Vishwas Saralaya

Effect of phenotypic switching on expression of virulence factors by Candida albicans causing candidiasis in diabetic patients

A total of 110 strains belonging to seven species of Candida were isolated from various forms of candidiasis in diabetic patients. They were Candida albicans 53 (47%), Candida tropicalis 36 (33%), Candida glabrata 9 (8%), Candida parapsilosis 4 (4%), Candida guilliermondii 2 (2%), Candida krusei 5 (5%) and Candida kefyr 1 (1%). All 53 strains of C. albicans isolated were observed to express virulence factors such as cell surface hydrophobicity (CSH), adherence to human buccal epithelial cell (BEC) and proteinase activity (100%), while phospholipase activity was observed in 52 (98%). Phenotypic switching and its influence on the pathogenicity of C. albicans were studied. Two C. albicans strains isolated from oral and vaginal thrush, respectively, in diabetic individuals, and the control strain C. albicans NCPF 3153A were induced to undergo phenotypic switching by exposure to UV light and the degree of expression of virulence factors by the different morphological forms was determined. Three different morphological forms of C. albicans were obtained, namely Star (S), Wrinkled (W) and Ring (R) types from the original Smooth (O) variety. It was found that proteinase activity was greatest with the W type followed by the R type then the O type. The S type produced the least proteinase. The phospholipase activity was greatest with O type followed by R type. The W and S types produced the least phospholipase. Expression of CSH and adherence was greatest in the O type followed by the R and then the W type and finally the S type. Differential expression of virulence factors occurs with different phenotypic forms of C. albicans and this may provide a particular morphological type with a distinct advantage over other types in causing candidiasis.

Characterization of Escherichia coli phylogenetic groups associated with extraintestinal infections in South Indian population

Background: Escherichia coli strains mainly fall into four phylogenetic groups (A, B1, B2, and D) and that virulent extra intestinal strains mainly belong to groups B2 and D. Aim: The aim was to determine the association between phylogenetic groups of E. coli causing extraintestinal infections (ExPEC) regarding the site of infection, expression of virulence factors, antimicrobial resistance patterns, and clinical outcome. This descriptive study was carried out in a multi specialty Tertiary Care Hospital. Materials and Methods: A total of 300 E. coli causing ExPEC were studied. Triplex polymerase chain reaction was used to classify the phylogenetic groups; hemolysin production was assessed on sheep blood agar and biofilm production in a microtiter plate assay. Production of extended spectrum of beta lactamase (ESBLs) was detected by combination disk method; AmpC was detected by AmpC disk test, Carbapenemase production was detected by modified Hodge test and metallo b lactamase by metallo beta lactamases (MBL) E test. Results: Of 300 isolates, 61/300 (20?%) belonged to phylogroup A, 27/300 (9%) to phylogroup B1, 104/300 (35%) were B2 and 108/300 (36%) belonged to group D, respectively. Phylogroups B2 and D were the most predominant groups in urinary tract infection and sepsis. Prognoses were better in infections with group A and B1 isolates, and relapses and death were common in infections with B2 and D. Expression of biofilm was greatest in B1 and hemolysin in group B2. Group A and B1 showed higher resistance to ciprofloxacin and were most frequent b lactamase (ESBL, AmpC, Carbapenemase and MBL) producers. Conclusions: Phylogenetic group B2 and D were predominant in ExPEC and exhibited least antimicrobial resistance among the groups. Resistance to multiple antibiotics was most prevalent in group A and B1. Regular monitoring of antimicrobial susceptibility in commensal strains is essential as they might transfer the property of antimicrobial resistance to pathogenic strains.

Prevalence of opportunistic infections in AIDS patients in Mangalore, Karnataka

A study was conducted to determine the prevalence of opportunistic infections in HIV-seropositive patients at Kasturba Medical College Hospital, Mangalore. Three hundred and seven HIV-positive patients were screened for various opportunistic pathogens. Tuberculosis was the most common infection followed by candidiasis, cryptosporidiosis and cryptococcal meningitis.

Characterization of plasmid mediated AmpC producing Escherichia coli clinical isolates from a tertiary care hospital in South India

CONTEXT Plasmid mediated AmpC (pAmpC) β-lactamase producing Escherichia coli are an emerging problem worldwide as they are now exhibiting resistance to multiple classes of antibiotics and are a major cause of therapeutic failure. AIMS The aim of this study was to characterize pAmpC β-lactamase producing extraintestinal E. coli, their phylogenetic distribution, resistance pattern, treatment options, and impact on patients clinical outcome. SETTINGS AND DESIGN This descriptive study was carried out in a multi-specialty tertiary care hospital. MATERIALS AND METHODS A total of 300 clinically significant, non-repeat isolates were studied. AmpC disk test was used for phenotypic AmpC-β-lactamase detection. Molecular types of pAmpC were determined by a multiplex polymerase chain reaction (PCR). Phylogenetic analysis was performed by triplex PCR methods. Metallo-beta-lactamase (MBL) detection was done by E test. Antibiogram, treatment, and clinical outcome were collected in a structured proforma. RESULTS Although 95 isolates (32%) were phenotypically positive for AmpC, PCR detected CIT type of AmpC gene in only 37 isolates. Majority of strains were from phylogroup A (85%) and B1 (58%) which are considered as commensal groups. Co-production of ESBLs was observed in 33 strains and 5 strains were found to be MBL producers. Most widely prescribed antibiotics were 3 rd generation cephalosporins (30%), carbapenems (19%) and aminoglycosides (16%). CONCLUSIONS Plasmid mediated AmpC producing isolates were found to exhibit a high degree of drug resistance, and they mainly belonged to commensal strains possibly due to misuse of antibiotics. Proper antibiotic policy is required to limit the spread of pAmpC producers or else it will lead to a therapeutic dead end in the near future.

Molecular characterization and clinical significance of extraintestinal pathogenic Escherichia coli recovered from a south Indian tertiary care hospital

• We Correlated extraintestinal E. coli with clinical outcome of mortality, recovery and relapse.

Virulence factor profiles, phylogenetic background, and antimicrobial resistance pattern of lactose fermenting and nonlactose fermenting Escherichia coli from extraintestinal sources.

Context: In recent years, nonlactose fermenting (NLF) Escherichia coli have been increasingly isolated in the microbiology laboratory, but their clinical significance has not yet been clearly elucidated. Aims: To characterize the lactose fermenting (LF) and NLF isolates on the basis of their virulence factors, phylogenetic background, and drug resistance property. Settings and Design: This descriptive study was carried out in a multi-specialty tertiary care hospital. Subjects and Methods: Three hundred nonrepeat E. coli isolates from inpatients were studied. Isolates were differentiated as LF and NLF on the basis of colony characteristics on MacConkeys agar. Possession of virulence and drug resistance genes was determined by multiplex polymerase chain reaction (PCR). Phylogenetic analysis was performed by triplex PCR methods. Antibiotic sensitivity testing was performed by disk diffusion method. Results: Of 300 isolates 39 (13%) were NLF isolates. Maximum number of NLF isolates belonged to phylogroups B2 and D when compared with LF isolates. The incidence of iutA, hlyA, and neuC genes were significantly higher in NLF isolates. The presence of drug resistance genes such as AmpC gene, SHV, and CTXM were higher in LF isolates. Conclusions: LF isolates demonstrated a higher antimicrobial resistance and NLF isolates possessed higher virulence properties. The microbiology laboratory should report lactose fermentation profile as it may help the physician to initiate appropriate treatment.

Is diabetes mellitus an important risk factor for the antibiotic resistance in extraintestinal pathogenic Escherichia coli

Escherichia coli is a major cause of extraintestinal infections in all age group. However, the infection becomes more severe when patients have some underlying condition such as Diabetes Mellitus. The aim of the study was to determine whether diabetic mellitus may act as an important risk factor for the E. coli to express drug resistance property. This descriptive study was carried out in a multi-specialty tertiary care hospital. One hundred and twenty-seven E. coli isolates from diabetic patients, and one hundred seventy-three isolates from nondiabetic patients were studied. Possession drug resistance genes were determined by multiplex polymerase chain reaction (PCR). Phylogenetic analysis was performed by triplex PCR. Antibiotic sensitivity testing was performed by Kirby-Bauer disk diffusion method. Among the study isolates from Diabetic patients maximum numbers were from phylogroup B2 (42.5%) and D (33%) similarly in case of nondiabetic patients B2 (29%) and D (38%) were the most common phylogroup. Presence of drug resistance genes among the diabetic and nondiabetic patients isolates were as followed extended-spectrum beta-lactamase (70% and 70.5%) AmpC (9.5% and 14.5%) and NDM-1 ( 7% and 4.5%) and by disk diffusion methods susceptibility pattern were meropenem (94% and 94%), imipenem (92% and 92%), amikacin (76% and 74%), and ampicillin/sulbactam (68% and 69%), respectively. The proportion of diabetic patients strains with the drug resistance characteristics were not significantly different from that seen in nondiabetic patients strains, which indicating that in a predisposed host additional or subtraction bacterial aids for drug resistance property are not a necessity.

Molecular characterisation of uropathogenic Escherichia coli isolates at a tertiary care hospital in South India

Uropathogenic Escherichia coli (UPEC) express a multitude of virulence factors (VFs) to break the inertia of the mucosal barrier of the urinary tract. The aim of the present study was undertaken to characterised the UPEC strains and to correlate carriage of specific virulence markers with different phylogroups and also to correlate these findings with clinical outcome of patients. A total of 156 non-repeated, clinically significant UPEC isolates were studied. Virulent genes were determined by two set of multiplex polymerase chain reaction (PCR). Phylogenetic analysis was performed by triplex PCR methods. Antibiograms and patients clinical outcomes were collected in a structured pro forma. Of the 156 patients infected by UPEC strains with significant bacterial counts the most common predisposing factors were diabetes (45.5%) followed by carcinoma (7%). On analysis of the VF genes of the isolates, a majority of strains (140; 90%) were possessing the fimH gene followed by iutA (98; 63%), papC (76; 49%), cnf1 (46; 29.5%), hlyA (45; 29%) and neuC (8; 5%), respectively. On phylogenetic analysis, 27 (17%) isolates were belong to phylogroup A, 16 (10%) strains to Group B1, 59 (38%) were from Group B2 and 54 (35%) were from Group D. High prevalence of antibiotic resistance was observed among the isolates. The incidence of papC, cnf1 and hlyA was significantly higher (P < 0.05) among the isolates from relapse patients. Our findings indicate that virulent as well as commensal strains are capable of causing urinary tract infection. Virulence genes as well as patients-related factors are equally responsible for the development of infections and also that virulence genes may help such isolates to persist even with appropriate chemotherapy and be responsible for recurrent infections.

Virulence property, phylogenetic background, and resistance pattern of Escherichia coli isolates from wound infections

Aims: The aim of the present study was to characterize the E. coli isolates from surgical wounds, traumatic wounds, and from foot ulcers on the basis of virulence and drug resistance. Subjects and Methods: A total of forty E. coli strains isolated from wound infections were studied. Phylogenetic background, virulence factors (VFs), and antibiotic resistance profiles were determined by phenotypic and genotypic methods. Correlation between phylogenetic groups, VFs, and drug resistance pattern were analyzed. Results: Analysis of virulence gene possession among the isolates indicated that a maximum number were carrying the fimH (39 strains; 97.5%) gene, followed by iutA (27; 67.5%), papC (16; 4%), hlyA (5; 12.5%), cnf1 ( 5; 12.5%), and neuC (1; 2.5%), respectively. The phylogroups B2 (32.5%) and D (42.5%) were more common. Thirty isolates (75%) were found to be positive for extended-spectrum β-lactamase genes. CIT type of plasmid-mediated AmpC was seen only in 6 (15%) isolates. Most effective antibiotics were carbapenem and sulfamethoxazole-trimethoprim groups of drugs. Conclusions: Our findings indicate that adherence factors and iron uptake systems are two of the more important CFs expressed by such isolates, and such strains are also observed to exhibit a higher degree of drug resistance. Carbapenems and co-trimoxazole may be considered as reliable and successful alternative medications for these isolates.

Clinical significance and phylogenetic background of extended spectrum β-lactamase producing Escherichia coli isolates from extra-intestinal infections

INTRODUCTION Escherichia coli producing extended spectrum-β-lactamases (ESBL), particularly CTX-M type ESBLs, have rapidly spread worldwide and pose a serious threat for healthcare-associated infections. We performed a molecular detection and characterization study of ESBL-related bla genes, including blaTEM, blaSHV, blaCTX-M, and blaCTX-M15, and also assessed the relationship between the phylogenetic background of strains carrying ESBL genes and the patients clinical outcome. METHODOLOGY A total of 300 non-repeated, clinically significant isolates were investigated. The molecular types of ESBL genes were determined using multiplex PCR. Phylogenetic analysis was performed using triplex PCR methods. Antibiograms and the patients clinical outcome were collected in a structured pro forma. RESULTS Among the 300 isolates, 212 (70.5%) isolates were found to carry ESBL genes. A total of 186 (62%) strains were positive for the blaCTX-M gene, and 171 isolates (approximately 92%) of these blaCTX-M producers were positive for blaCTXM-15. Phylogenetic analysis of the isolates indicated that 41 (67%) Group A, 22 (81.50%) group B1, 67 (64.5%) group B2 and 82 (76%) group D isolates carried different ESBL genes. Appropriate antibiotic therapy helped to resolve infection in 66.5% patients. CONCLUSION Our study documented the high prevalence of ESBLs in E. coli isolates, with CTX-M-15 as the predominant ESBL gene in the region, and these isolates predominantly belonged to commensal phylo-groups. Thus, an appropriate antibiotic and hospital policy is required to reduce the horizontal spread of ESBL genes among various bacterial strains, whereas in the near future, the spread of ESBL producers may result in therapeutic dead ends.