Antibiotic resistance and molecular characterization of shigella isolates recovered from children aged less than 5 years in Manhiça, Southern Mozambique.

The objective of this study was to assess antibiotic resistance and the molecular epidemiology of shigella isolates from a case-control study of diarrhoea, conducted from 2007 to 2012 in children aged less than 5 years in Manhiça district, southern Mozambique. All isolates were tested for antimicrobial susceptibility using the disc diffusion method. Polymerase chain reaction was used to detect different molecular mechanisms of antibiotic resistance. Serotyping was performed using specific antisera. The clonal relationship of Shigella flexneri and Shigella sonnei was assessed by pulsed-field gel electrophoresis (PFGE). Of the 67 shigella isolates analysed, 59 were diarrhoeal cases and eight were controls. S. flexneri (70.1%; 47/67) was the most common species, followed by S. sonnei (23.9%; 16/67). The most prevalent S. flexneri serotypes were 2a (38.3%; 18/47), 6 (19.2%; 9/47) and 1b (14.9%; 7/47). High rates of antimicrobial resistance were observed for trimethoprim-sulfametoxazole (92.5%; 62/67), tetracycline (68.7%; 46/67), chloramphenicol (53.7%; 36/67) and ampicillin (50.7%; 34/67). Multi-drug resistance (MDR) was present in 55.2% (37/67) of the isolates and was associated with a case fatality rate of 8.1% (3/37). PFGE revealed 22 clones (16 S. flexneri and 6 S. sonnei), among which P1 (31.9%; 15/47), P9 (17%; 8/47) and P2 (10.6%; 5/47) were the most prevalent clones of S. flexneri. In conclusion, S. flexneri was the most prevalent species, with MDR isolates mainly belonging to three specific clones (P1, P9 and P2). The case fatality rate observed among MDR isolates is a matter of concern, indicating the need for appropriate treatment.

Antimicrobial Use for and Resistance of Zoonotic Bacteria Recovered from Nonhuman Primates.

As a growing threat to human and animal health, antimicrobial resistance (AMR) has become a central public-health topic. Largescale surveillance systems, such as the National Antimicrobial Resistance Monitoring System (NARMS), are now established to monitor and provide guidance regarding AMR, but comprehensive literature on AMR among NHP is sparse. This study provides data regarding current antimicrobial use strategies and the prevalence of AMR in zoonotic bacteria recovered from NHP within biomedical research institutions. We focused on 4 enteric bacteria: Shigella flexneri, Yersinia enterocolitica, Y. pseudotuberculosis, and Campylobacter jejuni. Fifteen veterinarians, 7 biomedical research institutions, and 4 diagnostic laboratories participated, providing susceptibility test results from January 2012 through April 2015. Veterinarians primarily treated cases caused by S. flexneri, Y. enterocolitica, and Y. pseudotuberculosis with enrofloxacin but treated C. jejuni cases with azithromycin and tylosin. All isolates were susceptible to the associated primary antimicrobial but often showed resistance to others. Specifically, S. flexneri isolates frequently were resistant to erythromycin (87.5%), doxycycline (73.7%), and tetracycline (38.3%); Y. enterocolitica isolates to ampicillin (100%) and cefazolin (93.6%); and C. jejuni isolates to methicillin (99.5%) and cephalothin (97.5%). None of the 58 Y. pseudotuber-culosis isolates was resistant to any tested antimicrobial. Notably, resistance patterns were not shared between this study's NHP isolates and human isolates presented by NARMS. Our findings indicate that zoonotic bacteria from NHP diagnostic samples are broadly susceptible to the antimicrobials used to treat the clinical infections. These results can help veterinarians ensure effective antimicrobial therapy and protect staff by minimizing occupational risk.

Clinical implications of reduced susceptibility to fluoroquinolones in paediatric Shigella sonnei and Shigella flexneri infections.

OBJECTIVES: We aimed to quantify the impact of fluoroquinolone resistance on the clinical outcome of paediatric shigellosis patients treated with fluoroquinolones in southern Vietnam. Such information is important to inform therapeutic management for infections caused by this increasingly drug-resistant pathogen, responsible for high morbidity and mortality in young children globally. METHODS: Clinical information and bacterial isolates were derived from a randomized controlled trial comparing gatifloxacin with ciprofloxacin for the treatment of paediatric shigellosis. Time-kill experiments were performed to evaluate the impact of MIC on the in vitro growth of Shigella and Cox regression modelling was used to compare clinical outcome between treatments and Shigella species. RESULTS: Shigella flexneri patients treated with gatifloxacin had significantly worse outcomes than those treated with ciprofloxacin. However, the MICs of fluoroquinolones were not significantly associated with poorer outcome. The presence of S83L and A87T mutations in the gyrA gene significantly increased MICs of fluoroquinolones. Finally, elevated MICs and the presence of the qnrS gene allowed Shigella to replicate efficiently in vitro in high concentrations of ciprofloxacin. CONCLUSIONS: We found that below the CLSI breakpoint, there was no association between MIC and clinical outcome in paediatric shigellosis infections. However, S. flexneri patients had worse clinical outcomes when treated with gatifloxacin in this study regardless of MIC. Additionally, Shigella harbouring the qnrS gene are able to replicate efficiently in high concentrations of ciprofloxacin and we hypothesize that such strains possess a competitive advantage against fluoroquinolone-susceptible strains due to enhanced shedding and transmission.

Effect of combination therapy between thyme oil and ciprofloxacin on ulcer-forming Shigella flexneri.

INTRODUCTION: Shigella flexneri is a Gram-negative bacteria that has the ability to invade the epithelium of the colon and cause colon ulcers. METHODOLOGY: The ability of isolated Shigella flexneri from bloody diarrhea to cause colon ulcers was investigated by histopathological examination via oral administration of the bacteria to adult male albino Sprague-Dawley rats. The antibacterial activity of thyme oil, ciprofloxacin, and their combination were evaluated in vitro and in vivo. RESULTS: Oral administration of 12×108 CFU/mL of S. flexneri was able to cause colon ulcers. Thyme oil had the highest antibacterial activity among other investigated oils (minimum inhibitory concentration [MIC] 150µL/L). Ciprofloxacin had the highest antimicrobial activity against S. flexneri (MIC 0.4mg/L). The synergism between thyme oil and ciprofloxacin showed the maximum growth inhibition of S. flexneri. The synergistic activity of thyme oil and ciprofloxacin succeeded in healing the epithelial surface of the colon and decreased the inflammation of the lamina propria; it also decreased the bacterial load in the infected colon, while the commercial drug failed to heal the colon ulcer. Thyme oil, ciprofloxacin, and their combination showed different degrees of effects on the bacterial cell structure by transmission and scanning electron microscopes. CONCLUSIONS: The combination of thyme oil and ciprofloxacin gave synergistic activity, which proved to be more effective in inhibiting the growth of ulcer-forming S. flexneri, healing the colon ulcer, and decreasing infiltration of the lamina propria with inflammatory cells.

Surveillance of antibiotic susceptibility pattern among shigella flexneri strain isolated in Nagpur district during three years period, January 2009-January 2012.

OBJECTIVE: In the few cases of childhood dirrhea that require the antimicrobial therapy, the correct choice of the drug depends on detailed previous knowledge of local strains and pattern of antimicrobial resistance. Shigellosis is one of the most improtant examples of this group of intestinal infections. In order to establish such parameters in Nagpur city, this study was carried out to determine the antimcrobial resistance profile of Shigella flexneri isolated from patients suffering from diahhrea admitted to Various hoapitals in Nagpur district, India. MATERIALS AND METHODS: The study included 110 stool samples collected from patients during the 3 year period. All the isolates were characterized and confirmed by VITEK® 2 GN ID cards and antimicrobial susceptibility was tested by VITEK® 2 AST test cards. RESULTS: We received 73 positive cultures of S. flexneri out of 110 stool samples during three year periods of January 2009 to January 2012. S. flexneri strains presented a high resistance rate to Ampicillin (100%), Chloramphenicol (76.71%), Trimethoprime-sulfamethaxazole (TMP-SMZ) (68.49%) and low resistance to third- and fourth-generation Cephalosporin. None of the isolates was found to be resistant to Ciprofloxacin (MIC ≥ 4), Norfloxacin (MIC ≥12), and Nalidixic acid (MIC ≥30). CONCLUSION: Our results provide data on antimicrobial resistance to choose a proper antibiotic for the treatment of Shigellosis in our country. According to current findings, Quinolones and Cephalosporins are the drug of choice for the diarrheic patients. In conclusion, systematic monitoring is needed to identify changes in the antimicrobial resistance.

Antimicrobial susceptibility of Shigella flexneri and S. dysenteriae isolated from stool specimens of patients with bloody diarrhoea in Mwanza, Tanzania.

This study was conducted to determine frequency and pattern of antimicrobial susceptibility of Shigella species isolated from stool specimens collected from patients presenting with bloody diarrhoea in Mwanza City, Tanzania. The study was carried out from October 2004 to October 2005 and involved patients attending Sekou Toure Regional Hospital and Butimba Health Centre. Bacteriological cultures were done at the National Institute for Medical Research laboratory. A total of 489 patients (median age = 20 years) participated in the study and were able to provide stool specimens. Shigella species were isolated from 14% (69/489) of the stool specimens collected. Of the sixty nine strains of Shigella spp isolated, 62 (90%) were S. flexneri and 7 (10%) were S. dysenteriae. All Shigella strains isolated showed high resistance to ampicillin, tetracycline, trimethoprim-sulphamethoxazole and chloramphenicol, drugs commonly used for management of shigellosis in Tanzania. However all isolates were fully susceptible to ciprofloxacin, nalidixic acid, erythromycin, cefuroxime and gentamycin. S. flexneri showed resistance to amoxy-clavulanic_acid and azithromycin in 5% and 2% of isolates, respectively. None of the S. dysenteriae isolates were resistant to these two drugs. Entamoeba histolytica, Giardia lamblia and Schistosoma mansoni were microscopically detected in 16.5%, 4.4% and 5.3% of patients, respectively. These findings suggest that there is a need to carry out extensive susceptibility studies in different parts of the country with view of re-appraising the current guidelines for management of bloody diarrhoea in Tanzania.

Chronic vulvovaginitis caused by antibiotic-resistant Shigella flexneri in a prepubertal child.

A 7-year 8-month-old girl was diagnosed with a prolonged course of vulvovaginitis caused by Shigella flexneri. The child was symptomatic with intermittent vaginal bleeding, dysuria and foul smelling vaginal discharge for a 3-year period. Initial attempts to resolve the infection with successive courses of antibiotic therapy using ampicillin, trimethoprim-sulfamethoxazole, cefixime and amoxicillin/clavulanic acid failed. The child's infection was finally resolved by a 14-day course of ciprofloxacin.

Lack of reactivation of shigellosis in naturally infected enrofloxacin-treated cynomolgus monkeys after exogenous immunosuppression.

Four cynomolgus macaques housed at our facility became acutely ill with dysenteric symptoms. Enteric isolates established an etiologic diagnosis of Shigella flexneri. Enrofloxacin antimicrobial therapy cleared the infection with no perceptible bacterial shedding or clinical signs of disease. High-dose methyl-prednisolone therapy was administered to the four monkeys for 5 weeks. The animals were monitored for signs of shigellosis and bacterial shedding weekly throughout the study, for a total of 7 weeks. Although methylprednisolone therapy induced marked cellular immunosuppression in all four animals, as measured by in vitro assays, no animal had evidence of clinical shigellosis or bacterial shedding. These results suggest that cynomolgus macaques naturally infected with S. flexneri and appropriately treated with enrofloxacin are unlikely to have reactivation of shigellosis and shedding of bacteria in the feces during periods of stress or profound immunosuppression.

Stool cultures for Shigella spp: improved specificity by using MacConkey agar with xylose.

A total of 678 stool specimens were cultured on four different agars: on xylose-lysine-desoxycholate agar (XLD), MacConkey agar (Mac), MacConkey agar supplemented with xylose (Mac-X), and Hektoen enteric agar (HE). Isolation rates for shigellae were 77% on HE, 86% on Mac and Mac-X, and 91% on XLD. The specificities of the media were 61% for Mac, 75% for HE, and 78% for XLD and Mac-X. After overnight incubation, Mac-X is much easier to read than XLD, which requires incubation for at least 22 hours. Based on these results and also on the practical aspect that incubation for 22-21 hours does not fit well in our schedule, we now use Mac-X whenever shigellae need to be looked for (i.e. mainly patients with recent travel to tropical countries). As compared to our previous procedure the workload in the laboratory could be reduced by about 20%.

Diarreia causada por Shigella: aspectos clinicos e terapeuticos / Diarrhea caused by Shigella: clinical and therapeutical aspects

Os autores estudaram diarreias graves causadas por Shigella sp que foram atendidas no Servico de Emergencias do Hospital Universtario da USP durante tres anos. Esse agente foi isolado de 65 casos de diarreia aguda que corresponderam a 3,1 por cento dos casos graves e 22,3 por cento dos quadros clinicos de disenteria. A S.flexneri foi a mais isolada, seguida pela S.sonnei, na proporcao de 3:1...

Diarréia crônica e infecçöes repetidas em adulto / Chronic diarrhea and repeated infections in an adult

Um caso de infecçäo por Shigella flexneri em uma mulher de 34 anos de idade com hipogamaglobulinemia e diarréia é apresentado; o problema diagnóstico representado por diarréia no paciente com hipogamaglobulinemia é discutido. A revisäo de 7 outros pacientes com hipogamaglobulinemia tratados no HCRP é apresentado e é enfatizado que vários agentes patogênicos podem causar diarréia nesses pacientes

Efficacy of bovine milk immunoglobulin concentrate in preventing illness after Shigella flexneri challenge.

The protective efficacy of oral bovine immunoglobulin concentrates derived from colostrum against challenge with Shigella flexneri was studied in healthy adult volunteers in a randomized, double-blind fashion. Volunteers were given a product consisting of hyperimmune immunoglobulin concentrate with a high titer of anti-S. flexneri 2a lipopolysaccharide (LPS) with sodium bicarbonate or a control preparation with sodium bicarbonate three times a day for seven days. On the third day of treatment, volunteers received a challenge of 10(3) colony-forming units of S. flexneri 2a strain 2457T. None of the volunteers who received the high-titered hyperimmune product became ill, compared with 45% of volunteers who received the placebo (P less than 0.05). The duration of shedding of the challenge organism was decreased, and the active immune responses to S. flexneri LPS were less frequent and of lower magnitude in volunteers given the immunoglobulin concentrate than in those in the control group. High-titered, orally administered bovine immunoglobulin concentrate protects against shigellosis and may be useful in preventing shigellosis among travelers, military personnel, and individuals at risk during a Shigella outbreak.

Enrofloxacin treatment of long-tailed macaques with acute bacillary dysentery due to multiresistant Shigella flexneri IV.

Thirty-four cases of acute bacillary dysentery occurred within 90 days among macaques housed at the California Regional Primate Research Center. Cases were identified by depression, diarrhea with blood and leukocytic exudate, and/or leukocytosis with a left shift. Antimicrobial susceptibility testing of enteric isolates and plasmid profile analyses established an etiologic diagnosis of multiple antibiotic resistant Shigella flexneri IV infection. When standard therapies were invalidated by high frequencies of resistance among the isolates, therapy with enrofloxacin, a fluoroquinolone antimicrobial, was initiated to interrupt the epidemic. Serum concentrations of enrofloxacin and its primary metabolite ciprofloxacin were measured in selected cases. A serum concentration-time data analysis was performed to evaluate the oral enrofloxacin dose and dosing interval for nonfasted macaques. Once daily administration of 5 mg/kg enrofloxacin by gastric intubation produced 24-hour serum concentrations above the MICs for the Shigella isolates from this outbreak.

Clinical evaluation of enteric media in the primary isolation of Salmonella and Shigella.

Over a 1-year period, media for the isolation of enteric pathogens were compared on 455 stool specimens. Fifty-three pathogens were isolated, of which 56% were Shigella sonnei and 13% were Sh. flexneri. Of these isolates, 90% were found on xylose-lysine-desoxycholate agar, 87% on Hekton enteric agar, and 80% on MacConkey without crystal violet with 2% agar and 0.007% neutral red, but only 28% were recovered on Salmonella-Shigella agar. Less than one-half of the shigellae were recovered after Selenite-F enrichment. On the other hand, enrichment was the most helpful method for isolating salmonellae. Studies on cultures from which mixed isolates were obtained indicated that numbers and chance distribution have an effect on the results obtained. The performance of Salmonella-Shigella agar in the isolation of enteric pathogens was inferior, and the effort involved to obtain those isolates was greater than for Hekton enteric and xylose-lysine-desoxycholate agars.