD: -1.119; CI: -1.293; -0.945), yeasts and molds count (MD: -0.351; CI: -0.691; -0.084), and increased color component a* (MD: 0.859; CI: 0.266;1.452), color component L* (MD: 1.288; CI: 0.433; 2.143), LAB count (MD: 0.981; CI: 0.696;1.267), Staphylococci count (MD: 0.484; CI: 0.293; 0.675) and TVC (MD: 0.529; CI: 0.098; 0.959). The results of the sub-analysis suggest that the addition of LAB and LAB/CNS inocula have a greater effect on the physico-chemical and microbiological parameters studied in this work. In the meta-regression analysis, a positive linear relationship was found in starter culture sausages in comparison with control batch between LAB count and the dose of starter culture added, and in the pH and Enterobacteriaceae count with the passage of fermentation days. In contrast, a negative linear relationship was found between redness and increased casing diameter of the sausages. Therefore, our work shows impact that addition of starter cultures has on safety and quality of dry-fermented sausages.

Endogenous endophthalmitis caused by Staphylococcus capitis

Purpose

To report a rare case of endogenous endophthalmitis caused by Staphylococcus capitis.

Observation

A 34-year-old male patient with a history of gonococcal urethritis and arthritis presented with right endogenous endophthalmitis. Vitreous biopsy culture confirmed Staphylococcus capitis involvement. The patient was treated with pars plana vitrectomy, intravitreal vancomycin, and ceftazidime injections and systemic antibiotics.

Conclusion and importance

Staphylococcus capitis-related endogenous endophthalmitis has rarely been reported in the literature. None of the published reports specifically describe its clinical course and management.

Identification of coagulase negative staphylococcal species from bovine mastitis in India

Background

Staphylococcal mastitis is a major cause of concern to the dairy industry in India and several countries worldwide. Though Staphylococcus aureus is the major cause, coagulase negative staphylococcal species (CoNS) are being increasingly reported in recent years.

Aims

To investigate the incidence of coagulase negative staphylococcal species in bovine mastitis.

Methods

Isolation of staphylococci was carried out from 237 milk samples of cows and She buffaloes with clinical and subclinical mastitis from different regions of Andhra Pradesh and Karnataka. CoNS isolates were identified by tube coagulase test using fresh rabbit plasma and coagulase gene PCR. We employed the biochemical test scheme published elsewhere previously for identification of the CoNS isolates up to species and subspecies levels. Seven representative isolates were identified by 16S rDNA sequencing to check the accuracy of biochemical test based identification.

Results

The CoNS constitute the majority of the staphylococcal isolates from mastitis (80/125, 64%) in this region. Using biochemical test scheme, the CoNS isolates from bovine mastitis were identified as S. cohnii sub sp. cohnii, S. simulans, S. capitis sub sp. capitis, S. cohnii sub sp. xylosus, and S. lugdunensis. The CoNS species S. schleiferi, S. haemolyticus, S. sciuri, S. xylosus, S. chromogenes, and Macrococcus epidermidis were identified by 16S rDNA sequencing.

Conclusion

The 16S rDNA sequencing is the appropriate method for the identification of CoNS species. This study highlighted coagulase negative staphylococcal species as possible etiological agents of mastitis.

The emergence of Staphylococcus aureus as the primary cause of cardiac device-related infective endocarditis

BACKGROUND

Increasing use of cardiovascular implantable electronic devices (CIED), as permanent pacemakers (PPM), implantable cardioverter defibrillators (ICD), or cardiac resynchronization therapy (CRT), is associated with the emergence of CIED-related infective endocarditis (CIED-IE). We aimed to characterize CIED-IE profile, temporal trends, and prognostic factors.

METHODS

CIED-IE diagnosed at Rennes University Hospital during years 1992-2017 were identified through computerized database, and included if they presented all of the following: (1) clinical signs of infection; (2) microbiological documentation through blood and/or CIED lead cultures; (3) lead or valve vegetation, or definite IE according to Duke criteria. Data were retrospectively extracted from medical charts. The cohort was categorized in three periods: 1992-1999, 2000-2008, and 2009-2017.

RESULTS

We included 199 patients (51 women, 148 men, median age 73 years [interquartile range, 64-79]), with CIED-IE: 158 PPMs (79%), 24 ICD (12%), and 17 CRT (9%). Main pathogens were coagulase-negative staphylococci (CoNS: n = 86, 43%), Staphylococcus aureus (n = 60, 30%), and other Gram-positive cocci (n = 28, 14%). Temporal trends were remarkable for the decline in CoNS (P = 0.002), and the emergence of S. aureus as the primary cause of CIED-IE (24/63 in 2009-2017, 38%). Factors independently associated with one-year mortality were chronic obstructive pulmonary disease (COPD: hazard ratio 3.84 [1.03-6.02], P = 0.03), left-sided endocarditis (HR 2.25 [1.09-4.65], P = 0.03), pathogens other than CoNS (HR 3.16 [1.19-8.39], P = 0.02), and CIED removal/reimplantation (HR 0.41 [0.20-0.83], P = 0.01).

CONCLUSIONS

S. aureus has emerged as the primary cause of CIED-IE. Left-sided endocarditis, COPD, pathogens other than CoNS, and no CIED removal/reimplantation are independent risk factors for one-year mortality.

Physicochemical and microbiological characteristics of El-Guedid from meat of different animal species

El-Guedid is an Algerian traditional meat-based product that is prepared from red meats. It belongs to the wide diversity of salted/dried meat products. This study described the physicochemical and microbiological properties of different products from four animal origins and during all the conservation. Results indicated that these products were mainly characterized by a low moisture with an average decrease of water content between 15.6% and 16.3% for all the samples, and a decrease in water activity ranging from 0.66 to 0.68, while the salt content ranged from 8.8 to 19.3%. A decrease in pH values oscillated from (6.3-6.4) to reach (5.2-5.5) at T0 and T365 consecutively, in all the samples. Microbial analyses revealed the absence of pathogenic bacteria such as Listeria and Salmonella but the sporadic contamination by Staphylococcus aureus up to one month of ripening. Lactic acid bacteria and coagulase negative staphylococci were the dominant populations in El-Guedid with Leuconostoc mesenteroides, Lactobacillus sakei, and Staphylococcus saprophyticus as the main species identified. All these populations decreased along the process and reached low levels (2 log CFU/g) at the end of storage (365 days). The drastic drying of El-Guedid led to safe traditional meat product that could promote its production.

Pathogenesis of Staphylococcus epidermidis in prosthetic joint infections: Can identification of virulence genes differentiate between infecting and commensal strains?

BACKGROUND

Staphylococcus epidermidis is a commensal of human skin flora and a frequent causative microorganism in prosthetic joint infections (PJIs). To date, no single marker has been identified to distinguish infecting strains from commensal S. epidermidis populations.

AIM

We aimed to find possible genetic markers to distinguish between the two populations.

METHODS

We analyzed 50 S. epidermidis strains from patients with PJIs, 50 from skin of healthy individuals (commensal strains) and 17 from the surgical field of patients undergoing primary arthroplasty. In these three groups we studied the antimicrobial susceptibility profile, sequence type, biofilm formation, and virulence factors. Strains from the surgical field have not been compared previously with strains from the other two groups.

FINDINGS

S. epidermidis strains from PJI patients were significantly more antibiotic resistant than commensal strains and surgical field strains. A wide variety of sequences types was found in commensal and surgical field strains. The predominant sequence type was ST2 and it was only present in PJI strains (44%). Differences in biofilm production did not differ between populations. Virulence genes sdrF and bhp, the complete ica operon, and the insertion sequence IS256 were significantly predominant in PJI strains. In contrast, embp and hld genes and the mobile element ACME were more prevalent in commensal strains. Surgical field strains could be a valid control group to discriminate between infecting and commensal strains.

CONCLUSION

A combination of characteristic features can differentiate between infecting and commensal S. epidermidis strains in PJI, while a single marker cannot.

Staphylococcus pasteuri infective endocarditis: A case report

Staphylococcus pasteuri is a coagulase negative bacterium which although formally described in 1993, has only recently become possible to reliably speciate in diagnostic microbiology laboratories. S. pasteuri remains an extremely infrequent cause of human infection to date, namely bacteremia in an individual suffering acute myeloid leukemia, catheter-associated urinary tract infection in a patient receiving chemotherapy and endocarditis within a case series without specific clinical information. As such, our report provides the first detailed account of Staphylococcus pasteuri infective endocarditis entailing a subacute community-onset infection involving native aortic and mitral valves, multiple systemic emboli, and ultimately cardiothoracic surgery.

Healthcare-associated infections including neonatal bloodstream infections in a leading tertiary hospital in Botswana

Background: Healthcare-associated infections (HAIs) increase morbidity, mortality, length of hospital stay and costs, and should be prevented where possible. In addition, up to 71% of neonates are prone to bloodstream infections (BSI) during intensive care due to a variety of factors. Consequently, the objectives of this study were to estimate the burden of HAIs and possible risk factors in a tertiary hospital in Botswana as well as describe current trends in bacterial isolates from neonatal blood specimen and their antibiotic resistance patterns.Methods: Point Prevalence Survey (PPS) in all hospital wards and a retrospective cross-sectional review of neonatal blood culture and sensitivity test results, with data abstracted from the hospital laboratory database.Results: 13.54% (n = 47) of patients had HAIs, with 48.9% (n = 23) of them lab-confirmed. The highest prevalence of HAIs was in the adult intensive care unit (100% - n = 5), the nephrology unit (50% - n = 4), and the neonatal intensive care unit (41.9% - n = 13). One-fourth of HAIs were site unspecific, 19.1% (n = 9) had surgical site infections (SSIs), 17% (n = 8) ventilator-associated pneumonia/complications, and 10.6% (n = 5) were decubitus ulcer infections. There were concerns with overcrowding in some wards and the lack of aseptic practices and hygiene. These issues are now being addressed through a number of initiatives. Coagulase Negative Staphylococci (CoNS) was the commonest organism (31.97%) isolated followed by Enterococci spp. (18.03%) among neonates. Prescribing of third-generation cephalosporins is being monitored to reduce Enterococci, Pseudomonas and Acinetobacter spp. infections.Conclusions: There were concerns with the rate of HAIs and BSIs. A number of initiatives are now in place in the hospital to reduce these including promoting improved infection prevention and control (IPC) practices and use of antibiotics via focal persons of the multidisciplinary IPC committee. These will be followed up and reported on.

Genomic analysis of Staphylococcus capitis isolated from blood cultures in neonates at a neonatal intensive care unit in Sweden

Emergence of a genetically distinct, multidrug-resistant Staphylococcus capitis clone (NRCS-A) present in neonatal intensive care units has recently been extensively reported. The aims of the present study were to investigate which clones of S. capitis isolated from blood in a Swedish neonatal intensive care unit (NICU) have been present since 1987 and to investigate whether the NRCS-A clone has disseminated in Sweden. All S. capitis isolates from blood cultures of neonates (≤ 28 days of age) between 1987 and 2017 (n = 46) were whole-genome sequenced, and core genome multilocus sequence typing (cgMLST) was performed. Single-nucleotide polymorphism (SNP)-based phylogenetic relationships between the S. capitis isolates and in silico predictions of presence of genetic traits specific to the NRCS-A clone were identified. Furthermore, antibiotic susceptibility testing, including screening for heterogeneous glycopeptide-intermediate resistance, was performed. Thirty-five isolates clustered closely to the isolates previously determined as belonging to the NRCS-A clone and had fewer than 81 core genome loci differences out of 1063. Twenty-one of these isolates were multidrug resistant. The NRCS-A clone was found in 2001. Six pairs of isolates had differences of fewer than two SNPs. Genetic traits associated with the NRCS-A clone such as nsr, ebh, tarJ, and CRISPR were found in all 35 isolates. The increasing incidence of S. capitis blood cultures of neonates is predominantly represented by the NRSC-A clone at our NICU in Sweden. Furthermore, there were indications of transmission between cases; adherence to basic hygiene procedures and surveillance measures are thus warranted.

Staphylococcus capitis Osteomyelitis: Case Report

This case report describes an unusual invasive infection with Staphylococcus capitis, in a child with a history of repaired congenital heart disease and an acute presentation of osteomyelitis. Coagulase-negative staphylococci are rare causes of osteomyelitis without an implanted device in the bone and, as such, should prompt evaluation for associated infections that may be contributing to the unusual presentation. Additionally, this case highlights the importance of considering methicillin heteroresistance in staphylococcal infections when the clinical course is not proceeding as expected.

Simple and economical method for identification and speciation of Staphylococcus epidermidis and other coagulase negative Staphylococci and its validation by molecular methods

Coagulase-negative staphylococci (CoNS) have been increasingly recognized as a clinically important group of species that can cause several opportunistic nosocomial infections. There are at least 47 known species of Staphylococci and to differentiate all these species >40 biochemical tests need to be performed. The present study was able to refine the CoNS identification process by using only five tests to identify S. epidermidis from the rest and used six other tests to identify eleven other clinically significant CoNS species. A total of 242 CoNS isolates were collected from tertiary care hospitals and included in the study. The five-biochemical test scheme devised based on mathematical probability derived from a computer algorithm included fermentation of mannitol, maltose, mannose, trehalose and novobiocin susceptibility to differentiate S. epidermidis from other CoNS species. The remaining CoNS isolates other than S. epidermidis were further characterized with the help of six additional tests, which identified another eleven species. Species-specific PCR and 16SrDNA sequencing were used to confirm and validate the identification scheme. Species-specific PCR and 16SrDNA sequencing showed 100% agreement with non-divergent phenotypic test results, indicating that the five selected assays are highly specific for identifying S. epidermidis. In conclusion, this study used only 11 tests to identify most of the clinically significant CoNS that can reduce cost and time. This scheme is easy to perform in any laboratory with basic resources, the results of this study were validated using more accurate molecular methods such as PCR and 16S rDNA typing to confirm the utility of the proposed scheme.

Distribution of staphylococcal cassette chromosome mec types among methicillin-resistant coagulase negative staphylococci in central Iran

BACKGROUND AND OBJECTIVES

Methicillin-resistant coagulase-negative staphylococci (MR-CoNS) are important nosocomial pathogens. They may serve as a reservoir of SCCmec, the genomic island encoding amongst other methicillin resistance. This study was designed to determine the distribution of different SCCmec types from MR-CoNS isolated from clinical specimens in a tertiary hospital in central Iran, having high frequency of nosocomial methicillin-resistant staphylococcal infections.

MATERIALS AND METHODS

We evaluated isolates from patients attending the Vali-Asr Hospital located in the center of Iran, from February to December 2012. Multiplex PCR was performed for SCCmec typing. For isolates in which SCCmec could not be typed directly, additional ccr and mec complex analyses were performed.

RESULTS

Totally, 70 MR-CoNS isolates, comprising of 47 S. epidermidis strains (67%), 10 S. saprophyticus (14.3%), 9 S. hemolyticus (13%) and 4 S. lugdunensis (5.7%) were identified. Thirty-nine were characterized as type IVa 19 (27%), type III 11 (16%), type II 7 (10%) and type V 2 (3%). Only 20 isolates (28.6%) carried the ccr complex, while the current methods could not characterize the 11 remaining isolates.

CONCLUSION

A high level of SCCmec genetic diversity was found among MR-CoNS isolates. MR-CoNS may act as a reservoir of SCCmec IV for MRSA. This issue should be taken into consideration seriously.

Comparison of growth on mannitol salt agar, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, VITEK® 2 with partial sequencing of 16S rRNA gene for identification of coagulase-negative staphylococci

Mannitol salt agar (MSA) is often used in resources' limited laboratories for identification of S. aureus however, coagulase-negative staphylococci (CoNS) grows and ferments mannitol on MSA. 171 strains of CoNS which have been previously misidentified as S. aureus due to growth on MSA were collected from different locations in Nigeria and two methods for identification of CoNS were compared i.e. ViTEK 2 and MALDI-TOF MS with partial 16S rRNA gene sequencing as gold standard. Partial tuf gene sequencing was used for contradicting identification. All 171 strains (13 species) grew on MSA and ferments mannitol. All tested strains of S. epidermidis, S. haemolyticus, S. nepalensis, S. pasteuri, S. sciuri,, S. warneri, S. xylosus, S. capitis were correctly identified by MALDI-TOF while variable identification were observed in S. saprophyticus and S. cohnii (90%, 81%). There was low identification of S. arlettae (14%) while all strains of S. kloosii and S. gallinarum were misidentified. There is absence of S. gallinarum in the MALDI-TOF database at the period of this study. All tested strains of S. epidermidis, S. gallinarum, S. haemolyticus, S. sciuri,, S. warneri, S. xylosus and S. capitis were correctly identified by ViTEK while variable identification were observed in S. saprophyticus, S. arlettae, S. cohnii, S. kloosii, (84%, 86%, 75%, 60%) and misidentification of S. nepalensis, S. pasteuri. Partial sequencing of 16S rRNA gene was used as gold standard for most strains except S. capitis and S. xylosus where the two species were misidentified by partial sequencing of 16S rRNA contrary to MALDI-TOF and ViTEK identification. Tuf gene sequencing was used for correct identification. Characteristic growth on MSA for CoNS is also identical to S. aureus growth on the media and therefore, MSA could not differentiate between S. aureus and CoNS. The percentage accuracy of ViTEK was better than MALDI-TOF in identification of CoNS. Although partial sequencing of 16S rRNA gene was used as gold standard in this study, it could not correctly identify S. capitis and S. xylosus.

Comparison of the most common isolates of postoperative endophthalmitis in South Korea; Enterococcus species vs coagulase-negative staphylococci

BACKGROUND

To compare the related factors or manifestations of the two most common isolates of post-operative endophthalmitis, which were Enterococcus spp. and coagulase-negative staphylococci (CNS) in South Korea.

METHODS

Medical records were reviewed for cases of post-operative endophthalmitis caused by Enterococcus spp. and CNS at eight institutions between January 2004 and July 2010. Various factors including age, sex, residence, systemic diseases, smoking and drinking history, and best corrected visual acuity, and length of time between causative intraocular surgery and symptom development were compared between the two groups.

RESULTS

The total number of post-operative endophthalmitis cases was 128 and in 116 cases, microbiological culture tests from the aqueous humor or vitreous were performed. Among these cases, 67 (57.8%) were culture proven. Among these 67 cases, 19 (28.4%) were caused by Enterococcus spp., 14 (20.9%) were caused by Staphylococcus epidermidis endophthalmitis, and 5 (7.5%) were caused by other CNS spp. Age, sex, causative procedure, past medical history, social history, and laterality were not different in the two groups. Mean initial and final visual acuity were significantly worse in the Enterococcus spp. endophthalmitis group than in the CNS group (p = 0.049, 0.042, respectively). Length of time between the causative procedure and symptom development was significantly shorter in cases of Enterococcus spp. endophthalmitis (p = 0.004).

CONCLUSIONS

Enterococcus spp. induce more severe and rapid-onset postoperative endophthalmitis than CNS. Infectious endophthalmitis developed within 2 days after cataract operation could be caused by Enterococcus spp. and have chance to be poor prognosis in South Korea.

Nasal Carriage of Uncommon Coagulase-Negative Staphylococci in Nurses and Physicians of Tehran University Hospitals

Coagulase-negative staphylococci (CoNS) have been identified as a major cause of nosocomial infections. Nasal carriage of CoNS in nurses and physicians is known to be an important risk factor for potential hospital infections. This study was carried out to investigate the prevalence of nasal carriage of uncommon coagulase-negative staphylococci among nurse and physician staffs of Tehran University Hospitals. A total of 116 CoNS were isolated from anterior nares of the study participants working in different wards of the hospitals. Thirteen uncommon CoNS were identified using phenotypic and biochemical methods, were subsequently confirmed by API kits. Staphylococcus xylosus, Staphylococcus haemolyticus, and Staphylococcus capitis species accounted for 53.85%, 30.77%, and 15.38% from the isolates, respectively. Six isolates (46.15%) were found to be resistant to methicillin. In conclusion, screening of healthcare workers for uncommon CoNS colonization along with identification and testing for susceptibility of cultured isolates is of paramount importance in strengthening effective nosocomial infection control and prevention measures.

Studies on prevalence of biofilm associated genes and primary observation on sasX gene in clinical isolates of coagulase negative staphylococci (CoNS)

Coagulase negative staphylococci (CoNS) are nosocomial pathogens that cause indwelling medical device associated infections due to its biofilm forming potential and multiple antibiotic resistance. The current study focused on species identification, antibiotic resistance profile and molecular basis of biofilm formation and attachment of CoNS isolated from clinical samples. Along with this, molecular screening for mecA and newly identified surface colonization protein encoded by sasX gene was also conducted. S. epidermidis (n = 19, 47%) was identified as the most prevalent CoNS species and very interestingly two biofilm forming, mecA positive S. epidermidis isolates were found to carry all the biofilm associated genes screened in this study, which indicates its potential to form the strong biofilm. Another novel observation of the study is the detection of sasX gene in one biofilm positive S. epidermidis isolate. The study also identified one doxycycline resistant mecA positive, multidrug resistant S. haemolyticus isolate. In conclusion, the study signifies the existence of multiple biofilm related genes, multidrug resistance and the presence of sasX gene among clinical isolates of CoNS.

Diversity of antimicrobial resistance and virulence genes in methicillin-resistant non-Staphylococcus aureus staphylococci from veal calves

In this study we determined whether methicillin-resistant non-Staphylococcus aureus (MRNAS) from veal calves may be a potential reservoir of antimicrobial-resistance and virulence genes. Fifty-eight MRNAS were studied by means of DNA-microarray and PCR for detection of antimicrobial resistance and virulence genes. The isolates carried a variety of antimicrobial-resistance genes [aacA-aphD, aadD, aph3, aadE, sat, spc, ampA, erm(A), erm(B), erm(C), erm(F), erm(T), lnu(A), msr(A)-msr(B), vga(A), mph(C), tet(K), tet(M), tet(L), cat, fexA, dfrA, dfrD, dfrG, dfrK, cfr, fusB, fosB, qacA, qacC, merA-merB]. Some isolates carried resistance genes without showing the corresponding resistance phenotype. Most MRNAS carried typical S. aureus virulence factors like proteases (sspP) and enterotoxins (seg) genes. Most Staphylococcus epidermidis isolates carried the arginine catabolic element, and nearly 40% of the Staphylococcus sciuri isolates carried leukocidins, and/or fibronectin-binding protein genes. MRNAS were highly multi-resistant and represent an important reservoir of antimicrobial resistance and virulence genes.

Biofilm formation by coagulase-negative staphylococci: impact on the efficacy of antimicrobials and disinfectants commonly used on dairy farms

Coagulase-negative staphylococci (CNS) have traditionally been considered minor mastitis pathogens and are the bacteria most frequently isolated from intramammary infection. Previously, our laboratory demonstrated that a majority of CNS isolated from Canadian milk were able to form biofilm and this was strongly and positively associated with days in milk. Biofilms offer protection against antibiotics and disinfectants, and the presence of CNS biofilms near the end of the lactation cycle could have an impact on the prevention and recurrence of CNS infections in the next lactation cycle. The objective of this study was to investigate the effect of biofilm formation on efficacy of commonly used antibiotics and disinfectants against CNS. The minimal inhibitory concentration (MIC) and minimal biofilm eradication concentration (MBEC) of several CNS isolates were determined using microdilution method and the MBEC device, respectively. Biofilm cells were more resistant to a penicillin G/novobiocin combination and to ceftiofur than their planktonic counterparts and the increase in resistance ranged from 4× to 2048×. For the disinfectants, we determined the minimum contact time required for different teat disinfectants to eradicated planktonic cells and biofilms. The chlorhexidine-based teat disinfectants eradicated planktonic cells and biofilms within 30s. For iodine-based teat disinfectants, it took 2-10× longer to eradicate the biofilms than planktonic cells. In conclusion, CNS biofilms were less susceptible to antibiotics; however, chlorhexidine-based teat disinfectants were still effective against CNS biofilms. This reinforces the use of post-milking teat disinfectants as a preventive measure of intramammary infections.

Identification and antibiotic susceptibility pattern of coagulase-negative staphylococci in various clinical specimens

OBJECTIVE

Antibiotic resistance is a global problem and is more prevalent in developing countries. Coagulase-negative staphylococci (CoNS) are recognized as important pathogen for nosocomial infections. This study was carried out to identify CoNS in various clinical specimens and to determine its antimicrobial susceptibility pattern.

METHODS

A total of 2989 specimens of blood, pus and wound swab were collected from wards, casualty, ICU and OPD, out of these, staphylococci were isolated in 1000 specimens, of which 381 were identified as CoNS. Culture, gram stain, catalase, coagulase test and antimicrobial susceptibility pattern were done according to clinical manual of microbiology. A total of fourteen antibiotics were used in this study. Susceptibility testing was done by Kirby Bauer disc diffusion technique.

RESULTS

Antimicrobial resistance of CoNS were Oxacillin (70.3%), Amoxicillin (74.8%), Amoxicillin+clavulanate (32.8%), Ciprofloxacin (35.2%), Ofloxacin (33.6%), Ceftriaxone (30.4%), Erythromycin (58.3%), Clindamycin (16.3%), Daptomycin (42.5%), Kanamycin (52.2%), Fusidic acid (41.7%), Doxycycline (24.7%), Vancomycin (2.6%) and Linezolid (0.8%). Maximum Oxacillin resistance was between 80 to 90 percent in a group of patients having age of 45 to 65 years and those suffering from cancer or admitted in ICU.

CONCLUSION

The study concluded that CoNS showed significant level of resistance against most of the widely used therapeutic agents.

Prevalence, aetiology and antibiotic resistance profiles of coagulase negative staphylococci isolated in a teaching hospital

In this paper we carried out a study about prevalence of the clinically significant coagulase negative staphylococcal (CNS) isolates found in an university hospital. Two hundred four CNS isolates from 191 patients obtained between the period of 1998 to 2002, were studied. About 27% (52/191) of the infection cases studied were confirmed as CNS-associated diseases. Blood stream infection (BSI) was the most frequent CNS associated-disease (25%; 13/52). The great majority of the BSI was verified in the Neonatal Intensive Care Unit (NICU). The analysis of the 52 patients medical history showed that 85% of the BSI was acquired in hospital. Most of the CNS nosocomial infections were associated with the use of indwelling medical devices. The incidence of methicillin-resistance among significant CNS isolates was 38%. In this study, a high percentage of exogenous contaminant was verified (60%), indicating that contamination of clinical specimens during sample collection is critical.