Medically Important Coagulase Negative Staphylococci

In recent years, coagulase negative Staphylococci(CONS) are increasingly recognized as one of the major causes of health care associated infections (HCAI). CONS infections are one of the major causes of morbidity and mortality in hospitalized patients. As CONS colonize various parts of the skin and mucous membranes, most of infections are en-dogenous in origin. However, they are also transmitted exogenously via various medical/ surgical procedures. The aim of present review article is to update and summarize the information available on medically important CONS with special reference to epidemiology, laboratory diagnosis and antibiotic resistance.

Biochemical Characterization and Antibiotic Susceptibility of Coagulase Negative Staphylococci Isolates from Exudates and Body Fluids

Coagulase negative Staphylococci (CoNS) are increasingly being recognized as significant nosocomial pathogens, partly due to the growing appreciation of this group of organisms as opportunistic pathogens or due to increase in the use of transient or permanent medical devices in seriously ill and immunocompromised patients. Aims and Objectives 1) Isolation of CoNS from exudates and body fluids. 2) Biochemical characterization of CoNS. 3) Antibiotic susceptibility pattern of CoNS. Method 180CoNS isolated from various exudates and body fluids such as pus, wound swabs, endotracheal secretions, sputum, branchialaspitate, and central lining tube were collected. All the CoNS isolates were processed in the Microbiology Laboratory and identified by colony morphology, gram staining, catalase, slide, tube coagulase test, anaerobic acid from mannitol, and deoxyribonuclease. Bacitracin (0.04 U) and furazolidone (100 μg) susceptibilities were done to exclude Micrococcus and Stomatococcus spp. The following biochemical tests were done for the speciation of the CoNS: urease test, phosphatase test, polymyxin B disc test, novobiocin disk test, ornithine decorboxylase test, mannitol to acid, Voges-Proskauertest, mannose fermentation, trehalose fermentation and antibiotic susceptibility testing. Result Out of 180 isolates, 78 are Staphylococcus epidermidis (43.3%), 63 are Staphylococcus hemolyticus (35%), 21 are Staphylococcus hominis (11.6%), and 18 are Staphylococcus lugdunensis (10.0%). Maximum number of CoNS were isolated from pus specimens (58.33%), followed by wound swabs (18.33%). A total of 164out of 180 strains were negative for both bound and free coagulase. A total of 60 strains were bound coagulase slow positive and free coagulase negative. S. epidermidis was the most frequent isolate and 68 S. epidermidis isolates were identified if ornithine decorboxylase was considered positive, while negative 10 S. epidermidis isolates required inclusion of trehalose and mannitol for speciation. Antibiotic susceptibility testing showed maximum resistance to penicillin (78.3) followed by chloramphenicol (41.6%). No resistance to vancomycin was seen. Conclusion: The study revealed S. epidermidis is the predominant CoNS from endotracheal secretions and also pus samples. S. hemolyticus was isolated from pus and central lining tubes, S. hominis and S. lugdunensis were isolated mainly from wound swabs. The present study suggests if coagulase-ve Staphylococci are repeatedly isolated from patients with infection they should be taken seriously and ABST done on these isolates for proper diagnosis and treatment especially in nosocomial infections.

Prevalence of Methicillin Resistant Staphylococcus aureus, Extended Spectrum of Lactamase Producing Escherichia coli and Klebsiella Spps Isolates from ICU Patients at Tertiary Care Hospital, Aurangabad

Background and Objectives The microbial surveillance of intensive care units (ICUs) for multidrug resistant bugs is required for management of ICU patients. The objectives of the study were to find out the prevalence and antimicrobial susceptibility pattern of methicillin-resistant Staphylococcus aureus (MRSA) and extended spectrum of beta lactamase (ESBLs) producing Escherichia coli and Klebsiella isolates in clinical samples from ICU patients. Methods A total of 464 clinical samples were received in the department of microbiology for culture and sensitivity from ICU patients and were processed as per standard protocol. Detection of MRSA and ESBLs was carried out by using CLSI guidelines. Results A total of 164 were positive for culture. A total of 196 isolates were isolated, among that 57 were S. aureus and 34 were E. coli, 51 were Klebsiella spp. and remaining 54 isolates were other gram negative and gram positive organisms. Out of 57 S. aureus, 23 (42.6%) were detected as MRSA. 41.2% of E. coli and 45.1% of Klebsiella spp. were ESBL producers. The antibiotic sensitivity rates were found higher in MRSA than MSSA and also same in non-ESBL-producing and ESBL-producing strains which were statistically significant (p-value). Conclusion The maximum ESBL producing isolates were Klebsiella. spp than E. coli. Vancomycin and linezolid remains a drug of choice for MRSA. For ESBL-producing E. coli and Klebsiella, carbapenems remain the drug of choice. Institutional antimicrobial surveillance and proper infection control practices are essential to prevent and control multidrug resistant bugs in ICUs and hospital.